U.S. patent application number 14/593725 was filed with the patent office on 2016-05-12 for inductive sensing system for sports performance improvement.
This patent application is currently assigned to GOLF IMPACT, LLC. The applicant listed for this patent is Golf Impact, LLC. Invention is credited to Roger Davenport.
Application Number | 20160129332 14/593725 |
Document ID | / |
Family ID | 55911444 |
Filed Date | 2016-05-12 |
United States Patent
Application |
20160129332 |
Kind Code |
A1 |
Davenport; Roger |
May 12, 2016 |
INDUCTIVE SENSING SYSTEM FOR SPORTS PERFORMANCE IMPROVEMENT
Abstract
A measurement device may include one or more inductive
structures coupled to a signal processor that measures changes in
inductance. As the inductive structure moves in relation to an
external conducting object, inductance changes may occur in the
inductive structure. By analyzing the changes in inductance, the
system may determine spatial relationships concerning the
measurement device. Additionally, at least one inductive structure
may be placed behind a conductive impact surface, allowing for
measurement of impact characteristics without disturbing the impact
surface. The measurement device may be used in or on sports
equipment, such as a golf club.
Inventors: |
Davenport; Roger; (Fort
Lauderdale, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Golf Impact, LLC |
Ft. Lauderdale |
FL |
US |
|
|
Assignee: |
GOLF IMPACT, LLC
Fort Lauderdale
FL
|
Family ID: |
55911444 |
Appl. No.: |
14/593725 |
Filed: |
January 9, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14530851 |
Nov 3, 2014 |
|
|
|
14593725 |
|
|
|
|
14477902 |
Sep 5, 2014 |
|
|
|
14530851 |
|
|
|
|
13868078 |
Apr 22, 2013 |
8926445 |
|
|
14477902 |
|
|
|
|
13290124 |
Nov 6, 2011 |
8425340 |
|
|
13868078 |
|
|
|
|
13225433 |
Sep 3, 2011 |
8221257 |
|
|
13290124 |
|
|
|
|
13352313 |
Jan 17, 2012 |
8888604 |
|
|
14477902 |
|
|
|
|
13273216 |
Oct 13, 2011 |
|
|
|
13352313 |
|
|
|
|
13269603 |
Oct 9, 2011 |
|
|
|
13273216 |
|
|
|
|
12287303 |
Oct 9, 2008 |
9084925 |
|
|
13269603 |
|
|
|
|
13229635 |
Sep 9, 2011 |
8210960 |
|
|
13352313 |
|
|
|
|
13225433 |
Sep 3, 2011 |
8221257 |
|
|
13229635 |
|
|
|
|
12777334 |
May 11, 2010 |
7871333 |
|
|
13225433 |
|
|
|
|
Current U.S.
Class: |
473/223 |
Current CPC
Class: |
A61B 5/11 20130101; A63B
2220/10 20130101; A63B 2225/50 20130101; G06Q 10/0639 20130101;
A63B 69/3632 20130101; A61B 2503/10 20130101; A63B 60/46 20151001;
A63B 2220/40 20130101; A63B 53/0437 20200801; A63B 53/0466
20130101; A63B 2220/833 20130101; G09B 19/0038 20130101; A63B
2220/34 20130101; A63B 57/00 20130101; A63B 53/0433 20200801; A63B
60/00 20151001; G06K 9/00342 20130101; A63B 2209/00 20130101; A63B
2220/20 20130101; A63B 2220/56 20130101; A63B 53/0458 20200801 |
International
Class: |
A63B 69/36 20060101
A63B069/36; A63B 53/04 20060101 A63B053/04 |
Claims
1. A system for determining spatial relationships using inductance,
the system including: a first inductive structure; an external
conducting object; signal processing circuitry coupled to the first
inductive structure, the signal processing circuitry determining
changes in inductance caused by the first inductive structure
passing in the vicinity of the first inductive structure; and a
processor that determines a location of the first inductive
structure based on the determined changes in inductance.
2. The system of claim 1, wherein the system further includes a
non-transitory computer-readable medium that includes a plurality
of inductance change patterns to which the determined changes are
compared, the comparison yielding a derived flight path of the
inductive object.
3. The system of claim 1, wherein the conducting object includes
PCB and a metallization pattern.
4. The system of claim 1, wherein the conducting object includes a
three-dimensional metallization pattern.
5. The system of claim 1, wherein the signal processing circuitry
measures the duty cycle of a signal representing inductance
changes, and a processor compares a plurality of measured duty
cycles against a set of predetermined duty cycle patterns
corresponding to a metallization pattern of the conducting
object.
6. The system of claim 5, wherein the processor normalizes the
plurality of measured duty cycles for comparison against the
predetermined duty cycle patterns.
7. The system of claim 1, wherein the inductive structure is
mounted at a bottom of a golf club.
8. The system of claim 7, wherein the inductive structure is a coil
on a printed circuit board.
9. The system of claim 1, wherein the inductive structure is part
of a resonant circuit that includes a capacitive structure coupled
to the inductive structure, wherein the signal processing circuitry
determines inductance changes by measuring shifts in a resonant
frequency of the resonant circuit.
10. The system of claim 1, further including a force-related sensor
that senses a force-related attribute, wherein the inductance
changes in the inductive structure are sampled at a different
sampling rate by the signal processing circuitry than an output of
the force-related sensor, and wherein a processor aligns digital
values representing inductance changes with digital values
representing the force-related attribute.
11. A golf club head including: a shell; a clubface coupled to the
shell, the clubface having at least one conductive portion; a first
inductive element inside the shell and behind the clubface; signal
processing circuitry coupled to the first inductive structure, the
signal processing circuitry determining inductance changes caused
by the at least one conductive portion moving in relation to the
first inductive structure upon impact with a golf ball; and a
computer-readable medium that stores data representing the
inductance changes for use in analysis of the impact.
12. The golf club head of claim 11, wherein the first inductive
structure does not touch the clubface but experiences a change in
inductance based on the at least one conductive portion of the
clubface moving relative to the first inductive structure upon
impact.
13. The golf club head of claim 11, further including a plurality
of inductive elements, the plurality including the first inductive
structure and at least a second inductive structure, wherein the
plurality of inductive structures are included on a monolith that
is positioned substantially parallel to a back of the club face
within the shell.
14. The golf club head of claim 13, wherein the signal processing
circuitry determines inductance changes for each of the plurality
of inductive structures, and wherein a processor determines a
location of the impact based on differences in the inductance
changes between the plurality of inductive structures.
15. The golf club head of claim 11, wherein the club head further
provides the data to a processor that determines a force of the
impact based on an amount of inductance change at the first
inductive structure.
16. The golf club head of claim 11, further including a transmitter
that transmits the data to a processor that determines a location
relative to the first inductive structure based on the determined
changes in inductance.
17. The golf club head of claim 11, wherein the first inductive
structure is part of a resonant circuit that includes a capacitor
coupled to the first inductive structure, and wherein the signal
processing circuitry determines inductance changes by detecting
shifts in a resonant frequency of the resonant circuit.
18. An apparatus including: an inductive structure mounted on a
contact structure that is positioned relative to a conductor;
signal processing circuitry coupled to the inductive structure, the
signal processing circuitry determining inductance changes caused
by the inductive structure moving relative to the conductor upon
impact.
19. The apparatus of claim 18, wherein determining inductance
changes includes detecting a shift in a resonant frequency of a
resonant structure that includes the inductive structure.
20. The apparatus of claim 18, wherein the contact structure is a
flexible monolith that is attachable to a club face, and wherein
the inductive structure is one of a plurality of inductive
structures on the flexible monolith.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a continuation-in-part of patent
application Ser. No. 14/530,851, filed Nov. 3, 2014, which is a
continuation-in-part of patent application Ser. No. 14/477,902,
filed Sep. 5, 2014, which is a continuation-in part of patent
application Ser. No. 13/868,078, filed Apr. 22, 2013, entitled
"Golf Free Swing Measurement and Analysis system," which is a
continuation-in-part of application Ser. No. 13/290,124, filed Nov.
6, 2011 (issued as U.S. Pat. No. 8,425,340 on Mar. 23, 2013), which
is a continuation-in-part of application Ser. No. 13/225,433, filed
Sep. 3, 2011 (issued as U.S. Pat. No. 8,221,257 on Jun. 17, 2012).
application Ser. No. 14/477,902 is also a continuation-in-part of
U.S. patent application Ser. No. 13/352,313 ("Golf Swing
Measurement and Analysis System"), filed Jan. 17, 2012, which is a
continuation-in-part application of U.S. patent application Ser.
No. 13/273,216 filed Oct. 13, 2011, entitled "Golf Swing
Measurement and Analysis System" that is a continuation application
of patent application Ser. No. 13/269,603 filed Oct. 9, 2011,
entitled "Golf Swing Measurement and Analysis System" that is a
continuation-in-part application of patent application U.S. Ser.
No. 12/287,303 filed Oct. 9, 2008, entitled "Golf Swing Analysis
Apparatus and Method", and U.S. patent application Ser. No.
13/352,313 is also a continuation in-part of patent application
U.S. Ser. No. 13/299,635 ("Golf Free Swing Measurement and Analysis
System") filed on Sep. 9, 2011, which is a continuation-in-part of
patent application U.S. Ser. No. 13/225,433 filed on Sep. 3, 2011
entitled "Golf Free Swing Measurement and Analysis System," which
is a continuation in part of patent application Ser. No. 12/777,334
filed May 11, 2010, entitled "Golf Free Swing Apparatus and Method"
that is now U.S. Pat. No. 7,871,333. All of the above stated
applications are incorporated in their entirety by reference.
FIELD OF THE EMBODIMENTS
[0002] The embodiments generally relate to a measurement and
analysis system for determining the effectiveness of a movement,
such as determining the effectiveness of a golfer's swing based on
measurements made at the golf club head for free swing analysis
and/or impact analysis. The free swing analysis relates the dynamic
characterization of the object (e.g., club head) orientation and
motional descriptors time line for the entire swing related to a
predetermined spatial reference location. The impact analysis
related to impact on the object with respect to location and force
profiles. The system to measure both requires dynamics motional
analysis, a relative spatial analysis without a contact or impact
being made and analysis of impact.
BACKGROUND OF THE INVENTION
[0003] Systems and concepts for signal analysis have existed for
many years. The existing systems typically have sensors attached to
a device and sensor outputs are interpreted by a processor. This is
also the case in analyzing sports equipment, such as a golf club,
to determine improvements a player can make to their swing.
[0004] A system shown in U.S. Pat. No. 7,736,242 to Stites, shows
an integrated golf club with acceleration sensors on the shaft and
in the club head and communicates wirelessly. The system also
discloses a club head with an impact module that may include a
strain gage. The system in U.S. Pat. No. 7,736,242 does not teach
or suggest an integrated electronic system golf club head that
integrates impact sensors into the club head face in combination
with acceleration measurement sensors located in the club head and
further does not teach an antenna system that utilizes the
electrical properties and shape of the club head as an integral
component element of the antenna system design to increase power
efficiency and further operating time duration based on storage
capacity of energy device. The system does not provide for a method
of free swing analysis with the ability to relate a measurement
time line to a predetermined spatial reference location.
[0005] Another example of attaching sensors to a golf club is shown
in U.S. Pat. No. 4,898,389 to Plutt, who claims a self-contained
device for indicating the area of impact on the face of the club
and the ball, and a means for an attachable and detachable sensor
or sensor array that overlies the face of the club. Plutt's device
does not provide for an imbedded impact sensor array in the
clubface that functions in conjunction with internal three
dimensional g-force sensors to provide a superset of time varying
spatial force impact contours of the clubface with club head
acceleration force parameters that can be calibrated for highly
accurate spatial and force measurement. Plutt's device is
susceptible to location inaccuracy due to the removable constraint
of the sensors and is susceptible to sensor damage since the
sensors come in direct contact with the ball.
[0006] U.S. Pat. No. 7,672,781 to Churchill uses receiver signal
strength measurements with multiple directional antennas in
combination with linear calculation methods based on acceleration
measurements to determine the location of a movable bodies that
could be a golf club. Churchill fails to contemplate using RSSI
measurements without the use of directional sectorized antennas in
combination with acceleration measurements analysis applied to a
movable object with non-linear travel.
[0007] However, these systems fail to teach or suggest a
self-contained device or integrated electronic system golf club
head comprising the functions and methods of measuring a the entire
free swing with the ability to relate the free swing metrics time
line to a predetermined spatial location through the use of
inductive sensing and other measurements, such as measuring three
orthogonal acceleration axes across time with accelerometer(s) from
within the club head and measuring a spatial relationship variable
to a predetermined spatial location near or on the swing path by
means of receiver signal strength measurements. Further, they do
not provide free swing analysis capabilities with impact analysis
capabilities facilitated with inductive sensing and/or impact
sensors integrated within the club face in a single integrated
electronic club head. They also do not provide a convenient
recharging mechanism.
BRIEF SUMMARY OF EMBODIMENTS
[0008] Embodiments herein include a golf swing analysis system that
utilizes inductive sensing and optionally other techniques for
motional and orientation evaluation in conjunction with spatial and
impact evaluation. An embodiment may be capable of measuring and
providing comprehensive performance feedback for both free swings
and impact swings that include the entire swing. In other words,
the system is capable of measuring and analyzing an entire free
swing with no club/ball contact or a golf swing with club/ball
contact. Further, when a free swing analysis is being employed, the
system provides comprehensive results in the form of a time line
with a vast number of timing and dynamics swing metrics
represented. Further the time line is also associated to one or
more spatial locations related to the club head travel path, which
may be facilitated through inductive sensing. When swing and impact
analysis is being employed both dynamics swing metrics are provided
and a broad array of impact metrics such ball club face location,
impact forces, impact duration and others.
[0009] An embodiment disclosed herein may include a device that may
be part of or attachable to an object such as sports equipment
(e.g., a golf club), that determines spatial relationships and
impact characteristics based on inductive sensing. The device may
include a first inductive structure and circuitry for measuring the
inductance of the first inductive structure as it passes in
proximity to a conducting object, such as a coin, that is placed on
the ground. Measuring the inductance may be accomplished by
measuring the port impedance of the first inductive structure,
where port impedance includes inductance, capacitance, and
resistance. The device may additionally or alternatively include a
second inductive structure behind a conductive structure (e.g., a
club face or monolith) that may be used for measuring impacts on
the conductive structure. For example, if the conductive structure
is impacted and flexes towards the second inductive structure, the
inductance of the second inductive structure may change in
coordination with the flexing. The inductive sensing may be used in
addition to or instead of piezoelectric impact sensors in one
embodiment.
[0010] One embodiment and method of using inductive sensing to
correlate a component of the club's spatial location with the
discrete sensor measurement time locations on the motional sensor
measurement time line comprises at least one inductive structure,
where an inductive structure is defined any conducting structure
has at least two electrically connected terminals or at least one
electrical terminal and an electrically connected ground that
enables a measurable impedance or admittance that includes at least
an inductive component or inductance that is measured in Henrys.
For example, an inductive structure, could be, but not limited to,
a wire, a coiled wire, a discrete chip inductor, a coil on a PCB
board, a toroid, or an antenna.
[0011] The at least one inductive structure may be attached to a
location in or on the golf club in an embodiment. This location can
include but is not limited to the club head, the hosel, the shaft,
the handle or grip, or a combination of areas. The at least one
inductive structure may also be electrically connected to circuitry
that can operatively determine changes in inductance of the
inductive structure and output a signal representative of the
inductance changes such as direct inductance measurements using a
current step function vs voltage or a resonant circuit where
related parameters can be measured. The signal representative of
the inductance changes may be sampled and synchronized with all
other sensor measurements on the sensor measurement time line.
[0012] The system may further include at least one conducting
object as a location marker, the object including at least one
electrically conductive material. The conducting object may also
have a predefined 3D shape and size, and be placed at a location
with a predetermined relationship to the general golf swing (or
other movement of a different object or sporting equipment). For
example, the predetermined relationship may include placing the
conductive location marker on the ground, directly below where a
hypothetical or real ball location for the golf swing. Further, the
orientation of conductive location marker on the ground may be
aligned with what would be considered the ideal travel path of the
gold club head for a perfect swing.
[0013] In one embodiment, the conducting object is part of an
integrated golf club head. An integrated golf club head may
beneficially perform substantially similar to a regulation golf
club head of same type, while providing essential measurements of
free swing and or impact performance characteristics to the golfer
reliably over a time period that is of adequate length for a
training session or round of golf.
[0014] A first category of measured forces may include three
dimensional motional acceleration forces at the club head during
the entire golf swing including impact. The relationship between
force and acceleration is F(t)=m.sub.cha(t) where F(t) is the time
varying force vector, m.sub.ch is the known mass of the club head
and a(t) is the time varying acceleration vector experienced by a
given acceleration force sensor. The three dimensional axial domain
of the acceleration force vectors has its origin at or near the
center of gravity and the axial domain is orientated with one axis
referenced normal to the club head face and another axis aligned
with a known or less than 6 degree unknown angle offset to
anticipated non flexed shaft. The mechanism used to measure this
category of motional forces is a three dimensional g-force
acceleration sensor or sensors. The three orthogonal acceleration
measurements along with inductive sensing and/or RSSI (Receiver
Signal Strength Indicator) measurements are used for free swing
analysis to derive a result in the form of a swing metrics time
line that is related to a one or more spatial reference
location(s).
[0015] A second category of force measurements may include the
impact pressure forces that occur across the golf club head face
for the duration of time for clubface and ball impact. This time
varying pressure force is a scalar pressure profile normal to the
clubface that is a result of the impact force and location of the
ball on the clubface. The relationship between pressure and force
is p(t)=F.sub.normal-to-A (t) A where p(t) is the time varying
pressure experienced by a given pressure force sensor,
F.sub.normal-to-A (t) is the time varying vector component of the
force vector that is normal to the surface of the pressure force
sensor and also the clubface, and A is the surface area of a given
pressure force sensor element. The axial reference domain is the
same for the g-force sensors described above with respect to club
face. The mechanism to measure this category of pressure forces is
an array of one or more pressure force sensors embedded in the club
face that are measuring time varying impact pressure forces across
the club face during the entire duration of club head face and ball
impact.
[0016] The calculations for free swing analysis metric based on
three orthogonal acceleration measurements is provided in detail by
Davenport et al, U.S. Pat. No. 7,871,333, which is assigned to Golf
Impact and listed above in the Cross Reference to Related
Application section and incorporated by reference in its entirety.
Further the derivation of a swing metrics time line with a
relationship to one or more spatial locations using RSSI
measurements in combination with acceleration measurements is
provided in detail by Davenport applications U.S. Ser. No.
13/225,433 and U.S. Ser. No. 13/229,635, both assigned to Golf
Impact and incorporated by reference in their entirety.
[0017] The free swing time metrics that are calculated with
associated spatial relationship to one or more predetermined
locations include: [0018] 1. Dynamically changing characteristic of
club head velocity for a substantial portion before, through and
after a maximum velocity of said club head in correlation to the
dynamic spatial relationship of said club head to said predefined
location. [0019] 2. Dynamically changing characteristic of toe down
angle for a substantial portion before, through and after a maximum
velocity of said club head in correlation to the dynamic spatial
relationship of said club head to said predefined location. [0020]
3. Dynamically changing characteristic of club face angle for a
substantial portion before, through and after a maximum velocity of
said club head in correlation to the dynamic spatial relationship
of said club head to said predefined location. [0021] 4.
Dynamically changing characteristic of swing radius for a
substantial portion before, through and after a maximum velocity of
said club head in correlation to the dynamic spatial relationship
of said club head to said predefined location. [0022] 5.
Dynamically changing characteristic of club head spatial
acceleration for a substantial portion before, through and after a
maximum velocity of said club head in correlation to the dynamic
spatial relationship of said club head to said predefined location.
[0023] 6. Dynamically changing characteristic of club head radial
acceleration for a substantial portion before, through and after a
maximum velocity of said club head in correlation to the dynamic
spatial relationship of said club head to said predefined location.
[0024] 7. Dynamically changing characteristic of shaft flex lag
lead angle for a substantial portion before, through and after a
maximum velocity of said club head in correlation to the dynamic
spatial relationship of said club head to said predefined location.
[0025] 8. Dynamically changing characteristic of wrist cock angle
for a substantial portion before, through and after a maximum
velocity of said club head in correlation to the dynamic spatial
relationship of said club head to said predefined location. [0026]
9. a line that is coincident with the swing plane and swing plane
angle to ground. [0027] 10. Detailed club head swing tempo profile
which includes total time duration of tempo for the backswing,
pause and reversal, and power-stroke and provides rhythm described
as a percentage break down of each segment duration compared to
total tempo segment duration.
[0028] The impact metrics that are measured and or calculated
include: [0029] 1. Time varying pressure or force profile across
the golf clubface; [0030] 2. Location of impact of clubface and
ball on clubface; [0031] 3. Duration in time of club head face and
ball impact; [0032] 4. Maximum pressure or force measured on
clubface; [0033] 5. Total energy transferred from club to ball;
[0034] 6. Force vector components that are transferred to ball
launch and ball spin; [0035] 7. Estimated percent of total energy
components transferred to ball trajectory and ball spin; [0036] 8.
Orientation of ball spin referenced to club head face; [0037] 9.
Estimation of ball launch velocity; [0038] 10. Estimation of ball
spin velocity; [0039] 11. Impact error offset on clubface which is
a distance from actual impact location to optimum impact location
[0040] 12. Club head orientation percentage error from optimum in
relation to club head/ball impact (This could be described as an
error for each of three vectors describing forces on club head from
ball) and; [0041] 13. Measure of torque and angular momentum of the
club head as caused by the event of club head/ball impact.
[0042] The sensors are connected to electrical analog and digital
circuitry and an energy storage/supply device, also embedded within
the club head shell cavity. Further the analog and digital
circuitry with RSSI measurements circuitry also referred to as
electronics is electrically connected to an antenna system that
uses the club head shell as an electrical conductive element as
part of the antenna system. The analog and digital circuitry
electronic assembly conditions the signals from the sensors,
samples the signals from each sensor group category, converts to a
digital format, attaches a time stamp to each category or group
type of simultaneous sensor measurements, and then stores the data
in memory. The process of sampling sensors simultaneously for each
sensor category or group type is sequentially repeated at a fast
rate and may be a different rate between sensor categories or group
types, so that all measured points from each sensor category or
group type are relatively smooth with respect to time. The minimum
sampling rate is the "Nyquist rate" of the highest significant and
pertinent frequency domain component for each of the sensors'
category or group types time wave representations.
[0043] The electronics assembly further temporarily stores the
measured data sets and further formats the data into protocol
structures for wireless transmission. Each data set is queued and
then transmitted in a wireless protocol format from a radio
frequency transceiver circuit that is electrically connected to an
antenna system assembly electrical port. The antenna system
comprises at least two electrically conducting elements. One of the
electrically conducting elements of the antenna system assembly is
the electrically conductive club head shell. The shapes and sizes
of all antenna elements and objects are optimized as an antenna
system to provide a desired input electrical port impedance
characteristic and a desired radio wave radiation pattern for the
antenna system. Further the electrically conductive club head
element and club face assembly also provides the physical structure
and performance attributes of a functional golf club head.
[0044] The combined weight of all assemblies of the integrated
electronics system golf club head is substantially equal to that of
a regulation play club head of similar type. In addition, the
mounting location of all pieces of all assemblies either internal
to the club head shell or external to the club head shell are
configured so the center of gravity of the integrated electronics
system golf club head is substantially similar to that of
regulation play golf club head of similar type that is considered
to deliver good performance.
[0045] This invention also provides a variety of methods including
the sequence of steps that may be used to effectively optimize all
of the variable that are encountered with the design of integrated
electronic system golf club head, taking into account the many
tradeoffs between dual function requirements placed on individual
components and structures.
[0046] The present invention encompasses a variety of options for
the golfer to receive and interpret the information of swing,
impact and orientation metrics or a subset of total metrics
available. The human interface function is separate human interface
device that communicates wirelessly with the integrated electronic
system golf club head. The human interface function can provide all
or any subset of audible and visual outputs. Examples may include
wireless smart device such as a PDA or laptop computer or any other
device that has processing capabilities and a display and audio
capabilities and can be adapted to communicate wirelessly using
standard or non-standard wireless protocols. Some of the standard
wireless protocols may include but not limited to ZigBee,
Blue-Tooth or WiFi. Some of the non-standard protocol may include a
completely custom modulation with associated custom protocol data
structure or standard high level packet structure based on 802.11
or 802.15 with custom sub-packet data structure within high level
packet structure.
[0047] The preferred embodiment of the integrated golf club, in
addition to the previous described electronics, also has data
formatting for wireless transport using Bluetooth.TM. transceiver
protocols. The data, once transferred over the wireless link to the
laptop computer, are processed and formatted into visual and or
audio content with a proprietary software program specific for this
invention. Examples of user selectable information formats and
content could be: [0048] 1. a dialog window showing a graphical
representation of the clubface using a color force representation
of the maximum force gradient achieved conveying the area of impact
of the ball and along the side the graphic could show text
describing key metrics such as maximum force achieved, radial
acceleration of club at impact (related to club head velocity) and
total energy transferred to the ball; [0049] 2. a motion video of
the time varying nature of the forces on the clubface; [0050] 3. a
three dimensional graphic showing force vectors on club head from
ball; [0051] 4. an audio response which verbally speaks to the
golfer telling him/her the desired metrics; [0052] 5. a video
showing time varying acceleration vectors of the golf club head
during the swing and through impact; or [0053] 6. numerous other
combinations of audio and visual user defined.
BRIEF DESCRIPTION OF DRAWINGS
[0054] The above and other features of the present invention will
become more apparent upon reading the following detailed
description in conjunction with the accompanying drawings, in
which:
[0055] FIG. 1 is a perspective view of the present invention
integrated golf club head (golf club shaft not shown) with impact
pressure force sensors embedded in the clubface and a three
dimensional g-force acceleration sensor inside the club head;
[0056] FIG. 2 is a perspective view of the present invention as
shown in FIG. 1 except showing dashed line A and without depiction
of the sensors;
[0057] FIG. 2A is a cross sectional view of the club head of the
present invention of FIG. 2 taken along line A showing clubface
structure with two metal layers and there between the impact
pressure force sensor elements within embedding material monolith
and further sensor elements electrical connected to electronics
module within club head shell
[0058] FIG. 2B is a partially exploded cross sectional view of the
club head face assembly of the present invention showing two metal
layers both rigidly attached the club head shell housing;
[0059] FIG. 3 is a cross sectional view of the club head system
showing the clubface assembly, antenna assembly, three dimensional
acceleration measurement assembly, electronics assembly and energy
storage assembly with electrical connections between said
assemblies.
[0060] FIG. 4 is a graph showing two return loss measurements (S11)
of a single antenna, demonstrating the detuning effect on
electrical port impedance when antenna is placed near an electrical
conducting object
[0061] FIGS. 5, 5A and 5B show components of the antenna assembly
that include FIG. 5 the club head shell with electrically
conductive outer surface, FIG. 5A example types of some possible
additional conductive elements and FIG. 5B example types of some
possible electrically non-conducting objects
[0062] FIG. 6 shows an embodiment of an antenna system with a first
electrically conducting element that is the club head shell outer
surface attached to an electrically non-conducting object that is
further attach to and enclosing to a second electrically conducting
element of a wire type.
[0063] FIG. 6A shows another embodiment of an antenna system with a
first electrically conducting element that is the club head shell
outer surface attached to two separate electrically non-conducting
objects that each further attach individually and enclosing to two
separate electrically conducting elements, both of a wire type.
[0064] FIG. 7 shows an exemplary embodiment of an antenna system
configured to utilize fringe e-field effects to create radiating
apertures similar to patch type antennas. The antenna system
comprises a first electrically conducting element that is the club
head shell outer surface that attached to a first electrically
non-conducting object that is a dielectric sheet that is further
attached to a second electrically conducting element that is a
metal sheet.
[0065] FIG. 7A is a partially exploded cross sectional view of the
antenna system of FIG. 7 showing the two electrical contact points
that define the antenna system electrical port.
[0066] FIG. 7B is a cross-sectional view of club head utilizing the
antenna system of FIG. 7 showing another electrically
non-conducting RF transparent structure attached to club head shell
outer surface and covering antennas system components for improved
aerodynamic performance.
[0067] FIG. 8A is a block diagram of sensors and electronic
processing functions and electronic support functions of integrated
golf club head of the present invention.
[0068] FIG. 8B is an exemplary diagram of a computer system for use
in an integrated golf club head, in accordance with an
embodiment.
[0069] FIGS. 9, 9A, 9B and 9C details a golfer swing time lapse
showing associated trigger points that control and alter data
capture processing parameters within the electronics of the present
invention.
[0070] FIG. 10 is the club head shell showing club head wall with a
varying wall thickness structure embodiment for optimizing weight,
balance and structural integrity of overall club head shell.
[0071] FIG. 10A is a cross-sectional view of club head shell wall
of FIG. 10 showing a wall thickness profile structure embodiment
comprising two separate materials.
[0072] FIG. 11 is a perspective view of the club head acceleration
measurement assembly in the club head and the alignment of the
three orthogonal measurement axes x.sub.f, y.sub.f, and z.sub.f, to
the golf club structure.
[0073] FIG. 12 is a perspective view of the "inertial" motion axes
of the club head motion x.sub.cm, y.sub.cm and z.sub.cm as the
golfer swings the club and how these axes relate to the multi-lever
model components of the golfer's swing.
[0074] FIG. 13 shows the multi-lever variable radius model system
and two key interdependent angles .eta. and .alpha. and their
relationship between the two coordinate systems; the measured axes
of club head acceleration measurement assembly x.sub.f, y.sub.f and
z.sub.f, and a second coordinate system comprising the inertial
motion axes of club head travel x.sub.cm, y.sub.cm and
z.sub.cm.
[0075] FIG. 14 shows the club face angle .PHI. for different club
orientations referenced to the club head travel path.
[0076] FIG. 15 shows the toe down angle, .OMEGA., and it's
reference to the shaft bow state and measurement axis dynamics.
[0077] FIGS. 16 and 16A shows wrist cock angle .alpha..sub.wc, and
the shaft flex lag/lead angle .alpha..sub.sf which together sum to
the angle .alpha..
[0078] FIG. 17 shows the force balance for the multi-lever variable
radius swing model system and the inter-relationship to both axes
systems.
[0079] FIG. 18 shows the force balance for the flexible lever
portion of the multi-lever model for the toe down angle
.OMEGA..
[0080] FIG. 19 shows the user interface device, a laptop computer,
electrically connected to a cable connected to the wireless USB
module that may be placed at predetermined locations near the swing
path.
[0081] FIGS. 19A and 19B show and front view and a side view of the
club head travel path with possible predetermined locations for the
placement of the wireless USB module.
[0082] FIGS. 20A-C are exemplary illustrations of an impact
measurement system, in accordance with an embodiment.
[0083] FIGS. 21-21B are exemplary illustrations of an impact
measurement system, in accordance with an embodiment.
[0084] FIG. 22 is an exemplary graph of power signals from
piezoelectric elements, in accordance with an embodiment.
[0085] FIG. 23 is an exemplary device for signal processing and
recharging, in accordance with an embodiment.
[0086] FIGS. 24A-B are exemplary partial illustrations of a golf
club having an inductive structure for use with a conductive
object, in accordance with an embodiment.
[0087] FIG. 25 is an exemplary illustration of a device having an
inductive structure for use with a conductive object, in accordance
with an embodiment.
[0088] FIG. 26 is an exemplary illustration of swing paths and
corresponding inductive change signals, in accordance with an
embodiment.
[0089] FIGS. 27A-B are exemplary illustrations of a club head
having inductive structure(s) for detecting impact characteristics,
in accordance with an embodiment.
[0090] FIG. 28 is an exemplary illustration of system components
for measuring inductance changes in accordance with an
embodiment.
DETAILED DESCRIPTION OF EMBODIMENTS
[0091] An embodiment disclosed herein may include a device with one
or more piezoelectric elements and a processor, wherein the output
signal of each piezoelectric element may be divided such that a
first portion is analyzed and/or processed and a second portion is
used to recharge a battery. The ratio of the first portion to the
second portion may be dynamically adjusted by the processor in one
embodiment, based on detections made by the processor. The system
may include, for example, a non-conducting monolith with a
plurality of pressure sensors imbedded within it, including at
least first and second piezoelectric elements in one embodiment.
The system may also include pressure measurement circuitry (e.g.,
A/D converters) that captures positive and negative pressure values
of the first and second piezoelectric elements, wherein the
positive and negative pressure values are measured over a plurality
of sample points. This may be used, for example, with a golf club
for measurement of an impact of a golf ball with the club face and
used to build a time-varying impact pressure profile.
[0092] As shown in FIG. 1, the golf club head 10, has a three
dimensional g-force acceleration sensor 20 mounted within the
electrically conductive club head 10 shell cavity at a
predetermined location. In one of many embodiments for this
invention, the sensor(s) can be placed at a predetermined location
that is the center of gravity of the club head 10 for
simplification of metric calculations. However, the sensor(s) does
not have to be located at the center of gravity and all metrics
defined are still achievable. The club head 10, also has an array
of impact pressure force sensors 30 embedded in the golf club head
face 11. The hosel 8 may be made of a material that electrically
conductive or electrically non-conductive depending on embodiment
implementation and is attached to the club head 10. The hosel may
be adapted to connect and disconnect from a golf club shaft (not
shown) of the club.
[0093] As shown in FIGS. 2, 2A and 2B the club head 10 and a club
head cross section view FIG. 2A and FIG. 2B show selected
assemblies. FIG. 2A show cross sectional view 12 of club head 10
showing the construction of the club face 11 assembly having two
metal layers, the outer layer 13 and the inner layer 14. The outer
and inner layers 13, 14 are made with predetermined materials that
may be the same or different. In the preferred embodiment both
layer 13 and layer 14 are both made of a metal type material. The
pressure force sensors 30 are imbedded in a non-metallic,
non-electrical conducting medium of optimum physical properties 15
between the two layers 13 and 14 as part of the clubface 11. The
non-conducting medium 15 is a hard epoxy or similar material
monolith structure with the pressure sensors 30 and their
electrical connections embedded within it. Some examples of
possible materials include UV curable epoxies such as UV Cure 60-71
05.TM. or medium to hard composition of Vantico.TM. or one of the
compositions of Araldite.TM. or other suitable materials. The
monolith structure can be created with exact pressure sensor
placement and orientation with known injection molding
technologies. An example of this process would be to make an
injection mold that creates half of the monolith structure and has
half pockets for a precise fit for each of the sensors and
electrical connection ribbon. The sensors 30 with electrical
connections are then placed in the preformed pockets of the initial
half monolith. The initial half monolith with sensors is then
placed in a second injection mold which completes the entire
monolith. The sensors 30 are attached to a flex circuit ribbon 17a
that will extend out from the monolith structure, through a small
pass through opening in the inner layer 14, that connects to the
electronics assembly 18 in the club head cavity. The electronics
assembly 18 includes the RSSI circuitry that is used to measure
receiver signal strength which will be covered in more detail
later.
[0094] The non-conducting monolith material 15 with embedded
pressure sensors 30 can be pressure fit between the outer layer 13
and the inner layer 14. The outer layer 13 and the inner layer 14
can be connected to the club head shell housing 16 with
conventional club head construction techniques utilizing weld seams
or other attachment processes. Some techniques might include
Aluminum MIG (Metal Inert Gas) welding for aluminum to aluminum
connection and brazing for aluminum to titanium connections. The
clubface layers 13 and 14 can be titanium or comparable metal or
alloy and the club head housing components can be an aluminum or
alloy.
[0095] As shown in FIG. 2B, another cross sectional expanded view
which is the preferred embodiment of the present invention, the
inner metal layer 14 is a predetermined thickness and shape with a
defined rigidness the outer clubface layer 13 is a predefined
thickness and shape with a defined rigidness that define a club
face system when combined with monolith 15. Both the outer layer 13
and the inner layer 14 are rigidly attached to the club shell
housing 16 through the aforementioned welding process. In this
configuration, the pressure exerted and resulting deformation on
the outer layer 13 of golf clubface 11 resulting from ball and club
face impact create a time varying pressure profile on the
non-metallic medium monolith 15. The individual pressure sensors 30
each generate an output voltage proportional to the pressure
experienced by that sensor. The pressure force sensors each may be
any predetermined size and shape individually. However, the
pressure sensors elements 30 in the preferred embodiment are
piezoelectric elements made of a predetermined material with the
same predetermined shape, surface area and thickness, therefore
generating identical pressure force versus voltage profiles. In the
case where the clubface inner 14 and outer 13 metal layers are both
rigidly connected to the club head shell housing 16, the
deformation of the monolith 15 will be less near the edge 28 of the
clubface. This means that less pressure will be measured for the
same impact force by sensors closer to the edge of the club face
11. These variations will be a constant with respect to the fixed
geometric shape of club face system in combination with club head
10 shell and can be calibrated out in the digital signal process
with fixed calibration coefficients programmed into the processing.
Calibration coefficients may be determined through simulation or
during production on a per club head type basis.
[0096] The predetermined materials used and predetermined shapes
and thicknesses of all components of the club face structure
assembly are individually optimized to further optimize the
physical properties of the overall club face system to be
substantially similar to that of a regulation play golf club head
face of similar type and to provide adequate sensitivity of sensor
embedded 30 in monolith structure 15. The process for design
optimization of the club face system assembly defines the material
properties used for each individual piece of the club face assembly
and also the physical structure including size and shape of each
individual piece of the club face assembly. Further the defined
materials, shapes and sizes of all pieces further defines the club
head face system overall weight and form factor and mass
distribution. The process for design optimization of the club face
system is a sub process of the overall design optimization process
of the integrated electronics system golf club head.
[0097] The process for design optimizing the club face system takes
into account several considerations and tradeoffs. The primary two
objectives are to define a club face system structure that
physically performs like a regulation club face of similar type and
also provides adequate sensor sensitivity across the club face to
measure with reasonable resolution ball/club face impact relative
to a reasonable dynamic range of club head speeds at impact. An
example dynamic range for a driver type may be 45 MPH to 130 MPH.
Secondary goals are to achieve the lowest weight possible for the
club face system providing maximum flexibility for the final
optimization process that defines final weight and mass
distribution of integrated electronics system golf club head
design. Therefore a means of defining the optimal predetermined
materials, sizes and shapes for all components of the club face
assembly are done with the design optimization process for the club
face system include the steps of: [0098] 1. Choose club head type
[0099] 2. Choose a typical club head speed dynamic range for that
golf club type in association with targeted golfer population skill
level. [0100] 3. Choose a piezoelectric material that will provide
high electromechanical coupling coefficient for sensor element(s)
30 for electronic measurement resolution purposes. [0101] 4. Choose
metal material for outer club face layer 13 [0102] 5. Choose
material for inner club face layer 14 [0103] 6. Choose attachment
mechanism for club face assembly attachment to club head shell.
[0104] 7. Choose material for monolith for embedding sensor
elements 30 and define an initial size and shape of impact sensor
elements based on knowledge monolith material. [0105] 8. Start with
initial thickness and shape factor of outer club face layer 13
similar to that of a regulation club of that type. [0106] 9. Choose
an initial thickness shape factor for inner club face layer 14 that
is substantially thinner and has similar shape factor of initial
outer club face layer 13 [0107] 10. Choose an initial thickness of
monolith that is 1.5-2 times the thickness of the sensor elements
based on piezoelectric material selection in step 3. [0108] 11.
Model with a Finite Element Simulator that has piezoelectric
modeling capabilities such as PZ-Flex.TM. the layered structure
comprising, outer layer 13, monolith 15 and inner layer 14, with
all edges bound in accordance with step 6. [0109] 12. Through
simulation, record voltage waveforms for all sensor elements for
time varying loads applied to outer surface of outer layer 13
representing a golf ball impact of a predetermined speed and
predetermined location on club face. [0110] 13. Repeat step 11 for
different impact speeds from lowest to highest defined by the step
2 dynamic range for a specific location on the club face. [0111]
14. Repeat step 12 for different impact location on club face.
[0112] 15. Evaluate elastic response characteristics of club face
system compared to a regulation club face of similar club type in
relation to COR (Coefficient of Restitution). [0113] 16. Evaluate
electrical response of sensor outputs based on maximum amplitude
measure at maximum club head velocity with impact at the center of
the club face. [0114] 17. Evaluate electrical response of a sensor
with maximum output at minimum velocity for a ball impact near a
bound edge. [0115] 18. Define dynamic range regarding electrical
sensor out from step 16 defining high end of dynamic range across
club face and from step 17 for low end of dynamic range across club
face. [0116] 19. Evaluate if electrical dynamic range of sensor
outputs for entire club face (from step 18) provides adequate
sensitivity for defined data capture constraints of electronics
assembly. [0117] 20. Evaluate elastic response characteristics of
club face system (from step 15) are within a defined tolerance when
compared to a regulation golf club face of similar type. [0118] 21.
If steps 19 and 20 are satisfied, optimization is complete. If one
or both criteria are not satisfied adjust control parameters that
include thickness of metal layers 13 and 14 and monolith layer 15
in the flowing manner: If electrical dynamic range is too small to
provide adequate sensitivity do any single or combination of the
following: Increase metal layer thickness 14; Decrease metal layer
thickness 13; Decrease monolith layer 15. If electrical dynamic
range is larger than require for adequate sensitivity do any single
or combination of the following: Do nothing and move to strait to
elastic response adjustments if needed--and reduce sensor signal
levels uniformly in electronics assembly before data capture;
Increase metal layer thickness 13; Decrease metal layer thickness
14; Increase monolith layer 15. If elastic response of club face
system is to stiff do any single or combination of the following:
Decrease metal layer thickness 13; Increase monolith layer
thickness 15; Decrease metal layer thickness 14. If electric
response is too soft, do any single combination of the following:
Increase metal layer thickness 13; Decrease monolith layer
thickness 15; Increase metal layer thickness 14. [0119] 22. Select
control parameters to adjust electrical and mechanical responses
and feed new control parameters based on step 21 a, b, c, d into
step 11 and repeat process until club face system performance
criteria are met.
[0120] FIG. 3, shows a cross section view of the integrated
electronics system golf club head with assemblies related to
measurement and wireless communications represented. The three
orthogonal axes acceleration measurement assembly comprises a three
dimensional acceleration g-force sensor 20 or combination of one
and two dimensional g-force sensors to give three dimensional
measurement capabilities that are attached to a small printed
circuit board 29. The printed circuit board 29 is electrically
connected with electronics assembly 18 with a flex ribbon 17b. The
acceleration measurement assembly is mounted in a predetermined
spatial relationship to the club head shell structure. The
preferred embodiment defines the predetermined spatial relationship
to the club head shell structure to be the center of gravity of the
overall integrated electronics system golf club head. The mounting
method and structure of mounting mechanism is defined later in the
final design optimization process. An example of a resultant
possible mounting from final design optimization process is
described for clarity purposes. In one embodiment the small printed
circuit board 29 will be attached with a durable adhesive to a
metallic or non-metallic rigid protrusion 19 attached to the club
head 10 shell inner surface either by adhesive, weld, fastener, or
other well-known connection means. The protrusion 19 extending to
the spatial location that is predefined location for the sensor
circuit board 29 assembly. The surface areas 19a of the protrusion
19 on which the sensor's printed circuit board 29 is mounted has a
defined orientation within the club head to align the acceleration
measurement axes with the pre-defined reference axes of the club
head.
[0121] The electronics assembly 18 is located at a predetermined
location within club head shell 10 cavity. The predetermined
location and mounting method are defined later in the final design
and optimization process. The electronics assembly 18 is
electrically connected with flexible transmission line or coax
cable 17c to antenna elements and object(s) assembly 27 that is
located at a predetermined location on club head 10 shell outer
surface. Further electronics assembly 18 is electrically connected
with wire(s) 17d to energy source assembly 26 that is located at a
predetermined location within club head 10 shell. All assemblies
located in the club head 10 shell cavity may be mounted in their
individual predefined locations with mounting structures attached
to club head 10 shell cavity inner surface similar to structure 19
or may be held in their predetermined location within a light
weight molded form body that that is spatially fixed in club head
10 shell cavity and provides spatial support for each assembly
relative to club head 10 shell structure. The light weight molded
form body may be a durable light weight foam material or a light
weight plastic molded structure. The electronics assembly 18
provide circuitry for functions of: sensor data capture, wireless
communications and RSSI measurements from signals received through
antenna assembly 27.
[0122] All of the assemblies including: club face assembly,
electronics assembly 18, acceleration g-force sensors assembly 20,
antenna system assembly 27 and energy source assembly 26 each have
a predetermined weight that is defined in the design optimization
process of each separate assembly. The assemblies are combined and
assembled in the final design optimization process where final
individual predetermined location of assemblies and club head shell
wall thickness profiles are defined to further define the desired
weight and mass distribution of overall club head system. This
includes the optimized club head shell structure that is part of
the antenna system assembly to have a total weight substantially
similar to that of a regulation golf club head of similar type that
is recognized to have good performance. In addition, the
predetermined locations of the antenna components sub-assembly(ies)
and electronics assembly and the acceleration g-force sensor
assembly and the energy source assembly in conjunction with club
face assembly are optimized so that the center of gravity of the
integrated electrons system golf club head is substantially similar
to that of a regulation golf club head of similar type.
[0123] In general, mobile electronic devices that depend on a
battery or other energy storage device(s) and that utilize radio
wave wireless communications are challenged with size, weight and
operational time duration. The power consumption efficiency of an
electronics wireless system is heavily depend the ability to
efficiently convert electronic signals generated from within the
physical electronics to propagating radio waves with an intended
radiation pattern. The power efficiency of the conversion process
is typically dominated by the characteristics of the physical
antenna elements structures that further control the electrical
port impedance of the antenna system operating at a predetermined
frequency or frequency band.
[0124] The integrated electronics system golf club head antenna
system utilizes the electrical properties and defines physical
surface shape properties of the club head shell itself as part of
the antenna system. The components of the antenna system include at
least two or more electrically conducting elements and may include
at least one or more electrically non-conducting objects. The
preferred embodiment antenna system of this invention utilizes and
defines the club head shell and surface structure as one of the
electrically conducting elements. The design optimization process
for the antenna system defines the shape(s) size(s) and material
properties of all components of the antenna system. All components
of the antenna system are also in a predetermined fixed spatial
relationship with one another. The design optimization process of
the antenna system defines all components of the antenna system and
specifically defines a club head shell outer surface structure that
in combination with other antenna components provides desired
radiation patterns and desired electrical input port impedance to
optimize the power efficiency of the system that further enables a
smaller and lighter energy storage device. In addition, the wall
thickness of the club head 10 shell are further optimized in later
described processes to provide structural support for the overall
assembled club head to perform as a golf club head with
substantially similar physical performance criteria as a regulation
golf club head of similar type.
[0125] The integrated club head antenna system may be implemented
with one or a combination of techniques that launch radio wave and
influence radiation patterns. The first technique employs the club
head as a quasi-ground plane or ground object reflector that is in
a fixed spatial relationship with other electrically conducting
element or elements. The radiating element such as a wire operating
in the presence of a ground object produces two rays at each
observation angle, a direct ray from the radiating element and a
second ray due to the refection from the ground object affecting
radiation pattern. The second technique employs patch antenna
theory that requires a ground plane or quasi ground plane that in
combination with a conductive patch or sheet type electrically
conductive element creates a trapped wave resonant cavity. The
resonant structure facilitates electric field fringe effects to
generate electromagnetic radiating apertures. The required quasi
ground plane or quasi-ground object is implemented with the
conductive club head shell surface. In both techniques, the club
head shell is used as an electrically conductive element of the
antenna system and the structure of the electrically conductive
club head shell outer surface is an integral part of the overall
antenna system design and affects performance with regards to
electrical port impedance and the radiation pattern and reception
gain performance of the antenna system structure as a whole.
[0126] The preferred embodiment of the antenna system comprise at
least, a first electrically conducting element that is a golf club
head shell made of electrically conducting material and at least
one additional electrically conducting element and may have at
least one electrically non-conducting object.
[0127] The benefits of the integrated club head antenna system are
multifaceted, namely fewer parts, lighter weight and better
performance as compared to using an off the shelf antenna(s) that
is/are not designed to function in the constant presence of a metal
object namely the club head. For an off the shelf generic antenna
designed for a free space environment, both port impedance and
radiation pattern are also strongly influenced by all electrically
conducting objects in their near environment. The result of using
an off the shelf antenna in the near presence to a golf club head
has the effect of detuning the electrical port impedance creating
an impedance mismatch between the circuitry electrical output port
that is driving the electrical input port of the antenna system. As
shown in FIG. 4, an electrical port impedance change of an antenna
system is demonstrated with two different return loss (S11)
measurements on a network analyzer. The first S11 curve 70 shows an
antenna return loss with the intended impedance match between the
50 ohm network analyzer port and the intended 50 ohm impedance of
the electrical port of the antenna for the intended frequency band
72 in a relatively free space environment. The second S11 curve 71
is measured with the antenna system in the presence of a large
metal object in near proximity of the same antenna. The S11 curve
71 shows the significant impedance mismatch described with return
loss that is now taking place in the intended frequency band 72
between the 50 ohm port of the network analyzer and the antenna
system port. In summary, the presence of a metal object near an
antenna system (e.g., an inductive capacitance resonance structure)
significantly alters the input impedance of the electrical port of
the antenna and alters the overall radiation pattern of the
combination of antenna and reflecting object.
[0128] All of the variations of the invention assembly antenna
system comprise at least, a first electrically conducting element
that is a golf club head shell made of electrically conducting
material and at least one additional electrically conducting
element and may have at least one electrically non-conducting
object.
[0129] As shown in FIG. 5 the first conducting element of the
antenna system is the electrically conductive club head 10 shell
that has an outer surface 50 with club face assembly included. The
outer conductive surface 50 comprises regional surfaces that
include the top surface 51 and bottom surface 52 and side surfaces
that include a toe side surface 54 and heal side surface 53. The
shape and contour of one or more of the outer surface components
may be modified to optimize the antenna system performance.
[0130] As shown in FIG. 5A the second or other or additional
electrical conducting element(s) of the antenna system can be any
predefined shape(s). Some examples of additional electrical
conducting elements are a wire 60 of a predefined length L and
predefined form factor or a metal sheet in a plane 61 form factor
or domed shape (not shown) form factor or any other surface form
factor of predefined descriptive dimension such as length and width
and other dimensions describing shape or a combination thereof.
[0131] As shown in FIG. 5B a least one or more electrically
non-conducting object(s) may each be any predefined shape and size
with a predefined dielectric property. The predefined shape(s) and
the predefined dielectric properties are defined in the design
optimization process for the antenna system. The function of the
electrical non-conducting object is to physically hold the
additional electrical conducting elements in a predetermined
orientation to a predefined surface structure of the electrically
conductive club head shell outer surface and affect the electric
field in a predetermined way of the additional electrically
conducting element. An exemplary electrically non-conducting object
62 may be a shape that is adapted to attach to a predetermined
location on the club head shell outer surface 50 and further
supports an additional electrically conducting element such as wire
60 at a predetermined spatial relationship to the club head shell
and electrically non-conducting object 62 has the material
dielectric property similar to air. Another exemplary electrically
non-conducting object 63 is a sheet of material that may be a plane
type shape with a predetermined length, width and thickness and
further a predetermined dielectric constant that is substantially
higher than that of air and that attaches to the club head shell 10
outer surface 50 at a predetermined location and is further
attached to the metal plane 61 with metal plane 61 located at a
predefined location on the surface of electrically non-conducting
object 63.
[0132] FIG. 6 and FIG. 6A show antenna systems that utilize the
conducting club head 10 shell as ground reflector for an antenna
system. FIG. 6 shows an exemplary antenna system configurations
comprises a club head 10 shell outer surface 50 that is connected
to an electrically non-conducting object 62 in a predefined
location on club head 10 shell outer surface 50, that further
attaches to and supports a second electrically conductive element
(not shown, but within non conducting object 62) that is held in a
predetermined spatial relationship to club head 10 shell outer
surface 50. The electrical port of antenna system is defined by two
electrical connections points (not shown), the first electrical
connection point is on the interior surface of the electrically
conductive club head 10 shell and the second connection point is a
location on the second or additional electrically conducting
element (not shown, but within non conducting object 62) that is
fed through an insulating pass through (not shown) of the club head
10 shell. The club head shell surface structure and all
predetermine or predefined dimension and locations and spatial
relationships of all electrically conducting elements and
electrically non conducting object are defined to optimize the
antenna system electrical port impedance characteristics for a
predefined frequency band and the antenna system radiation pattern
for desired characteristics.
[0133] As shown in FIG. 6A another exemplary antenna system
configuration comprises the club head 10 shell with two separate
electrically non-conducting object 62 and 62a, each with an
individual predetermined size and shape factors and each attached
at a separate predetermine location on club head 10 shell outer
surface 50. Further each electrically non-conducting object further
supports separate additional electrically conducting elements
(element not show but each within respective electrically
non-conducting objects) each with an individual predetermined fixed
spatial relationship to club head 10 shell outer surface 50. The
electrical port of the antenna system is defined by two electrical
connection points. The first connection point is on the interior
surface of the electrically conductive club head 10 shell and the
second electrical connection point is a single point that is
electrically connected both second and third electrically
conducting additional elements (not shown, but within respective
electrically non-conducting objects 61 and 62a). Further each
individual electrically conducting additional element is fed
through an individual insulating pass through in the club head 10
shell and the electrical connections between the two additional
electrically conducting elements is made in the interior cavity of
the club head shell (not shown) defining the second electrical
connection point of the antenna system electrical port. The club
head shell surface structure and all predetermine dimension and
locations of all electrically conducting elements and electrically
non conducting objects are defined to optimize the antenna system
electrical port impedance characteristics for a predefined
frequency band and the antenna system radiation pattern for desired
characteristics.
[0134] As shown in FIG. 7 and FIG. 7A another embodiment of the
antenna system is based on a patch antenna structure. As shown in
FIG. 7 an exemplary antenna system comprises a first electrically
conducting element that is the club head 10 shell that has a top
surface 51 that is adapted to be flat in a given surface area. An
electrically non conducting object 80 is attached to the top
surface 51 at a predetermined location and orientation to top
surface 51. Further electrically non-conducting object 80 has a
predetermined size and shape and material properties and in this
example the object 80 is a material with a predetermined dielectric
property value. Further electrically non-conducting object 80 has
attached to it at a predetermined location, an additional
electrically conducting element 81 with a predetermined size and
shape. As shown in FIG. 7A a cross sectional expanded view of this
example antenna system shows the club head 10 shell top surface 51
attached to electrically non conducting object 80 further attached
to the additional electrically conducting element 81. Further FIG.
7A shows the antenna system electrical port connection points 82
and 83. The electrical port connection point 82 is electrically
connected with wire or transmission line that passes through an
electrically insulated pass-through in club head 10 shell wall and
another pass-through in non-conducting object 80 to additional
electrically conducting element 81 where wire or transmission line
is electrically connected to additional electrically conducting
element 81. The electrical port connection point 83 is electrically
connected to electrically conductive club head 10 shell directly or
with short wire. The club head 10 shell outer surface 50 structure
and all predetermine dimension, shapes and locations of all
electrically conducting elements and electrically non-conducting
objects are defined to optimize the antenna system electrical port
impedance for desired characteristics for a predefined frequency
band and the antenna system radiation pattern for desired
characteristics.
[0135] Another antenna system example comprises a first conducting
element that is the electrically conducting club head 10 shell, and
at least two more additional electrically conducting elements
comprising at least one that is adapted for patched type
structure(s) and at least one adapted for a wire type structure(s)
of individual predetermined size and shape. Further the antenna
system may have electrically non-conducting objects of
predetermined size and shape associated with each of the additional
conducting elements. The club head shell 10 outer surface 50
structure and all predetermine dimension, shapes and locations of
all additional electrically conducting elements and electrically
non-conducting objects are defined to optimize the antenna system
electrical port impedance for desired characteristics for a
predefined frequency band and the antenna system radiation pattern
for desired characteristics.
[0136] Another embodiment antenna system has more than one
electrical port where each port has two electrical contact points.
This antenna system comprises at least three electrically
conducting elements and first electrically conducting element is
the golf club head 10 shell and at least two addition electrically
conducting elements. The first electrical port comprises two
electrical contact points and first electrical contact point is
electrically connected the first electrically conducting element
club head and second electrical contact point is connected to one
or more additional conducting element(s) but not all additional
conducting elements. The second or additional electrical ports(s)
each have two electrical contact points and the first electrical
contact point is electrically connected to the first electrically
conducting element the club head and the second electrical contact
point is electrical connected to at least one additional
electrically conducting element that is not electrically connected
to the electrical contact point of first port or other additional
port(s). The benefit of an integrated electronics system golf club
head with multiple antenna ports is the system can then support
full duplex operation with constant receive and transmit taking
place simultaneously on two different frequencies or two different
frequency bands. In addition an antenna system with multiple ports
could support MIMO (Multiple Input Multiple Output) wireless
communication structures supporting much higher communication data
rates.
[0137] All attachments required between electrically conducting
elements and electrically non-conducting objects may be
accomplished with an electrical conductive or non-conductive
adhesive or fasteners.
[0138] All of the antenna system embodiments may have additional
electrical non-conducting structures that attached to the club head
10 shell external surface that further cover antenna system
components to provide a smooth surface of overall club head
structure to provide a similar aerodynamic structure to that of a
similar golf club head type. The material properties of the
aerodynamic enhancement structures include radio frequency
transparency with regards to radio wave signals. In other words do
not affect radio waves as radio waves pass through the aerodynamic
enhancement structures.
[0139] FIG. 7B shows a cross sectional view example of club head 10
with a patch configuration antenna system assembly embodiment with
an aerodynamic enhancement structure 85. Aerodynamic enhancement
structure 85 attaches to club head 10 shell outer surface 50
covering modified top surface area 51 and electrically conducting
element 81 and electrically non-conducting object 80. Aerodynamic
enhancement structure 85 may be attached to club head 10 outer
surface 50 with a non-conducting adhesive or fastener. The benefit
of the aerodynamic enhancement structure is that it allows greater
manipulation of the club head 10 shell outer surface 50 structure
for more flexibility in antenna system design, while providing the
aerodynamic properties of club head overall outer surface structure
to be substantially similar to that of a high performance club head
of similar type.
[0140] As previously recited, the antenna system has numerous
control variables that affect the electrical performance of the
total electronics system and the structural physical performance of
the club head. To define the predetermined values for all of the
control variables in the antenna system to meet electrical and
physical requirements, a design optimization process is used. A
means of antenna system design optimization comprises a process
with the steps of: [0141] 1. Define the club head type for the
system. [0142] 2. Define the frequency band of operation for the
antenna system [0143] 3. Define the desired radiation pattern of
the antenna system [0144] 4. Define the antenna system desired
electrical port impedance characteristic based the predefined
electronics drive port electrical impedance characteristic in
regards to the predefined frequency band of operation. [0145] 5.
Define an estimated number of additional electrically conducting
elements and what club head surface areas will be utilized for
desired radiation pattern coverage around club head. [0146] 6. If
any of the additional electrically conductive elements are intended
for patch structures define an estimate of the property of
dielectric constant for the electrically non-conducting object
based on frequency band and general surface area available for
selected club head surface area. [0147] 7. Calculate through know
estimation equations an initial estimates of size, shape and
dimensions of addition electrically conducting elements of the wire
type, and assume free space environment based on predefined
frequency of operation that defines related wavelengths of
operation. Standard or non-standard conducting element structures
may be used. Typical and standard structures include but are not
limited to wire type structures such as short dipole, 1/4 wave
dipole, half wave dipole, helix, L, F etc. Non-standard structures
can also be used, however, estimate calculation equations will need
to be derived independently based on Maxwell equations. [0148] 8.
Calculate through know estimation equations based on defined
frequency band the initial estimates of size, shape and dimensions
of addition electrically conducting element(s) of the patch type
and size, shape and dimensions of electrically non-conducting
object(s), in conjunction with a predefined dielectric property of
the associated electrically non-conducting object(s). Assume an
ideal planer ground connected to the electrically non-conducting
object and assume free space environment based on predefined
frequency of operation that defines related wavelengths. Standard
or non-standard conducting element structures may be used. Typical
and standard structures include but are not limited to patch or
leaky transmission line type structures on an ideal ground planer
surface such as layered and multilayered structures with a variety
of coupling feed types. These estimates will be a starting point
for further considering non-planer structures and a non-ideal
ground planes such as the club head shell. [0149] 9. Using
estimated size and shape and location for club head structure and
all additional electrically conducting elements and all
electrically non-conducting objects build a model in ANSYS HFSS 3d
full wave electromagnetic field solver. [0150] 10. For an antenna
system that use wire type additional electrically conducting
elements only: (a) Adjust spatial location and orientation of
addition electrical conducting elements in relation to club head
shell to achieve desired radiation pattern. (b) Adjust club head
shell outer surface area region contours related to each additional
electrically conducting elements to further tune radiation pattern.
(c) Adjust size, shape and dimensions of previous estimates (Step
6) of additional electrically conducting elements to achieve a
desired input port impedance characteristic in the define frequency
band. (d) Repeat steps 9a through 9b and further adjust end results
of step 9c to retune radiation pattern and input port impedance
characteristics. (e) Define electrically non-conducting object
structures including size and shape for attachment to defined
predetermined club head shell outer surface area structure to
further attach additional electrically conductive elements of
defined predetermined size and shape in defined predetermined
spatial reference to club head shell outer surface area region.
[0151] 11. For an antenna system that use patch type additional
electrically conducting elements only: (a) Adjust spatial location
and orientation addition electrical conducting elements with
associated fixed relation electrically non-conducting objects in
relation to club head shell to achieve desired radiation pattern.
(b) Adjust club head shell outer surface area region contours
related to each additional electrically conducting elements to
further tune radiation pattern. (c) Adjust size, shape and
dimensions of previous estimates (Step 7) of additional
electrically conducting elements to achieve a desired input port
impedance characteristic in the define frequency band. (d) Repeat
steps 10a through 10b and further adjust end results of step 10c to
retune radiation pattern and input port impedance characteristics.
[0152] 12. For Antenna system that utilize both wire type and patch
type additional conducting elements: (a) Conduct steps 9a and 10a.
(b) Conduct steps 9b and 10b. (c) Conduct steps 9c and 10c. (d)
Conduct steps 9d and 10d. (e) Conduct step 9e. [0153] 13. Evaluate
assembled antenna system including all electrically conducting
elements and electrically non-conducting based on electrical
performance as an antenna with port impedance and radiation pattern
performance criteria and physical properties as a golf club head
with aerodynamics as a criteria. If aerodynamics of club head outer
surface structure not satisfactory implement aerodynamic
enhancement structures. [0154] 14. Define weight of antenna
assembly with all components including aerodynamic enhancement
structure (if used). At this point the electrically conducting club
head shell has zero wall thickness and therefore zero weight. The
distribution of club head shell wall thickness will be defined
later in the overall design optimization process of when all
assemblies are put together.
Inductive Sensing Embodiments
[0155] As previously stated above, the presence of a metal object
near an antenna system significantly alters the input impedance of
the electrical port of the antenna and alters the overall radiation
pattern of the combination of antenna and reflecting object. Using
similar principles to the impedance matching and return loss
analysis of FIG. 4, in one embodiment, an embodiment Uses
inductance measurements to determine (1) a club head spatial
location and/or (2) impact characteristics. In particular,
inductance is a component of the impedance measurements previously
discussed with regard to FIG. 4. Inductance is a property of a
conductor, whereby a change in current flowing through the
conductor induces (i.e., creates) a voltage or electromotive force
in both the conductor itself (i.e., self-inductance) and in any
nearby conductor(s) (i.e., mutual inductance). Inductance is
characterized by the ratio of the voltage to the rate of change in
current which has the units of Henrys (H).
[0156] Although the following examples may refer to a golf club or
golf club head for convenience, other devices and sports equipment
may be equipped with an inductive structure to similarly determine
spatial location and/or impact characteristics.
[0157] (a) Spatial Location
[0158] In one embodiment, inductive sensing is used to track the
relative spatial location of sports equipment, such as a golf club,
during a stroke or swing. The spatial location of a club head may
include a physical location in space relative to at least one point
of interest, such as the anticipated ball location. An embodiment
may allow for a club head to track a free swing, for example, where
there is not an abrupt change in sensor outputs from ball impact to
otherwise provide a reference point. Instead, the system may use
inductive sensing to determine a spatial reference point for all
other sensor measurements on a time line.
[0159] By measuring inductive change to determine spatial location,
a system may track the club's movement without requiring the use of
magnets inside the club or as a marker in one embodiment. Magnets
may otherwise add mass to the club that causes it to swing or
operate unlike a normal golf club. It also may eliminate the need
for actively emitting signals from external components outside of
club, which may require batteries and as a result a more intrusive
marker.
[0160] In one embodiment, the system may measure inductive change
for free swing analysis as was described earlier in the antenna
sections with regard to FIG. 4, such as in paragraph 0040, where an
antenna in free space has a given port impedance that changes when
an object made of conductive material not part of the antenna
design is either introduced into the environment near the antenna
or there is a change in orientation of conducting object(s) already
in the vicinity of the antenna. The electrical port impedance is
primarily determined by inductance, capacitance and resistance of
the electrical port. The majority of the impedance changes result
from inductance changes and the associated resistive loss changes
due to the inductor's environmental changes with respect to
conducting objects. In one embodiment, measuring the shift in the
port impedance of the antenna constitutes measuring an inductance
change for the purposes of this disclosure. The change in impedance
of a reactance component (capacitance and inductance) may be due to
the inductance change.
[0161] Similarly, in one embodiment, an inductive structure is
included a golf club or a device that attaches to sports equipment,
such as a golf club, and the system may determine the relative path
and location of the inductive structure and/or sports equipment by
inductance change measurements taken at the device. A processor may
measure inductance values of the inductive structure (which, for
the purposes of this disclosure, may include measuring parameters
that are directly related to inductance value changes). By placing
one or more conducting objects on the ground, the inductance of the
inductive structure will change with respect to proximity and or
orientation of conducting objects as the inductive structure moves
through the nearby environment.
[0162] As used herein, the "inductive structure" may be any
conducting structure that has at least two electrically connected
terminals or at least one electrical terminal and an electrically
connected ground that enables a measurable impedance or admittance
at the terminals, wherein the structure includes at least an
inductive component or inductor that is measured in Henrys.
Examples of inductive structures may include a wire, a coiled wire,
a discrete chip inductor, a coil on a PCB board, a toroid, and/or
an antenna. Further the inductance component of the measured port
impedance may be further broken into two additive components: a
first component of inductance referred to as "self-inductance,"
which defines the inductance contribution from the inductive
structure itself, and second component of inductance referred to as
"mutual inductance," which defines the inductance contribution from
conducting object(s) in the environment near the inductive
structure. In particular, when a conducting object is introduced in
the vicinity of an inductive structure, the conducting object may
induce a current that causes additional induction in the inductive
structure also, adding to or canceling out the existing current in
the inductive structure and causing an inductance change.
[0163] Tuning to FIG. 24A, an exemplary illustration of a system
2400 that includes a golf club head 2420 with an integrated
inductive structure 2430 is presented. In this example, the golf
club head 2420 may be used for free swing analysis without relying
on an impact to determine motional and orientation characteristics,
creating a spatial reference associated with motional and
orientation characteristics. In one embodiment, the inductive
structure 2430 may be fabricated into the underside of the club
head 2420. This may give inductive structure 2430 greater proximity
to a conducive marker placed on the ground, allowing for more
accurate inductance change measurements in one embodiment. In this
example, the inductive structure is a coil that may be printed on a
printed circuit board (PCB). In another embodiment, the inductive
structure 2430 may be shielded by a portion of the shell of the
club head to prevent damage to the inductive structure 2430 when
the club head 2420 contacts the ground during a swing. The
inductive structure 2430 may a passive structure that is coupled to
active electronics, wherein the active electronics may be powered
with a low voltage in one embodiment. This voltage may be turned on
based on detected activities of a user, such as by analyzing
acceleration or velocity of the club head.
[0164] Continuing with FIG. 24A and as shown in FIG. 28, the
inductive structure 2430 may be electrically connected to capacitor
2805 to create a resonant circuit or other resonant structure 2810
in one embodiment. As used herein, a "resonant structure" may refer
to a combination of one or more inductive structures and capacitive
structures that has at least one electrical port with a measurable
variable impedance or admittance across frequencies and at least
one resonant frequency. For example, a simple 1/2 wave dipole
antenna can be a resonant structure, as previously discussed with
regard to FIG. 4 and related disclosures. Another example would be
a discrete inductor component electrically coupled to a discrete
capacitor of a resonant structure.
[0165] A capacitive structure 2805, on the other hand, may be any
conducting structure that has at least two electrically connected
terminals or at least one electrical terminal and an electrically
connected ground that enables a measurable impedance or admittance,
and that also includes a capacitance (which may be measured in
Farads).
[0166] Further, the inductive structure 2430 may include multiple
inductive structures at multiple different locations in one
embodiment. One or more inductive structure may be attached to one
or more locations in or on the golf club, including the club head,
the hosel, the shaft, the handle or grip, or a combination of these
areas.
[0167] Turning to FIG. 24B, the system 2400 may also include a
conducting object 2550, which may act as a marker that is placed at
a predefined location (e.g., at the hypothetical or real location
of a golf ball). In the example of FIG. 24B, the conducting object
2550 is a press-stamped piece of sheet metal with 3D shape
attributes. These 3D shape attributes and the placement location
and orientation on the ground may enable precise determination of a
club head travel path over the conducting object and the height
above conductive location marker.
[0168] In one embodiment, the conducting object may be part of a
golf tee. In another embodiment, the conducting object is a coin
that the user places on the ground. In general, the conducting
object 2550 may be a simple conductor, which advantageously may not
require special materials such as magnets, nor does it require
active emitters that require a power source. Thus, the conducting
object 2550 may be convenient to use and keep track of, with a very
low replacement cost if it gets lost.
[0169] As the club or other device is swung and passes over the top
of the conducting object 2550, the change in inductance may define
the spatial location of the club head at that instant. For example,
the maximum peak inductance may indicate the closest proximity of
the club to the conducting object, establishing a reference point
for all other sensor readings. By taking a series of inductance
value samples over a timeline, the system may be able to determine
a flight path based on patterns in the change in inductance values,
as will be discussed with regard to FIG. 26.
[0170] In one embodiment, a plurality of different conducting
objects may be placed at different locations in one embodiment. In
general, the number and type of inductive structures used and the
number and shape and location of the conducting objects may allow
the system to better determine one or more 3D spatial locations
along orientation and motional parameters. Different types and
shapes of inductive or conducting structures that have measurable
inductance can include coils printed on PCB (Printed Circuit
Boards) such as FR4, wire air wound structures, springs, and
others.
[0171] The inductive structure 2430 may be electrically connected
to inductance measurement circuitry within the club head 2420, such
as a processor and analog-to-digital converters, to measure the
inductance change of the inductive structure 2430. The inductive
measurement circuitry may include any circuitry or measurement
equipment that is connected to an inductive structure or resonant
structure, and that also has the ability to measure electrical
parameters that are related to and affected by inductive changes.
In the example of FIG. 28, a resonant structure 2810 including an
inductive structure 2430 and capacitive structure
[0172] In one embodiment, inductance may be measured directly by
measuring the time vs. current response of an object in one
embodiment, or be calculated from the frequency response of a
resonant circuit if the capacitance component value of the resonant
circuit is known in another embodiment. In one embodiment, the
inductance measurement circuitry outputs a signal representative of
the inductance changes such as direct inductance measurements using
a current step function vs voltage or a resonant circuit where
related parameters can be measured. This inductance change signal
may be sampled at a rate determined by a resonant frequency of the
inductance circuit in one embodiment. These samples may be taken
simultaneously with or correlated to the samples of other sensors,
providing a sensor measurement time line that correlates with club
head spatial location above the conducting object (a coin, for
example). As used herein, sampling inductance values may include
the inductance values or changes in inductance values.
[0173] In one embodiment, the inductance change measurement
circuitry is based on creating a resonant circuit with a
predetermined resonance frequency based on the inductive
structure's 2430 self-inductance and an added capacitor of defined
capacitance. The resonant circuit may be further connected to a
signal processor that measures, samples and digitizes the resonant
frequency characteristics that is directly related to change in the
inductance of the inductive structure and outputs a discrete signal
scaled to the inductive change.
[0174] One such example is presented in FIG. 28. As shown in FIG.
28, a resonance circuit 2810 includes an inductive structure 2430
coupled to a capacitive structure 2805. The resonance circuit is
then connecting to a signal processor for determining inductance
changes. In one embodiment, the signal processor may include
circuitry 2820 for resonant parameter measurement and digitization.
In particular, the circuitry 2820 may measure resonant frequencies
in one embodiment, and include digital signal processing 2830 to
determine whether a shift occurs in the resonant frequency by
measuring the frequency peaks. As used herein, determining
inductance changes may include measuring inductance directly in one
embodiment, or measuring resonant parameters, such as frequency
shifts, in another embodiment. Once the inductive changes have been
determined, the processor or some other processor may further match
the processed digital signal against pre-programmed patterns that
are stored in memory.
[0175] Turning to FIG. 26, an exemplary top-down view of travel
paths 2610 of a golf club head relative to a conducting object 2600
during a golf swing. In this example, the conducting object may be
rectangular with conducting zones (e.g., at 2631 and 2634) and
non-conducting zones (e.g., at 2632). The middle of the conducting
object 2600 may represent a hypothetical ball location 2636 in an
embodiment. The conducting object 2600 may be formed by metalizing
a pattern on PCB board. By creating a metalized pattern, the
conducting object 2600 in turn may cause a pattern in inductance
changes for an inductive object that passes over or beside the
conducting object. In this example, the metalized pattern includes
conductive strips at the start 2631 and end borders, and a
metalized saw-tooth pattern (including 2634) between the boarders.
During the golf swing, as the club head travels over the conducting
object 2630, including the conductive borders and saw tooth
pattern, the conductive regions cause inductance changes caused by
mutual inductance between the inductive structure and the metalized
regions of the conducting object 2630. The inductance changes may
define a set of measurements 2650 on the aggregate sensor
measurement time line that are correlated to the club head
transferring through the anticipated ball location (e.g., the
conducting object location 2630).
[0176] As shown in this example, digital inductance signals 2650
indicate inductance changes based on the paths 2610 taken with
respect to the metalized pattern of the conducting object 2600,
which in turn creates a unique inductive change pattern along each
different path, Paths A-D 2612, 2614, 2616, and 2618. This is
because each different path causes the inductive object to
experience different inductive changes because it crosses the
metalized (conductive) regions of the conducting object 2600
differently (e.g., for different amounts of time). The closer the
inductive object gets to the metalized portion, the higher the
inductive change becomes. As a result, the signals 2650 in this
example reflect the duty cycles of the inductance change signal as
it passes over the metalized regions of the conducting object 2600.
For example, when the inductive structure passes over a
non-conducting region, the signal is low, and where the inductive
structure passes over a metalized (conductive) region, the signal
is higher. As an analogy, if a flashlight where shining downward on
the metalized object, the amount of inductance change would relate
to how much of the light was on metalized regions versus
non-metalized regions. As more metallization falls within the scope
of the inductive structure, the larger the mutual inductance
effect, which in turn causes greater inductive change measured at
the port of the inductive structure. Signal paths 2650 embody
example measurements at that port. Because the club head in this
example passes over the conductive object at a substantially
uniform height, the peaks of the signals 2650 are also
substantially uniform. In another embodiment, such as with a
three-dimensional conductive object, the peaks of the signals may
not be of substantially uniform amplitude, which may also allow
calculation of how high above the object the club head is
passing.
[0177] Thus, by analyzing the signal patterns, the system may be
able to determine the spatial location and/or path of a club or
other object with an inductive element along a timeline 2660, based
on the metalized pattern present on the conducting object 2600. In
one embodiment, the determined spatial location may be relative to
the inductive structure. For example, the spatial location of a
club face may be determined by first determining the location of
the inductive structure, and then applying a known offset between
the location of the inductive structure and the club face.
[0178] As shown in FIG. 28 at step 2840, a processor may compare
the signal pattern(s) to pre-programmed patterns stored in memory
to characterize the travel path of the inductive structure. This
may include comparing a plurality of measured duty cycles against a
set of predetermined duty cycle patterns corresponding to a
metallization pattern of the conducting object in one embodiment.
The comparison may also or alternatively include normalizing or
scaling the detected pattern to be similar in length to the stored
patterns in one embodiment. Additionally, the stored patterns may
differ depending on the shape of the conducting object and/or the
metallization pattern on the conducting object in one embodiment.
Although FIG. 26 presents a top-down view 2600, in another
embodiment the inductance is measured according to a
three-dimensional pattern, such as by including raised metalized
sections. This may allow the system to determine how high above the
conducting object the inductive structure traveled.
[0179] Other metallization patterns or shapes are possible for the
conducting object 2600. For example, the conducting object 2600 may
instead have a pattern of rings that are positioned within one
another. The rings may be metalized at different thicknesses to
create unique inductance change patterns depending on the path of
the inductive object.
[0180] The sequenced measurements based on inductance may be
captured, synchronized, and aligned in time with all other sensor
measurements on the aggregate sensor measurement time line 2660 in
an embodiment. By synchronizing the inductance values with all
discrete sensor measurements during the swing on the aggregate
sensor measurement time line, the object's (e.g., club's) spatial
location during the swing may be synchronized with a specific
sensor measurement or a specific group of sensor measurements that
are a subset of a larger sequenced group of motional sensor
measurements that make up the motional sensor measurement time
line. Further, the sampling rate of the inductance-to-digital
converter may be synchronized or quazi-synchronized (e.g., using a
different sampling rate) with sampling and digital conversion of
the motional sensors. If the sampling rates of the inductance
digital conversion and motional sensor digital conversion are not
synchronized (not integer multiple of one another) in an
embodiment, then floating point processing may be used align
samples on a unified time line. Additionally, the resonant
frequency of the inductive circuit may be used to determine the
nearest samples of the other sensors, and using a ratio of the
different sampling rates, synchronizing between a multiplying
factor based on that ratio. An alignment factor may be used to
estimate samples at points between the surrounding actual samples
that are taken.
[0181] In one embodiment, the inductance change measurement
circuitry measures inductive changes based on v(t)=L di/dt. In
another embodiment, measuring inductance changes may be
accomplished by using a resonance-based antenna such as a 1/2 wave
or 1/4 wave antenna structure connected to circuitry that measures
a resonance shift that occurs from an inductance change of the
antenna using a peak detection circuitry in the frequency domain.
As still another example of support circuitry used in measuring
inductance, a resonance circuit may be used that couples an
inductive structure to a capacitive structure with resistive
losses. The resonant circuit may be further electrically connected
to an inductance-to-digital converter. The measured inductance
changes may be aligned in time, giving a club head or other device
the ability to sense when it is in proximity to a conducting
object.
[0182] In another embodiment, the inductive structure 2430 may be
part of a device 2500 that attaches to sporting equipment. For
example, FIG. 25 provides an exemplary illustration of a device
2500 that includes an inductive structure 2510 that may be attached
to sports equipment, such as a golf club 2550. The inductive
structure 2510 may be attached to the bottom of the club head 2550
in one embodiment, giving it proximity to a conducting object that
may be placed on the ground at the location that the golfer intends
to swing the club. However, the inductive structure may be placed
elsewhere on the sporting equipment in another embodiment, such as
on the front or tip of the club head. The device 2500 may include
one or more attaching members 2520 and 2530 to secure the device to
the sports equipment. The attaching members 2250 and 2530 may be
durable elastic straps in one embodiment, allowing the device 2500
to be attached to golf club heads of different sizes or other
sports equipment or objects altogether. The same functionality
described herein with respect to a golf club may be incorporated
within the device 2500.
[0183] (b) Club Face Impact Sensing
[0184] Another embodiment of club face impact sensing uses
inductive sensing to measure the deformation of the club face. In
one embodiment, inductive sensing may be used by a processor to
measure club face deformation without the inductive structure(s)
(i.e., inductive sensing element(s)) making any contact with the
club face structure or changing the mechanical properties of the
club face. This may allow for the manufacture and use of golf clubs
with striking surfaces that are uncompromised compared to a
regulation golf club, yet also provide the ability to measure
impact characteristics.
[0185] Turning to FIGS. 27A and 27B, in one embodiment a club head
may include one or more inductive structure(s) 2730, 2732, 2734,
and 2736 attached (e.g., at connection point 2778) to the inner
portion of the club head shell 2780 in close proximity to but not
in contact with the back of the club face 2790. The number of
inductive structures may vary for different embodiments. In one
embodiment, a separate monolith 2760 includes the inductive
structures 2732, 2734, and 2736, and is aligned in parallel with
the club face 2790, creating a space 2770 between the sensing
monolith 2760 and the club face 2790. The inductive structures 2750
of this example may be simple spiral inductors formed on a printed
circuit board. However, in other embodiments, other types of
inductive structures described herein may be used.
[0186] At least a portion of the club face 2790 may be made out of
a conductive material, such as a metal. In this way, the conductive
club face may act as the conducting object. The club head shell or
body may be made of any desirable material or combination or
materials that are electrically conductive or non-conductive.
Additionally, the club head may be any type of club head, such as a
driver, hybrid, iron, or putter.
[0187] As the ball hits or impacts the conductive club face 2790,
one or more small deformations of the club face can be measured as
an inductance change relative to each of the one or more inductive
structures 2730, 2732, 2734, and 2736. As the conductive surface
moves closer to an inductive structure, mutual inductance may occur
in one embodiment. Thus, the inductance measured at the inductive
structure's port may change. Because the club face 2790 may not
touch the inductive structure(s) during impact, this may
advantageously allow for measuring aspects of the impact without
adversely affecting the performance of the golf club or other
sports instrument.
[0188] As mentioned earlier, there are several ways of measuring
the inductance changes through the use of additional circuitry that
may sample measurable derivative parameters directly dependent on
the inductance change of the inductive structure(s). By measuring
and comparing the inductance changes at each inductive structure
2730, 2732, 2734, and 2736, the system may determine location,
force, and other impact characteristics already described herein.
For example, the impact may cause the conductive club face
structure 2790 to move closest to the inductive structure 2734
located nearest to the impact point of a particular example impact.
The system may compare inductance change measurements of all the
inductive structures 2730, 2732, 2734, and 2736, and determine that
the impact was closest to inductive structure 2734 based on the
inductance changing the most compared to the other inductive
structures 2730, 2732, and 2736.
[0189] For club heads that have a natural open space within the
club head, such as a driver or hybrid, the inductive structure(s)
2750 may be mounted in close proximity to the internal back surface
of the club face 2790.
[0190] For club heads that do not have a natural open space within
the club head, an internal pocket may be created where the
inductive structure(s) 2750 may be mounted in close proximity to
the club face 2790 internal back surface.
[0191] The inductive structure(s) 2750 mounted in close proximity
to the club face may be further connected to additional circuitry.
As one example, the inductive structure(s) 2750 may be mounted to
one or more resonant circuits that make it easy to measure
properties of the resonance such as resonance frequency and quality
factor of resonance frequency that are a direct function of the
inductance changes of the inductive structure that are dependent on
changes of proximity and orientation of conductive structures near
the inductive structure.
[0192] In another embodiment, an apparatus may be attached to a
golf club for club face impact sensing. As one example, a contact
structure, such as a flexible plastic monolith, may include at
least one inductive structure (e.g., a coil). The contact structure
may be attached to a golf club head in front of the club face, such
that the contact structure will make contact with a ball during an
ordinary golf swing. The contact structure may include a conductor
such as a conductive layer positioned in proximity to the at least
one inductive structure in one embodiment. In another embodiment,
the club face itself may act as the conductor.
[0193] The apparatus may allow a user to practice a golf swing
indoors in one embodiment, such as by hitting whiffle balls inside
the user's home. Upon impact with the whiffle ball (or other
object) the contact structure may flex, causing the at least one
inductive structure to change position relative to the conductor.
This in turn may cause a change in inductance values from the at
least one inductive structure. In one embodiment, the apparatus
determines inductance changes at least in part by detecting a shift
in a resonant frequency of a resonant structure that includes the
inductive structure.
[0194] The apparatus may include signal processing circuitry
coupled to the inductive structure to detect the inductance changes
when the inductive structure moves relative to the conductor. By
providing multiple inductive structures on the contact surface, a
system may be able to make insights regarding the impact, as
described herein. Additionally, in one embodiment the apparatus may
include other sensors, gyroscopes, and accelerometers that produce
signals that are incorporated in the swing and/or impact analysis,
as described herein.
[0195] In one embodiment, the contact structure is a flexible
monolith, such as a piece of plastic. The at least one inductive
structure may be positioned on the opposite side of a contact
surface of the flexible monolith, such that it is between the
contact surface and the club face.
[0196] A thin foam layer, such as a double-sided foam tape, may
separate the at least one inductive structure from the conductor at
a predefined uniform thickness. In one embodiment, the thin layer
also is used to attach the apparatus to a club face. An example
thin layer used in one embodiment is 3M tape.
[0197] The apparatus may further include its own processor,
transmitter, and battery in one embodiment. In one embodiment,
these elements are designed into a skirt region around the club
face. The transmitter may use common wireless protocols, such as
Bluetooth, to communicate with smart devices such as a phone,
tablet, or notebook.
Example System Components
[0198] As shown in FIG. 8A, the electronics assembly is the central
processing and electrical connection hub for all other assemblies
with electronic components. The sensor categories, three
dimensional g-force sensor(s) 200 and the pressure force sensors
100 are electrically connected to electronics that capture the time
varying electrical signals of all of the sensors. Additionally RSSI
measurements are made by RSSI circuitry in the wireless transceiver
500 and synchronized with three dimensional g-force sensor 200
measurements. The electrical signals may or may not use signal
conditioning 300 and or 300a before they are input to sample and
hold functions 401 and 401a. The sample and hold functions 401 or
401a samples all sensor(s) individually in a sensor category
simultaneously at a rate defined for each sensor category. The
sampling rate of each sensor category may be the same between
sensor categories or may be different between sensor categories.
Further the sampling rate of an individual sensor category may be
constant or may be dynamically change during the golf swing based
on logic triggers in the controller 406 associated with monitoring
sensor levels of either one or both sensor categories. During the
time duration that individual sample and hold stores sensor
amplitude value in each of the sensor categories then analog to
digital conversion function(s) 402 and or 402a takes each sample
value and converts it to a digital representation. All of the
digital samples for each sensor category are associated with that
single sample time on a measurement time line of acquisition in
"the apply sequencing sensor category tag and time reference"
function 403 and then are moved into digital memory 404. The
sampling rate for each sensor category of the simultaneous sample
and hold function 401 and 401 a are at, or faster than, the
"Nyquist rate" determined by the highest pertinent frequency
component associated with each sensor category. After all data has
been loaded into memory storage 404 from a given golfer's swing,
additional swing data can be captured and stored or the data is
further processed and formatted 405 for transfer to a user
interface function. All of the functions listed are coordinated by
a controller function 406, which may be integrated together with
other functions 400 such as a sophisticated PIC (Periphery
Interface Control) module with DSP (Digital Signal Processing)
functionality. In a preferred embodiment, the signal is processed
and formatted 405 to be applied to a wireless transceiver 500
function. The wireless transceiver function includes electronic
circuitry that provides electronic signals to an electrical drive
port that is further connected to the antenna system 500a
electrical input port(s). The antenna system emits and receives
radio frequency waves for transfer of information between a remote
user interface, such as a laptop computer with wireless transceiver
capabilities. Further when receiving radio wave signals the
transceiver is measuring the receiver signal strength of those
signals. All of the functions in FIG. 8A that require electrical
power to function are supplied by an energy source such as battery
power supply 600 that is detachable from the integrated golf club
or rechargeable if it is implemented as a permanent component of
the golf club head.
[0199] The electronics controller 406 dynamically organizes and
controls the electrical sequencing and processing of the signals
based on a fixed startup sequence and then triggers. When the
integrated electronic system golf club head is initially turned on,
the controller starts capturing and monitoring the g-force
sensor(s) 20 measurement axes values form sensors 200 and measuring
receiver signal strength at the antenna system 501 a. After startup
the controller 406 comprises logic implemented with firmware
residing and executing in controller 406 that defines a trigger
events that may indicate for example weather the club head is
moving or still or what portion of the swing is taking place based
g-force sensor data. Further more complex triggers may be defined
for triggers based on a combination of g-force sensor data and
impact sensor data. Based on a predefined trigger events occurring
the controller instructs electronic circuitry to individually or in
any combination start or stop or adjust any operational function or
combination of functions for example: memory storage of a given
sensors category, wireless transmission, sample rate for individual
sensor categories or any other electronic function affecting system
operation and or mode of operation. The benefits of the of a system
based on predefined logic triggers based on sensor inputs is the
ability to optimize the state of operation of electronic function
when needed to acquire the minimal amount of data to fully describe
the desired swing characteristics and further reducing electronic
function operations when not needed to minimize overall energy
consumption. The lower overall energy consumption of the
electronics allows for smaller lighter energy source or energy
storage supply which contributes to the overall design flexibility
of achieving an integrated electronics system golf club head with
weight, center of gravity and physical structural performance
similar to that of a regulation golf club head of similar type.
[0200] FIG. 8B depicts an exemplary processor-based computing
system 201 representative of the type of computing system that may
be present in or used within the golf club head or at a receiver
that receives swing and/or impact data from the golf club or
attached module. The computing system 201 is exemplary only and
does not exclude the possibility of another processor- or
controller-based system being used in or with one of the
aforementioned components.
[0201] In one aspect, system 201 may include one or more hardware
and/or software components configured to execute software programs,
such as software for storing, processing, and analyzing data. For
example, system 201 may include one or more hardware components
such as, for example, processor 205, a random access memory (RAM)
module 210, a read-only memory (ROM) module 220, a storage system
230, a database 240, one or more input/output (I/O) modules 250,
and an interface module 260. Alternatively and/or additionally,
system 201 may include one or more software components such as, for
example, a non-transitory computer-readable medium including
computer-executable instructions for performing methods consistent
with certain disclosed embodiments. It is contemplated that one or
more of the hardware components listed above may be implemented
using software. For example, storage 230 may act as digital memory
that includes a software partition associated with one or more
other hardware components of system 201. System 201 may include
additional, fewer, and/or different components than those listed
above. It is understood that the components listed above are
exemplary only and not intended to be limiting.
[0202] Processor 205 may include one or more processors, each
configured to execute instructions and process data to perform one
or more functions associated with system 201. The term "processor,"
as generally used herein, refers to any logic processing unit, such
as one or more central processing units (CPUs), digital signal
processors (DSPs), application specific integrated circuits
(ASICs), field programmable gate arrays (FPGAs), and similar
devices, such as a controller. As illustrated in FIG. 2A, processor
205 may be communicatively coupled to RAM 210, ROM 220, storage
230, database 240, I/O module 250, and interface module 260.
Processor 205 may be configured to execute sequences of computer
program instructions to perform various processes, which will be
described in detail below. The computer program instructions may be
loaded into RAM for execution by processor 205.
[0203] RAM 210 and ROM 220 may each include one or more devices for
storing information associated with an operation of system 201
and/or processor 205. For example, ROM 220 may include a memory
device configured to access and store information associated with
system 201, including information for identifying, initializing,
and monitoring the operation of one or more components and
subsystems of system 201. RAM 210 may include a memory device for
storing data associated with one or more operations of processor
205. For example, ROM 220 may load instructions into RAM 210 for
execution by processor 205.
[0204] Storage 230 may include any type of storage device
configured to store information that processor 205 may need to
perform processes consistent with the disclosed embodiments.
[0205] Database 240 may include one or more software and/or
hardware components that cooperate to store, organize, sort,
filter, and/or arrange data used by system 201 and/or processor
205. For example, database 240 may include information to that
tracks swing and/or impact data based on embodiments herein.
Alternatively, database 240 may store additional and/or different
information. Database 240 may also contain a plurality of databases
that are communicatively coupled to one another and/or processor
205, of may connect to further database over the network.
[0206] I/O module 250 may include one or more components configured
to communicate information with a user associated with system 201.
For example, I/O module 250 may include a console with an
integrated keyboard and mouse to allow a user to input parameters
associated with system 201, such as the identification of the
golfer to independently track different users of the same smart
golf club. I/O module 250 may also include a display including a
graphical user interface (GUI) for outputting information on a
monitor. I/O module 250 may also include peripheral devices such
as, for example, a printer for printing information associated with
system 201, a user-accessible disk drive (e.g., a USB port, a
floppy, CD-ROM, or DVD-ROM drive, etc.) to allow a user to input
data stored on a portable media device, a microphone, a speaker
system, or any other suitable type of interface device.
[0207] Interface 260 may include one or more components configured
to transmit and receive data via a communication network, such as
the Internet, a local area network, a workstation peer-to-peer
network, a direct link network, a wireless network, or any other
suitable communication platform, such as Bluetooth. For example,
interface 260 may include one or more modulators, demodulators,
multiplexers, demultiplexers, network communication devices,
wireless devices, antennas, modems, and any other type of device
configured to enable data communication via a communication
network.
[0208] As shown in FIGS. 9, 9A,9B, and 9C, the progression of a
golf swing is shown to provide an example of how triggers may work
by modifying electronic functions during the golf swing to provide
all required information while reducing overall average energy
consumption rate from battery source. This is only an example and
numerous other trigger configurations are anticipated and would be
obvious to a person of ordinary skill in the art after reviewing
this example. FIG. 9 shows the golfer during the backswing 801 and
only acceleration g-force sensor measurement are be captured at a
predefined sampling rate and stored and transmitted. FIG. 9A shows
the progression of the swing and at point 802 a predetermined
trigger is invoked. The trigger's logic criteria is based on a
combination of acceleration g-force measurements that determines
the swing is substantially into the power-stroke and the invoked
trigger causes the controller to increase the sampling rate of the
g-force acceleration sensors and RSSI and to start or initiate
measuring and sampling and storing the impact force sensors at the
predetermined rate and further transmitting synchronized time
stamped measurements from memory storage of all sensors out of club
head wirelessly. FIG. 9B shows further progression of the golf
swing and another trigger is invoked at point 803 indicating the
club head is making contact with the ball 803a based on impact
sensor inputs. The invoked trigger that occurs at point 803 causes
the controller to start a timer which after a predetermined time
duration relating to location at position 804 shown in FIG. 9C
shuts off the sampling and capture and storage of impact sensor
measurements and further reduces the sampling rate of the
acceleration g-force sensors. Further, wireless transmitter
continues to transmit both g-force and impact sensor measurements
from memory until all impact measurements in memory have been
wirelessly transmitted out. Further wireless transceiver continues
to transmit only acceleration g-force sensors data. Further and not
shown in the figures, if golf club is set down and is not moving
another trigger is invoked based on g-force sensor, and the
wireless transmitter is shut off until time when movement is
detected again invoking another trigger causing the wireless
transmitter is turned back on. In this example the acceleration
g-force sensor sample rate and the RSSI sample rate are the same,
however, in another embodiment the sample rate of the acceleration
g-force sensor measurement and the RSSI can be different and
controlled independently, as long as the signals are on
synchronized single time line.
[0209] The electronics assembly comprises input and output
electrical connections to all other assemblies. As previously shown
in FIG. 3 the other assemblies that have electrical connections to
the electronics assembly 18 are: club face assembly impact sensors
30, g-force sensor assembly 29 for orthogonal acceleration
measurements, antenna system assembly 27 and energy supply assembly
26. The electronics assembly comprises electronic components,
integrated circuits and various electronic connectors assembled on
a printed circuit board. The electronics assembly is optimized for
minimal weight and volume while providing reliable predefined
electronic functionality within an impact and shock environment.
The size and weight of the electronics assembly is defined by the
total aggregate weight of all pieces included in assembly with
attachment vehicles such as solder. The design optimization process
for electronic assembly include the steps of: Define swing speed
dynamics range for golf population targeted. Define estimates of
maximum impact forces that will be experienced by club head when
ball club head impact take place. Select electronic components and
IC and connectors that provide required electronic functions and
that are robust to function under shock estimates defined in step
2. Layout printed circuit board for all electronics components.
Assemble circuit board with all components, ICs and connectors to
define electronics assembly. Record the default out port impedance
inherent to an off the shelf RF circuitry such as an RF integrated
circuit for use in antenna system design. Measure electronics
assemble to define size and weight. Define firmware code for
electronic process and logic triggers to provide required data to
describe swing characteristics and minimize overall current power
consumption. Define by measurement the average power consumption
for a golf swing including all electronic processing functions of
assembly including wireless transceiver functions with matched
impedance load for intended frequency band.
[0210] The energy source assembly comprises components that
facilitate the storage and release of energy to operate
electronics. The energy source components may comprise various
electrical components for enabling and disabling energy or power to
electronics, connectors for electrically connecting to all
electronics, and physical structure for assembly of all components
and physical structure for supporting assembly either internal or
external to club head shell cavity. The energy storage cells may be
batteries or capacitors or supper capacitors or other component
devices or combination of, that can store and release electrical
energy. Further, batteries may be of rechargeable or disposable
types.
[0211] The design optimization process for the energy source
assembly focuses defining a design that has minimal weight and
volume while providing operation of electronics for predetermined
time duration. The energy source assembly design optimization
process includes the steps of: Define require time duration of
operations such as training session or a round of golf. Define
total power requirements to operate all electrical power consuming
assemblies associated with integrated electronics system golf club
head. Define the total energy required to supply power for time
duration defined in step 1. Define energy storage cell type and
size and or number of energy storage cells required to provide
total energy defined in step 3. Define all electrical and physical
support components required for energy cell(s) integrations. Define
assembled energy assembly weight, volume and shape, and mass
distribution.
Energy Harvesting Embodiments
[0212] Another assembly for purposes of energy harvesting may be
included in the integrated electronics system golf club head or
another device, and harvest energy from the impact sensor elements
generated power signal. The impact sensor elements may be made of
piezoelectric materials that do not require a power supply to
function. The piezoelectric elements, however, generate and provide
an output voltage and current waveform when a force is applied to
the elements such as the impact of a golf ball on the club face
assembly. A portion of the generated electrical power signal
comprising voltage and current from the impact sensor elements may
be used to apply charge to an energy storage cell device in a
recharging fashion. The portion of power signal extracted from the
impact sensor element(s) is done in a ratio format, so the shape of
the signal waveform from impact sensor elements applied to the
processing electronics is not changed. Further with the ratio of
signal amplitude extracted for recharging purposes known, no
information carried by signal portion applied to electronics
processing is lost.
[0213] Although a golf club head is discussed herein as an example,
the system may be part of different sports equipment, such as a
tennis racquet, in a device unrelated to sports equipment, or in a
device that may be attached to sports equipment. The embodiments
discussed herein are not limited to golf embodiments, and the golf
embodiments are illustrative and exemplary only.
[0214] Additionally, although this application may refer to an
"impact sensor" or "pressure sensor" for convenience, both may also
be used to detect vibrations and/or other force-related parameters
in an embodiment. These sensors may include a piezoelectric
element, and in one embodiment, the piezoelectric element may
include a cantilever structure that can detect vibration. Unless
otherwise stated, any structure for sensing pressure or vibrations
may be used as a pressure sensor in an embodiment. The vibrations
may be detected in addition to one or more force-related parameters
that include pressure, linear acceleration, angular acceleration,
and torque. These parameters may be detected singularly by a sensor
or in combination by the sensor. The power signal output by the
piezoelectric element may be an analog signal that is based on the
surface charge changes of the piezoelectric element, which in turn
result from deformation of the piezoelectric element due to the
force-related parameter. The power signal may be utilized by signal
processing circuitry to measure the respective force-related
parameter. Although "pressure" may be referred to for simplicity
and illustration, any one or more of the force-related parameters
may be measured by the piezoelectric elements unless stated
otherwise. Over time, these force-related parameters may
characterize impact or vibration.
[0215] In one embodiment, the system may dynamically adjust the
ratio of power that is used for processing and the portion that is
used to charge the energy storage cell device (and/or any other
portions that may be utilized in an embodiment). For example, a
processor may dynamically adjust the ratio in controlling how much
of the power signal the signal divider sends to the signal
processing circuitry versus the energy storage assembly. As used
herein "dynamically adjusting the ratio" may include automatically
setting one or more variables that control the signal divider
functionality, and also may include any other method of
automatically adjusting a first amount of the power signal that is
sent to energy storage and adjusting a second amount of the power
signal that is sent elsewhere. The processor may make a dynamic
adjustment based on a pre-programmed timeline, which may be invoked
by at least one trigger event, such as detecting that acceleration
or velocity meet a threshold. In another embodiment, the dynamic
adjustment is part of an on-going analysis or decision algorithms
based on sensor outputs. The on-going decision analysis (e.g.,
algorithms) may take into account multiple sequential thresholds
being met by a given sensor output within a defined time frame. In
an embodiment, the on-going analysis may further include
multi-input time-sensitive logic-based triggers based on many
sensors inputs simultaneously that provide intelligent feedback and
control to the entire electronics functionality. Thus, the
processor may change the ratio to split the power signal
differently while adapting to user activities, allowing more of the
signal to be sent to energy harvesting when impact signal analysis
is less important.
[0216] In one embodiment, the processor may shift towards more
signal processing based on an acceleration and/or velocity
threshold being met. For example, if the processor detects that
sports equipment, such as a golf club, is being swung then more or
all of the power signal may be directed to signal processing.
Conversely, after the impact is over, the processor may send more
or all of the power signal to the energy storage assembly. In
addition, in one embodiment, the splitter may have more than two
outputs which all may be automatically adjusted by the processor.
For example, the splitter may have a first output coupled to energy
storage, a second output coupled to backup capacitor storage, a
third output coupled to signal processing, and a fourth output
coupled to a light emitting diode. Adjusting the ratio may include
changing the amount of power signal sent to any of these
outputs.
[0217] In one embodiment, signal analysis may cause the processor
to adjust the ratio differently for two different periods: (1)
impact analysis and (2) vibration analysis. For example, in one
embodiment, the duration of club face impact with a ball is
approximately 400 micro seconds, but the club may continue to
vibrate after impact for an additional period of time, such as
several milliseconds (depending on the club head). During the
post-impact vibration period, the processor may adjust the ratio
such that an increased portion or all of the power signal is
harvested for energy storage. This is because, in one embodiment,
the vibration characteristics, shapes, and patterns do not need to
be analyzed as precisely, and therefore a smaller range of power
signal amplitudes may be adequate for the vibration analysis. In
another embodiment, the processor may continue to send most or all
of the power signal to energy storage until detecting that a swing
is taking place, at which point the processor may shift back into
an impact detection state, directing more or all of the power
signal back to signal analysis circuitry.
[0218] Similarly, because less precision may be needed for
vibration analysis than impact analysis, the processor may also
dynamically slow the sampling rate after 400 micro seconds pass
from initial impact. In one embodiment, the Nyquist frequency may
be determined based on the frequency band containing the highest
pertinent resonant frequencies for the object being monitored, and
the sampling rate may adjust downward to the Nyquist rate.
[0219] In another embodiment, when the processor reduces the
portion of the power signal that is measured by the signal
processing circuitry, this may shrink the voltage amplitude of the
measured portion of the power signal. Thus, the processor may also
apply and/or send an offset variable indicative of the current
ratio to the processing circuitry so that amplitude samples taken
of the various power signals are normalized in the digital domain.
For example, when the processor controls the ratio such that 80% of
the power signal is sent to processing circuitry, the processor may
also apply a multiplier of 1.25 to normalize the amplitude samples
relative to if the full power signal had been sent to the
processing circuitry. As another example, if the ratio is
dynamically changed so that only 10% of the power signal is sent to
the processing circuitry, a multiplier of 10 may be applied to the
samples to normalize the values relative to the full power signal.
The processor may additionally or alternatively track the ratio or
relative amounts of power signal sent down each splitter output in
one embodiment. Thus, when the processor dynamically changes the
ratio, it may also associate each change with time-aligned data
derived from the relative amounts of the power signal.
[0220] A device (for example, a club head) may also include
multiple pressure sensors in one embodiment, and each of them may
be coupled to different signal dividers. The processor may control
each signal divider with substantially the same ratio, such that
each signal divider will divide the power signals the same way at a
given point in time. In another embodiment with multiple pressure
sensors, first and second normalizing multipliers may be used on
the power signals of first and second pressure sensors,
respectively. The first and second normalizing multipliers may be
different to compensate for one of the pressure sensors being
located closer to the edge of the golf club face than the other.
This is because the golf club face may flex more towards the center
of the face than toward the edges, which may cause identical
pressure sensors to perform differently at the different
locations.
[0221] Turning to FIG. 22, an example chart 2300 of multiple sensor
outputs 2310 are shown, spanning both an impact period 2320 and a
vibration period 2330. The x axis in this example represents time.
Samples may be taken, for example, simultaneously every 4
microseconds in one embodiment. The y axis in this example
represents the amplitudes of the power signals output from each of
the six sensors 2310. These amplitudes indicate the amount of
pressure on each respective piezoelectric sensor. The amplitude
values may be multiplied by a predetermined amount to convert the
amplitude samples into standard pressure measurement units, such as
pascals (Pa). This calculation may also take into account
calibration, which may involve a second multiplier in one
embodiment or a sensor specific multiplier that takes into account
the ratio in a second embodiment. The pressure measured by each
pressure sensor element, in combination with known club face
flexibility clamping profile of the club face/club head structure
can be used to characterize a time-varying club face surface
deformation profile. resulting from impact that further can
translated into the pressure time location profile exerted by the
ball on the club face.
[0222] As shown in the example chart 2300 of FIG. 22, a first
piezoelectric element may output a first power signal 2340 that has
the highest peak amplitude during impact period 2320. This
indicates that the ball hit nearest to this first sensor. The other
sensors (e.g., piezoelectric elements) also output power signals,
which can be analyzed to determine a precise location of impact. A
second sensor may output a negative amplitude signal 2350,
indicating a negative pressure experienced by the second sensor
element, for example, as described with regard to FIGS. 21A and
B.
[0223] Once the peak at impact is detected and the power amplitude
signal begins to fall, the processor may switch into vibration
analysis mode for the vibration period 2330. Although, FIG. 22
shows the amplitudes of the full power signals, at this point the
processor may change the ratio of power signals such that smaller
amplitude power signals are sent to signal processing. However, the
larger portion may be sent to energy storage, still leaving the
signal processing may be precise enough to analyze various
vibration resonances to make further determinations regarding the
original impact. In another embodiment, the processor may adjust
the ratio to send all of the post-impact power signal to energy
storage.
[0224] In one embodiment, during the vibration analysis period
2330, resonance patterns are evaluated based on the power signals
output from each of the pressure sensors. Different structures may
support different vibration resonances, with different dominant
resonances. For example, a driver may resonate differently than a
putter, both of which resonates differently than a tennis racquet,
which in turn resonates differently than a baseball bat. The way
the sports equipment resonates may inform about the way ball was
struck. For example, if the processor looks at the amplitudes at a
predetermined dominant resonance frequency and determines that the
amplitudes are above a threshold over a prolonged resonance period,
this may indicate that the ball was hit too close to the edge of a
club face.
[0225] In one embodiment, the impact sensors are at other locations
in addition to or instead of at the club face. For example, in one
embodiment the impact sensors may be at the shaft or grip of a golf
club. In another embodiment, the impact sensors may be built into
the hosel and/or side walls of the club head. The vibration
resonance patterns and even impact characteristics may be
determined from these other locations in an embodiment.
[0226] Turning to FIG. 23, a device 2200 having piezoelectric
elements 2210 and 2220 is shown. The device 2200 may attach to
different sports equipment in an embodiment, or to a different
moveable object in another embodiment. For example, the device 2200
may attach to the club head, shaft, or grip of the club in one
embodiment. In another embodiment, the device 2200 may attach to,
for example, a tennis racket shaft, a baseball bat, a hockey stick,
or other sporting equipment. The device 2200 may attach to the
sporting equipment by being clamped, tightened, and/or wrapped
around the shaft of the sports equipment (e.g., a golf club) just
beyond the grip in one embodiment. The various elements described
herein with regard to a golf club head may also apply to device
2200.
[0227] In one embodiment, the device 2200 may have one or more
piezoelectric sensor elements 2210 and 2220 oriented to detect
vibrations on the shaft caused by striking the ball. In one
embodiment, a first piezoelectric sensor 2210 may detect vibrations
at substantially a 90 degree angle from a second piezoelectric
sensor 2220, thereby allowing for vibration detection along
multiple axes.
[0228] Like with the piezoelectric sensors integrated into a club
head, sensors 2210 and 2220 may provide first and second power
signals, respectively, which each may be split according to a
predetermined ratio such that a first portion of each power signal
is used to charge a battery in device 2200, whereas a second
portion of each power signal is processed to analyze
characteristics specific to the sporting equipment.
[0229] For example, the vibrations may indicate an impact with a
ball, and may further form patterns that provide information about
the impact, similar to those described with respect to the
integrated club head. For example, when attached to a baseball bat
a vibration profile may indicate whether the ball was hit on the
sweet spot of the bat, or whether the ball was hit too close to the
end of the bat or too close to the batter's hands. Similarly, the
vibration profile may indicate whether a tennis ball is hit in the
middle of the racquet strings, close to a beam or grommet, or on
the beam or grommet. The vibration differences along the different
axes may also yield information regarding the angle of impact,
which, in a sport such as tennis, may also inform regarding spin
placed on the ball on a particular shot.
[0230] In one embodiment, the processor may determine the ball was
hit at the sweet spot based on the vibrations falling into a known
frequency band for the expected resonance of the sports instrument.
In response, the processor may change the ratio to output a third
portion of the power signal to a green LED, the LED giving a visual
indicator that the ball was struck well. Alternatively or in
addition, the processor may increase the portion of the power
signal that is sent to energy storage, since analysis of the sweet
spot vibrations may not be necessary. If the processor determines
the ball was not hit at the sweet spot, it may change the ratio to
send some of the power signal to a red LED, the red LED indicating
that the ball was not hit optimally.
[0231] In another embodiment, a third piezoelectric sensor 2230 may
be placed substantially in-line with the first piezoelectric sensor
2230. These sensors 2210 and 2230 may be part of a single monolith
in one embodiment. The processor may compare power signals output
by in-line sensors 2210 and 2230 to better calculate an impact
location along a particular axis, based on amplitude differences
and time offset for similar waveforms between the two sensors 2210
and 2230.
[0232] Optimization
[0233] The process of optimizing the overall assembly of the
integrated electronics golf club head is focused on defining a
system golf club head that has all measurements and electronic
processing and communication capabilities desired and that
functions substantially similar to regulation golf club head of
similar type based on physical properties. Further, the specific
physical properties being substantially similar include:
coefficient of restitution of club face, overall weight of club
head and center of gravity of club head. The system club head
variables that are defined in this final optimization process
include: placement of all assemblies, components and elements in
relation to club head shell outer surface and in conjunction
defining the club head shell wall thickness profile. The
optimization process for the aggregation of all assemblies and
structures for the integrated electronics system golf club head
include the steps of: Define what functions are to be included in
system club head that defines what assemblies will be utilized in
or on club head. Define the shape, weight and mass distribution of
utilized assemblies from previous optimization processes results
for each individual assembly except antenna system. In a CAD
(Computer Aided Design) mechanical design tool such as
Solidworks.TM., model each assembly as representative shape, volume
and mass density for each assembly from step 2 except antenna
system. In CAD tool, model antenna system with club head shell
structure with zero mass (zero wall thickness) and without club
face assembly and having an outer surface shape or contour and all
other elements and objects with mass defined in antenna
optimization process. In CAD tool attach club face assembly with
antenna system assembly where club face assembly is attached to
club head shell outer surface to form entire outer surface of club
head system. In CAD tool define an estimated spatial relation all
assemblies from step 2 with in assembly antenna system shell shape
and club face assembly forming cavity in step 5 that further
results in a center of gravity of aggregate of all assemblies near
intended center of gravity for overall club head system. Add wall
thickness in a uniform manner consistent with earlier define
material that has a defined mass density to define a club head
system with desire overall weight consistent with a regulation golf
club head of similar type. Adjust in combination: (a) wall
thickness profile maintaining mass volume of material and outer
surface structure of club head shell and (b) spatial relationships
of assemblies to club head shell outer surface to define the
desired center of gravity of the overall club head system. Define
an addition weight and mass distribution entity for mounting method
and materials used for supporting internal assemblies in defined
spatial relationship from step 8 that defines an addition weight
and mass distribution entity. Reduce or increase mass of material
used for club head shell wall thickness and iterate through steps 8
and 9 until overall club head system desire weight and desired
center of gravity are achieved. Validate through CAD structural
analysis that club head shell physical structure wall thickness and
mounting methods support the physical stresses required for
swinging and impact consistent with a golf club head in use as a
golfing instrument. If validation is successful optimization is
complete. If validation fails alter both club head shell wall
thickness profile structure to provide more structural support
where needed using define mass allocation and iterate through steps
8-11.
[0234] As seen in the overall optimization process of the
integrated electronics system golf club head design, the process
requires providing structural integrity of club head shell
structure with a predetermine weight that is less than a typical
club head shell of similar type without additional assemblies. The
club head wall thickness profile variable and the materials profile
selected are the central control factors defining structural
integrity within the confines of a predetermined weight limit and
predetermined center of gravity.
[0235] FIG. 10 shows a club head shell 2000 with exemplary varying
wall thickness profile type for the benefit of minimal weight and
robust structural integrity. The club head shell 2000 (without the
club face) has an outer surface 50 and an inner cavity 2001 and
inner cavity 2001 has an inner surface (not labeled). This first
embodiment of the club head shell structure defines a wall
thickness profile that comprises areas of increased thickness 2002
and allows the predetermined and predefined outer surface 50 shape
or contour to remain constant and unchanged. Exemplary areas of
increased thickness 2002 are shown protruding into the inner cavity
2001 as interconnected ribs and are only shown for a small portion
of the total shell for clarity of illustrative drawing purposes,
however, would be implemented throughout the club head shell
structure in predetermined area locations of the shell 2000 based
on known applied stress and acceptable strain requirements. The
areas of increased thickness 2002 in this example can be described
as rib like structures that are similar to truss systems that
provide large structure force support with a conservative use of
materials. The areas of increased thickness 2002 or interconnected
ribs adapted to be a truss like system provides structural
resilience to stresses experienced by the club head shell,
especially a ball impact on the club face and stress areas around
the hosel connection. The areas of increased thickness 2002 or
ribbed structural system allows forces acting on the club head
shell to be distributed along interconnected ribs allowing the
shell wall thickness between the ribs to be very thin for the
benefit of weight and mass distribution control. The areas of
increased thickness 2002 and the protrusion thickness differences
as compared to areas of minimal wall thickness define a volume of
material that may be made of any predetermined material that is the
same as, or similar to, or non-similar to, the material of the
outer surface 50 with electrically conductive properties. In this
embodiment the material properties of the said volume of material
for areas of increased wall thickness are the same as the material
properties of the outer surface 50. Further the minimal wall
thickness of the club head shell with regards to antenna function
purposes requires only a few microns to a few mils of thickness as
defined by skin effects related to the material property of
electrical conductivity of metal(s) or alloy(s) used for the outer
surface. Therefore, the minimum thickness of the club head shell
wall thickness covering and between the areas of increased
thickness 2002 or ribs is dominated only by the requirement of
structural enhancement through support of the ribs. The areas of
increased thickness 2002 or ribbed structures and minimal thickness
areas are described entirely with the wall thickness profile of the
club head shell 2000. Further the areas of increased thickness 2002
or ribs system on inner portion of club head shell may be any
predetermined three dimensional pattern(s) or non-symmetric design
that meets the desired structural physical properties and weight
and mass distribution goals of club head shell system.
[0236] As shown in FIG. 10A another embodiment of the club head
shell structure utilizes multiple materials. FIG. 10 A shows a
close up of a cross section view showing a multi material wall
thickness profile structure. The first material 2003 is used for
the club shell outer surface area 50 and the portion of the wall
thickness profile from the surface area 50 to a depth into the wall
defined by minimum wall thickness 2004. The first material 2003 is
a material such as a metal or alloy that has electrically
conductive properties required by the antenna system. The second
material 2005 is used for areas of increased wall thickness 2002
and may be a light weight composite or other type material with
high structural strength and low mass density for light weight
structural support. Example of such materials may be but not
limited to a resin based carbon fiber composite. The first material
and second material may be attached with a high strength adhesive
or other attachment bonding process.
[0237] The club head shell structure with predetermined varying
wall thickness profile is modeled and designed as a single entity,
however for manufacturing purposes the design is segmented into two
or more pieces that are attached through welding or other affixing
process. An example of the segmented two pieces may be a crown and
a base that allow attachment of other electronics based assemblies
before attachment of crown and based and club face.
[0238] The preferred embodiment of the measurements and analysis
system functions in the following manner. As the golfer swings the
club, the club head is in bidirectional wireless communication with
a second module and in this embodiment a wireless USB module that
is placed at a predetermined location near the swing path of the
integrated electronics golf club head. The wireless USB Module is
also in wired communication with a user interface device that in
this embodiment is a laptop computer. As the golf swing is in
progress weather it is a free swing or a swing with impact the club
head is capturing sensor data and receiver signal strength data
from the wireless USB. The integrated electronics club head is also
transmitting the all sensor measurements synchronized with the
receiver signal strength measurements to the wireless USB module
that then further transmits the data through a wired connection to
the user interface device that in the case is a laptop. Residing on
the laptop is application software that runs algorithms to
interpret all data that has been measured at the club head. The
following sections describe how these algorithms to interpret and
calculate the swing metrics from the measurement made at the club
head.
[0239] The following section of this patent application describe
the algorithms used in the processing software to interpret all
sensors and receiver signal strength measurements made at the club
head during free swing and during impact to provide a rich set golf
metrics describing the quality of a golf free swing or a golf swing
with impact.
[0240] FIG. 11 shows the preferred embodiment of the invention,
which is the acceleration measurement assembly 5101 with three
orthogonal measurement axes x.sub.f-axis 5104, z.sub.f-axis 5105
and y.sub.f-axis 5106 that is attached inside the club head 5201 as
earlier described in the system optimization process.
[0241] For the club head acceleration measurement assembly 5101
mounted perfectly in the club head 5201 the following relations are
achieved: The z.sub.f-axis 5105 is aligned so that it is parallel
to the club shaft 5202. The x.sub.f-axis 5104 is aligned so that is
orthogonal to the z.sub.f-axis 5105 and perpendicular to the plane
5203 that would exist if the club face has a zero loft angle. The
y.sub.f-axis 5106 is aligned orthogonally to both the x.sub.f-axis
5104 and z.sub.f-axis 5105.
[0242] With these criteria met, the plane created by the
x.sub.f-axis 5104 and the y.sub.f-axis 5106 is perpendicular to the
non-flexed shaft 5202. In addition the plane created by the
y.sub.f-axis 5106 and the z.sub.f-axis 5105 is parallel to the
plane 5203 that would exist if the club face has a zero loft angle.
However, in the manufacturing process of the integrated electronics
club head there may be variations in alignment of the orientation
of the acceleration measurement assembly 5101 that are detected and
corrected with a correction algorithm that is covered later.
[0243] The mathematical label a.sub.sx represents the acceleration
force measured by a sensor along the club head acceleration
measurement assembly 5101 x.sub.f-axis 5104. The mathematical label
a.sub.sy represents the acceleration force measured by a sensor
along the club head acceleration measurement assembly 5101
y.sub.f-axis 5106. The mathematical label a.sub.sz represents the
acceleration force measured by a sensor along the club head
acceleration measurement assembly 5101 z.sub.f-axis 5105.
[0244] If the club head acceleration measurement assembly of the
preferred embodiment is not aligned exactly with the references of
the golf club there is an algorithm that is used to detect and
calculated the angle offset from the intended references of the
club system and a method to calibrate and correct the measured
data. This algorithm is covered in detail after the analysis is
shown for proper club head acceleration measurement assembly
attachment with no mounting angle variations.
[0245] Club head motion is much more complicated than just pure
linear accelerations during the swing. It experiences angular
rotations of the fixed sensor orthogonal measurement axes,
x.sub.f-axis 5104, y.sub.f-axis 5106 and z.sub.f-axis 5105 of
acceleration measurement assembly 5101 around all the center of
mass inertial acceleration force axes during the swing, as shown in
FIG. 12. As the golfer 5301 swings the golf club 5302 and the club
head 5201 travels on an arc there are inertial center of mass axes
along which inertia forces act on the center of mass of the club
head 5201. These are the x.sub.cm-axis 5303, y.sub.cm-axis 5305 and
z.sub.cm-axis 5304.
[0246] The three orthogonal measurement axes x.sub.f-axis 5104,
y.sub.f-axis 5106 and z.sub.f-axis 5105 of acceleration measurement
assembly 5101, along with a physics-based model of the multi-lever
action of the swing of the golfer 5301, are sufficient to determine
the motion relative to the club head three-dimensional center of
mass axes with the x.sub.cm-axis 5303, y.sub.cm-axis 5305 and
z.sub.cm-axis 5304.
[0247] The mathematical label a.sub.z is defined as the
acceleration along the z.sub.cm-axis 5304, the radial direction of
the swing, and is the axis of the centrifugal force acting on the
club head 5201 during the swing from the shoulder 5306 of the
golfer 5301. It is defined as positive in the direction away from
the golfer 5301. The mathematical label a.sub.x is the defined club
head acceleration along the x.sub.cm-axis 5303 that is
perpendicular to the a.sub.z-axis and points in the direction of
instantaneous club head inertia on the swing arc travel path 5307.
The club head acceleration is defined as positive when the club
head is accelerating in the direction of club head motion and
negative when the club head is decelerating in the direction of
club head motion. The mathematical label a.sub.y is defined as the
club head acceleration along the y.sub.cm-axis 5305 and is
perpendicular to the swing plane 5308.
[0248] During the golfer's 5301 entire swing path 5308, the
dynamically changing relationship between the two coordinate
systems, defined by the acceleration measurement assembly 5101
measurements coordinate system axes x.sub.f-axis 5104, y.sub.f-axis
5106 and z.sub.f-axis 5105 and the inertial motion acceleration
force coordinate system axes x.sub.cm-axis 5303, y.sub.cm-axis 5305
and z.sub.cm-axis 5304, must be defined. This is done through the
constraints of the multi-lever model partially consisting of the
arm lever 5309 and the club shaft lever 5310.
[0249] The multi lever system as shown in FIG. 13 shows two
interdependent angles defined as angle .eta. 5401 which is the
angle between the club head acceleration measurement assembly 5101
z.sub.f-axis 5105 and the inertial z.sub.cm-axis 5304 and the angle
.alpha. 5403 which is the sum of wrist cock angle and shaft flex
lag/lead angle (shown later in FIGS. 16 and 16A). The angle .eta.
5401 is also the club head rotation around the y.sub.cm-axis 5106
(not shown in FIG. 13 but is perpendicular to the page at the club
head center of mass) and is caused largely by the angle of wrist
cock, and to a lesser extent club shaft flexing during the swing.
The length of the variable swing radius R 5402 is a function of the
fixed length arm lever 5309, the fixed length club shaft lever 5310
and the angle .eta. 5401. The angle .eta. 5401 can vary greatly,
starting at about 40 degrees or larger at the start of the
downswing and approaches zero at club head maximum velocity. The
inertial x.sub.cm-axis 5303 is as previously stated perpendicular
to the inertial z.sub.cm-axis 5304 and variable radius R 5402.
[0250] FIG. 14 shows the angle .PHI. 5501 which is the club face
angle and is defined as the angle between the plane 5502 that is
perpendicular to the club head travel path 5307 and the plane that
is defined for zero club face loft 5203. The angle .PHI. 5501 also
represents the club head rotation around the z.sub.f-axis 5105. The
angle .PHI. 5501 varies greatly throughout the swing starting at
about 90 degrees or larger at the beginning of the downswing and
becomes less positive and perhaps even negative by the end of the
down stroke. When the angle .PHI. 5501 is positive the club face
angle is said to be "OPEN" as shown in club head orientation 5503.
During an ideal swing the angle .PHI. 5501 will be zero or said to
be "SQUARE" at the point of maximum club head velocity as shown in
club head orientation 5504. If the angle .PHI. 5501 is negative the
club face angle is said to be "CLOSED" as shown in club head
orientation 5505.
[0251] FIG. 15 shows angle .OMEGA. 5601 which is referred to as the
toe down angle and is defined as the angle between the top of a
club head 5201 of a golf club with a non-bowed shaft state 5602 and
a golf club head 5201 of a golf club with bowed shaft state 5603
due to the centrifugal force pulling the club head toe downward
during the swing. The angle .OMEGA. is a characteristic of the
multi-lever model representing the non-rigid club lever. The angle
.OMEGA. 5601 also represents the club head 5201 rotation around the
x.sub.f-axis 5104 (not shown in FIG. 15, but which is perpendicular
to the y.sub.f-axis 5106 and z.sub.f-axis 5105 intersection). The
angle .OMEGA. 5601 starts off at zero at the beginning of the
swing, and approaches a maximum value of a few degrees at the
maximum club head velocity.
[0252] FIGS. 16 and 16A show the angle .alpha. 5403 which is the
sum of angles .alpha..sub.wc 5701, defined as the wrist cock angle,
and .alpha..sub.sf 5702, defined as the shaft flex lag/lead angle.
The angle .alpha..sub.sf 5702 is the angle between a non-flexed
shaft 5703 and the flexed shaft state 5704, both in the swing plane
5308 defined in FIG. 12, and is one characteristic of the non-rigid
lever in the multi-lever model. The shaft leg/lead flex angle
.alpha..sub.sf 5702 is caused by a combination of the inertial
forces acting on the club and the wrist torque provided by the
golfer's 5301 wrists 5705 and hands 5706 on the shaft grip
5707.
[0253] FIG. 17 shows the force balance for the multi-lever swing
system. The term a.sub.v 5805 is the vector sum of a.sub.x 5804 and
a.sub.z 5803. The resulting force is given by
F.sub.v=m.sub.sa.sub.v where m.sub.s is the mass of the club head
system. The term F.sub.v 5806 is also, from the force balance, the
vector sum of the tensile force, F.sub.t 5807, in the shaft due to
the shoulder torque 5801, and F.sub.wt 5808, due to wrist torque
5802. The angle between force vector F.sub.v 5806 and the swing
radius, R 5402, is the sum of the angles .eta. 5401 and
.eta..sub.wt 5809.
[0254] There are several ways to treat the rotation of one axes
frame relative to another, such as the use of rotation matrices.
The approach described below is chosen because it is intuitive and
easily understandable, but other approaches with those familiar
with the art would fall under the scope of this invention.
[0255] Using the multi-lever model using levers, rigid and
non-rigid, the rotation angles describing the orientation
relationship between the acceleration measurement assembly measured
axis coordinate system and the inertial acceleration force axes
coordinate system can be determined from the sensors in the club
head acceleration measurement assembly 5101 through the following
relationships:
a.sub.sx=a.sub.x cos(.PHI.)cos(.eta.)-a.sub.y sin(.PHI.)-a.sub.z
cos(.PHI.)sin(.eta.) 1.
a.sub.sy=a.sub.x sin(.PHI.)cos(.eta.)+a.sub.y
cos(.PHI.)+a.sub.z(sin(.PHI.)-sin(.PHI.)sin(.eta.)), 2.
a.sub.sz=a.sub.x sin(.eta.)-a.sub.y sin(.OMEGA.)cos(.PHI.)+a.sub.z
cos(.eta.) 3.
[0256] The following is a reiteration of the mathematical labels
for the above equations.
[0257] a.sub.x is the club head acceleration in the x.sub.cm-axis
303 direction.
[0258] a.sub.y is the club head acceleration in the y.sub.cm-axis
305 direction.
[0259] a.sub.z is the club head acceleration in the z.sub.cm-axis
304 direction.
[0260] a.sub.sx is the acceleration value returned by the club head
acceleration measurement assembly 5101 sensor along the
x.sub.f-axis 5104.
[0261] a.sub.sy is the acceleration value returned by the club head
acceleration measurement assembly 5101 sensor along the
y.sub.f-axis 5106.
[0262] a.sub.sz is the acceleration value returned by the club head
acceleration measurement assembly 5101 sensor along the
z.sub.f-axis 5105.
During a normal golf swing with a flat swing plane 5308, a.sub.y
will be zero, allowing the equations to be simplified:
a.sub.sx=a.sub.x cos(.PHI.)cos(.eta.)+a.sub.z
cos(.OMEGA.)-sin(.PHI.) 4.
a.sub.sy=a.sub.x
sin(.PHI.)cos(.eta.)+a.sub.z(sin(.PHI.)-sin(.PHI.)sin(.eta.))
5.
a.sub.sz=a.sub.x sin(.eta.)+a.sub.z cos(.eta.) 6.
These equations are valid for a "free swing" where there is no
contact with the golf ball.
[0263] The only known values in the above are a.sub.sx, a.sub.sy,
and a.sub.sz from the three sensors. The three angles are all
unknown. It will be shown below that a.sub.x and a.sub.z are
related, leaving only one unknown acceleration. However, that still
leaves four unknowns to solve for with only three equations. The
only way to achieve a solution is through an understanding the
physics of the multi-lever variable radius swing system dynamics
and choosing precise points in the swing where physics governed
relationships between specific variables can be used.
[0264] The angle .PHI. 5501, also known as the club face approach
angle, varies at least by 180 degrees throughout the backswing,
downswing, and follow through. Ideally it is zero at maximum
velocity, but a positive value will result in an "open" clubface
and negative values will result in a "closed" face. The angle .PHI.
5501 is at the control of the golfer and the resulting swing
mechanics, and is not dependent on either a.sub.x or a.sub.z.
However, it cannot be known a-priori, as it depends entirely on the
initial angle of rotation around the shaft when the golfer grips
the shaft handle and the angular rotational velocity of angle .PHI.
5501 during the golfer's swing.
[0265] The angle .OMEGA. 5601, on the other hand, is dependent on
a.sub.z, where the radial acceleration causes a centrifugal force
acting on the center of mass of the club head, rotating the club
head down around the x.sub.f-axis into a "toe" down position of
several degrees. Therefore, angle .OMEGA. 5601 is a function of
a.sub.z. This function can be derived from a physics analysis to
eliminate another unknown from the equations.
[0266] The angle .eta. 5401 results from both club shaft angle 5702
lag/lead during the downswing and wrist cock angle 5701. Wrist cock
angle is due both to the mechanics and geometry relationships of
the multi lever swing model as shown in FIG. 12 and the amount of
torque exerted by the wrists and hands on the shaft.
[0267] Before examining the specifics of these angles, it is worth
looking at the general behavior of equations (4) through (6). If
both angle .OMEGA. 5601 and angle .eta. 5401 were always zero,
which is equivalent to the model used by Hammond in U.S. Pat. No.
3,945,646, the swing mechanics reduces to a single lever constant
radius model. For this case:
a.sub.sx=a.sub.x cos(.PHI.) 7.
a.sub.sy=a.sub.x sin(.PHI.)) 8.
a.sub.sz=a.sub.z 9.
[0268] This has the simple solution for club face angle .PHI.
of:
tan ( .PHI. ) = a sy a sx ##EQU00001##
[0269] In Hammond's patent U.S. Pat. No. 3,945,646 he states in
column 4 starting in line 10 "By computing the vector angle from
the acceleration measured by accelerometers 12 and 13, the position
of the club face 11 at any instant in time during the swing can be
determined." As a result of Hammond using a single lever constant
radius model which results in equation 10 above, it is obvious he
failed to contemplate effects of the centrifugal force components
on sensor 12 and sensor 13 of his patent. The large error effects
of this can be understood by the fact that the a.sub.z centrifugal
acceleration force is typically 50 times or more greater than the
measured acceleration forces of a.sub.sx and a.sub.sy for the last
third of the down swing and first third of the follow through.
Therefore, even a small angle .OMEGA. 5601 causing an a.sub.z
component to be rotated onto the measured a.sub.sy creates enormous
errors in the single lever golf swing model.
[0270] In addition, the effect of the angle .eta. 5401 in the multi
lever variable radius swing model is to introduce a.sub.z
components into a.sub.sx and a.sub.sy, and an a.sub.x component
into a.sub.sz. The angle .eta. 5401 can vary from a large value at
the start and midpoint of the down stroke when a.sub.z is growing
from zero. In later portion of the down stroke a.sub.z becomes very
large as angle .eta. 5401 tends towards zero at maximum velocity.
Also, as mentioned above, the angle .eta. 5401 introduces an
a.sub.x component into a.sub.sz. This component will be negligible
at the point of maximum club head velocity where angle .eta. 5401
approaches zero, but will be significant in the earlier part of the
swing where angle .eta. 5401 is large and the value of a.sub.x is
larger than that for a.sub.z.
[0271] The cos(.eta.) term in equations (4) and (5) is the
projection of a.sub.x onto the x.sub.f-y.sub.f plane, which is then
projected onto the x.sub.f axis 5104 and the y.sub.f axis 5106.
These projections result in the a.sub.x cos(.PHI.)cos(.eta.) and
a.sub.x sin(.PHI.)cos(.eta.) terms respectively in equations (4)
and (5). The projection of a.sub.x onto the z.sub.f-axis 5105 is
given by the a.sub.x sin(.eta.) term in equation (6).
[0272] The sin(.eta.) terms in equations (4) and (5) are the
projection of a.sub.z onto the plane defined by x.sub.f axis 5104
and the y.sub.f axis 5106, which is then projected onto the x.sub.f
axis 5104 and y.sub.f axis 5106 through the a.sub.z
cos(.PHI.)sin(.eta.) and a.sub.z sin(.PHI.)sin(.eta.) terms
respectively in equations (4) and (5). The projection of a.sub.z
onto the z.sub.f-axis 5105 is given by the a.sub.z cos(.eta.) term
in equation (6).
[0273] The angle .OMEGA. 5601 introduces yet another component of
a.sub.z into a.sub.sy. The angle .OMEGA. 5601 reaches a maximum
value of only a few degrees at the point of maximum club head
velocity, so its main contribution will be at this point in the
swing. Since angle .OMEGA.5601 is around the x.sub.f-axis 5104, it
makes no contribution to a.sub.sx, so its main effect is the
a.sub.z sin(.OMEGA.) projection onto the y.sub.f-axis 5106 of
equation (5). Equations (4) and (5) can be simplified by re-writing
as:
a.sub.sx=(a.sub.x cos(.eta.)-a.sub.z
sin(.eta.))cos(.PHI.))=f(.eta.)cos(.PHI.) and 11.
a.sub.sy=(a.sub.x cos(.eta.)-a.sub.z sin(.eta.))sin(.PHI.)+a.sub.z
sin(.OMEGA.)=f(.eta.)sin(.PHI.)+a.sub.z sin(.OMEGA.) where 12.
f(.eta.)=a.sub.x cos(.eta.)-a.sub.z sin(.eta.). From (11): 13.
14. f ( .eta. ) = a sx cos ( .PHI. ) ##EQU00002##
which when inserted into (12) obtains:
a.sub.sy=a tan(.PHI.)+a.sub.z sin(.OMEGA.) 15.
[0274] From equation (15) it is seen that the simple relationship
between a.sub.sx and a.sub.sy of equation (10) is modified by the
addition of the a.sub.z term above. Equations (4) and (6) are
re-written as:
16. a x = a sx cos ( .eta. ) cos ( .PHI. ) + a z sin ( .eta. ) cos
( .eta. ) ##EQU00003## 17. a z = a sz cos ( .eta. ) - a x sin (
.eta. ) cos ( .eta. ) . ##EQU00003.2##
[0275] These equations are simply solved by substitution to
yield:
18. a z = a sz cos ( .eta. ) - a sx sin ( .eta. ) cos ( .PHI. ) .
19. a x = a sz sin ( .eta. ) + a sx cos ( .eta. ) cos ( .PHI. ) .
##EQU00004##
[0276] Equation (19) can be used to find an equation for sin(.eta.)
by re-arranging, squaring both sides, and using the identity,
cos.sup.2(.eta.)=1-sin.sup.2(.eta.), to yield a quadratic equation
for sin(.eta.), with the solution:
20. sin ( .eta. ) = a x a sz + a sx 2 cos 2 ( .PHI. ) 1 - cos 2 (
.PHI. ) ( a sz 2 - a x 2 a sx 2 ) a sz 2 + a sx 2 cos 2 ( .PHI. ) .
##EQU00005##
[0277] To get any further for a solution of the three angles, it is
necessary to examine the physical cause of each. As discussed above
the angle .eta. 5401 can be found from an analysis of the angle
.alpha. 5403, which is the sum of the angles .alpha..sub.wc 5701,
due to wrist cock and .alpha..sub.sf 5702 due to shaft flex lag or
lead.
[0278] Angle .alpha. 5403, and angle .eta. 5401 are shown in FIG. 4
in relationship to variable swing radius R 5402, fixed length arm
lever A 5309, and fixed length club shaft lever C 5310. The
mathematical equations relating these geometric components are:
R.sup.2=A.sup.2+C.sup.2+2AC cos(.alpha.) 21.
A.sup.2=R.sup.2+C.sup.2-2RC cos(.eta.) 22.
[0279] Using R.sup.2 from equation (21) in (22) yields a simple
relationship between .alpha. and .eta.:
.alpha.=cos.sup.-1((R cos(.eta.)-C)/A) 23. [0280] The swing radius,
R 5402, can be expressed either in terms of cos(.alpha.) or
cos(.eta.). Equation (21) provides R directly to be:
[0280] R= {square root over (C.sup.2+A.sup.2+2AC cos(a))} 24.
Equation (22) is a quadratic for R which is solved to be:
R=C cos(.eta.)+ {square root over (C.sup.2(cos(.eta.)-1)+A.sup.2)}.
25. [0281] Both .alpha. 5403 and .eta. 5401 tend to zero at maximum
velocity, for which R.sub.m=A+C. [0282] The solutions for the
accelerations experienced by the club head as it travels with
increasing velocity on this swing arc defined by equation (25)
are:
[0282] 26. a z = V .GAMMA. 2 R - V R t ##EQU00006## 27. a x = 2 R V
R V .GAMMA. + R t ( V .GAMMA. R ) ##EQU00006.2##
[0283] The acceleration a.sub.z is parallel with the direction of R
5402, and a.sub.x is perpendicular to it in the swing plane 5308.
The term V.sub..GAMMA. is the velocity perpendicular to R 5402 in
the swing plane 5308, where .GAMMA. is the swing angle measured
with respect to the value zero at maximum velocity. The term
V.sub.R is the velocity along the direction of R 5402 and is given
by dR/dt. The swing geometry makes it reasonably straightforward to
solve for both V.sub.R and its time derivative, and it will be
shown that a.sub.z can also be solved for which then allows a
solution for V.sub..GAMMA.:
28. V .GAMMA. = Ra z + R V r t ##EQU00007##
[0284] Now define:
29. a z - radial = V .GAMMA. 2 R ##EQU00008##
[0285] so that:
V.sub..GAMMA.= {square root over (Ra.sub.Z-radial)} 30.
[0286] Next define:
31. a ch = V .GAMMA. ( t ) t = .DELTA. V .GAMMA. ( T ) .DELTA. t ,
##EQU00009## [0287] Because (31) has the variable R 5402 included
as part of the time derivative equation (27) can be written:
[0287] 32. a x = a ch + 2 R V R V .GAMMA. ##EQU00010##
[0288] Also equation (26) can be written:
33. a z = a z - radial - V R t ##EQU00011##
[0289] The acceleration a.sub.v 805 is the vector sum of a.sub.x
5804 and a.sub.z 5803 with magnitude:
34. a v = a x 2 + a z 2 = a x sin ( .beta. ) = a z cos ( .beta. )
##EQU00012##
[0290] where
35. .beta. = tan - 1 ( a x a z ) ##EQU00013##
[0291] The resulting magnitude of the force acting on the club head
is then:
F.sub.v=m.sub.sa.sub.v 36.
[0292] FIG. 17 shows this force balance for F.sub.v 5806. If there
is no force F.sub.wt 5808 acting on the golf club head due to
torque 5802 provided by the wrists, then F.sub.v 5806 is just
F.sub.t 5807 along the direction of the shaft, and is due entirely
by the arms pulling on the shaft due to shoulder torque 5801. For
this case it is seen that:
.beta.=.eta. for no wrist torque. 37.
[0293] On the other hand, when force F.sub.wt 5808 is applied due
to wrist torque 5802:
.beta.=.eta.+.eta..sub.wt where: 38.
F.sub.wt=F.sub.v sin(.eta..sub.wt). 39.
[0294] The angle .eta..sub.wt 5809 is due to wrist torque 5802.
From (38):
40. .eta. = ( 1 - .eta. wt .beta. ) .beta. = C .eta. .beta.
##EQU00014## [0295] where C.sub.n<1 is a curve fitting parameter
to match the data, and is nominally around the range of 0.75 to
0.85. From the fitted value:
[0295] .eta..sub.wt=(1-C.sub..eta.).beta. 41.
[0296] Using (41) in (39) determines the force F.sub.wt 5808 due to
wrist torque 5802.
[0297] To solve for angle .OMEGA. 5601 as previously defined in
FIG. 15 the force balance shown in FIG. 18 is applied to accurately
determine the toe down angle .OMEGA. 5601. A torque 5901 acting on
club head 5201 with mass M is generated by the acceleration vector
5902 on the z.sub.cm-axis 5304 with magnitude a.sub.z acting
through the club head 5201 center of mass 5903. The center of mass
5903 is a distance 5904 from the center axis 5905 of club shaft
5202 with length C 5310 and stiffness constant K. The mathematical
label for distance 5904 is d. Solving the force balance with the
constraints of a flexible shaft K gives an expression for .OMEGA.
5601:
.OMEGA. = C .OMEGA. C ( Ma z KC 1 + Ma z KC ) . 42 ##EQU00015##
[0298] It is worth noting that from equation (42) for increasing
values of a.sub.z there is a maximum angle .OMEGA. 5601 that can be
achieved of d C.sub..OMEGA./C which for a typical large head driver
is around 4 degrees. The term C.sub..OMEGA. is a curve fit
parameter to account for variable shaft stiffness profiles for a
given K. In other words different shafts can have an overall
stiffness constant that is equal, however, the segmented stiffness
profile of the shaft can vary along the taper of the shaft.
[0299] An equation for angle .PHI. 5501 in terms of angle .OMEGA.
5601 can now be found. This is done by first using equation (17)
for a.sub.z in equation (15):
a sy = a sx sin ( .PHI. ) cos ( .PHI. ) + a sz cos ( .eta. ) sin (
.OMEGA. ) - a sx sin ( .eta. ) sin ( .OMEGA. ) cos ( .PHI. ) . 43
##EQU00016##
[0300] Re-arranging terms:
(a.sub.sy-a.sub.sz cos(.eta.)sin(.OMEGA.))cos(.PHI.)=a.sub.sx
sin(.PHI.)-a.sub.sx sin(.eta.)sin(.OMEGA.) 44. [0301] Squaring both
sides, and using the identity cos.sup.2(.PHI.)=1-sin.sup.2(.PHI.)
yields a quadratic equation for sin(.PHI.):
[0301] sin.sup.2(.PHI.)[a.sub.sx.sup.2+(a.sub.sy-a.sub.sz
cos(.eta.)sin(.OMEGA.)).sup.2]-2a.sub.sx.sup.2
sin(.PHI.)sin(.eta.)sin(.OMEGA.)+a.sub.sx.sup.2(sin(.eta.)sin(.OMEGA.)).s-
up.2-(a.sub.sy-a.sub.sz
cos(.eta.)sin(.PHI.)sin(.eta.)sin(.OMEGA.)).sup.2=0 45.
[0302] Equation (45) has the solution:
sin ( .PHI. ) = 1 2 b 1 [ - b 2 + b 2 2 - 4 b 1 b 3 ] . 46
##EQU00017##
[0303] where the terms in (46) are:
b.sub.1=a.sub.sx.sup.2+(a.sub.sy-a.sub.sz
cos(.eta.)sin(.OMEGA.)).sup.2
b.sub.2=-2a.sub.sx.sup.2 sin(.eta.)sin(.OMEGA.)
b.sub.3=a.sub.sx.sup.2(sin(.eta.)sin(.OMEGA.)).sup.2-(a.sub.sy-a.sub.sz
cos(.eta.)sin(.OMEGA.)).sup.2 [0304] Equations (42) for .OMEGA.
5601, (46) for .PHI. 5501, and (20) for .eta. 5401 need to be
solved either numerically or iteratively using equations (32) for
a.sub.x, (33) for a.sub.z, and (25) for R 5402. This task is
extremely complex. However, some innovative approximations can
yield excellent results with much reduced complexity. One such
approach is to look at the end of the power-stroke segment of the
swing where V.sub.R and its time derivative go to zero, for which
from equations (32), (33), (35) and (40):
[0304] .eta. = C .eta. tan - 1 ( a ch a x - radial ) . 47
##EQU00018## [0305] In this part of the swing the a.sub.sx term
will be much smaller than the a.sub.sz term and equation (18) can
be approximated by:
[0305] a.sub.z=a.sub.z-radical=a.sub.sz cos(.eta.) 48. [0306]
During the earlier part of the swing, the curve fit coefficient
C.sub..eta. would accommodate non-zero values of V.sub.R and its
time derivative as well as the force due to wrist torque 5802.
[0307] The maximum value of .eta. 5401 is nominally around 40
degrees for which from (48) a.sub.ch/a.sub.z-radial=1.34 with
C.sub..eta.=0.75. So equation (47) is valid for the range from
a.sub.ch=0 to a.sub.ch=1.34 a.sub.z-radial, which is about a third
of the way into the down-stroke portion of the swing. At the
maximum value of .eta. 5401 the vector a.sub.v 5805 is 13 degrees,
or 0.23 radians, off alignment with the z.sub.f axis and its
projection onto the z.sub.f axis 5105 is a.sub.sz=a.sub.v
cos(0.23)=0.97a.sub.v. Therefore, this results in a maximum error
for the expression (48) for a.sub.z=a.sub.z-radial of only 3%. This
amount of error is the result of ignoring the a.sub.sx term in
equation (18). This physically means that for a.sub.z in this part
of the swing the a.sub.z-radial component value dominates that of
the a.sub.sx component value. Equation (47) can not be blindly
applied without first considering the implications for the function
f(.eta.) defined by equations (13) and (14), which has a functional
dependence on cos(.PHI.) through the a.sub.sx term, which will not
be present when (47) is used in (13). Therefore, this cos(.PHI.)
dependence must be explicitly included when using (47) to calculate
(13) in equation (12) for a.sub.sy, resulting in:
a.sub.sy=(a.sub.x cos(.eta.)-.alpha..sub.z
sin(.eta.))tan(.PHI.)+a.sub.z sin(.OMEGA.) 49.
[0308] Equation (49) is applicable only when equation (47) is used
for the angle .eta. 5401.
[0309] A preferred embodiment is next described that uses the
simplifying equations of (47) through (49) to extract results for
.PHI. 5501 and .eta. 5401 using (42) as a model for .OMEGA. 5601.
It also demonstrates how the wrist cock angle .alpha..sub.we 5701
and shaft flex angle .alpha..sub.sf 5702 can be extracted, as well
as the mounting angle errors of the accelerometer acceleration
measurement assembly. Although this is the preferred approach,
other approaches fall under the scope of this invention.
[0310] The starting point is re-writing the equations in the
following form using the approximations a.sub.z-=a.sub.z-radial and
a.sub.x=a.sub.ch. As discussed above these are excellent
approximations in the later part of the swing. Re-writing the
equations (4) and (49) with these terms yields:
a.sub.sx=a.sub.ch cos(.PHI.)cos(.eta.)-a.sub.z-radial
cos(.PHI.)sin(.eta.) 50.
a.sub.sy=a.sub.ch tan(.PHI.)cos(.eta.)+a.sub.z-radial
sin(.OMEGA.)-a.sub.z-radial tan(.PHI.)sin(.eta.) 51.
a.sub.z-radial=a.sub.sz cos(.eta.) 52.
[0311] Simplifying equation (31):
a ch = V t . 53 ##EQU00019##
[0312] In this approximation V=V.sub..GAMMA. is the club head
velocity and dt is the time increment between sensor data points.
The instantaneous velocity of the club head traveling on an arc
with radius R is from equation (29):
V= {square root over
(a.sub.z-radialR)}=a.sub.z-radial.sup.1/2R.sup.1/2 for which
54.
a ch = V t = 1 2 ( 1 R R t + 1 a z - radial a z - radial t ) Ra z -
radial . 55 ##EQU00020##
[0313] Using equation (52) for a.sub.z-radial in (55):
a ch = 1 2 ( 1 R R t + 1 a sz a sz t - tan ( .eta. ) .eta. t ) Ra
sz cos ( .eta. ) . 56 ##EQU00021## [0314] During the early part of
the downswing, all the derivative terms will contribute to
a.sub.ch, but in the later part of the downswing when R is reaching
its maximum value, R.sub.max, and .eta. is approaching zero, the
dominant term by far is the da.sub.sz/dt term, which allows the
simplification for this part of the swing:
[0314] a ch = 1 2 ( 1 a sz a sz t ) Ra sz cos ( .eta. ) . ( 57 )
##EQU00022##
[0315] With discreet sensor data taken at time intervals .DELTA.t,
the equivalent of the above is:
a ch = R cos ( .eta. ) .DELTA. t ( a sz ( t n ) - a sz ( t n - 1 )
) . 58 ##EQU00023## [0316] It is convenient to define the behavior
for a.sub.ch for the case where R=R.sub.max and .eta.=0, so that
from equation (52) a.sub.z-radial=a.sub.sz, which defines:
[0316] a chsz = R max .DELTA. t ( a sz ( t n ) - a sz ( t n - 1 ) )
. 59 ##EQU00024##
[0317] Then the inertial spatial translation acceleration component
of the club head is:
a ch = a chsz = R cos ( .eta. ) R max . 60 ##EQU00025## [0318]
Substituting equation (52) and (60) back into equations (50) and
(51) we have the equations containing all golf swing metric angles
assuming no acceleration measurement assembly mounting angle errors
in terms of direct measured sensor outputs:
[0318] a.sub.sx=a.sub.chsz( {square root over (R cos(.eta.))}/
{square root over (R.sub.Max)})cos(.PHI.)cos(.eta.)-a.sub.sz
cos(.eta.)cos(.PHI.)sin(.eta.) 61.
a.sub.sy=a.sub.chsz( {square root over (R COS(.eta.))}/ {square
root over (R.sub.Max)})tan(.PHI.)cos(.eta.)+a.sub.sz
cos(.eta.)sin(.OMEGA.)-a.sub.sz cos(.eta.)tan(.PHI.)sin(.eta.) 62.
[0319] Using equation (62) to solve for .PHI., since this is the
only equation that contains both .eta. and .OMEGA., yields:
[0319] tan ( .PHI. ) = a sy - a sz cos ( .eta. ) sin ( .OMEGA. ) a
chsz ( R cos ( .eta. ) / R Max ) cos ( .eta. ) - a sz cos ( .eta. )
sin ( .eta. ) . 63 ##EQU00026##
[0320] Now there are two equations with three unknowns. However,
one of the unknowns, .eta., has the curve fit parameter C.sub..eta.
that can be iteratively determined to give best results for
continuity of the resulting time varying curves for each of the
system variables. Also, there are boundary conditions from the
multi-lever model of the swing that are applied, to specifics
points and areas of the golf swing, such as the point of maximum
club head velocity at the end of the downstroke, where: [0321] 1.
For a golf swing approaching max velocity the value of .eta.
approaches zero, [0322] 2. .OMEGA. is at a maximum value when
centrifugal force is highest, which occurs at maximum velocity.
[0323] 3. The club face angle, .OMEGA., can vary greatly at maximum
club head velocity. However, regardless of the angle at maximum
velocity the angle is changing at a virtual constant rate just
before and after the point of maximum club head velocity. [0324]
This knowledge allows for all equations to be solved, through an
interactive process using starting points for the curve fit
parameters.
[0325] The angle .OMEGA. 601 is a function of a.sub.sz through
equations (42), (48) and (52). The curve fit constant,
C.sub..OMEGA., is required since different shafts can have an
overall stiffness constant that is equal, however, the segmented
stiffness profile of the shaft can vary along the taper of the
shaft. The value of C.sub..OMEGA. will be very close to one,
typically less than 1/10 of a percent variation for the condition
of no acceleration measurement assembly mounting angle error from
the intended alignment. Values of C.sub..OMEGA. greater or less
than 1/10 of a percent indicates a acceleration measurement
assembly mounting error angle along the y.sub.cm-axis which will be
discussed later. Re-writing equation (42) using (52):
.OMEGA. = C .OMEGA. m s a sz cos ( .eta. ) C ( KC + m s a sz cos (
.eta. ) ) . 64 ##EQU00027##
[0326] The constants in equation (64) are: [0327] C.sub..OMEGA.
Multiplying curve fit factor applied for iterative solution [0328]
d Distance from housel to center of gravity (COG) of club head
[0329] m.sub.s mass of club head system, including club head and
Club Head Module [0330] a.sub.sz The measured z.sub.f-axis 5105
acceleration force value [0331] K Stiffness coefficient of shaft
supplied by the golfer or which can be determined in the
calibration process associated with the user profile entry section
of the analysis program [0332] C Club length
[0333] The angle .eta. 5401 is found from equation (47):
.eta. = C .eta. tan - 1 ( a ch a z - radial ) . 65 ##EQU00028##
[0334] The curve fit parameter, C.sub..eta., has an initial value
of 0.75.
[0335] An iterative solution process is used to solve equations
(61), (63), and (64), using (65) for .eta. 401, which has the
following defined steps for the discreet data tables obtained by
the sensors: [0336] 1. Determine from sample points of a.sub.sz the
zero crossing position of a.sub.chsz. This is the point where the
club head acceleration is zero and therefore the maximum velocity
is achieved. Because the samples are digitized quantities at
discrete time increments there will be two sample points, where
a.sub.chsz has a positive value and an adjacent sample point where
a.sub.chsz has a negative value. [0337] 2. Course tune of .OMEGA.
5601: Use initial approximation values to solve for the numerator
of tan (.PHI.) of equation (63) with respect to the sample point
where a.sub.ch passes through zero: [0338] a. Numerator of tan
(.PHI.)={a.sub.sy-a.sub.sz cos(.eta.)sin(.OMEGA.)} [0339] b. The
numerator of tan (.PHI.) in equation 63 represents the measured
value of a.sub.sy minus a.sub.z-radial components resulting from
angle .OMEGA. with the following conditions at maximum velocity:
[0340] i. Toe down angle .OMEGA., which is at its maximum value at
maximum club head velocity, where maximum a.sub.sz is achieved at
.eta.=0, for which a.sub.sz=a.sub.z-radial From equation (52).
[0341] ii. Angle .eta. 5401, which is a function of wrist cock and
shaft flex lag/lead, is zero when maximum velocity is reached and
a.sub.ch is zero. [0342] c. Use the multiplying constant
C.sub..OMEGA. to adjust the .OMEGA. 5601 equation so that the tan
(.PHI.) numerator function sample point value, equivalent to the
first negative sample point value of a.sub.ch, is set to the value
zero. [0343] 3. Use new course tune value for the .OMEGA. 5601
function to calculate .OMEGA. 5501 from equation (63) for all
sample points. [0344] 4. Next, fine tune the multiplying constant
C.sub..OMEGA. of the .OMEGA. 5601 function by evaluating the slope
of .PHI. 5501, for the point pairs before, through, and after
maximum velocity. [0345] a. Examine sample point pairs of the total
tan (1) function given by equation (63) before maximum velocity,
through maximum velocity, and after maximum velocity, evaluating
slope variation across sample pairs. [0346] b. Evaluate sequential
slope point pairs comparing slopes to determine a variation metric.
[0347] c. Tune multiplying constant C.sub..OMEGA. of .OMEGA. 5601
function in very small increments until the slope of .PHI. 5501 of
all sample point pairs are equivalent. [0348] d. Now the value of
the .OMEGA. function is defined but the value of .eta. is still
given with the initial value of C.sub..eta.=0.75. Therefore, even
though the value of .PHI. 5501 is exact for values very near max
velocity where .eta. 5401 approaches zero, values of .PHI. 5501 are
only approximations away from maximum velocity since .PHI. 5501 is
a function of .eta. 5401, which at this point is limited by the
initial approximation. [0349] 5. Calculate all sample points for
the for the following functions: [0350] a. The fine tuned function
.OMEGA. 5601 [0351] b. Approximate function .eta. 5401 with
C.sub..eta.=0.75. [0352] c. Function .PHI. 5501 from equation (63)
[0353] i. Which will be exact for sample points close to maximum
velocity [0354] ii. Which will be an approximation for the sample
points away from max velocity because the function .eta. 5401 is
still an approximate function. [0355] 6. Tune the multiplying curve
fit constant C.sub..eta. of the .eta. 5401 function using equation
(61). This is done by rewriting equation (61) into a form which
allows the comparison of a.sub.sx minus the a.sub.sz components
which must be equal to a.sub.chsz. The evaluation equation is from
(61): [0356] a. . . .
[0356] {a.sub.sx+a.sub.sz
cos(.eta.)cos(.phi.)sin(.eta.)}/{cos(.phi.)cos(.eta.)}=a.sub.chsz(
{square root over (R cos(.eta.))}/ {square root over (R.sub.Max))}
[0357] b. If everything were exact, the two sides of this equation
would be equal. If not, they will differ by the variance:
[0357] Variance={a.sub.sx+a.sub.sz
cos(.eta.)cos(.phi.)sin(.eta.)}/{cos(.phi.)cos(.eta.)}-a.sub.chsz(
{square root over (R cos(.eta.))}/ {square root over (R.sub.Max)})
[0358] c. This variance metric is summed across a significant
number of sample points before and after maximum velocity for each
small increment that C.sub..eta. is adjusted. [0359] d. The minimum
summed variance metric set defines the value of the constant
C.sub..eta. for the .eta. 5401 function. [0360] 7. Compare the
value of C.sub..eta. obtained at the conclusion of the above
sequence with the starting value of C.sub..eta., and if the
difference is greater than 0.1 repeat steps 3 through 7 where the
initial value for C.sub..eta. in step 3 is the last iterated value
from step 6.d. When the difference is less than 0.1, the final
value of C.sub..eta. has been obtained. [0361] 8. Angle .alpha.
5403 is now solved from equation (23) with .eta. 5401 across all
sample points: .alpha.=cos.sup.-1((R cos(.eta.)-C)/A) [0362] a.
.alpha. 5403 represents the sum of wrist cock angle and shaft flex
lag/lead angle as defined by .alpha.=.alpha..sub.wc+.alpha..sub.sf.
[0363] b. In a standard golf swing the wrist cock angle is a
decreasing angle at a constant rate during the down stroke to
maximum club head velocity. Therefore, the angle can be
approximated as a straight line from the point where wrist cock
unwind is initiated. [0364] c. The slope of the angle
.alpha..sub.wc 5701 is: [0365] i. [.alpha..sub.wc(at wrist cock
unwind initiation)-.alpha..sub.wc(club head max
Velocity)]/.DELTA.T, where .DELTA.T is the time duration for this
occurrence. [0366] d. Since .alpha..sub.wc 5701 goes to zero at the
point of maximum velocity and the time duration .DELTA.T is known,
the function of angle .alpha..sub.wc 5701 is now defined. [0367] 9.
The shaft flex angle .alpha..sub.sf 5702 is now defined as
.alpha..sub.sf=.alpha.-.alpha..sub.wc for all sample points during
down stroke. Any deviation from the straight line function of
.alpha..sub.wc 5701 is due to shaft flex. The iterative analysis
solution described above is based on the club head acceleration
measurement assembly being mounted so that the x.sub.f-axis 5104,
y.sub.f-axis 5106, and z.sub.f-axis 5105 associated with the club
head acceleration measurement assembly 5101 are aligned correctly
with the golf club structural alignment elements as previously
described in FIG. 11.
[0368] Since the acceleration measurement assembly 5101 is
installed in the club head during the manufacturing process, the
cost of manufacturing the integrated electronics golf club head is
higher when more stringent requirements are placed on the
orientation accuracy of the acceleration measurement assembly 5101.
To reduce this cost the manufacturing accuracy requirements are
reduced by using an algorithm that can detect orientation offsets
of the acceleration measurement assembly 5101 and correct the
measured data in accordance with the detected offset.
[0369] During the manufacturing an angle rotation error around the
rotation around the y.sub.f-axis 5106 causing the x.sub.f-axis 5104
and z.sub.f-axis 5105 to be misaligned with their intended club
structure references. The mathematical label that describes this
error angle of rotation is .lamda.. In addition, there can be an
error angle rotation around the x.sub.f-axis 5104 causing the
y.sub.f-axis 5106 and the z.sub.f-axis 5105 to be misaligned with
the intended club structure references. The mathematical label that
describes this angle of rotation is .kappa.. This mounting error
can be experimentally determined using a standard golf swing.
[0370] For a linear acceleration path the relationship between true
acceleration and that of the misaligned measured value of a.sub.sx
is given by the following equations where a.sub.sx-true is defined
as what the measured data would be along the x.sub.f-axis 5104 with
.lamda.=0 degrees. A similar definition holds for a.sub.sz-true
along the z.sub.f axis 5105. Then:
a.sub.sx-true=a.sub.sx/cos(.lamda.) 66.
a.sub.sz-true=a.sub.sx/cos(.lamda.) 67. [0371] However, the travel
path 5307 is not linear for a golf swing which creates a radial
component due to the fixed orientation error between the offset
acceleration measurement assembly measurement coordinate system and
the properly aligned acceleration measurement assembly measurement
coordinate system. As a result, any misalignment of the club head
acceleration measurement assembly axis by angle .lamda. creates an
a.sub.z-radial component as measured by the misaligned x.sub.f-axis
5104. The a.sub.z-radial component contributes to the a.sub.sx
measurement in the following manner:
[0371] a.sub.sx=a.sub.sx-true+a.sub.sz sin(.lamda.) 68. [0372] The
angle .lamda. is constant in relation to the club structure, making
the relationship above constant, or always true, for the entire
swing. The detection and calibrating correction process of the
mounting variation angle .lamda. is determined by examining
equations (50) and (53) at the point of maximum velocity where by
definition: [0373] .eta. goes to zero [0374] a.sub.ch goes to
zero
[0375] Therefore, at maximum velocity a.sub.sx-true must also go to
zero. At maximum velocity:
a sx - true = a sx - a sz sin ( .lamda. ) = 0. 69 .lamda. = sin - 1
( a sx a sz ) . 70 ##EQU00029## [0376] Now the measured data arrays
for both the affected measurement axis x.sub.f-axis 5104 and
z.sub.f-axis 5105 must be updated with calibrated data arrays.
[0376] a.sub.sx-cal=a.sub.sx-a.sub.sz sin .lamda. 71.
a.sub.sz-cal=a.sub.sz/cos .lamda. 72. [0377] The new calibrated
data arrays a.sub.sx-cal and a.sub.sz-cal are now used and replaces
all a.sub.sx and a.sub.sz values in previous equations which
completes the detection and calibration of club head acceleration
measurement assembly mounting errors due to a error rotation around
the y.sub.f-axis 5106.
[0378] The detection of mounting error angle .kappa. is achieved by
evaluating C.sub..OMEGA. resulting from the iterative solution
steps 2 though 4 described earlier. If C.sub..OMEGA. is not very
close or equal to one, then there is an additional a.sub.z-radial
contribution to a.sub.sy from mounting error angle .kappa.. The
magnitude of mounting error angle .kappa. is determined by
evaluating .OMEGA. 601 at maximum velocity from equation (64) where
for no mounting error C.sub..OMEGA.=1. Then the mounting angle
.kappa. is determined by:
.kappa.=(C.sub..OMEGA.-1)(dm.sub.sa.sub.sz
cos(.eta.))/(C(KC+m.sub.sa.sub.sz cos(.eta.))) 73. [0379] As
previously described for mounting angle error .lamda., the mounting
error angle .kappa. affects the two measurement sensors along the
y.sub.f-axis 5106 and the z.sub.f-axis 5105. Consistent with the
radial component errors resulting from the .lamda. 1201 mounting
angle error, the .kappa. mounting angle error is under the same
constraints. Therefore:
[0379] a.sub.sx-cal=a.sub.sx-a.sub.sz sin(.kappa.) 74
a.sub.sz-cal=a.sub.sz/cos .lamda. 72. [0380] The new calibrated
data arrays a.sub.sy-cal and a.sub.sz-cal are now used and replaces
all a.sub.sy and a.sub.sz values in previous equations which
complete the detection and calibration of club head acceleration
measurement assembly mounting errors due to a mounting error
rotation around the x.sub.f-axis 5104.
[0381] Thereby, the preferred embodiment described above, is able
to define the dynamic relationship between the acceleration
measurement assembly 5101 measured axes coordinate system and the
inertial acceleration force axes coordinate system using the
multi-lever model and to define all related angle behaviors,
including acceleration measurement assembly 5101 mounting
errors.
[0382] All of the dynamically changing golf metrics described as
angle and or amplitude values change with respect to time. To
visually convey these metrics to the golfer, they are graphed in
the form of value versus time. The graphing function can be a
separate computer program that retrieves output data from the
computational algorithm or the graphing function can be integrated
in to a single program that includes the computational
algorithm.
[0383] The standard golf swing can be broken into four basic
interrelated swing segments that include the backswing, pause and
reversal, down stroke, also called the power-stroke, and
follow-through. With all angles between coordinate systems defined
and the ability to separate centrifugal inertial component from
inertial spatial translation components for each club head
acceleration measurement assembly measured axis, the relationships
of the data component dynamics can now be evaluated to define
trigger points that can indicate start points, end points, or
transition points from one swing segment to another. These trigger
points are related to specific samples with specific time
relationships defined with all other points, allowing precise time
durations for each swing segment to be defined. The logic function
that is employed to define a trigger point can vary since there are
many different conditional relationships that can be employed to
conclude the same trigger point. As an example, the logic to define
the trigger point that defines the transition between the back
swing segment and the pause and reversal segment is:
[0384] If a.sub.z-radial(tn)<1.5 g [0385] AND [0386]
a.sub.sx-linear(tn)=0 [0387] AND [0388] AVG(a.sub.sx-linear(tn-5)
thru a.sub.sx-linear(tn))<-1.2 g [0389] AND [0390]
AVG(a.sub.sx-linear(tn) thru a.sub.sx-linear(tn+5))>+1.2 g
[0391] By defining the exact time duration for each swing segment
and understanding that each swing segment is related and continuous
with an adjacent segment, the golfer can focus improvement
strategies more precisely by examining swing segments
separately.
[0392] For the free swing the ability to correlate the acceleration
measurements and resulting dynamics golf metrics time line to a
spatial reference allows key dynamics swing metrics to be further
evaluated in the contexts of space. This offers golfers great
analytical benefit when evaluating a free golf swing that does not
impact an object. The swing metrics can be analyzed in relation to
key spatial reference locations, such as anticipated ball location,
peak elevation of backswing, peak elevation of power-stroke, peak
elevation of follow through and others such as club head travel
path 90 degrees out from right or left shoulder. These spatial
reference points all offer their own set of benefits when analyzing
the varied dynamic swing metrics in reference to spatial locations
near the club head travel path. True swing efficiency and
effectiveness can now be evaluate without the motional
perturbations that occur when the golf club strikes and object such
as a golf ball. The benefit of analyzing a free swing as opposed to
an impact swing can be demonstrated with a fundamental example of
evaluating swing efficiency with respect to the dynamic swing
metric of club head velocity which is directly related to
achievable ball trajectory distance. In this example a golfer may
want to improve and optimize their swing style for maximum
distance. Using free swing measurements and analysis that provides
dynamic club head velocity in relation to an anticipated ball
location allows the golfer to evaluate if they are reaching maximum
club head velocity before, at, or after the anticipated ball
location. This is not possible with club/ball impact because of the
abrupt velocity reduction resulting from impact eliminating the
ability to determine where maximum velocity would have occurred
after impact. Further, the swing style can be modified for maximum
power and efficiency by aligning club head maximum velocity with
anticipated ball location for maximum energy transfer at
anticipated ball location. The same benefit themes demonstrated
with the club head velocity example also can be applied to all
dynamics swing metrics such as but not limited to, club head
spatial acceleration and maximum club head spatial acceleration,
club face angle and where the club face angle reached a square
position, shaft flex lag/lead angle and many others.
[0393] These measurement and evaluation capabilities are not
available with swing analyzers that only rely on impact with a golf
ball, because the impact itself abruptly changes all swing metrics
including club head orientation, club head motion and shaft actions
and therefore eliminates the possibility of comprehensive analysis
of true swing performance. Only swing analyzers that analyze both
free swing and swing and impact completely characterize the need
metric for true optimization.
[0394] The embodiment of correlation methods are demonstrated using
the integration of conventional Receiver Signal Strength Indicator
(also referred to as RSSI) functionality into the previously
recited free swing measurement and analysis portion of this system.
The system uses RSSI to determine relative spatial relationships
between the Club Head acceleration measurement assembly 5101
(acceleration measurement assembly) and the wireless USB Module
during the entire swing. The spatial relationships, such as nearest
together or farthest apart or equivalents or ratios are used to
identify club head location(s) at a point or points in time that
correspond to time location(s) on the acceleration measurement time
line thereby correlating space and time.
[0395] FIGS. 19, 19A and 19B of the embodiment of the time-space
correlation shows the system configuration and operation. As shown
in FIG. 19 the system comprising a user interface 51302 (a laptop
in this example) with computation engine, display and standard
input output port connections, in this example a USB port and is
connect to a USB Cable 51601 (wired connection) that is further
connected to USB Module 51301 (second module). The USB module 51301
(second module) is placed remotely from user interface 51302 at a
predetermine location. FIGS. 19A and 19B show a front view
perspective and a side view perspective respectively of the club
head travel path 5307 of a golf swing and FIG. 19B further shows an
anticipated location of a golf ball 51602. A predetermined single
location can be anywhere near the anticipated golf head travel path
5307. Examples of predetermined location options can include, but
not limited to, location 51603, 51604, 51605 and 51606. In this
embodiment the USB module 51301 is located at predetermined
location 51603 that is close to club head travel path 5307 and in
front of anticipated ball location 51602. Operationally, the golfer
takes a swing, the Club Head Acceleration measurement assembly 5101
(acceleration measurement assembly) attached to club head, travels
along the club head travel path 5307 and simultaneously Club Head
Acceleration measurement assembly 5101 measures three dimensional
acceleration and synchronously and time aligned measures received
strength for received wireless signal transmitted by USB module
51301. Further, Club Head Acceleration measurement assembly 5101
(acceleration measurement assembly) is capturing and transmitting
measurement data comprising acceleration and received signal
strength measurements to USB Module 51301 for further transport to
User Interface 51302 with computational engine.
[0396] A software application of the first embodiment of the
time-space correlation resides on User Interface 51302
computational engine and comprising all functions for user
interface, display and data processing of measurements within
software application. The data processing of measurements includes
the previously recited algorithms for club head alignment
calibration and acceleration data analysis. Further, software
application implements a third algorithm that processes the
receiver signal strength measurements in conjunction with
synchronized acceleration measurements to determine time space
correlation. The third algorithm processes steps of the first
embodiment of the time-space correlation include the step of:
[0397] 1. Digitally low pass filter RSSI measured time line data to
reduce effects of RF multipath fading [0398] 2. Processes filtered
RSSI data using peak detection and minimum detection methods to
determine time points on time line of highest and lowest signal
strength [0399] 3. Flag and label time point of peak RSSI
measurement defining the relationship of Club Head Acceleration
measurement assembly 5101 and USB Module 51301 at minimum spatial
separation. [0400] 4. Flag and label time point of minimum RSSI
measurement defining the spatial relationship of Club Head
Acceleration measurement assembly 5101 and USB Module 51301 at
maximum spatial separation. [0401] 5. Label the correlated time
points on the acceleration measurements and dynamics golf metrics
results time line defining space time relationship.
[0402] For swing and impact analysis the impact with the ball can
serve as the detectable predetermined spatial location on the
measurements time line to correlate the measurement time line to
space. For impact analysis the determination of key metrics such
as, location on club face, duration of impact time, dynamic force
profile across club face and total energy of impact based on direct
measurements of the sensor elements with known placement within the
club face. The calibration of these sensor elements within the
monolith with the club face has been describes in the club face
assembly section of this application.
Positive and Negative Impact Pressure Detection
[0403] In another embodiment, a distributed sensor system in the
club face may measure the pressure resulting from a ball impacting
the club face by measuring both increasing and decreasing relative
pressure from a static pressure state. The increasing pressure may
be described as a positive pressure, whereas the decreasing
pressure may be described as a negative pressure. The increase
(positive) and/or decrease (negative) in pressure may be detected
at a plurality of piezoelectric sensor elements. For example, the
impact may cause deformation of the club face structure that
includes both deforming the club face inward (increasing pressure)
at one location while also deforming the clubface outward
(decreasing pressure) at another location. As described below with
regard to FIGS. 20A-C, one or more sensors may track both types of
deformations, creating time-varying impact pressure profiles based
on both the positive and negative pressures that are generated.
[0404] Turning to FIG. 20A, a cross section of a curved club face
surface 270 is shown, in an idle position 271. For example, a
driver may have a convex hitting surface such as the one shown in
FIG. 20A. Although the curved surface 20A is used as an example for
discussion purposes, similar measurements as described herein may
also be accomplished with a flat surface, and can be used for all
club types, such as drivers, hybrids, irons, wedges and
putters.
[0405] FIG. 20B illustrates an exemplary impact of a ball 280 with
a club face surface 270. As shown in this example, the ball 280 may
compress upon impact with the club face surface 270, and the club
face surface 270 may deform inward at the impact location. As
shown, the club face surface 270 may deform into position 272
(solid line), which is shown relative to the idle position 271
(dashed line) for illustrative purposes. In so doing, while a
location at the impact point may be pressed inward, another
location on the club face may be pushed outwards from the stress
and strains of the impact that are translated in the club face and
club head structure. The distance between reference points 290a and
290b shows an example of the club face being pushed outwards at a
location on the other side of the club face relative to the impact
point.
[0406] Turning now to FIG. 20C, an exemplary club face distributed
sensor system 299 is shown. In one embodiment, the club face
distributed sensor system 295 can measure both positive and
negative time-varying impact pressure values on piezoelectric
sensor elements caused by the deformation of the club face
structure and, through measuring both, create a more accurate and
reliable time-varying impact pressure profile. This may allow a
golfer to more accurately assess the impact of a golf swing on a
ball 280, and better determine what adjustments to make to his or
her swing.
[0407] In the example of FIG. 20C, pressure sensors 292 and 294 are
piezoelectric sensors that are embedded in a monolith 295. Although
only two sensors 292 and 294 are illustrated, more or less than two
impact sensors may be used in another embodiment.
[0408] The pressure sensitivity and deformation measurement
capability of the piezoelectric sensor elements 292 and 294 within
the monolith 295 may be altered and enhanced in one embodiment by
applying a static compression force on the monolith 295 and, in
this example, embedded piezoelectric elements 292 and 294. In other
words, a static compression pressure may be exerted on the monolith
295 and embedded sensor elements 292 and 294 even when there are no
external impacts occurring on the club face.
[0409] Applying static pressure to compress the monolith 295 may
increase the sensitivity and dynamic range of negative impact
pressure caused by the club face surface bowing outward. However,
such adjustment may simultaneously reduce the dynamic range of the
positive impact pressure measureable due to the inherent linear
range limit of signal amplitude or charge quantity versus material
deformation of piezoelectric materials.
[0410] The piezoelectric material element may have a physical
deformation limit for both compression strain (reduction in
thickness) or stretching strain (increase in thickness) and beyond
these limits produce minimal changes in surface charge creation.
Thus, the flow of the charge between poles of the piezoelectric
element, which defines the amplitude of signal being generated by
the piezoelectric element, may be limited based on the physical
deformation limits, which may be taken into consideration when
applying a static compression as an offset. Many of the higher
electromechanically coupling piezoelectric material classes, such
as piezo-ceramics have much higher usable linear operation ranges
from compression forces causing a compressive deformation as
opposed to tensile forces causing stretching or elongations
deformation. The limited dynamic ranges of tensile forces causing
stretching for piezo electric sensor elements may create
catastrophic failures that include the piezo material cracking
and/or the conducting electrodes be pull off for the piezo material
if limits are surpassed. This may be taken into account when
applying static compression to create an offset.
[0411] In another embodiment, the static pressure may be applied
non-uniformly to the monolith, such that different pressure sensors
of the same type within the monolith receive different static
pressures. This may be used, for example, to calibrate the
different sensors based on their relative locations to the edge of
the monolith.
[0412] Turning to FIG. 21, an example piezoelectric material
element is shown in three different strain states 311, 312, and
313, with a polarity of associated surface charge resulting from
each strain state 311, 312, and 313. The piezo element in a static
strain state 311 can be defined as having a neutral charge balance
between the upper and lower surfaces (i.e., poles) of the
piezoelectric element. The static state may include an amount of
compression in one embodiment. However, upon impact, dynamic states
may occur that cause a charge differential between the front and
back surfaces of the piezo element. For example, the piezo element
may enter a dynamic compressed strain state 312, causing a positive
surface charge relative to the piezo element in the static strain
state 311. Further, the piezo element may enter a dynamic expansion
stain state 313 and have a negative surface charge as relative to
the piezo element in a static strain state 311.
[0413] The flow of this charge across a load, from one pole to the
other, essentially may define a pressure signal being output from
the piezo electric material. Thus, a dynamic compression strain
placed upon impact may produce a positive signal, whereas an
expansion strain upon impact may produce a negative signal.
[0414] FIG. 21A shows an example piezo element dynamic strain
deformation to surface charge relationship curve 301 a for a piezo
element with no static pre-compression. The neutral point 310
represents where no dynamic (e.g., impact) strain is taking place
and there is neutral surface charge relationship on the piezo
element surfaces. The piezo element dynamic strain deformation to
surface charge relationship curve 301 has a linear range wherein
the quantity of charge generated caused by a magnitude of strain
deformation is a fixed ratio. The linear range upper limit 308 and
lower limit 309 define the piezo element linear operating dynamic
range 304. In one embodiment, the linear operating range 304 can
further be segmented into a positive charge linear operating range
305 and a negative charge linear operating range 306. As can be
seen, the positive charge linear operating range 305 caused by
compression may be much larger than the negative charge linear
operating range 306 caused by expansion.
[0415] FIG. 21B shows an example dynamic strain deformation to
surface charge relationship curve 301b for a piezo element with
static pre-compression added. The addition of an amount of static
pre compression 307 to the piezo element may cause the piezo
element linear operating dynamic range 304 to be more evenly
divided between the positive charge linear operating range 305a
(caused by compression) and a negative charge linear operating
range 306a (caused by expansion). This may enable the relative
negative pressure resulting from a portion of the club face bowing
outward to be fully measureable in one embodiment. In other words,
by applying static pressure to compress the monolith 295, the
dynamic range and measurement capability may be increased with
regard to club face 270 surface deformations 272 that bow outward
(e.g., between 290b and 290a) based on an impact on the club face
surface at another location.
[0416] Returning to FIG. 20C in view of the above, by
pre-compressing the sensor elements 292 and 294 with a static
pressure (in a non-impact state), the dynamic range of the sensor
elements 292 and 294 may be simultaneously reduced for positive
pressure and increased for negative pressure. Both measurements may
be utilized in determining an impact pressure in one embodiment.
For example, upon impact with a golf ball, a portion of the surface
bowing outward may be measured as a negative pressure. This may
provide information regarding location of impact (away from the
negative pressure point), and also may be utilized to more
accurately measure the positive pressure at the impact point. For
example, because this outward bowing (e.g., between 290b and 290a)
reduces the pressure experienced by the sensor element 294,
measuring this negative pressure at sensor 292 may allow the system
299 to provide data for creation of a more accurate time-varying
impact pressure profile.
[0417] In another example, only one impact sensor may be used to
detect impact location based on positive or negative pressure. For
example, the impact pressure sensor may be offset from the center
of the monolith such that a negative pressure indicates that impact
occurred on the other side of the center of the monolith relative
to the impact sensor.
[0418] Continuing with the example of FIG. 20C, the system 299 may
include pressure measurement circuitry coupled to the plurality of
piezoelectric elements 292 and 294. The pressure measurement
circuitry may measure positive and negative pressures on the first
and second piezoelectric elements 292 and 294, wherein the positive
and negative pressures are measured over a plurality of sample
points during impact of a golf ball with the club face and used to
build a time-varying impact pressure profile. The pressure
measurement circuitry may be implemented as part of the controller
(i.e., processor) in one embodiment, and may utilized analog to
digital converters, such as is shown in FIG. 8.
[0419] Additionally, the positive and negative impact pressure
values may be sampled simultaneously (at the same point in time) in
one embodiment. For example, the outputs of each of the first
sensor 292 and second sensor 294 may be captured in parallel. If
the ball impacts the club closer to the second sensor 294, as shown
in the example of FIG. 20C, then the circuitry may simultaneously
capture a negative value from the first sensor 292 (based on
outward flexing) and a positive value from the second sensor 294
(based on inward compression).
[0420] The system 299 may transmit these values to a receiver, such
as a computer, that builds an impact pressure profile based on
multiple samples that occur during impact, including multiple sets
of simultaneous samples. The receiver may utilize the negative
pressure values to better calculate the actual pressure on the club
face by compensating the positive pressure values. The receiver may
also better detect the location of impact on the club face based on
a pressure comparison that includes negative pressure values in the
analysis.
[0421] As described previously with regard to FIGS. 21-21B, in one
embodiment, the sensor element sensitivity, dynamic range and
ability to measure both inward and outward deformation can be
adjusted by adjusting the static pressure on the monolith in a
non-impact state. A fixed static compression from the manufacture
or a mechanical mechanism can be built into the club head in one
embodiment, and in addition or alternatively, the golfer may adjust
the monolith compression with a screw. For example, static
compression may be adjusted by turning a screw that applies
pressure by tightening a vice on the front and back (internal at
the cavity) sides of the monolith. In another embodiment, the
static pressure is applied primarily to the internal side of the
monolith 295. Also, more elaborate mechanical mechanisms can be
used to allow the golfer to adjust different portions of the club
face separately.
[0422] Adjusting the static pressure, and thereby adjusting
sensitivity, may beneficially allow for accurate measurement impact
at different club speeds. For example, the same club may be
adjusted differently to increase pressure to analyze a golfer who
has a 70 mile per hour swing (e.g., more sensitivity needed) versus
a 140 mile per hour swing (e.g., less sensitivity needed). This
type of measurement can also be used in club fitting, where the
club face structural design is based on typical swing speed of the
golfer, similar to how staff stiffness is adjusted during a club
fitting.
[0423] In another embodiment, the club head system 299 may
automatically adjust the static pressure placed on the monolith and
embedded sensors. For example, the processor (e.g., controller) in
the club head system 299 may detect a club speed or may be in
communication with a receiver (e.g., computer) that calculates club
speed based on swing data received from the club head. In response
to determining that club speed is relatively high, such as 140
miles per hour, the controller (e.g., processor) may decrease the
static pressure (e.g., by 15%) because less sensitivity is needed.
Whereas a relatively slow club swing, such as 70 miles per hour,
could cause the controller in system 299 to increase the static
pressure to create more sensitivity.
[0424] In still another embodiment, the system 299 may
automatically adjust the pressure based on the speed of the club
swing. The receiver may determine that adjustment is necessary
based on its calculations of both swing and impact data (e.g.,
perceiving a fast swing versus a high static pressure). In this
case, the receiver may send a message to the club head and the
controller (i.e., processor) in system 299 may actuate a small
motorized screw, clamp, or other mechanism for generating pressure
on the monolith 295. In another embodiment, the processor in the
club head may detect a threshold difference in swing speed versus
static pressure and trigger the adjustment.
[0425] Alternatively, the receiver may track the static pressure
and the club swing, and alert the user to manually adjust the
static pressure based on a threshold difference between the present
static pressure and optimal static pressure based on an average
club swing over the last several (e.g., 5) swings.
[0426] In addition, in one embodiment a custom club face structure
may be fabricated quickly at golf fitting locations using 3D
printing. Design parameters for the custom club face may be based
on motional swing and club face impact analysis on a per golfer
basis. Thus, using an embodiment herein, custom club faces may also
be possible during a club fitting.
[0427] The first step of creating the custom club face may include
characterizing the golfer impact profile with respect to power,
consistency, and broadness of skill sets. The golfer's power can be
characterized by the typical club head velocity when the club head
hits the ball. The golfer's impact consistency may be determined
via a statistical analysis over many hits of the impact location on
the clubface. The consistency impact location analysis where the
average and median impact location are with respect to the ideal
sweet spot and also statistical standard deviations the average and
median location.
[0428] Finally, the broadness of the golfers skill sets may be
analyzed. The broadness of skills analysis may include determining
the different impact methods a golfer uses, such as impacts that
are intended to create a varying degrease of ball spin and
direction of spin, such as a draw. The custom club face design may
have a customizable thickness profile that varies for different
locations of the club face to counter or accentuate the impact
methods common with the particular golfer. These different areas of
offer tradeoff in localized stiffness and can be used for trading
off a large size of the sweet spot for a smaller rigid sweet spot
that offers more power. Further, using close proximity thicker and
thinner areas can create small wave type deformation during impacts
that can help grip the ball enhancing the ability to intentionally
apply spin to the ball.
[0429] Although specific embodiments of the invention have been
disclosed, those having ordinary skill in the art will understand
that changes can be made to the specific embodiments without
departing form the spirit and scope of the invention. The scope of
the invention is not to be restricted, therefore, to the specific
embodiments. Furthermore, it is intended that the appended claims
cover any and all such applications, modifications, and embodiments
within the scope of the present invention.
[0430] Although particular materials are mentioned as examples
herein, these examples are not exhaustive. Other materials may be
used to build a roll-up shelf in accordance with an embodiment
herein.
[0431] Other embodiments of the invention will be apparent to those
skilled in the art from consideration of the specification and
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with a
true scope and spirit of the invention being indicated by the
following claims.
* * * * *