U.S. patent application number 11/649438 was filed with the patent office on 2007-05-17 for golf swing tempo measurement system.
This patent application is currently assigned to Yale University. Invention is credited to Robert D. Grober.
Application Number | 20070111811 11/649438 |
Document ID | / |
Family ID | 36074755 |
Filed Date | 2007-05-17 |
United States Patent
Application |
20070111811 |
Kind Code |
A1 |
Grober; Robert D. |
May 17, 2007 |
Golf swing tempo measurement system
Abstract
A biofeedback system including an elongated member, for feeding
back sounds indicative of swing tempo of the elongated member is
provided. The system comprises a plurality of acceleration
measuring devices adapted to measure accelerations at a plurality
of locations along the elongated member; a first microcontroller
for processing the measured acceleration signals to reduce effects
of gravity and forming a digital number related to an angular
rotational speed raised to a power; the digital number comprising a
plurality of bits; a second microcontroller for receiving the
digital number and associating the bits with a plurality of groups
each having an associated tonal composition and amplitude value
indicative of bit content and for forming commands indicative of
the tonal composition and amplitude value; and a synthesizer
responsive to commands and producing an audio signal; and an output
for outputting the audio signal.
Inventors: |
Grober; Robert D.; (Milford,
CT) |
Correspondence
Address: |
Arthur G. Schaier;Carmody & Torrance LLP
P.O. Box 1110
50 Leavenworth Street
Waterbury
CT
06721-1110
US
|
Assignee: |
Yale University
|
Family ID: |
36074755 |
Appl. No.: |
11/649438 |
Filed: |
January 4, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10948374 |
Sep 22, 2004 |
7160200 |
|
|
11649438 |
Jan 4, 2007 |
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Current U.S.
Class: |
473/131 |
Current CPC
Class: |
A63B 2220/40 20130101;
A63B 69/3638 20130101 |
Class at
Publication: |
473/131 |
International
Class: |
A63B 69/36 20060101
A63B069/36 |
Claims
1. A biofeedback system including an elongated member, for feeding
back sounds indicative of swing tempo of the elongated member, the
system comprising: a plurality of acceleration measuring devices
adapted to measure accelerations at a plurality of locations along
the elongated member; a first microcontroller for processing the
measured acceleration signals to reduce effects of gravity and
forming a digital number related to an angular rotational speed
raised to a power; said digital number comprising a plurality of
bits; a second microcontroller for receiving the digital number and
associating the bits with a plurality of groups each having an
associated tonal composition and amplitude value indicative of bit
content and for forming commands indicative of the tonal
composition and amplitude value; and a synthesizer responsive to
the commands and producing an audio signal; and means for
outputting the audio signal.
2. The system as claimed in claim 1, wherein the power to which the
angular rotational speed is raised is at least substantially 2.
3. A method of feeding back synthesized sounds indicative of swing
tempo of an elongated member, the method comprising the steps of:
generating a plurality of acceleration signals indicative of the
acceleration of the elongated member at different locations
thereof; processing the acceleration signals to reduce the
contribution of gravity in the signals; forming a sequence of
digital samples of the processed acceleration signals, each sample
comprising a plurality of bits related to an angular rotational
speed raised to a power; defining groups of the plurality of bits
in a sample, each group having an associated tonal composition and
amplitude value related to a group's digital value; generating
commands for the synthesis of sounds representative of the tonal
composition and amplitudes of the groups; and feeding back
synthesized sounds.
4. A biofeedback system including an elongated member for feeding
back sounds indicative of swing tempo of the elongated member, the
system comprising: a plurality of sensors coupled to the elongated
member for deriving digital signals indicative of motion of the
elongated member; means for processing the signals to reduce an
effect of gravity, generating a multi-bit digital number indicative
of an angular velocity raised to a power and associating the bits
into a plurality of groups each having an associated tonal
composition and amplitude indicative of bit content and for forming
commands indicative of the tonal composition and amplitude value; a
synthesizer responsive to the commands for producing audio signals;
and means for outputting the audio signals.
5. The system as claimed in claim 4, wherein the power to which the
angular rotational speed is raised is at least substantially 2.
6. A method of feeding back sounds indicative of swing tempo of an
elongated member, the method comprising the steps of: providing a
plurality of sensors mounted along the elongated member for
deriving digital signals indicative of motion of the elongated
member; processing the signals to eliminate or reduce an effect of
gravity, generating a multi bit digital number indicative of the
angular velocity raised to a power at at least two positions along
the elongated member, and mapping the bits into a plurality of
groups each having an associated tonal composition and an amplitude
indicative of bit content; synthesizing a sound signal having the
tonal composition associated with a group and amplitude indicative
of the bit value of the group; and outputting the audio signal.
7. A biofeedback system for converting motion characteristics of an
elongated member into sounds, the biofeedback system comprising: a
plurality of sensors positioned along the elongated member to
capture motion parameters as multi-bit digital numbers; a processor
to map the bits of each of the numbers into a plurality of groups
each having an associated tonal composition and an amplitude
indicative of bit content; a synthesizer for generating an audio
signal responsive to the mapped bits; and means for outputting the
audio signal.
8. A method for providing biofeedback signals to a user using
sensors to capture motion characteristics of an elongated member,
the method comprising: providing a plurality of sensors positioned
along the elongated member for capturing motion parameters thereof
as multi-bit digital numbers; mapping the bits of each of the
numbers into a plurality of groups each having an associated tonal
composition and an amplitude indicative of bit content;
synthesizing a sound signal responsive to the mapped bits to
produce a signal having the tonal composition associated with a
group and amplitude indicative of bit content; and outputting the
signal.
9. The system as claimed in claim 1, wherein the elongated member
is a golf club.
10. The system as claimed in claim 4, wherein the elongated member
is a golf club.
11. An elongated member for use in the biofeedback system as
claimed in claim 1.
12. An elongated member for use in the biofeedback system as
claimed in claim 4.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a device for providing audio
biofeedback associated with the motion or tempo of a golf
swing.
[0003] 2. Background of the Invention
[0004] An important key to a reproducible swing, whether in golf,
tennis, fishing, bowling, baseball, etc. is consistent tempo; once
the player gets the correct swing for a given game situation,
he/she must be able to repeat the swing in the same situation. A
consistent tempo indicates that speed variations throughout the
swing are repeated from swing to swing.
[0005] Perception of the tempo in a swing is generally very
difficult in sports. An athlete's perception of fast and slow can
vary from day to day, moment to moment, depending on mood, level of
adrenaline, etc. Achieving consistent performance is further
complicated by the fact that visual aids generally require
diversion of attention away from more crucial focal points.
Moreover, training is generally focused on tactile and visual
perception by an observer other than the athlete and communicating
problems with swing speed variation and tempo is difficult.
Therefore finding a quantitative method of perceiving tempo, which
does not interfere with the action of the swing, would be a useful
athletic training/performance aid.
[0006] A natural pathway for perceiving tempo is through sound and
music and has the advantage that the player can focus on his/her
swing. Through extensive exposure to music, which is universal in
all cultures, we are sensitized to the timing associated with tempo
from an acoustic sensory perspective.
[0007] The instantaneous motions in a golf swing occur faster than
one can consciously control, yet controlled speed and tempo are
crucial to successful, reproducible performance. Further, muscle
memory, which yields an unconscious coordination of muscle
activity, can be learned by repetitive practice of a correct tempo.
The auditory pathway is therefore an excellent mechanism for
subconsciously providing swing tempo information without
distracting the athlete.
[0008] A golf swing's tempo indicates the speed variation of the
golf club as it traverses a circular route between the back swing,
through impact with the ball and the follow through. Since a golf
swing is dominated by motion in a circular path, the tempo of the
swing is indicative of the time history, or tempo of the club's
angular speed. Moreover, since the centripetal acceleration of a
body traveling in a circular motion is a function of the angular
velocity of the body, accelerometers mounted near a golf club head
provide signals, which can be used to indicate tempo.
[0009] The centripetal acceleration at a particular point on a
swinging club can be measured with an accelerometer at the point of
interest and whose sensing axis is aligned along the axis of the
shaft. In general, this centripetal acceleration, a.sub.c, can be
used to yield an instantaneous measurement of the angular velocity
squared of the club through the relation a.sub.c=.omega..sup.2r,
where .omega. is the angular velocity of the club shaft and r is
the effective radius through which the accelerometer is moving.
[0010] The prior art appears to have recognized that measurement
errors can occur due to the influence of gravity. The error signal,
which can be confused with a desired centripetal acceleration
signal, may be reduced or eliminated by making a differential
measurement using two accelerometers located at different positions
along the axis of the shaft; each accelerometer senses identical
gravitational acceleration, but the centripetal acceleration scales
as the effective radius of motion.
[0011] However, being able to fully benefit from accelerometers
mounted on a golf club and the use of audio feedback has been
somewhat elusive, but not for a lack of effort. For example, U.S.
Pat. No. 6,261,102 describes converting the accelerometer output
into an audio signal for biofeedback. With the axis of an
accelerometer along the axis of the club, it measures the
centripetal acceleration and from that value determines the square
of the club's angular velocity. A signal proportional to the square
of the club's angular velocity is then converted to frequency and
fed to the person as an audio signal. Unfortunately, there is a
perceived deficiency in its lack of compensating for the effects of
gravity and tendency to create unpleasant "chirp like" sounds
because of the large speed changes during a golf swing.
[0012] Two other relevant prior art patents suffer from similar
deficiencies. Specifically, U.S. Pat. No. 5,233,544 to Kobayashi,
while describing the use of multiple accelerometers along the golf
club shaft, fails to recognize a potential for sound quality
problems nor does he describe or suggest the use of multiple tones
as provided in the present invention. Further, Kobayashi uses an
angular velocity signal rather than an angular velocity squared
signal and therefore does not provide for the sensitivity benefits
of the velocity squared signal.
[0013] U.S. Pat. No. 5,694,340, to Kim, likewise describes the use
multiple accelerometers to develop acceleration signals but fails
to describe, suggest or appreciate the benefits of multiple
accelerometers to cancel deleterious effects of gravity. Further,
although Kim does use multiple frequencies, these different
frequencies are used to distinguish between three axes and not to
eliminate chirp or improving the tonal quality of the sound.
[0014] Accordingly, further advancements in the art are desirable.
In particular, it would be desirable to provide a biofeedback
system for a piece of athletic equipment, such as by way of example
and not limitation, a golf club, that eliminates or at least
reduces the effect of linear accelerations (not due to rotational
motion) such as gravity that occur along the axis of the golf club
and uses the angular velocity squared signal for increased
sensitivity and improved sonification to produce pleasing sounds
whose tonal composition and amplitude changes to indicate tempo.
The present invention overcomes the foregoing deficiencies while
achieving the objectives and advantages set forth herein.
OBJECTIVES AND SUMMARY OF THE INVENTION
[0015] It is thus an objective of the present invention to overcome
the perceived deficiencies in the prior art.
[0016] It is another objective of the present invention to provide
an improved arrangement of measurement devices that are used to
cancel the effects of gravity, thus providing an improved indicator
of swing tempo.
[0017] It is another objective of the present invention to provide
improved sensitivity for measuring changes in tempo by using a
signal related to the angular velocity squared signal.
[0018] Another objective of the present invention is to provide
improved audio feedback using tonal composition and amplitude
characteristics that are pleasing to the ear.
[0019] Yet another objective of the present invention is to provide
a system in which measured signals or information and commands
derived from the measured signals can be stored for later playback
and analysis.
[0020] Still another objective of the present invention is to
provide an improved audio feedback path that utilizes a wireless
link for carrying the biofeedback signal.
[0021] Generally speaking, and in accordance with the present
invention a biofeedback system including an elongated member, for
feeding back sounds indicative of swing tempo of the elongated
member is provided. In a preferred embodiment, the system comprises
a plurality of acceleration measuring devices adapted to measure
accelerations at a plurality of locations along the elongated
member; a first microcontroller for processing the measured
acceleration signals to reduce effects of gravity and forming a
digital number related to an angular rotational speed raised to a
power; said digital number comprising a plurality of bits; a second
microcontroller for receiving the digital number and associating
the bits with a plurality of groups each having an associated tonal
composition and amplitude value indicative of bit content and for
forming commands indicative of the tonal composition and amplitude
value; and a synthesizer responsive to the commands and producing
an audio signal; and means for outputting the audio signal.
[0022] In another preferred embodiment, the present invention
comprises the steps of generating a plurality of acceleration
signals indicative of the acceleration of the elongated member at
different locations thereof; processing the acceleration signals to
reduce the contribution of gravity; forming a sequence of digital
samples of the processed acceleration signals, each sample
comprising a plurality of bits related to an angular rotational
speed raised to a power; defining groups of the plurality of bits
in a sample, each group having an associated tonal composition and
amplitude value related to a group's digital value; generating
commands for the synthesis of sounds representative of the tonal
composition and amplitudes of the groups; and feeding back
synthesized sounds.
[0023] In yet a further embodiment, the system of the present
invention comprises a plurality of sensors coupled to the elongated
member for deriving digital signals indicative of motion of the
elongated member; means for processing the signals to reduce the
effect of gravity, generating a multi-bit digital number indicative
of an angular velocity raised to a power and associating the bits
into a plurality of groups each having an associated tonal
composition and amplitude indicative of bit content and for forming
commands indicative of the tonal composition and amplitude value; a
synthesizer responsive to the commands for producing audio signals;
and means for outputting the audio signals.
[0024] In an alternative methodology, the present invention
comprises the steps of providing a plurality of sensors mounted
along the elongated member for deriving digital signals indicative
of motion of the elongated member; processing the signals to
eliminate or reduce an effect of gravity, generating a multi bit
digital number indicative of the angular velocity raised to a power
at at least two positions along the elongated member, and mapping
the bits into a plurality of groups each having an associated tonal
composition and an amplitude indicative of bit content;
synthesizing a sound signal having the tonal composition associated
with a group and amplitude indicative of the bit value of the
group; and outputting the audio signal.
[0025] In still yet another embodiment, a biofeedback system for
converting motion characteristics of the elongated member into
sounds is provided and comprises a plurality of sensors to capture
motion parameters of the elongated member as multi-bit digital
numbers; a processor to map the bits of each of the numbers into a
plurality of groups each having an associated tonal composition and
an amplitude indicative of bit content; a synthesizer for
generating an audio signal responsive to the mapped bits; and means
for outputting the audio signal. In a related methodology, the
present invention comprises the steps of providing a plurality of
sensors to capture motion parameters of the elongated member as
multi-bit digital numbers; mapping the bits of each of the numbers
into a plurality of groups each having an associated tonal
composition and an amplitude indicative of bit content;
synthesizing a sound signal responsive to the mapped bits to
produce a signal having the tonal composition associated with a
group and amplitude indicative of bit content; and outputting the
signal.
[0026] In a specific embodiment, the elongated member is a golf
club.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is an illustration of a biofeedback system
constructed in accordance with the present invention;
[0028] FIG. 2 is a block diagram of the electronics located in a
golf club of a preferred embodiment of the present invention;
[0029] FIG. 3 is a sketch used in an analysis of a golf swing using
a golf club, but which is equally applicable in the analysis of a
swing of any elongated member, such as a tennis racket for
example;
[0030] FIG. 4 is a typical plot of angular velocity squared for the
configuration of FIG. 3;
[0031] FIG. 5 is a typical plot of angular velocity for the
configuration of FIG. 3;
[0032] FIG. 6 is a block diagram of a processor portion of a
preferred embodiment of the present invention;
[0033] FIG. 7 is plot of an amplitude characteristic of a single
tonal group; and
[0034] FIG. 8 is a plot of amplitude characteristics for all tonal
groups used to represent 12 bit digital data of the present
invention.
[0035] While all features may not be labeled in each Figure, all
elements with like reference numerals refer to similar or identical
parts.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Reference is first made to FIGS. 1 and 2 wherein a
biofeedback system constructed in accordance with the present
invention is shown at 100 and a golf club constructed in accordance
with the present invention and generally indicated at 200, is
disclosed. As the present invention is also directed to a system
for providing audio biofeedback, along with the golf club at 200,
system 100 preferably comprises a processor unit, generally
indicated at 300 and a monitor generally indicated at 250, both of
which in the preferred embodiment are wirelessly coupled to each
other and/or club 200.
[0037] The golf club at 200 comprises an elongated member,
generally indicated at 215, which itself comprises at least a shaft
and may additionally comprise a clubhead 230. A first accelerometer
220 and a second accelerometer 225 are coupled to member 215. Upon
a swing of the elongated member 215, accelerometers 220 and 225
monitor acceleration along the axis of member 215. Preferably
located in member 215 is additional circuitry, generally indicated
at 245, comprising two (2) A/D converters 254 and 255 respectively
operatively coupled to accelerometers 220, 225, a microprocessor
260 coupled to converters 254, 255 and a wireless transceiver 265
coupled to the output of microcontroller 260. Microprocessor 260
takes the difference of the digitized outputs of accelerometers 220
and 225 and transmits the information to processor unit 300 via
antenna 235. To be clear, an accelerometer provided in the club
head is still deemed to be an accelerometer along the elongated
member.
[0038] Processor 300 receives the transmitted data via an antenna
315 and, after sonifying the signal as discussed below, outputs a
biofeedback audio signal to speaker 355 or monitor 250 in a known
manner. Monitor 250 may comprise an earpiece 252 and a belt/pocket
mounted receiver 256. In an alternate embodiment, an integrated
receiver and headset may be worn by the user.
[0039] By way of general background, reference is now made to FIG.
3 at 205 wherein swing analysis parameters are depicted and golf
club 200, with accelerometers 220 and 225 having their measurement
axis aligned with the axis of the golf club, is shown. A player
(not shown), having arms indicated at 105 and wrists indicated at
110, is swinging club 200 with head 230 in a circular motion 135
around wrists 110 with an angular velocity of .omega. radians per
second in an attempt to hit ball 140.
[0040] The centripetal acceleration at a particular point on the
swinging club can be measured with an accelerometer at the point of
interest and whose sensing axis is aligned along the axis of the
member. In general, this centripetal acceleration, a.sub.c, can be
used to yield an instantaneous measurement of the angular speed of
the club through the relation a.sub.c=.omega..sup.2r, where .omega.
is the angular velocity of the club head (assuming the
accelerometer at or near the head) and r is the effective radius
through which the accelerometer is moving.
[0041] To estimate the maximum magnitude of this acceleration, it
has been noted that a player can achieve club heads speeds on the
order of 100 mph. The typical radius defining the circular motion
on which the club head moves is on the order of 5 feet but an
accelerometer would typically be located at about the 4.5 foot
position. This yields a maximum measured centripetal acceleration
on the order of 1200 m/s.sup.2. It is more conventional to
normalize by the gravitational acceleration 9.8 m/s.sup.2, yielding
approximately 120 g. This is useful as a means of defining the
necessary dynamic range of the measurement.
[0042] A measurement error is due to the influence of gravity. The
accelerometer measures all accelerations it experiences along its
sensing axis. The gravitational pull of earth yields a constant
acceleration of 9.8 m/s.sup.2, which is denoted as 1 g and directed
towards the center of the earth. The direction of the gravitational
acceleration is denoted by arrow "g", which defines vertical for
the invention.
[0043] As shown in FIG. 3, the orientation of golf club 200 with
respect to the direction of gravitational acceleration g changes as
the club head 230 moves along path 135. This changing orientation
causes a time varying error signal related to the gravitation
acceleration to appear at the outputs of accelerometers 225 and
220.
[0044] The error signal, which can be confused with the desired
centripetal acceleration signal, is eliminated by making a
differential measurement using data from accelerometers 220 and 225
located respectively at r.sub.1 and r.sub.2. As one skilled in the
art would recognize, each accelerometer senses identical
gravitational acceleration but the centripetal acceleration scales
as the effective radius of motion. Summarizing this statement,
a.sub.1=.omega..sup.2r.sub.1+{right arrow over (g)}{circumflex over
(r)} (1) [0045] where a.sub.1, is the acceleration measured at
accelerometer 220; and a.sub.2=.omega..sup.2r.sub.2+{right arrow
over (g)}{circumflex over (r)} (2) where a.sub.2 is the
acceleration measured at accelerometer 225. Note that {right arrow
over (g)}{circumflex over (r)} indicates the magnitude of the
gravitational acceleration along the axis of the member. Taking the
difference of equations (1) and (2) yields;
a.sub.2-a.sub.1=.omega..sup.2(r.sub.2-r.sub.1), (3) which is
proportional to .omega..sup.2 (i.e. the angular velocity squared)
and independent of the gravitational acceleration, while
(r.sub.2-r.sub.1) is a fixed number.
[0046] It is clear from Equation 3 that maximizing the separation
between the two accelerometers optimizes the resulting signal. This
suggests placing one accelerometer at or near the grip end and
another at or near the head end which is set forth in the preferred
embodiment.
[0047] A typical plot of an .omega..sup.2, an angular velocity
squared signal, is shown in FIG. 4. The square root of the signal
in FIG. 4, which is .omega., the angular velocity, is shown in FIG.
5. A study of FIGS. 4 and 5 show that the use of an .omega..sup.2
signal yields improved sensitivity and greater output level changes
for swing speed changes. We note that .omega..sup.2 is also a
measure of the rotational kinetic energy of a club.
[0048] The present invention sonifies the .omega..sup.2 signal by
mapping or associating the bits in a 12 bit digital representation
of the substantially instantaneous acceleration difference value
into intervals or groups of bits and giving each group its own
"sound"; one or more instruments playing chords or notes. Providing
each group with its own sound and varying the amplitude of each
sound as a function of the value of the bits in the group adds
information to the audio biofeedback signal and aids in discerning
tempo. The overall effect is a changing tonal composition and
volume while maintaining harmonic relationships and avoiding
frequency chirp.
[0049] The preferred embodiment of the present invention uses a
MIDI Wavetable Generator to generate the unique sounds for the
chosen groups.
[0050] Referring again to FIGS. 1 and 2, it can be seen that
accelerometer 225 reads the higher of the two centripetal
accelerations, as it is located nearer club head 230. The analog
outputs of the accelerometers are fed to A/D converters 254 and 255
where they are converted into digital data streams and fed via
serial link 262 to microprocessor 260 for processing. The preferred
embodiment includes Microchip MCP3201 12 bit A/D converters to
convert the analog output of the accelerometers to a digital data
stream fed to microprocessor 260, which preferably is a Microchip 8
bit microcontroller, the PIC 16F873A.
[0051] Microprocessor 260 performs subtraction of the accelerometer
readings and formats the resulting 12 bit NRZ data for transmission
to processor 300 by transceiver 265. In alternate embodiments the
subtraction operation is performed in processor 300.
[0052] Transceiver 265 is preferably a Chipcon CC1000 configured to
receive the NRZ serial data from microprocessor 260, reformat the
data into synchronous Manchester coding and feed antenna 235 at 915
MHZ. Initialization values, which include data formatting,
frequency selection, etc. are stored in flash memory in
microprocessor 260 and fed to transceiver 265 by serial link 266.
Acceleration data from microcontroller 260 is sent to transceiver
265 by serial link 264.
[0053] Selection of a suitable accelerometer for the preferred
embodiment proceeds as follows. As noted above, with a typical
radius defining the circular motion on the order of 5 feet, a club
head speed on the order of 100 mph, and an accelerometer mounted at
about 4.5 feet from the grip end of member 215, an acceleration by
accelerometer 225 would experience an acceleration of approximately
1200 m/s.sup.2 or approximately 120 g. Therefore, the preferred
accelerometers are those having a g range of 120 g's, such as the
Analog Devices ADXL 193 (AD 22282). In an alternate embodiment for
golfers with significantly faster swings, accelerometers having a g
range of 250 g's, such as an ADXL 193 (AD22282), may be utilized,
and in a third embodiment for golfers with relatively slow swings,
accelerometers having a g range of 50 g's, such as the ADXL 78
(AD22280), may be used. In an alternative embodiment, accelerometer
220 may have a rating lower than that of accelerometer 225 because
accelerometer 220 is closer to grip 222 and will therefore
experience centripetal accelerations lower that that experienced by
accelerometer 225. For this latter embodiment the output of
accelerometer 220 would preferably be scaled to facilitate the
subtraction of equations (1) and (2) to give equation (3).
[0054] Alternatively, a plurality of accelerometers of the
foregoing types may be provided and selectable by a switch (not
shown) on club 200, thus allowing the same club to be used by
different golfers having greatly different swing speeds or the same
golfer under conditions requiring greatly different swing speeds.
In another embodiment, selection of the accelerometer may be
performed by a wireless radio link between transceiver 265 and
transceiver 330.
[0055] FIG. 6 is a block diagram of the circuits in processor 300.
The 12 bit data transmitted by transceiver 265 and antenna 235 is
received by antenna 315 and demodulated back to NRZ code by
transceiver 330 and fed to microcontroller 335 via a NRZ serial
stream. Serial busses 332 and 334 provide communications between
blocks 330 and 335, serial bus 337 provides communications between
blocks 335 and 340, and bus 342 provides communications between
blocks 340 and 345.
[0056] Microcontroller 335 which is preferably a PIC 16F873A,
receives the 12 bit digital data stream and maps the bits of the 12
bit acceleration signal into 6 Groups; groups 1-4 have 9 bits while
Group 5 includes 8 bits and Group 6 includes 7 bits. The bits that
define each group in the preferred embodiment are shown in Table 1.
TABLE-US-00001 TABLE 1 Group Defining Bits 1 .sub. b.sub.8-b.sub.0
2 .sub. b.sub.9-b.sub.1 3 b.sub.10-b.sub.2 4 b.sub.11-b.sub.3 5
b.sub.11-b.sub.4 6 b.sub.11-b.sub.5
[0057] The bits in each group are treated as a word and
microcontroller 335 calculates the numerical value of the word. For
example if the "word" b.sub.8-b.sub.0 had the value 000001010, the
value of the word would be 10.
[0058] For groups having non zero word values, microcontroller 335
preferably transmits MIDI commands to synthesizer 340 to turn "ON"
the tone(s) for a particular group and commands an amplitude for
the "ON" group equal to a value proportional to the word value of
the group. The MIDI commands thus generated are serially
communicated to synthesizer 340. Synthesizer 340 interprets the
MIDI commands and converts them into biofeedback signal values as
discussed in further detail below. The preferred embodiment uses
using a CRYSTAL Single Chip Wavetable Music Synthesizer CS9236 that
is General MIDI compliant. In an alternate embodiment tonal groups
are prerecorded, recalled from memory and combined to form a
synthesized biofeedback signal.
[0059] In the preferred embodiment, synthesizer 340 is programmed
by microcontroller 335 to associate each group with a particular
MIDI channel. Each MIDI channel is programmed to play a particular
chord which in the preferred embodiment, includes two notes known
musically as fifths and includes a "root" and its perfect "fifth".
When using fifths with a base frequency of f.sub.0, the related
fifth is of frequency 1.5 f.sub.0. Other harmonic relationships are
switch selectable by the panel control 370 in FIG. 6. Moreover
alternative embodiments may utilize sets of notes with different
harmonic relationships and/or sets of notes that are not
harmonically related. The preferred instrument for all groups is a
rock organ, although another instrument for all groups or different
instruments for each group are selectable by the panel control
370.
[0060] The note-group relationship or tonal composition for the
preferred embodiment is shown in Table 2 where C4 is middle C
(approx. 261.6 Hz), C3 is an octave below (approx. 130.8 Hz) and C5
is an octave above (approx. 523.2 Hz) middle C, etc. TABLE-US-00002
TABLE 2 MIDI Root Fifth Group Channel Frequency Note Frequency Note
1 1 f.sub.0 C3 1.5 f.sub.0 G3 2 2 2 f.sub.0 C4 3 f.sub.0 G4 3 3 3
f.sub.0 G4 4.5 f.sub.0 D5 4 4 4 f.sub.0 C5 6 f.sub.0 G5 5 5 5
f.sub.0 E5 7.5 f.sub.0 B6 6 6 6 f.sub.0 G5 9 f.sub.0 D6
The amplitude (volume) of each MIDI channel is determined by the
bit value of the corresponding group. For example, in Group 1, the
volume is defined by bits b.sub.8-b.sub.0 of the 12-bit full-scale
signal, where b.sub.0 is the least significant bit. When the word
value of bits b.sub.8-b.sub.0 is between 0 and 127, the output
volume is set proportional to the word value. When the value is
between 128 and 255, the output volume is limited to a value
proportional to 127. When the value is between 256 and 511, the
output volume is set equal to (511-word value of bits in the
group)/2. This yields a waveform for Group 1, for example, that
increases with angular acceleration squared until a maximum value
of 127, stays at 127 then has a negative slope and decreases back
down to zero as angular acceleration squared increases further.
This amplitude characteristic is shown in FIG. 7.
[0061] This basic process is the same for all groups. Since each of
Groups 1-4 is defined by 9 bits each of their respective amplitude
curves will follow that shown in FIG. 7. Since Group 5 is defined
by 8 bits and Group 6 by 7 bits, their respective amplitude
characteristics will reach 127 but not reverse direction and have a
negative slope. The resulting orchestration of pitch and volume for
all Groups is shown in FIG. 8. The net effect is a changing volume
and tonal content with increasing signal in a format that can
maintain harmonic relationships and avoid frequency chirp.
[0062] While Table 2 shows each chord associated with a particular
channel, alternate embodiments provide multiple chords on one or
more channels.
[0063] Processor 300 includes flash memory 365 for storing the
sonified data (in the form of MIDI Commands and 12 bit acceleration
data). The former is preferably used for playback during a practice
session while the 12 bit acceleration data may be used in
conjunction with a home computer in lieu of processor 300 or for
experimentation with alternate sound and sonification effects.
[0064] Information may be downloaded from processor 300 via data
port 375 or, in an alternative embodiment, by removing a memory
card. Likewise, at the player's option, alternative sonification
schemes can be uploaded to processor 300 via data port 375 and
selectable via control panel 370.
[0065] The output of synthesizer 340 is a digital data stream
representing the sonified angular velocity squared signal and a
measure of the rotational kinetic energy of the club. This signal
is fed to D/A converter 345 for conversion to an analog value. This
analog value is fed to audio amplifier 360 and fed to speaker 355.
The analog signal from D/A converter 345 is also available at a
connector (not shown) which optionally connects to wireless
transmitter 350 having antenna 320. Wireless transmitter 350 uses
transmissions via radio waves but in an alternate embodiment
infra-red signals are used.
[0066] In yet another feature of the present invention, golf swing
curves having the general form of FIG. 4 may be superimposed or
otherwise compared to each other to give a visual indication (and
comparison) of swing tempo among repeated swings of a single user
or among various users. Such information can thereafter be stored
for later review and/or visually communicated, for example, to a
user at home. In this way, a user may be able to analyze the
golfswing(s) of professionals, for example, who are using the golf
club 200 of the present invention.
[0067] It can thus be seen that the present invention provides
numerous advantages not found in the prior art. For example, the
present invention provides audio feedback using sonified angular
velocity squared values, correction of the angular velocity squared
values for the acceleration of gravity and the use of changing
tonal composition and amplitude, rather than swept frequencies, to
indicate tempo.
[0068] While the invention has been particularly shown and
described with respect to preferred embodiments thereof, it will be
understood by those skilled in the art that changes in form and
details may be made therein without departing from the scope and
spirit of the invention. For example, all the microprocessor
functions could be provided in one unit if the microprocessor has
the needed speed, etc. for carrying out the methodology and
functions set forth above. Therefore, the distribution of
components as set forth above are exemplary and not in a limiting
sense. In a similar manner, all references to the power to which
the angular rotational speed is raised is noted as 2, but should
someone slightly vary this quantity, the claims should not be so
limiting, and therefore noted herein as at least substantially
(although preferably exactly) 2. Additionally, it should be
understood that acceleratometers placed along the elongated member
can be placed in or on the member, both of which are covered by the
claims herein. Lastly, it is likewise conceivable that sensors are
used which are not physically mounted on the member, such as on a
wall, for example, and the rights are hereby reserved to provide
claims to such an embodiment where the acceleration of the
elongated member is measured from one or more physically separated
sensors.
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