U.S. patent application number 09/858829 was filed with the patent office on 2002-11-21 for apparatus for measuring dynamic characteristics of golf game and method for asessment and analysis of hits and movements in golf.
Invention is credited to Boscha, Bogie.
Application Number | 20020173364 09/858829 |
Document ID | / |
Family ID | 25329293 |
Filed Date | 2002-11-21 |
United States Patent
Application |
20020173364 |
Kind Code |
A1 |
Boscha, Bogie |
November 21, 2002 |
Apparatus for measuring dynamic characteristics of golf game and
method for asessment and analysis of hits and movements in golf
Abstract
The apparatus of the invention consists of three force sensors
built into the head of the club head, a main electronic unit built
into the shaft or grip of the club and electrically connected to
the sensors within the club, and a remotely located data
acquisition, processing and displaying unit connected with the
electronic units within the club via an IR or RF transmitter which
is a part of the main electronic unit. A first force sensor
measures a force in the direction perpendicular to the front face
of the club head (axis X'). The second sensor measures a force in
the direction perpendicular to axis X' in the plane of the club
head face which either contains the longitudinal axis of the shaft
or is parallel thereto (axis Y'). The third sensor the direction
perpendicular to the plane X'-Y'. The data collected during the
game from the aforementioned self-contained system makes it
possible to conduct complete dynamic analysis of swings and hit and
correlate the results of this analysis with actual movements of the
ball. The data and results of the analysis can be presented on the
display of the data acquisition and processing system in a simple
graphical or digital form convenient for observation and
understanding by a player.
Inventors: |
Boscha, Bogie; (Metuchen,
NJ) |
Correspondence
Address: |
Ilya Zborovsky
6 Schoolhouse Way
Dix Hills
NY
11746
US
|
Family ID: |
25329293 |
Appl. No.: |
09/858829 |
Filed: |
May 17, 2001 |
Current U.S.
Class: |
473/131 |
Current CPC
Class: |
A63B 2220/40 20130101;
A63B 2225/50 20130101; A63B 69/3632 20130101; A63B 69/362
20200801 |
Class at
Publication: |
473/131 |
International
Class: |
A63B 057/00 |
Claims
1. An apparatus for measuring dynamic characteristics of golf game
consisting in that a golf club hits a golf ball for delivering said
ball to a target location, said apparatus comprising: a golf club
having a shaft, a grip at the upper end of said shaft, and a club
head at the lower end of said shaft, said club head having a center
of mass and a face plane for contact with said club ball; at least
one bi-directional sensor assembly comprising: a first force sensor
rigidly connected to said club head and oriented along a first line
passing though said center of mass of said club head for measuring
a force in the direction of said first line and a normal to said
face plane; and a second force sensor rigidly connected to said
club head and oriented along a second line perpendicular to said
first line and located in said face plane or in a plane parallel
thereto; a main electronic unit rigidly connected to said golf club
and electrically connected to said at least one bi-directional
sensor assembly, said main electronic unit comprising a signal
transmitting unit; a power supply unit with switching means for
supplying an electric power to said at least one bi-directional
sensor assembly and to said main electronic unit, said power supply
unit being supported by said golf club; and a data acquisition and
display unit located remotely from said golf club and comprising a
signal receiving unit for wirelessly receiving signals from said
signal transmitting unit, a data processing unit, and a display
unit for displaying the data being processed in said data
processing unit.
2. The apparatus of claim 1, wherein said shaft has a first
interior cavity inside said shaft, said club head has a second
interior cavity inside said club head, said grip has a third
interior cavity inside said grip, said bi-directional sensor
assembly being located in said second interior cavity and rigidly
fixed therein, and said main electronic unit being located in a
location selected from said first interior cavity and said third
interior cavity.
3. The apparatus of claim 2, wherein said signal transmitting unit
and said signal receiving unit are selected from a group of IR and
RF signal transmitting units and signal receiving units,
respectively.
4. The apparatus of claim 1, wherein said data acquisition and
display unit comprises a data processing and displaying unit
selected from a group consisting of a PC, a laptop, and a
palmtop.
5. The apparatus of claim 3, wherein said data acquisition and
display unit comprises a data processing and displaying unit
selected from a group consisting of a PC, a laptop, and a
palmtop.
6. The apparatus of claim 1, further provided with a third force
sensor rigidly connected to said club head and oriented along a
third line passing though said center of mass of said club head for
measuring a force in the direction of said face plane and a normal
to a plane formed by said first line and said second line, said
third force sensor forming in combination with said second force
sensor a second bi-directional sensor assembly.
7. A system for measuring dynamic characteristics of golf game
consisting in that a golf club hits a golf ball for delivering said
ball to a target location, said system comprising: a golf club
having a shaft with a first cavity, a grip with a second cavity at
the upper end of said shaft, and a club head with a third cavity at
the lower end of said shaft, said club head having a center of mass
and a face plane for contact with said club ball; a first force
sensor located in said third cavity and rigidly fixed to said club
head, said first force sensor being oriented along a first line
passing though said center of mass of said club head for measuring
a force acting on said center of mass of said club head in the
direction of said first line and of a normal to said face plane;
and a second force sensor rigidly connected to said club head and
oriented along a second line perpendicular to said first line and
located in said face plane or in a plane parallel thereto, said
first force sensor and said second force sensor forming a first
bi-directional sensor assembly; a third force sensor rigidly
connected to said club head and oriented along a third line passing
though said center of mass of said club head for measuring a force
acting on said center of mass of said club head in the direction of
said face plane and of a normal to a plane formed by said first
line and said second line, said third force sensor forming in
combination with said second force sensor forming a second
bi-directional sensor assembly; a main electronic unit rigidly
connected to said golf club and located in a location selected from
said first cavity and said second cavity, said main electronic unit
being electrically connected to said first bi-directional sensor
assembly and to said second bi-directional sensor assembly, said
main electronic unit comprising a signal transmitting unit; a power
supply unit with switching means for supplying an electric power to
said first bi-directional sensor assembly, said second
bi-directional sensor, and to said main electronic unit, said power
supply unit being located in a location selected from said first
cavity and said second cavity; and a data acquisition and display
unit located remotely from said golf club and comprising a signal
receiving unit for wirelessly receiving signals from said signal
transmitting unit, a data processing unit, and a display unit for
displaying the data being processed in said data processing
unit.
8. The apparatus of claim 7, wherein said signal transmitting unit
and said signal receiving unit are selected from a group of IR and
RF signal transmitting units and signal receiving units,
respectively.
9. The apparatus of claim 7, wherein said data acquisition and
display unit comprises a data processing and displaying unit
selected from a group consisting of a PC, a laptop, and a
palmtop.
10. The apparatus of claim 8, wherein said data acquisition and
display unit comprises a data processing and displaying unit
selected from a group consisting of a PC, a laptop, and a
palmtop.
11. A method for assessment and analysis of hits and movements of a
golf club comprising the steps of: providing a self-contained
system comprising: a golf club having a shaft, a grip at the upper
end of said golf shaft, and a club head at the lower end of said
shaft, said golf club head having a center of mass and a face for
contacting a golf ball during the play, said system further
comprising at least one bi-directional sensor assembly built into
said golf club and comprising a first force sensor rigidly
connected to said club head and oriented along a first line passing
though the center of mass of said club head for measuring a force
in the direction of said first line and of a normal to said face
plane and a second force sensor rigidly connected to said club head
and oriented along a second line perpendicular to said first line
and located in said face plane or in a plane parallel thereto; a
main electronic unit built into said golf club and electrically
connected to said at least one bi-directional sensor assembly, said
main electronic unit comprising a signal transmitting unit; a power
supply unit with switching means for supplying an electric power to
said at least one bi-directional sensor assembly and to said main
electronic unit, said power supply unit being supported by said
golf club; and a data acquisition and display unit located remotely
from said golf club and comprising a signal receiving unit for
wirelessly receiving signals from said signal transmitting unit, a
data processing unit, and a display unit for displaying the data
being processed in said data processing unit; establishing a fixed
three-axes orthogonal coordinate system with the first origin in
said center of mass of said golf ball prior to the instant of
impact applied to said ball from said golf club; establishing a
moveable three-axes orthogonal coordinate system with the second
origin in said center of mass of said club head; registering
positions of said second origin by said at least one bi-directional
sensor assembly at sequential periods of time during movements of
said golf club prior to hit on said ball to form a golf dynamic
data; transmitting said golf dynamic data from said main electronic
unit via said data transmitting unit to said data receiving unit;
processing said data in said data processing unit; and displaying
said data in said display unit.
12. The method of claim 11, wherein said golf dynamic data are said
forces acting in the directions of axes of said moveable three-axes
orthogonal coordinate system in sequential moments of time.
13. The method of claim 12, wherein said golf dynamic data is
transmitted from said data transmitting unit to said data receiving
unit in the form of IR signals.
14. The method of claim 12, wherein said golf dynamic data is
transmitted from said data transmitting unit to said data receiving
unit in the form of RF signals.
15. A method for assessment and analysis of hits and movements of a
golf club comprising the steps of: providing a self-contained
system comprising: a golf club having a shaft, a grip at the upper
end of said golf shaft, and a club head at the lower end of said
shaft, said golf club head having a center of mass and a face for
contacting a golf ball during the play, said system further
comprising; two bi-directional sensor assemblies built into a golf
club and comprising a first force sensor rigidly connected to said
club head and oriented along a first line passing though the center
of mass of said club head for measuring a force applied to said
club head in the direction of said first line and of a normal to
said face plane, a second force sensor rigidly connected to said
club head and oriented along a second line perpendicular to said
first line and located in said face plane or in a plane parallel
thereto, and a third force sensor oriented along a third line
perpendicular to a plane formed by said first plane and said second
plane; a main electronic unit built into said golf club and
electrically connected to said two bi-directional sensor
assemblies, said main electronic unit comprising a signal
transmitting unit; a power supply unit with switching means for
supplying an electric power to said at least one bi-directional
sensor assembly and to said main electronic unit, said power supply
unit being supported by said golf club; and a data acquisition and
display unit located remotely from said golf club and comprising a
signal receiving unit for wirelessly receiving signals from said
signal transmitting unit, a data processing unit, and a display
unit for displaying the data being processed in said data
processing unit; establishing a fixed three-axes orthogonal
coordinate system with the first origin in the center of gravity of
said golf ball prior the instant of impact applied to said ball
from said golf club; establishing a moveable three-axes orthogonal
coordinate system with the second origin in said center of mass of
said club head; registering positions of said second origin by at
least one of said two bi-directional sensor assemblies at
sequential periods of time during movements of said golf club prior
to hit on said ball to form a golf dynamic data; transmitting said
golf dynamic data from said main electronic unit via said data
transmitting unit to said data receiving unit; processing said data
in said data processing unit; and displaying said data in said
display unit.
16. The method of claim 15, wherein said moveable three-axes
orthogonal coordinate system having a first axis in a direction of
said first line, a second axis in a direction of said second line,
and a third axis in a direction of said third line.
17. The method of claim 16, wherein said data is transmitted from
said data transmitting unit to said data receiving unit in the form
of IR signals.
18. The method of claim 16, wherein said data is transmitted from
said data transmitting unit to said data receiving unit in the form
of RF signals.
19. The method of claim 17, wherein said graphical form comprising
at least one curve in a coordinate system in which an abscissa is a
time and an ordinate is an acceleration developed by said center of
mass of said club head.
Description
CROSS REFERENCES TO RELATED APPLIOCATIONS
[0001] "Not Applicable".
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] "Not Applicable".
REFERENCE TO "MICROFICHE APPENDIX"
[0003] "Not Applicable".
BACKGROUND OF THE INVENTION.
[0004] 1. Field of the Invention
[0005] The present invention relates to the field of golf and, in
particular, to apparatus for measuring dynamic characteristics of
golf game and to a method for assessment and analysis of hits and
movements in golf. More specifically, the invention relates to a
system based on the use of force sensors which are built into the
head of a golf club and are connected in a wireless manner to a
remotely controlled display system.
[0006] 2. Description of the Related Art
[0007] Golf is one of the most popular sports in the world for
people of all ages and skill levels. According to the definition
from Encyclopedia Britanica, the game consists of playing the ball
on a teeing ground and trying to put it into a hole by successive
strokes in accordance with the rules. The stipulated round consists
of 18 holes, and most golf courses have 18. Standard 18-hole
courses measure from 6500 to 7000 yards (5900 to 6400 meters). Some
courses have only nine holes; these are played twice in a
stipulated round. The clubs are designed for the various positions
in which the ball may come to rest and for the various distances to
the hole. The objective is to put the ball into the hole with
fewest strokes.
[0008] Golf balls have a maximum weight of 1.62 ounces (45.93
grams) and a minimum diameter of 1.68 inches (4.27
centimeters).
[0009] The golf clubs are different in length and suppleness of
shaft, weight, size and shape of head, the angle at which the shaft
ends and the head begins (the lie), and the angle of the face of
the club from the vertical (the loft). In the average, good players
set there are usually either three or four woods clubs and nine or
ten irons. No two clubs in a set are the same.
[0010] It is understood that the hit applied to the ball determines
the entire trajectory of the ball flight and the result of the game
in general. Obtaining of quantitative information about the
dynamics of the hit makes it possible to correct the results of the
game during the play. It is known that the game of golf involves
the use of various golf clubs having heads of different geometries
and shapes. Along with other factors, such as the characteristics
of swing, swing speed, the geometry of the club head determines the
nature of hit and the initial angle of the ball trajectory. It is
also known that in a simplified form the phenomenon of impact can
be characterized via the law of momentum conservation. This means
that the velocity and the direction of a golf ball after the hit
can be represented via the following expression:
P=M.multidot.{overscore (V)}, where in a first approximation M is
the mass of the club head, and {overscore (V)} is the velocity
vector of the club head at the moment of impact. It is understood
that in an ideal case vector {overscore (V)} determines direction
of the ball flight after the impact applied to the ball from the
club head. Theoretically, the law of momentum conservation must
predetermine the initial velocity and direction of ball flight. In
reality, however, the ideal condition described above can never be
realized in practice. First of all, this is because in the ideal
case the vector of the impact from the club head must pass exactly
through the center of the ball mass (i.e., the center of the ball),
which is difficult to realize in practice with each impact. Second
of all, any deviation from the aforementioned ideal impact will
generate a lateral displacements of the ball trajectory from the
desired path, as well as rotation of the ball caused by the
aforementioned lateral displacements and by deformation of the
ball, which can never be ideally elastic.
[0011] In other words, the conditions described above will always
cause deviations from ball trajectory from t the he desired one.
Therefore obtaining of quantitative characteristics of the hit
applied from golf club to the golf ball based on real measurements
rather than on the player's sensations is an important factor for
revealing an actual correlation between the characteristics of the
impact and results of the game.
[0012] Attempts have been made heretofore to described dynamics of
the golf motions. For example, U.S. Pat. No. 5,297,796 issued to
Peterson; Jon R. on Mar. 29, 1994 describes a visual monitoring
system for a golfer to simultaneously watch his/her golf swing
while the swing is being made. The system includes one or more
video cameras and a video monitoring screen mounted below a
transparent surface where the swing is being made with a golf club
for viewing the swing without distorting the head of the golfer
during the golf swing.
[0013] A disadvantage of the system of U.S. Pat. No. 5,297,796
consists in that it is an external system that employs a plurality
of television or video cameras placed around the golfer to capture
what part of the swing is desired to be seen. The presence of
cameras on the field and the presence of the video monitoring
screen below a transparent surface where the swing is being made
may confuse the player and cause him/her to play unnaturally, as if
he/she will unconsciously be afraid to hit the camera and the
screen with the ball. Thus the aforementioned system only imitates
the game for training purposes. Furthermore, the system is
expensive and is limited in its capacity.
[0014] U.S. Pat. No. 5,688,183 issued on Nov. 18, 1997 to Sabatino,
et al. described a golf club head velocity monitor disposed at or
near the golfer's hands. Accordingly, the velocity measuring
apparatus of that invention embodied as a small, lightweight,
self-contained device secured, e.g., to a golfer's hands in the
manner of a wristwatch, or may be secured to a standard golf glove
in place of the ordinarily supplied ball-marking button, or may be
secured to the golf club shaft in the vicinity of the grip.
According to this invention, the system may contain several sensors
from which club head velocity measurements may be inferred. These
sensors are disposed in a substantially fixed relationship to the
golf club during a swing to be monitored. The sensors are
preferably acceleration sensors. One sensor may measure the
centripetal acceleration along the shaft of the golf club; other
sensors may measure acceleration in a plane which is generally
perpendicular to the golf club shaft. Using two or more sensors,
the club face orientation and/or direction of motion at impact with
a ball may be determined.
[0015] A disadvantage of the device of U.S. Pat. No. 5,688,183
consists in that the presence of sensors on the player's wrist will
restrict movements of the player's hand and the measurements will
produce unnatural results.
[0016] Attempts have been made to solve the above problems by
incorporating the sensor into the club head. Thus U.S. Pat. No.
5,646,345 issued on Jul. 8, 1997 to Butler, Jr. describes an
acceleration-responsive device attached to the club head. The
device includes a support for a rod between two spaced portions of
the support. A weighted disc is mounted for movement on the rod and
is held by a spring at one end of the rod. An indicator is also
mounted for movement on the rod adjacent the disc. A tube is
coupled to the support to facilitate swinging movement of the
device where, due to the acceleration thereof, the disc is moved
along the rod and pushes the indicator along the rod. When the
swinging movement ceases, the disc is returned to the one end of
the rod, while the indicator remains at the position to which it
was moved. A scale reading of a decal adjacent the moved indicator
provides a indication of the acceleration attained during the
swinging of device. This reading can be applied to a graph to
assist the user of device in the selection of golf clubs having a
shaft stiffness most appropriate for the user's physiological
particularities.
[0017] The club of the type described in U.S. Pat. No. 5,646,345
differs from a regular golf club, so that the training of the
golfer with this club or selection of the club suitable for the
golfer's playing habits will not match real conditions. However,
neither this system, nor any other known system provides
satisfactory description of the dynamics of the golf ball hit with
complete registration and analysis of the golfer's performance
characteristics under natural field conditions of the game and with
the use of a club maximally close to the real one.
BRIEF SUMMARY OF THE INVENTION
[0018] It is an object of the invention to provide a self-contain
compact and accurate system built into the golf club head and
remotely connected in wireless manner to a system for automatically
registering in a real time the dynamics of the golfer's swing and
hit. Another object is to provide the system of the aforementioned
type which can be realized in real field conditions of the golf
game without any distortions of the game nature and without causing
in a golfer any feeling leading to unnatural behavior. Still
another object is to provide a system of the aforementioned type
which collects the maximum possible data of different game
characteristics sufficient for analysis and complete correlation of
the game characteristics with the game results. Another object is
to provide a method for collecting data on dynamics of the golf
game, transmitting them wirelessly to a data acquisition and
processing unit, and displaying the collected data in a simple and
clearly understandable form.
[0019] The apparatus of the invention consists of three force
sensors built into the head of the club head, a main electronic
unit built into the shaft or grip of the club and electrically
connected to the sensors within the club, and a remotely located
data acquisition, processing and displaying unit connected with the
electronic units within the club via an IR or RF transmitter which
is a part of the main electronic unit. A first force sensor
measures a force in the direction perpendicular to the front face
of the club head (axis X'). The second sensor measures a force in
the direction perpendicular to axis X' in the plane of the club
head face which either contains the longitudinal axis of the shaft
or is parallel thereto (axis Y'). The third sensor the direction
perpendicular to the plane X'-Y'. The data collected during the
game from the aforementioned self-contained system makes it
possible to conduct complete dynamic analysis of swings and hit and
correlate the results of this analysis with actual movements of the
ball. The data and results of the analysis can be presented on the
display of the data acquisition and processing system in a simple
graphical or digital form convenient for observation and
understanding by a player.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0020] FIG. 1 is a general view of the system of the invention
illustrating a golf club, golf ball, and a data acquisition and
display unit.
[0021] FIG. 2 is a sectional view of the club head along the line
II-II of FIG. 1.
[0022] FIG. 3A is an example of a block diagram of the sensor
assembly suitable for measuring forces in the X'-Y' plane.
[0023] FIG. 3B is a block diagram of a custom-designed infrared
receiver.
[0024] FIG. 4 is another embodiment of the invention which utilizes
a digital transceiver operating in RF range of frequencies.
[0025] FIG. 5 is a schematic view of the golf club and of the ball
in the X-Y plane in connection with the dynamics movements of the
golf club and of the ball.
[0026] FIG. 6a is a schematic view in which the swing
characteristics of the golf club are presented as a function of an
instant angular position .PHI. of the club with respect to the
coordinate X.
[0027] FIG. 6b is a is a schematic view in which the swing
characteristics of the golf club are presented as a function of an
instant angular position .PHI. of the club with respect to the
coordinate Z.
[0028] FIG. 7a is an example of a golfswing graph in the form that
can be presented on the display of the apparatus of the invention:
the graph illustrates consecutive steps of a "free" swing performed
without collision with the ball, the curve showing a sharp peak
corresponding to a position of the ball in case if the club would
collide with the ball.
[0029] FIG. 7b is a graph similar to the one shown in FIG. 7a and
illustrating one of the swings in case of collision with the
ball.
DETAILED DESCRIPTION OF THE INVENTION
[0030] A general view of the system of the invention for
measurement, acquisition, and processing of dynamic data of the
golf game is shown in FIG. 1. The system consists of a sensor
assembly 20, e.g., three or two unit acceleration sensors, built
into the head 22 of a golf club 24. The club may be of any type
used in the game, such as driver, iron, wedge, etc. The sensor
assembly 20 is preferably a group of microsensors of the type
ADXL210 produced by Analog Devices, Inc., Ma, USA. The sensor
assembly 20 has small dimensions, which allow it to be easily built
into the interior of the golf club head 22, and a small mass as
compared to the mass of the club head. In order to incorporate the
microsensors 20, the head 22 has a cavity 26. It is understood that
the cavity 26 has dimensions much smaller than the size of the head
22.
[0031] Reference numeral 27 designates a hollow shaft with a grip
29 closed at the top end with a cap 31.
[0032] FIG. 2 is a sectional view of the club head 22 along the
line II-II of FIG. 1. It can be seen from FIG. 2 that X'-X'
component of the microsensor assembly 20 is oriented within the
head cavity 26 so that it is positioned on the same line X-X with
the direction of impacts normally applied from the head 22 to a
golf ball 28 at the moment hit. Other sensor components are also
oriented in the direction of their respective axes. It is also seen
that the sensor assembly 20 is rigidly fixed within the head cavity
26 by a threaded insert 30 inserted into the cavity 26 and attached
to the head 22.
[0033] In the club 24 of the invention the shape and dimensions of
the club and its head 22 are the same as those of a conventional
club.
[0034] For convenience of the description of motions that occur in
the golf game, it is advantageous to introduce a fixed system of
coordinates the origin of which is located in the point O that
coincides with the position of the center of gravity of the ball 28
directly prior the instant of impact applied to the ball from the
club 24.
[0035] Thus, the aforementioned axis X-X (FIG. 2) is a horizontal
axis which conventionally should coincide with the horizontal
surface of the golf field. Respectively, the axis Y-Y is a vertical
axis perpendicular to the X-X axis, and Z-Z is a lateral axis
perpendicular to the plane formed by the axes X-X and Y-Y. It is
obvious that the axis Z-Z is also a horizontal axis. It is also
understood that the trajectory of the ball 28 after the hit can be
described by a set of coordinates in the X,Y,Z system. This system
of coordinates is required for representing the final position of
the ball 28 on the golf field when the ball is at rest after
completion of its motion. This means that the position of the axis
X-X is defined by at least two points, i.e., the initial position
of the ball prior to the hit and the position of the target hole in
the field. However, in order to describe and analyze the dynamics
of impact, i.e., the dynamics of interaction of the club head 22
with the ball 28, it would be advantageous to introduce another
coordinate system with the original O' in the center of mass of the
head 22. This coordinate system is fixed with respect to the club
head 22 and is characterized by three mutually orthogonal axes
X'-X', Y'-Y', and Z'-Z', where axis X'-X' is the axis which is
perpendicular to the surface of the head face 36 and characterizes
the direction of hit; the Y'-Y' axis is perpendicular to the axis
X'-X' and coplanar or parallel to the club shaft 27, and the Z'-Z'
axis is perpendicular to the plane formed by the axis X'-X' and
Y'-Y'.
[0036] It is important that the position of the sensor 20 within
the cavity 26 of the club head 22 be rigidly fixed with respect to
the plane X'-Y'.
[0037] Reference numeral 38 (FIG. 1) designates an electronic unit
for receiving measurement data from the sensor assembly 20 and for
wirelessly transmitting these data to a remotely located data
processing unit 40 for processing and displaying the obtained data.
The electronic block 38 is located in the tubular shaft 29 of the
club 24 and is connected to the sensor 20 by conductors 42 guided
through the interior of the shaft 29. A battery 41 for supplying
electric power to the electronic block 38 and the sensor assembly
20 is located inside the grip 29 in its upper end directly under
the cap 31 so that it could be conveniently removed from the grip
together with the cap 31.
[0038] Now the sensor 20, and the units 38 and 40 will be described
in more detail.
[0039] In fact, the aforementioned sensor 20 consists of three
components or unit sensors for measuring forces in the directions
of axis X'-X', Y'-Y', and Z'-Z'. These unit sensors are capable of
measuring accelerations of the club head 22 in the direction of the
aforementioned axes.
[0040] The sensor assembly 20 used in the measurement system of the
invention is a pair of identical bi-directional sensor
accelerometers. These sensors were chosen for use in a real device
tested by the applicant for the following reasons:
[0041] 2 Axis of Acceleration Sensing on a Single IC Chip
[0042] 10 milli-g Resolution
[0043] Duty Cycle Output with 1 ms Acquisition Time
[0044] Low power >0.5 mA
[0045] Direct Interface to Popular Microprocessors
[0046] BW Adjustment with a Single Capacitor
[0047] +2.7V to +5.25V Single Supply Operation
[0048] 1000 g Shock Survival (in destructive test)
[0049] The ADXL210 is a low-cost, low-power, complete 2-axis
accelerometer with a measurement range of .+-.10 g and can measure
both dynamic acceleration (during head movement and impact) and
"static acceleration" (e.g., "g").
[0050] The outputs are digital signals with duty cycles (i.e., a
ratio of pulse-width to period) are proportional to acceleration in
the direction of two axes being sensed (X'-X' and Y'-Y'). The
outputs can be measured directly by the main electronic block
38.
[0051] The sensor assembly 20 is mounted in a miniature PC board 45
(FIG. 2). A block diagram of the sensor assembly 20 for measuring
forces in the X'-Y' plane is shown in FIG. 3A. It can be seen that
the sensor assembly consists of an X'-sensor unit 20a and a
Y'-sensor unit 20b which are connected, via respective demodulators
44 and 46, to a counter 48 via a duty cycle modulator 50. The
counter 48 requires an A/D converter or logic (not shown). The
output period of the sensor is adjustable from 0.5 ms to 10 ms via
a single resistor 52. If a voltage output is desired for
presentation of measurement results in the directions of axes X'
and Y', a voltage output proportional to acceleration is available
from the X'.sub.FILT pin 54 and the Y'.sub.FILT pin 56,
respectively. The bandwidth of the ADXL210 acceleration sensor may
be set from 0.01 Hz to 5 kHz via capacitors 58 (for X' axis) and 59
(for Y' axis).
[0052] The second sensor assembly, which measures forces that occur
at the moment of hit in the Y'-Z' plane is identical to the one
described above for hit in the X'-Y' plane. Therefore the block
diagram of the second sensor assembly is not shown. It will differ
from the diagram of FIG. 3a in that the unit sensors 20b and 20c
are used instead of 20a and 20b for measuring forced in the
direction of axes Y'-Y' and Z'-Z'.
[0053] As has been mentioned above, the sensors measure a force
acting in the directions of sensor orientation. Since the force is
proportional to accelration F=m.multidot.a, where m is a mass of
the club head and a is acceleration of the club mass center), the
results of measurements can be represented as accelerations.
Integration of acceleration produces velocity. The next step,
integration of the velocity, produces trajectory of the club
movement. Interrelations between the force, speed, path of
movement, and time make it possible to obtain a complete
description of the dynamic behavior of the club in time. All these
operations are performed with the use of the electronics of the
system of the invention in real time and the results can be
visually illustrated in various forms on the display 51 of the
system (FIG. 1).
[0054] It is understood that accuracy and speed of calculations
depend on the construction and quality of the electronic units of
the system. Therefore the elements of the electronic part of the
system have to be selected with reference to the specific
requirements so that the number of steps of integrations could be
sufficient for complete representation of the entire process. In
other words, the quicker is the electronics, the smoother are the
curves on the display.
[0055] The Y'-Y' axis chip output 60 (FIG. 3A) is used to measure
the swing parameters. This measurement is determined by the
position of the club head 22, and hence of the sensor assembly 20,
above the ground in a vertical plane. On the other hand, the X'-X'
axis chip output 62 is used to measure the off-center hits that
results in slice or draw. In golf, the "slice" is a shot struck
which curves pretty severely from left to right (for a right-handed
golfer), and the "draw" is a shot when a right-handed player hits a
control hook, which goes from right to left. Information taken from
the X'-X'-axis output 62 and from the Y'-Y'-axis output 60 is sent
from the sensor assembly 20 to a main electronic unit 38 (FIG. 1)
which is located in the club grip 29 and is connected to the sensor
via wires 42 (2 twisted pair for signals and one for voltage). The
Z'-Z' axis chip output (not shown) is used to measure parasitic
deviations of the ball movement in the lateral direction from the
ideal or central hit.
[0056] The ADXL210 sensor assembly is specifically designed to work
with low-cost microprocessors.
[0057] The main electronic unit 38 consists of a microprocessor 70
located in the grip 29 of the golf club 24 (FIG. 1), an interface
unit 72 for connection to the sensor assembly 20, the
aforementioned battery 41 with the switch 68, and an IR transmitter
(not shown) which is a part of the microprocessor 70. Since the
microprocessor 70 of the type required for the application in the
golf-club control system of the invention is commercially
available, e.g., in the form of an MSP430 microprocessor of Texas
Instruments, the internal structure of this microprocessor is
omitted from the description. The interface 72 is located in the
grip 29 and can be custom-made for connection to the sensor
assembly 20. The commercially produced ADXL210-type sensor and the
microprocessor MSP430 are interfaceable.
[0058] This microprocessor was chosen due to its miniature
dimensions and low-power characteristics (+1.8 to 3.6 V, 250 .mu.A
at 1 MHz). The main electronic unit 38 is powered from the same
battery 41 as the sensor assembly 20. The power supply to the main
electronic unit 38 and to the sensor assembly 20 is controlled by a
switch 68 located in a recess (not shown) on the side surface of
grip 29 in order to protect the system from accidental switching on
during transportation or storage of the club 24. The main
electronic unit 38 processes the data received from the sensor
assembly 20 and presents this data in a digital form. The MSP430
microprocessor 70 is interfaced to an infrared transmitter (not
shown) which is capable of transmitting the aforementioned digital
output data shown by arrows G to the data processing unit 40 for
processing and displaying the obtained data.
[0059] The data processing and displaying unit 40 is located
remotely either in the form of a IR receiver 47 in combination with
a display unit 51, e.g., in form of a laptop-type personal computer
placed in the field of direct vision of the player for observation
of the results of the game or in the form of a pocket-size
mini-display.
[0060] The IR receiver 72 can be represented by a MAX3120 IrDA
1,2-compatible infrared transceiver commercially produced by MAXIM,
California. This receiver is suitable and optimized for
battery-powered space-constrained applications. It consumes only
120.mu.A while supporting data rates up to 115 kbps over a wide 3 V
to 5.5 V operating range. This unit is extremely compact and can be
used in conjunction with light-emitting diodes built into miniature
and hand-,as well as with the palm-top computer displays.
[0061] The signal receiving unit 47 is a custom-designed infrared
receiver the block diagram of which is shown in FIG. 3B. The unit
is plugged into the PC RS232 interface of the data processing and
displaying unit 40 and is characterized by the following
features:
[0062] 1) Powered from the laptop or palmtop serial port (does not
require a separate battery or external power supply);
[0063] 2) Obeys the Infrared Data Association (IrDA) protocol;
[0064] 3) Generates a 16.times.Baud clock from the received
infrared signal;
[0065] 4) Contains RS232 compatible driver for data transmission to
the laptop or palmtop.
[0066] All the elements of the signal receiving unit 47 are mounted
on a single printed circuit board and comprise the pin diode PD
connected to the following sequentially arranged main elements: an
infrared transceiver MAX3120, two timer modules, i.e. TLC555(1) and
TLC555(2), IRDA encoder/decoder, and MAX233A driver.
[0067] FIG. 4 illustrates another embodiment of the invention which
utilizes a digital transceiver operating in RF range, e.g., 900 MHz
or 2.4 GHz. These ranges coincide with those used in commercial
wireless telephone communication systems. As shown in FIG. 4, which
is partial sectional view of the upper part of the club, the top
end of a club grip 74 is closed with a cap 76 which supports an
electric battery 78 inserted into the interior of the grip 74. The
battery 78 is electrically connected to a main electronic unit 80.
The detailed construction of the main electronic unit 80 used in
this embodiment is omitted since, in principle, it is the same as
in the embodiment shown in FIG. 1 and differs from it only in that
the transmitter operates in the RF range instead of infrared range
of frequencies.
[0068] Correspondingly, a remotely located data processing unit 82
has a receiver 86 operating in the same frequency range as the main
electronic unit 80. An example of such a transmitter-receiver pair
is any commercially available compact radio telephone having a
telephone transmitter mounted into the grip 74 and the telephone
receiver mounted into the remotely located data processing unit
82.
[0069] The remotely located data processing unit 40 (FIG. 1) or 82
(FIG. 4) consists of a central processing unit 45 (FIG. 1) or 84
(FIG. 4), such as a conventional laptop or palmtop with appropriate
displays 51 (FIG. 1) or 90 (FIG. 4), a signal receiving unit 47
(FIG. 1) or 86 (FIG. 4), and a modem-type converter 49 (FIG. 1) or
88 (FIG. 4). Reference numeral 92 designates a battery switch.
[0070] In order to use the system of the invention for monitoring
the golf game or for training purposes, it is require merely to
place the remotely located data processing unit 40 (FIG. 1) or 82
(FIG. 4) into a position convenient for use. For this purpose, the
display unit 51 (FIG. 1) or 90 (FIG. 4) can be placed within the
vision field of the player or can be located in a different place
for analyzing the result of the game after the game is completed.
For example, the pocket-size palmtop can be kept in the player's
pocket, and the larger-size displays can be located in the couch's
office or on the ground in front of the player.
[0071] Prior to the use, the system is switched on by activating
the switch 68 (FIG. 1) or 92 (FIG. 4) when the club is held in
contact with the ball at the starting point O' of the back swing
(FIG. 2). For the ball, the normal position is the origin of the X,
Y, Z coordinate system, while for the club the normal position the
one in which the center of mass of the head 22 is located in the
origin of the X', Y', Z' coordinate system. In other words, the
player is visually aimed at the ball to orfient the club head face
square to the ball's center of mass to establish the intended
trajectory of the ball flight.
[0072] The dynamics of the golf club movements and of the ball
prior to the impact on the ball as well as after the impact will
now be considered with reference to FIG. 5 which is a schematic
view of the golf club 24 and the ball 28 in the X-Y plane. The
example shown in FIG. 5 relates to the maximum swing of the golf
club for developing the maximum force of the hit, which ensures the
longest trajectory of the ball flight and thus allows for more
representative analysis.
[0073] Let us assume that the club 24 is raised to the highest
position on axis Y (vertical position where Y=H) and prior to
initiation of the club movement the center of the mass of the club
24 is located in a point I having coordinates X.sub.0 and Y.sub.0.
In this point the velocity vector {overscore (V)} is equal to 0. In
each moment of time the movement of the club 24 can be presented as
an instant rotation of the 24 around an instant center of rotation
which is located in the area of the golfer's shoulder. In this
case, the radius of rotation is approximately equal to the length
of the club plus the part of the hand which rotates. When the
golfer starts moving the club 24 and moves the center of mass of
the club head 22 from the initial point I with coordinates X.sub.0,
Y.sub.0 to the point A with coordinates X.sub.1, Y.sub.1, the
instant center of rotation of the club is shifted from the point
O.sub.I to the point O.sub.A. The instant linear velocity vector at
this moment can be represented as {overscore (V)}.sub.A. Similarly,
as the club swing is continued, the center of mass of the club head
22 is shifted from the point A with coordinates X.sub.1, Y.sub.1 to
the point B with coordinates X.sub.2, Y.sub.2, the instant center
of rotation of the club is shifted from the point O.sub.A to the
point O.sub.B. The instant linear velocity vector at this moment
can be represented as {overscore (V)}.sub.B, and so on. Thus the
trajectory of the center of mass of the club head 22 is shown in
FIG. 5 in the form of a curve TR in the X-Y plane. If necessary,
the trajectory can also be presented in the Y-Z and X-Z planes, so
that combination of all these three presentations can be plotted
into a three-dimensional view on the display.
[0074] It is more convenient, however, to present the swing
characteristics as a function of an instant angular position .PHI.
of the club with respect to the coordinate X. This graph is shown
in FIG. 6, which illustrates the function {overscore (V)} (.PHI.).
It can be seen that the velocity {overscore (V)} increases in
non-linear manner as the swing progresses reaching a certain high
value {overscore (V)}.sub.collision directly prior to the hit. The
moment of hit on the ball 28 is shown as a sudden drop in velocity
of the club 24. According to our assumption, the hit corresponds to
.PHI.=90.degree. with the square face of the club head. The drop on
the curve {overscore (V)} (.PHI.) occurs due to elastic
deformations of the club head 22 during collision with the ball 28.
It can be seen from FIG. 6a that after the moment of collision and
relaxation of club head deformations, the velocity is still growing
for a certain short period of time due to movement of the golfer's
hand by inertia. FIG. 6a is a schematic view in which the swing
characteristics of the golf club are presented as a function of an
instant angular position .PHI. of the club with respect to the
coordinate X. After this short period of acceleration the velocity
is rapidly reduced as the golfer discontinues the club swing.
[0075] It can be seen from FIG. 5 that the instant centers of
rotation of the club head mass travels within a certain limited
area in the zone of the golfer shoulder. In other words, as the
zone of deviations for the centers of rotation of the club head
mass is small, the approximation shown in FIG. 5 is
justifiable.
[0076] It should be noted that the club 24 does not move purely in
the X-Y plane but also experiences some movement in the X-Z plane
or Y-Z plane of the aforementioned X,Y,Z coordinate system. It is
understood that at the moment of hit the Z coordinate should be
equal to 0. However, in a real game, the trajectory of the club
swing will never be ideally in the X-Y plane, and some deviations
in the Z-axis direction will always take place. These deviations
will generate Z-component of the impact which will lead to lateral
scatterings from the desired direction with Z=0. The Z(.PHI.)
function is shown in FIG. 6b which is a schematic view presenting
swing characteristics of the golf club as a function of an instant
angular position .PHI. as a function of X.
[0077] It is well known that the length of any ballistic
trajectory, which is the case of the ball flight as well, is
determined by the initial velocity and the angle at the initial
point of the trajectory. The aforementioned angle depends on the
angular position of the club head face in the X-Y at the moment of
hit. Since the swing is always approximately the same, the
trajectory of the ball is determined by the selection of a specific
club head. This is because the club heads of different types are
characterized by different inclinations of the club head faced with
respect to the club shaft.
[0078] The club known as driver has a club head plane inclined to
the shaft at an angle that in the case of the ideal central hit on
the ball ensures the maximum length of the ball trajectory. In
other word, a hit in which the direction of hit transfer from the
club to the ball occurs along a line which connects the center of
mass of the head with the center of the ball mass is considered as
a central hit. The central hit with the maximum destination for the
ball is achieved at the most optimal angle of hit equal to
45.degree.. If the hit deviates from the central, the ball will not
reach the target. Such deviations are measured by the X'-X' and
Y'-Y' sensosr.
[0079] Such analysis is conventional, since the real game is
characterized by a great variety of moves, swings, types of clubs,
and golfer's habits. For example, some strikes may have the center
of rotation of the club head mass in the apex of a cone with a
swinging motion of the club around the apex as the center. In other
cases the center of rotation performs movements close to linear
movements, etc.
[0080] In spite of the aforementioned deviations from the theory of
the golf dynamics described above, the system of the invention is
advantageous in that for each individual golfer the dynamics of the
game at various stages of the game can be presented in a
quantitative form as a set of data transmitted from the sensor 20
built into the club head 22 to the main electronic unit 38 and
shown in the display 40 in any convenient digital or graphical form
obtained after processing the data. For example, the data acquired
by the system can be presented in the form of graphics shown in
FIGS. 5 and 6.
[0081] Another example of graphic presentation of the golf dynamics
data is shown in FIGS. 7a and 7b.
[0082] FIG. 7a is an example of a golfswing graph in the form that
can be presented on the display of the apparatus of the invention.
Thus, curve 101 (FIG. 7a) shows beginning of the golf back swing.
The sensor begins to sense a negative force to get activated. The
back swing motion starts at point O' (FIGS. 2 and 7a), where the
golf club face 36 is in contact with the ball 28. The negative
force is developed due to beginning of the back swing. In the back
swing the trajectory of the club head moves to the left of FIG. 7a
till point I (X.sub.0, Y.sub.0) (FIG. 5). In FIG. 7a the time for
the back swing has to be measured on the same scale as for the
forwards swing but in the opposite direction. The entire cycle of
back and forward swings takes no more than 3 sec. The forward
swing, which is described by a curve 102 in FIG. 7a, is initiated
at point I (X.sub.0, Y.sub.0) (FIG. 5) and ended at point E (FIG.
5) where movement of the club 24 is discontinued. Peak 103 on the
graph of FIG. 7a corresponds to the position of the ball 28. The
curve 102 shows a free swing, i.e., a swing without collision with
the ball.
[0083] FIG. 7b is a graph similar to the one shown in FIG. 7a.
However, this curve illustrates a swings (curve 104) in case of
collision with the ball. The point of collision is marked by a
reversed peak 105. After the collision with the ball at point 105,
the club continues to move forward by inertia with gradual decrease
in speed to zero at point 106.
[0084] The curve 108 in FIG. 7b corresponds to a back swing similar
to 101 in FIG. 7a. Arrows in the curves of both graphs show
directions of the movements. Electronically, the system of the
invention operates in the manner described below.
[0085] When a golfer addresses the ball 28, i.e., takes a position
for hitting the ball 28 on completion of set up with the club head
22 next to the ball 28, the golfer may activate the system either
by pushing on the switch 68 (FIG. 1) or activating the system by
voice (if a voice-activation system is available). The swing is
normally is performed within about 3 sec from this moment.
[0086] The infrared signals are transmitted from the main
electronic unit 38 located in the club 24 (FIG. 1) to the receiver
shown in FIG. 3B. The signals are conventionally shown by arrows G
in FIG. 1. For the case of RF transmission, the signals transmitted
from the main electronic unit 74 to the receiver 82 are
conventionally shown by arrows G' in FIG. 4. The timer TLC555(2) is
configured to generate 16.times. baud clock for infrared receiver
MAX3120. The timer TLC555(1) is used to synchronize the baud clock
of the timer TLC555(2) to the start of each received byte of the
signal. It does this by holding the reset input to the timer
TLC555(2) which is active until the first IR pulse is received.
This is assumed to be the start bit of a received byte. When the
timer TLC555(1) senses this event, it generates a pulse (1 byte
wide for a preset baud rate). This pulse is fed to the timer
TLC555(2) rest input. This allows the timer TLC555(2) to start
generating 16.times. clock pulses for the IRDA encoder/decoder
module. When the timer TLC555(1) times out (1 byte times), it then
resets the timer TLC555(2) out (1 byte time) and waits for the next
byte to repeat the cycle. Precision components (or potentiometers)
are connected to the timers (reset pulse and 16.times. clock) for
desired baud rate.
[0087] Thus it has been shown that the invention provides a
self-contain compact and accurate system built into the golf club
head and remotely connected in wireless manner to a system for
automatically registering in a real time the dynamics of the
golfer's swing and hit. The aforementioned system can be realized
in real field conditions of the golf game without any distortions
of the game nature and without causing in a golfer any feeling
leading to unnatural behavior. The system collects the maximum
possible data of different game characteristics sufficient for
analysis and complete correlation of the game characteristics with
the game results. The invention also provides a method for
collecting data on dynamics of the golf game, transmitting them
wirelessly to a data acquisition and processing unit, and
displaying the collected data in a simple and clearly
understandable form.
[0088] Although the invention has been shown in the form of
specific embodiments, it is understood that these embodiments were
given only as examples and that any changes and modifications are
possible, provided they do not depart from the scope of the
appended claims. For example, the sensors and other parts of the
electronics can be installed outside the club and attached to the
rear face of the club head. The display unit can be installed on
the golf card in front of the driver's seat. The main electronic
unit may send to the golfer through a feedback circuit a sound
signal informing about results of the hit. Although two sensor
assemblies were mentioned and described for measuring forces and
accelerations along three mutually perpendicular axes, only one
bi-directional sensor assembly can be used for approximated
analysis of the golf dynamics. If necessary, the electronics of the
system can be activated by a voice signal.
* * * * *