U.S. patent application number 14/717741 was filed with the patent office on 2015-11-26 for tennis training system.
The applicant listed for this patent is Crowdsense Pty Ltd. Invention is credited to Robert CROWDER.
Application Number | 20150335946 14/717741 |
Document ID | / |
Family ID | 54555322 |
Filed Date | 2015-11-26 |
United States Patent
Application |
20150335946 |
Kind Code |
A1 |
CROWDER; Robert |
November 26, 2015 |
TENNIS TRAINING SYSTEM
Abstract
A body worn electronic device and method for training a player
to improve upon the stroke of an article such as a racket in a
sport wherein the device senses parameters of the player's strokes
to create a stoke profile, compares the sensed parameters of the
stroke profile with electronically stored comparative stroke
profiles and wherein feedback may be provided to the player based
on the comparison of the players stroke profile and the comparative
stroke profile.
Inventors: |
CROWDER; Robert; (Elwood,
AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Crowdsense Pty Ltd |
Melbourne |
|
AU |
|
|
Family ID: |
54555322 |
Appl. No.: |
14/717741 |
Filed: |
May 20, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62000631 |
May 20, 2014 |
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Current U.S.
Class: |
473/461 |
Current CPC
Class: |
A63B 24/0006 20130101;
A63B 69/38 20130101; A63B 2208/0204 20130101; A61B 5/1122 20130101;
A61B 5/681 20130101; A61B 2503/10 20130101; G09B 19/0038 20130101;
A63B 71/0619 20130101; A63B 2220/836 20130101; A63B 2220/40
20130101 |
International
Class: |
A63B 24/00 20060101
A63B024/00; A63B 71/06 20060101 A63B071/06; A63B 69/38 20060101
A63B069/38 |
Claims
1. A system for improving stroke technique in tennis, the system
comprising: (i) a limb-mountable device comprising one or more
electronic sensors configured to collect data capable of defining a
tennis stroke profile of a user, (ii) a processor device in
operable connection with the sensor(s), (iii) a memory device
comprising data defining a comparator tennis stroke profile, and
optionally (iv) a user feedback device, wherein the processor
device comprises software configured to compare the user tennis
stroke profile with the comparator tennis stroke profile, and
provide feedback to the user via the feedback device identifying
similarities and/or differences between the user tennis stroke and
the comparator tennis stroke.
2. The system of claim 1 wherein the comparator stroke profile is
superior to that of the user stroke profile.
3. The system of claim 1 or claim 2 wherein the limb-mountable
device is configured to be mountable on or about the wrist of the
user.
4. The system of claim 1 wherein one of the one or more sensors is
an accelerometer and/or a rotation sensor and/or a
magnetometer.
5. The system of claim 1 wherein the one or more sensors are
selected and/or combined to discern at least 6 degrees of
freedom.
6. The system of claim 1 wherein the one or more sensors are
selected and/or combined to discern at least 9 degrees of
freedom.
7. The system of claim 1 wherein the processor device and/or memory
device is/are disposed in, on, or about the limb-mountable
device.
8. The system of claim 1 wherein the feedback device is a mobile
processor-based device.
9. The system of claim 1 wherein the mobile processor-based device
is a smart phone.
10. A limb-mountable device configured to be operable in the system
of claim 1.
11. The limb-mountable device of claim 10 comprising one or more
sensors, a processor device and a memory device.
12. The limb-mountable device of claim 10 wherein one of the one or
more sensors is an accelerometer and/or a rotation sensor and/or a
magnetometer.
13. The limb-mountable device of claim 10 wherein the one or more
sensors are selected and/or combined to discern at least 6 degrees
of freedom.
14. The limb-mountable device of claim 10 wherein the one or more
sensors are selected and/or combined to discern at least 9 degrees
of freedom.
15. Software configured to be operable in the system of claim
1.
16. A method for improving the stroke of a user, the method
comprising the steps of: electronically recording data capable of
defining a user stroke profile, providing a comparator stroke
profile, comparing the user stroke profile to the comparator stroke
profile, and providing feedback to the user indentifying
similarities and/or differences between the user stroke profile and
the comparator stroke profile.
17. The method of claim 16 wherein the comparator stroke profile is
superior to the user stroke profile.
18. The method of claim 16 wherein the step of electronically
recording data capable of defining a user stroke profile comprises
use of the limb-mountable device.
19. The method of claim 16 wherein the step of comparing the user
stroke profile to the comparator stroke profile comprises use of
the limb-mountable device.
20. The method of claim 16 wherein the step of providing feedback
to the user comprises use of a mobile processor-based device.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed to electronic devices
useful in training a tennis player in correct stroke technique. In
particular, the devices are worn on the body of a player under
training.
BACKGROUND TO THE INVENTION
[0002] The development of correct stroke technique in tennis is an
important factor in mastering the game. There are a large number of
strokes that may be used by a tennis player, with each being
difficult to learn.
[0003] Prior art methods of teaching include the execution of
drills which typically aim to concentrate the player's attention on
achieving a particular result, such as placing the ball in a
certain part of the court, or achieving top spin on the ball. While
drills may be executed without the assistance of a coach, the
player is not provided with any feedback on how to improve his or
her stroke technique. Instead, a trial and error approach is common
with the player altering various aspects of the stroke until a
satisfactory result is achieved.
[0004] More successful methods of training include direct
instruction from a coach. Typically, the coach observes the
player's stroke technique, and suggests improvement in real time.
The player may adjust his or her stroke according to the coach's
suggestions and will hopefully note a direct improvement in an
ability to strike the ball correctly.
[0005] Electronic devices may be used in tennis coaching. Some
prior art methods include the use of video analysis whereby a
player is recorded with a video camera during stroke execution, and
deficiencies noted by a coach. The coach generally points out any
stroke errors while reviewing the video with the player. As the
player is viewing as a third person, he is more aware of his errors
and how to correct them, under the guidance of a coach.
[0006] While coaching is undoubtedly of great assistance to a
tennis player, there is a significant cost involved by way of
professional fees charged. Accordingly, many players are only
coached for short periods of time, and at long intervals.
[0007] Furthermore, there are undoubtedly differences in the
ability of coaches to identify deficiencies in a player's stroke
and to also suggest effective remedial action. Where a lesser or
moderately skilled coach is employed, a player will typically blame
himself or herself for any lack of improvement or for a slow
improvement. This may lead to general dissatisfaction with the
game, and possibly even lead to the player deciding to terminate
training.
[0008] Even where a coach is very skilled, some players become
nervous under direct observation and instruction, and may not relax
sufficiently to allow for the required improvement in stroke
execution.
[0009] It is an aspect of the present invention to overcome or
alleviate a problem of the prior art by providing an electronic
device that is capable of assisting in training a tennis player in
correct stroke technique. It is a further aspect to provide an
alternative to prior art devices used in tennis training.
[0010] The discussion of documents, acts, materials, devices,
articles and the like is included in this specification solely for
the purpose of providing a context for the present invention. It is
not suggested or represented that any or all of these matters
formed part of the prior art base or were common general knowledge
in the field relevant to the present invention as it existed before
the priority date of each provisional claim of this
application.
SUMMARY OF THE INVENTION
[0011] In a first aspect, but not necessarily the broadest aspect,
the present invention provides a system for improving stroke
technique in tennis, the system comprising: (i) a limb-mountable
device comprising one or more electronic sensors configured to
collect data capable of defining a tennis stroke profile of a user,
(ii) a processor device in operable connection with the sensor(s),
(iii) a memory device comprising data defining a comparator tennis
stroke profile, and optionally (iv) a user feedback device, wherein
the processor device comprises software configured to compare the
user tennis stroke profile with the comparator tennis stroke
profile, and provide feedback to the user via the feedback device
indentifying similarities and/or differences between the user
tennis stroke and the comparator tennis stroke.
[0012] In one embodiment, the comparator stroke profile is superior
to that of the user stroke profile.
[0013] In one embodiment the limb-mountable device is configured to
be mountable on or about the wrist of the user.
[0014] In one embodiment one of the one or more sensors is an
accelerometer and/or a rotation sensor and/or a magnetometer. The
one or more sensors may be selected and/or combined to discern at
least 6 degrees of freedom, or at least 9 degrees of freedom.
[0015] In one embodiment, the processor device and/or memory device
and/or sensors is/are disposed in, on, or about the limb-mountable
device.
[0016] In one embodiment, the feedback device is a mobile
processor-based device, which may be a smart phone.
[0017] In a second aspect, the present invention provides a
limb-mountable device configured to be operable in the system as
described herein.
[0018] In one embodiment, the limb-mountable device comprises one
or more sensors, a processor device and a memory device.
[0019] In one embodiment, the one or more sensors is an
accelerometer and/or a gyroscope and/or a magnetometer. The one or
more sensors may be selected and or combined to discern at least 6
degrees of freedom, or at least 9 degrees of freedom.
[0020] In a third aspect the present invention provides software
configured to be operable in the system as described herein.
[0021] In a fourth aspect the present invention provides a method
for improving the stroke of a user, the method comprising the steps
of: electronically recording data capable of defining a user stroke
profile, providing a comparator stroke profile, comparing the user
stroke profile to the comparator stroke profile, and providing
feedback to the user indentifying similarities and/or differences
between the user stroke profile and the comparator stroke
profile.
[0022] In one embodiment, the comparator stroke profile is superior
to the user stroke profile.
[0023] In one embodiment, the step of electronically recording data
capable of defining a user stroke profile comprises use of the
limb-mountable device a described herein.
[0024] In one embodiment, the step of comparing the user stroke
profile to the comparator stroke profile comprises use of the
limb-mountable device as described herein.
[0025] In one embodiment, the step of providing feedback to the
user comprises use of a mobile processor-based device.
BRIEF DESCRIPTION OF THE FIGURES
[0026] FIG. 1A is a diagram showing the spatial arrangement of
components on printed circuit boards adapted to be included in a
wrist band of the present invention.
[0027] FIG. 1B is a diagram showing the spatial arrangement of the
components shown in FIG. 1A on the wrist of a user, demonstrating
the orientation with respect to the hand and elbow of the user.
[0028] FIG. 2 is a flow diagram showing the data processing
sequence, steps and dependencies. Each block can be considered to
be a data processing function with specific data inputs and
outputs.
DETAILED DESCRIPTION OF THE INVENTION
[0029] After considering this description it is apparent to one
skilled in the art how the invention is implemented in various
alternative embodiments and alternative applications. However,
although various embodiments of the present invention is described
herein, it is understood that these embodiments are presented by
way of example only, and not limitation. As such, this description
of various alternative embodiments should not be construed to limit
the scope or breadth of the present invention. Furthermore,
statements of advantages or other aspects apply to specific
exemplary embodiments, and not necessarily to all embodiments
covered by the claims.
[0030] Throughout the description and the claims of this
specification the word "comprise" and variations of the word, such
as "comprising" and "comprises" is not intended to exclude other
additives, components, integers or steps.
[0031] Reference throughout this specification to "one embodiment"
or "an embodiment" means that a particular feature, structure or
characteristic described in connection with the embodiment is
included in at least one embodiment of the present invention. Thus,
appearances of the phrases "in one embodiment" or "in an
embodiment" in various places throughout this specification are not
necessarily all referring to the same embodiment, but may.
[0032] The present invention is predicated at least in part on the
Applicant's finding that a player's tennis stroke may be improved
by the use of an electronic device having sensors which (in real
time) provide data allowing for the construction of a stroke
profile, and to compare that stroke profile with that of a superior
profile such as that of an accomplished tennis player. Feedback is
provided to the player to identify aspects of their stroke profile
which should be altered in order to more faithfully replicate the
superior stroke profile. Accordingly, in a first aspect the present
invention provides a system for improving stroke technique in
tennis, the system comprising: [0033] (i) a limb-mountable device
comprising one or more electronic sensors configured to collect
data capable of defining a tennis stroke profile of a user, [0034]
(ii) a processor device in operable connection with the sensor(s),
[0035] (iii) a memory device comprising data defining a comparator
tennis stroke profile, and optionally [0036] (iv) a user feedback
device, wherein the processor device comprises software configured
to compare the user tennis stroke profile with the comparator
tennis stroke profile, and provide feedback to the user via the
feedback device indentifying similarities and/or differences
between the user tennis stroke and the comparator tennis
stroke.
[0037] The present system is a significant departure from prior art
approaches, which rely to a large extent on the observation of a
player by a trained person (such as a coach) in order to identify
and correct dysfunctional stroke technique. A player utilizing the
present system may be presented with feedback based on a comparison
of his or her stroke profile with that of an accomplished player
(the comparator stroke) allowing aspect(s) of user's stroke profile
to be altered to be closer to that of the accomplished player. The
stroke profile of the accomplished player is typically superior to
that of the user, and may be constructed from real data (for
example, by the accomplished player executing a stroke while using
the present system) or constructed by reference to video or
photographic record of the accomplished player executing a stroke.
It is anticipated that a user may wish to emulate the technique of
a certain professional player, and may be enabled by the present
system to upload that player's stroke profile into the memory
device.
[0038] The profile of the comparator tennis stroke may not be
constructed with reference to the stroke of any single player, and
may be a composite of a number of players. Alternatively, the
comparator stroke profile may be completely or partially
artificially constructed based on sound biomechanical principles in
tennis which are known to the skilled artisan.
[0039] In some embodiments, the comparator stroke profile is
roughly equivalent or inferior to the user stroke profile. These
circumstances are typically encountered in circumstances where the
comparator stroke profile is constructed from a user tennis stroke.
The ability for a user to compare their own stroke profiles over a
period of time may be useful in some training strategies to
identify an improvement, lack of improvement, or even a decline in
stroke technique.
[0040] As used herein, the term "stroke profile" is intended to
include a physical aspect of a tennis stroke which may be
represented by a dataset, or constructed from a dataset, the
dataset being provided by the sensor(s) of the limb-mountable
device. For example, the stroke profile may comprise time-based
positional information which describes the relative position of the
device (and therefore the user's wrist). The sensor data may be
translated into a real time estimate of sensor orientation
(typically in quaternion or euler angle representation). This
provides an indication of device/wrist orientation rather than
position (which can in turn be interpreted). Thus, in that
circumstance the profile comprises a spatial path along which the
device travels in executing a stroke. Further information may be
overlaid such as velocity, angular velocity, acceleration and the
like to provide a more complete or substantially complete
description of the stroke which is electronically storable in
memory and processable.
[0041] The stroke profile may be constructed from a dataset
covering (in a substantially continuous manner) the entirety of a
tennis stroke. Alternatively, the stroke profile may be constructed
from a dataset covering only a segment of a tennis stroke, or a
number of discontinuous segments of a tennis stroke. As another
alternative, the stroke profile may be constructed from data taken
at only a single time point, or a number of discontinuous time
points of a tennis stroke.
[0042] It is understood that a stroke profile having incomplete, or
even minimal information may also be useful in certain embodiments
of the present systems. For example, in some circumstances velocity
information alone may be useful where a user's serve is acceptable,
except for his or her propensity to briefly pause before the main
swing. In that situation, a point in the stroke profile of zero
velocity is sufficient information to indicate further improvement
in the user's serve is necessary, and efforts made to avoid the
halt in service action.
[0043] The terms "superior", "inferior" and "equivalent" when used
as descriptors for a stroke profile, in comparison with the user
stroke profile. A stroke profile may be superior, inferior or
equivalent with respect to any parameter of a stroke profile, or
the result of striking a tennis ball with a physical stroke of the
profile.
[0044] For example, an effective forehand stroke may have a spatial
path which is substantially C-shaped, with a long follow through.
The user's stroke profile may have a short follow through, which is
suboptimal for power. Accordingly, the effective forehand stroke
profile is considered superior to that of the users. As another
example, the wrist in an effective forehand stroke rapidly
accelerates around half way through the stroke to increase racket
head speed. The user's stroke profile may have a consistent
velocity throughout, and accordingly, the user's stroke profile is
inferior to the effective stroke profile given the lower speed at
which the ball is struck.
[0045] The limb-mounted device comprises a processor which is in
operable connection with the sensors. The operable connection may
be direct such that data output of the sensors is transmitted
directly to the processor. Indirect connections are also
contemplated, such as where the sensor output is communicated to a
memory device, with the stored data subsequently transmitted to the
processor.
[0046] The processor device comprises software configured to
compares the user stroke profile with the comparator stroke
profile. Typically, the comparison is undertaken using time-matched
data from the user and comparator profile data streams. Matching of
the data from the two profiles may first require analysis of one or
both profiles to identify events or segments of the profile(s). It
will be understood that in the comparison of user stroke profile
and comparator stroke profile, raw datasets may be compared.
Alternatively, the raw datasets are first processed into the
segment(s) or time point(s).
[0047] For example, in the serve a first event in the stroke
profile may be the first movement of the wrist which signifies
commencement of the stroke, a second event may be the sharp
reversal in direction which signifies the commencement of the main
swing, and a third event may be the subsequent deceleration of the
wrist signifying the end of the stroke. A similar analysis may be
conducted on the comparator stroke profile such that the data from
the two stroke profiles may be paired on a time-base with reference
to the three events.
[0048] In one embodiment, the comparator stroke profile is not
analysed in this way, but instead has embedded event data which has
been independently validated.
[0049] The processor device may perform this pre-comparison
analysis, or a second processor device may be implemented for that
task.
[0050] The software may be configured to identity similarities and
or differences in the stroke profiles under comparison. The
differences may be output as qualitative information (for example
short, long, high, low, fast, slow), or may be quantitative (for
example, velocity, angular rotation, distance)
[0051] While the sensor data may be transmitted by wired or
wireless transmission to a processor external to the limb-mountable
device, it is preferable that the processor is integral with the
device.
[0052] The feedback device may be integral with the limb-mountable
device, or may be a separate device. The feedback device may
provide feedback by way of audio and/or visual means including
pre-recorded or synthesized speech, a graph, a photograph, a video,
text, an animation, or a haptic stimulus.
[0053] A preferred feedback device is a mobile processor-enabled
device, and particularly a smart phone or similar contrivance. In
some embodiments of the system, the feedback is constructed by the
software of the limb-mounted device, and transmitted to the
feedback device for presentation thereon. In other embodiments, the
feedback device constructs the feedback based on one or more of the
sensor data, the user stroke profile, or a comparison of the user
stroke profile and the comparator stroke profile.
[0054] The feedback may be generated and presented to the user in
real time (i.e. during stroke execution), allowing the user to
receive instant feedback while hitting a number of consecutive
shots. This approach allows a user to continuously refine their
stroke technique while playing in an attempt to more closely
replicate the comparator stroke. As is understood, feedback in this
circumstance may be limited to simple qualitative signals provided
by audio tones, or short passages of synthesised speech.
[0055] Alternatively, the feedback may be presented after a
training session, in which case more complex information may be
presented. For example, graphics showing the spatial path of the
wrist of the user overlaid with the path of the comparator stroke
may be presented as feedback. Such graphics may be overlaid with
velocity information or angular rotation information to provide a
more complete comparative analysis for the user. The user can note
where the two strokes diverge, and modify his or her stroke
accordingly.
[0056] The system may be further configured to provide feedback on
stroke consistency, typically as a rating. The stroke consistency
may be defined by reference to the comparator stroke profile or the
user's previous stroke profile(s).
[0057] Other types of feedback are further contemplated, including
shot frequency, total shot count and breakdown, quality of shots
and overall game, total play time plus effort expended on the court
(in the form of calories burnt and distance travelled). This type
of feedback is typically suited more so to an analysis conducted
over the course of a game, a set, or a match.
[0058] A user may also be provided with feedback detailing
achievements over a period of time, such as a playing season. The
system may be configured to including feedback such as personal
bests, improvement in a particular stroke, if the user has the best
technique in their area, or at their club (this last feedback type
requiring a number of users to deposit feedback into a shared
server). Any achievements may be further shared on a social media
platform such as Twitter.TM. or Facebook.TM..
[0059] The limb-mountable device of the present system may be
configured to sit snugly on the player's wrist, preferably in a
manner similar to a wrist watch, or a sweat band.
[0060] A number of advantages are provided by the sensors being
mounted on the user, rather than on the racket. Good stroke
technique is driven to a large extent by forearm (and particularly
the wrist) movement, which in turn dictates racket movement. Thus,
attempting to emulate a superior stroke profile based on
comparative data from racket-based sensors will only assist the
user in placing the racket in the same position as for the superior
stroke. Instead, the present systems assist the user in placing
their body in the same position as that required for a superior
stroke.
[0061] Understanding biomechanical movements of the wrist is
fundamental to stroke technique. The greater extent to which
precise wrists movements are recorded and assessed, the better the
user will understand whether or not their technique is consistent
with a comparator technique.
[0062] It is particularly advantageous in comparative systems such
as the present, that comparisons are made in the position and
rotational movements of the wrist. These are the precise movements
which should be isolated in order to understand technique. If these
movements are correct, then the racket movement will more likely be
correct.
[0063] As another advantage, reducing noise in the measurement
system allows for greater accuracy of measurement. Applicant has
found that embedding sensors away from the racket handle (such as
about the wrist) reduces vibrational forces which occur through the
racket when the ball is struck. These vibrational forces create
noise in the data obtained by the sensors. While additional
filtering and processing can minimise the noise, these processes
have a detrimental impact on battery life of the device and in any
event lead to a less precise understanding of the movement of the
wrist.
[0064] The device comprises a sensor (and typically a number of
sensors) which act to collect substantially real time data useful
in the construction of a stroke profile. In one embodiment, sensors
are selected such that information on the position and orientation
of the device (and therefore the wrist) is obtainable. It is known
in the art that the output of a combination accelerometer output
and gyroscope output can be used to track the position and the
orientation of an object. For example, inertial measurement units
(IMUs) are known which can reliably sense and process multiple
degrees of freedom (DoF), even in highly complex applications and
under dynamic conditions. These units typically contain multi-axis
combinations of precision gyroscopes, accelerometers, and
magnetometers.
[0065] In one embodiment, the limb-mountable device comprises three
accelerometers, three gyroscopes, and optionally three
magnetometers. The accelerometers are typically disposed with their
measuring axes are orthogonal to each other. These sensors measure
inertial acceleration. The three gyroscopes are typically placed in
a similar orthogonal pattern, measuring angular velocity. As the
skilled person appreciates, position may be derived from the sensor
data and the gyroscope only provides instantaneous rate of angular
velocity which is a relative figure and not an absolute figure.
Other sensor data are used to relate the output of the gyroscope
back to a fixed frame of reference or coordinate system.
[0066] The optional inclusion of three magnetometers provides an
absolute reference for yaw or heading. The gyroscope data may be
used to provide granular data on yaw with the magnetometer data
used to correct for drift that accumulates over time It is noted
that the processor(s) and/or software of the present system are
typically configured to execute any calculations required to
provide useful information (such as the relative orientation of the
limb-mountable device) from the accelerometer, gyroscope and
optionally the magnetometer output.
[0067] Other information useful in the construction of a stroke
profile may be provided by the sensors. For example, it is useful
to identify the point in the stroke at which the ball is struck. A
contemporaneous change in linear and angular momentum of the
limb-mountable device may be reflective of a ball strike.
Alternatively, the total acceleration data (square root of x 2+y
2+z 2) may be used to identify ball impact. The moment of impact
has a characteristic peak combined with vibration in this data.
[0068] Other calculations executed in the present system are
directed to reference models which calculate the relative position
of the racket face. The calculations may accept as input from the
user information relating to the grip used to hold the racket for
serves, forehands, backhands and volleys. For example, a semi
western grip on the forehand. This allows for an accurate picture
of how the movements of racket and wrist interact. Preferably, this
process is applicable for all tennis strokes.
[0069] Some embodiments of the invention comprise two or more
limb-mountable devices. For example, the system may comprise a
first wrist-mountable device for the left limb, and a second
wrist-mountable device for the right limb. Where the user is
right-handed the second wrist-mountable device operates as
discussed above, while the second wrist mountable device obtains
positional data on the right hand. As is understood by the skilled
person, the position of the non-playing hand can be important in
maintaining balance, and correction to the position of that hand
may lead to an improvement in the user's stroke technique.
[0070] In another embodiment, the system comprises a first
wrist-mountable device for an upper limb, and a second
ankle-mountable device for a lower limb, in tennis, the positioning
of feet (and particularly the leading foot) can be important in
improving stroke technique.
[0071] In a further embodiment, the system comprises two or more
limb-mountable devices configured to be mounted on two or more
regions of the dominant arm of the user. For example, there may be
a wrist-mounted device, and an upper arm-mounted device. This
system allows for a stroke profile to include information regarding
an bend in the arm at the elbow joint. In some strokes a straight
arm is necessary at some time during the stroke, and information on
the relative positions of the upper and lower arms may be relevant
in the improvement of stroke technique.
[0072] It is contemplated that the system may further comprise
non-limb mountable devices capable of providing data relating to
body orientation, hip rotation, head orientation position and the
like. Accordingly, devices mountable on the head, neck, chest,
waist, hips and buttocks may also be included in the system.
[0073] In another aspect, the present invention provides a
limb-mountable device configured to be operable in the systems as
described herein. The limb-mountable device may be constructed from
elastomeric materials to ensure a snug fit on the limb. Movement of
the device relative to the wrist is to be avoided, and so materials
and surfaces which limit slippage a preferred especially in
consideration of the lubricating effect of perspiration.
[0074] It is preferred that the limb-mountable device is light, so
as to minimise any effect of the device on the user's stroke during
data collection. Preferably, the device has a mass of less than
about 5 g, 6 g, 7 g, 8 g, 9 g, 10 g, 11 g, 12 g, 13 g, 14 g, 15 g,
16 g, 17 g, 18 g, 19 g, 20 g. In one embodiment, the device has a
mass of between about 10 g and about 15 g.
[0075] In another aspect the present invention provides software
configured to be operable in the present systems. The software of
part thereof may be embodied in the form of firmware in the
processor device or memory device of the limb-mountable device. The
software of part thereof may also be embodied in the form of an
application executable on a mobile device (such as a smart phone),
and therefore operable in an iOS or Android operating system
environment for example.
[0076] In a further aspect, the present invention provides a method
for improving the stroke of a user, the method comprising the steps
of: electronically recording data capable of defining a user stroke
profile, providing a comparator stroke profile, comparing the user
stroke profile to the comparator stroke profile, and providing
feedback to the user indentifying similarities and/or differences
between the user stroke profile and the comparator stroke profile.
The method may include the use of any system, any limb-mountable
device, or any feedback device, or any software as described
herein.
[0077] The present invention will now be further described by way
of the following non-limiting preferred embodiments.
Preferred Embodiments of the Invention
[0078] An exemplary wristband captures and analyses the movements
of the player by way of an array of onboard sensors, processors and
micro controllers. The sensors are (i) a tri-axial accelerometer,
(ii) a gyroscope and (iii) a magnetometer. Collectively these
sensors have nine degrees of freedom (9DoF). Working together the
sensors provide the ability to monitor an object's position, and
the forces acting upon it, in time and space.
[0079] Reference is made to FIG. 1A, which shows a diagram of the
components of a wrist-band of the present invention. The components
are generally disposed in two layers, the lower layer comprising
the battery 12 being a lithium polymer battery with 100-150 mAh
capacity and dimensions of 35.times.25.times.3 mm., which is the
upper layer 14 comprising two circuit boards 16. Disposed on the
circuit board is a microcontroller being a EFM32WG390
Microprocessor (Silicon Wave Inc; RF Micro Devices Inc) 18. This
microprocessor rate of up to 48 Mhz, which is sufficient to process
the data output by the inertial sensors 20. The inertial sensors
are ST LSM303D (a dual sensor triaxial magnetometer and
accelerometer) and ST L3GD2OH (a triaxial gyroscope)
(STMicroelectronics Inc).
[0080] These two inertial sensors 20 are disposed adjacent each
other on the circuit board 16 with the orientation of the x-axis of
each sensor pointing down towards the hand. The PCB is housed in
the wristband with the sensors positioned on the top of the wrist.
Each of the three sensors takes measurements through three axes, x,
y and z. Combined together they represent 9 degrees of freedom
(9DoF) with the output data being interpreted to provide
information on the position of the wrist in space as a function of
time. They also capture forces acting on the wrist such as
momentum, angular rotation, acceleration and force. Again, the
sensor outputs are not used directly to provide this information.
The sensors provide vector linear acceleration, vector angular
velocity and vector magnetic field strength data. Sensor fusion
algorithms are then used to derive orientation data.
[0081] The memory 22 is in operable communication with the
microprocessor 18 and inertial sensors 20. A Bluetooth module 24
being a dual mode Bluetooth transceiver-Bluetooth classic and
Bluetooth low energy, is included to transmit feedback to a
proximal smart phone of the user (not shown). The two circuit
boards 16 are operably connected by a bus 26. The battery 12 is
slightly curved to accommodate the curved surface of the wrist
operably connected to the circuit board 16 by flexible wire 28.
[0082] In FIG. 1B the battery 12 and circuit boards 16 are shown
layered, and positioned with reference to the wrist of a user. The
battery 12 is curved, with the bus 26 forming a hinge between the
two circuit boards 16. The ability of the circuit boards 16 to flex
relative to each other allows them to conform to some extent to the
curvature of the battery and the curve of the mechanics of the
device.
[0083] The sensors are embedded in the wristband and capture the
movement and orientation of the wrist holding the racket. The data
output by the sensors is processed on board the device constantly,
this includes analysing the data using a set of on board algorithms
which determine shot type, and the characteristics of the shot.
This data is then stored on the device using the inbuilt memory
[0084] The data processing functionality inside the wristband is
responsible for translating raw sensor data into specific shot
characteristic data and carrying out the associated analysis. While
the sensor is in one of the normal active modes, it is continuously
processing this raw data and looking for evidence that a shot has
been played. On detecting such an event, it will analyse the shot
to determine a wide range of characteristics related to that shot
(including shot type) and log or stream the results of that shot.
In addition, the system will keep track of the overall play data
(shot frequency, total play time, etc.).
[0085] Turning to FIG. 2 there is shown a flow diagram detailing an
exemplary scheme for processing raw data from wristband sensors.
The sensors 50 output raw data in the form of accelerometer data,
gyroscope data, magnetometer data and temperature data. The raw
data is firstly adjusted by reference to a calibration standard 52,
and output as calibrated data. Further processing 54 of the
calibrated data provides orientation data which is used for stroke
detection 56 either directly or after LP filtering 58. The
orientation data is also co-processed with complementary data 60
before LP filtering 58.
[0086] The orientation data is directly processed for stroke
characterisation extraction 60, and also indirectly after LP
filtering 58. Stroke characterization extraction 60 followed by
stroke evaluation involves analysis of the LP filtered orientation
data to identify and characterize stroke events in the data in
order to resolve what type of shot has been played (forehand,
backhand, lob, serve etc), any relevant event characteristics which
together form a stroke profile.
[0087] When a shot has been detected 56, play analysis 64 is
triggered, involving the comparison of the stroke profile of the
user with that of a superior stroke profile. The play analysis 64
is reliant on the identification of the shot type and event
characteristics output by the shot evaluation step 62. The play
analysis is presented to the user in the form of feedback on a
smart phone (not shown).
[0088] Shot detection is based on carrying out peak detection of
the low pass filtered total acceleration data. This peak detection
is based on first identifying any occasion where the filtered total
acceleration exceeds a predefined threshold. Once such an event has
been detected, the peak itself is determined using a peak detection
algorithm on the raw data itself.
[0089] With respect to characteristic extraction, a range of shot
characteristic data is extracted at this stage. This data is used
in turn to determine the shot type and other data in the Shot
Evaluation stage. The type of data extracted in this processing
stage includes: [0090] Minimum and maximum peaks for yaw, pitch and
roll. [0091] Time of minimum and maximum peaks for yaw, pitch and
roll. [0092] Difference between minimum and maximum peaks for yaw,
pitch and roll. [0093] Maximum angular rate [0094] Maximum angular
rate at moment of ball impact
[0095] The characteristics extracted form an overall stroke profile
of every shot played.
[0096] Each shot is broken down into a number of separate phases or
stages. In this way, it is possible to identify and measure
different characteristics related to shot technique more
accurately. Each of these phases has a specific measurable duration
(with the exception of the ball impact itself which is taken to
occur at a specific point in time).
[0097] For some shots (and particularly non-serve shots), the
following process and phases of movement are identified: [0098] 1.
Ready/waiting for the next shot. [0099] 2. Backswing [0100] 3.
Swing (to impact) [0101] 4. Ball impact [0102] 5. Follow through
[0103] 6. Set-up for next shot [0104] 7. Ready/waiting for the next
shot.
[0105] With regard to shot evaluation, this processing step
evaluates the specific shot type and characteristics related to
that specific shot. The output from this step is the primary data
that is presented to the player for each shot and is used in
construction a summary of overall user performance.
[0106] Evaluating overall performance is undertaken by reference to
the quality of each shot. To achieve this, the system uses a
process of comparison against an extensive library of ideal stroke
technique. The library contains characteristic information, data
markers and limits against which the user's data is compared.
Algorithms then identify differences between the user's data, and
the library to determine the specific points of feedback to return
to the player on their mobile device.
[0107] Examples include, but are not limited to; amount of wrist
rotation during follow through of the forehand, momentum of racket
head during serving motion. Depending on the size of the variance
the device can determine against these characteristics the relative
quality of a players game.
[0108] The algorithms determine the quality of a players shot and
overall game by analysing the size of the variance in the data,
relative to a set of ideal models.
[0109] With respect to play analysis, the output of this process
step is a summary of the overall play session. This includes shot
frequency, total shot count and breakdown, quality of shots and
overall game, total play time plus effort expended on the court (in
the form of calories burnt and distance travelled).
[0110] A key feature of play analysis is the consistency rating,
which is combined with other data to provide an overall user score.
The overall user score aggregates all shot evaluation data to
determine how often the user is repeatedly achieving the correct
technique. This applies to every shot hit by the user.
[0111] The data collected over time on the users overall
performance and overall user score allows the user to monitor their
improvement over time. This may be broken down further to relate to
performance in each session, or to focus on one stroke in
particular. The users overall score can also be used to compare
with other players in the community. From mobile devices, a player
can challenge another player nearby.
[0112] It should be appreciated that in the above description of
exemplary embodiments of the invention, various features of the
invention are sometimes grouped together in a single embodiment,
figure, or description thereof, for the purpose of streamlining the
disclosure and aiding in the understanding of one or more of the
various inventive aspects. This method of disclosure, however, is
not to be interpreted as reflecting an intention that the claimed
invention requires more features than are expressly recited in each
claim. Rather, as the following claims reflect, inventive aspects
lie in less than all features of a single foregoing disclosed
embodiment. Thus, the claims following the Detailed Description are
hereby expressly incorporated into this Detailed Description, with
each claim standing on its own as a separate embodiment of this
invention.
[0113] Furthermore, while some embodiments described herein include
some but not other features included in other embodiments,
combinations of features of different embodiments are meant to be
within the scope of the invention, and form different embodiments,
as would be understood by those skilled in the art. For example, in
the following claims, any of the claimed embodiments can be used in
any combination.
[0114] In the description provided herein, numerous specific
details are set forth. However, it is understood that embodiments
of the invention may be practiced without these specific details.
In other instances, well-known methods, structures and techniques
have not been shown in detail in order not to obscure an
understanding of this description.
[0115] Thus, while there has been described what are believed to be
the preferred embodiments of the invention, those skilled in the
art will recognize that other and further modifications may be made
thereto without departing from the spirit of the invention, and it
is intended to claim all such changes and modifications as falling
within the scope of the invention. For example, components and
functionality may be added or deleted from diagrams and operations
may be interchanged among functional blocks. Steps may be added or
deleted to methods described within the scope of the present
invention.
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