U.S. patent application number 14/510685 was filed with the patent office on 2015-04-23 for movement analysis method, movement analysis apparatus, and movement analysis program.
The applicant listed for this patent is SEIKO EPSON CORPORATION. Invention is credited to Kenya KODAIRA, Kazuo NOMURA, Masafumi SATO, Kazuhiro SHIBUYA.
Application Number | 20150111657 14/510685 |
Document ID | / |
Family ID | 52826635 |
Filed Date | 2015-04-23 |
United States Patent
Application |
20150111657 |
Kind Code |
A1 |
SHIBUYA; Kazuhiro ; et
al. |
April 23, 2015 |
MOVEMENT ANALYSIS METHOD, MOVEMENT ANALYSIS APPARATUS, AND MOVEMENT
ANALYSIS PROGRAM
Abstract
A designation unit designates a checkpoint of sporting equipment
on which a swing motion is performed. A first calculation unit
calculates a movement path of the sporting equipment, which is
being swung, using an output of an inertial sensor. A second
calculation unit calculates a posture of an interest part of the
sporting equipment at the checkpoint using the output of the
inertial sensor up to the checkpoint on the movement path of the
sporting equipment. The display unit displays the posture of the
interest part of the sporting equipment at the checkpoint.
Inventors: |
SHIBUYA; Kazuhiro;
(Shiojiri-shi, JP) ; NOMURA; Kazuo; (Shiojiri-shi,
JP) ; KODAIRA; Kenya; (Azumino-shi, JP) ;
SATO; Masafumi; (Hara-mura, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SEIKO EPSON CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
52826635 |
Appl. No.: |
14/510685 |
Filed: |
October 9, 2014 |
Current U.S.
Class: |
473/223 ;
473/409; 700/91 |
Current CPC
Class: |
A63B 69/3632 20130101;
G06K 9/00342 20130101; G09B 19/0038 20130101 |
Class at
Publication: |
473/223 ;
473/409; 700/91 |
International
Class: |
A63B 24/00 20060101
A63B024/00; A63B 69/36 20060101 A63B069/36 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 18, 2013 |
JP |
2013-217642 |
Claims
1. A movement analysis method comprising: acquiring information
about a swing movement path of sporting equipment and information
about a posture of an interest part of the sporting equipment; and
outputting a state of the posture of the interest part of the
sporting equipment at a designated checkpoint in the swing movement
path of the sporting equipment.
2. The movement analysis method according to claim 1, wherein the
designated checkpoint is designated using at least one of
positional information and time information of the sporting
equipment which is being swung.
3. The movement analysis method according to claim 1, further
comprising: acquiring information about a rotation angle of the
sporting equipment, the rotation angle varying around a long axis
of a shaft section of the sporting equipment during a swing; and
associating the interest part of the sporting equipment in the
swing movement path with the information about the rotation
angle.
4. The movement analysis method according to claim 1, wherein the
interest part of the sporting equipment is an impact surface.
5. The movement analysis method according to claim 1, further
comprising: displaying an object image which shows the interest
part in association with the swing movement path of the sporting
equipment.
6. The movement analysis method according to claim 5, further
comprising: displaying a mark which changes an orientation
according to change in the state of the posture of the interest
part of the sporting equipment.
7. The movement analysis method according to claim 1, further
comprising: displaying the state of the posture of the interest
part in a viewing position, the viewing position being a position
at which an examinee looks at the interest part of the sporting
equipment during a swing.
8. The movement analysis method according to claim 1, wherein the
swing movement path is calculated based on output of an inertial
sensor which is mounted on at least one of the sporting equipment
and an examinee.
9. The movement analysis method according to claim 3, wherein the
rotation angle is calculated based on an output of an inertial
sensor which is mounted on the shaft section of the sporting
equipment.
10. A movement analysis apparatus comprising: a designating section
that designates a checkpoint of sporting equipment which is being
swung; a path calculating section that calculates a movement path
of the sporting equipment using an output of an inertial sensor; a
posture calculating section that calculates a state of a posture of
an interest part of the sporting equipment at the checkpoint in the
movement path of the sporting equipment; and an output section that
outputs the posture of the interest part of the sporting equipment
at the checkpoint.
11. A non-transitory computer-readable medium storing a movement
analysis program, the program causing a computer to execute the
steps of: acquiring information about movement path of sporting
equipment, which is being swung, and information about a posture of
an interest part of the sporting equipment using an output of an
inertial sensor; designating a designated checkpoint in the
movement path of the sporting equipment; and outputting a state of
the posture of the interest part of the sporting equipment at the
designated checkpoint.
12. The movement analysis method according to claim 1, the method
further comprising: acquiring information about a predetermined
condition regarding at least one of information of an examinee and
a dimension of the sporting equipment which is being swung.
13. The movement analysis method according to claim 12, wherein the
designated checkpoint is designated based on the predetermined
condition.
14. A movement analysis apparatus comprising: a storage section
that stores a predetermined condition regarding at least one of
information of an examinee and a dimension of sporting equipment
which is being swung; a designating section that designates a
checkpoint of sporting equipment during a swing based on the
predetermined condition; a path calculating section that calculates
a movement path of the sporting equipment using an output of an
inertial sensor; a posture calculating section that calculates a
state of a posture of an interest part of the sporting equipment at
the checkpoint in the movement path of the sporting equipment; and
an output section that outputs the posture of the interest part of
the sporting equipment at the checkpoint.
15. The movement analysis apparatus according to claim 14, wherein
the predetermined condition is information about a height of the
examinee.
16. The movement analysis apparatus according to claim 14, wherein
the predetermined condition is a length of the interest part from
the inertial sensor.
17. The movement analysis apparatus according to claim 14, wherein
the output section outputs the movement path of the sporting
equipment, the movement analysis apparatus further comprising: a
display device configured to display the posture of the interest
part of the sporting equipment at the checkpoint in association
with the movement path.
Description
CROSS REFERENCE
[0001] The entire disclosure of Japanese Patent Application No.
2013-217642, filed Oct. 18, 2013, is expressly incorporated by
reference herein.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to a movement analysis method,
a movement analysis apparatus, and a movement analysis program.
[0004] 2. Related Art
[0005] A movement analysis apparatus is used for analysis of a
movement called a swing motion. An inertial sensor is mounted on
sporting equipment or an examinee who operates the sporting
equipment. The swing motion is visually reproduced based on output
of the inertial sensor. As a detailed example of the movement
analysis apparatus, for example, a golf swing analysis apparatus
which is disclosed in JP-A-2008-73210 may be shown.
[0006] In golf, the direction of a struck ball is greatly affected
by the direction of a face of a club head at an impact moment. As
known, when trying to align the face of the club head by twisting
the wrist immediately before the impact, the alignment is delayed
and the face is not properly aligned at the impact due to twisting
of the wrist, thereby negatively affecting the result of the swing.
It is difficult to observe wrist behavior during a golf swing
through optical motion capture using a camera or the like, and it
is difficult to trace a minute wrist twisting behavior. When minute
tracing is performed, it is necessary to use a plurality of
high-precision cameras, thereby resulting in a large-scale
measurement apparatus. In addition, measurement can be performed
only indoor in optical motion capture, in which a camera or the
like is used, and thus it is difficult to use the measurement
apparatus in a general outdoor driving range.
[0007] An amateur golfer imposes a checkpoint for swing by
himself/herself for raising a score. A back swing to the top from
the address, a downswing to the impact from the top, and a follow
swing reaching the finish from the impact are successively
performed. Therefore, it is difficult to recognize a checkpoint
during the swing. When a swing motion is visually reproduced based
on the output of the inertial sensor, it is difficult to see a
swing motion at a particular checkpoint of interest within the
series of the swing motions. The problem is not limited to golf and
is common to other sports, for example, baseball, tennis, and the
like.
SUMMARY
[0008] An advantage of some aspects of the invention is to provide
a movement analysis method, a movement analysis apparatus, and a
movement analysis program capable of easily displaying a state of a
golf club or an arm at a checkpoint visually.
[0009] (1) An aspect of the invention provides a movement analysis
method including: acquiring and calculating information about
movement path of sporting equipment which is being swung and
information about a posture of an interest part of the sporting
equipment; and outputting and displaying a state of the posture of
the interest part of the sporting equipment at a designated
checkpoint on the movement path of the sporting equipment.
[0010] In the movement analysis method according the aspect of the
invention, the checkpoint of the sporting equipment on which a
swing motion is performed is designated. For example, the movement
path and the posture of the interest part of the sporting equipment
are calculated using data which is output from an inertial sensor
when the sporting equipment is being swung. Therefore, a position
of the checkpoint on the acquired movement path of the sporting
equipment may be understood. The posture of the interest part of
the sporting equipment at the checkpoint, which is designated on
the movement path of the sporting equipment, is displayed. When the
posture is used for swing evaluation, it is possible to support the
improvement of the movement of an examinee.
[0011] (2) In the movement analysis method according the aspect of
the invention, the checkpoint may be designated using at least one
of positional information and time information of the sporting
equipment which is being swung.
[0012] Although the checkpoint is designated on the movement path
of the sporting equipment, it is possible to designate the
checkpoint using the positional information (for example, the same
height as the eyes of the examinee or the like) or the time
information (for example, time that elapses from the start of
backswing or downswing or the like) of the sporting equipment. In
the inertial sensor, sampling is performed per unit time and
acceleration, angular velocity, and the like are detected. Detected
data is managed per unit time (for example, per time or per a
sampling counter number). Two-step integration is performed on the
amount of change (acceleration) per unit time during, for example,
a period of the sampling counter number t=1 to m, and the position
of the sporting equipment in the sampling counter number t=m is
acquired. The position on the movement path of the sporting
equipment and time are compared with the checkpoint, with the
result that a point on the movement path which coincides with or is
the closest to the checkpoint is specified, and thus a sampling
counter number t=m, which corresponds to the point, is
specified.
[0013] (3) The movement analysis method according the aspect of the
invention may further include: acquiring information about a
rotation angle which varies around a long axis of a shaft section
of the sporting equipment which is being swung; and associating
interest part of the sporting equipment in the movement path with
information about the rotation angle.
[0014] The rotation angle, which is generated around the axis of
the shaft section of the sporting equipment at the checkpoint is
acquired by performing integration on the angular velocity, which
is acquired using the inertial sensor, within a range from an
initial rotation angle position to the checkpoint. The rotation
angle, which is generated around the axis of the shaft section of
the sporting equipment, is an important factor which is associated
with the behavior of the wrist and which indicates the direction of
a hitting surface (a direction of a face surface in a case of a
golf club and a direction of a string surface in a case of a tennis
racket) in a case of a hitting equipment. In this manner, it is
possible to recognize the behavior of the wrist at the checkpoint
as the rotation angle which is generated around the axis of the
shaft section of the sporting equipment at the checkpoint. When the
rotation angle is used for the swing evaluation, it is possible to
support the improvement of the movement of the examinee.
[0015] (4) In the movement analysis method according the aspect of
the invention, the interest part of the sporting equipment may be
the hitting surface. For example, in the case of the hitting
equipment such as the golf club, the change during the swing in the
direction of the hitting surface, such as the face surface of the
club head, is the matter of concern. However, the swing is too
rapid to recognize. When the posture of the hitting surface at the
checkpoint is displayed, it is possible to effectively check the
swing.
[0016] (5) The movement analysis method according to the aspect of
the invention may further include displaying an object image which
shows the interest part in association with the movement path of
the sporting equipment.
[0017] In this manner, since an object which emulates the sporting
equipment is displayed as a matter which shows the posture of the
interest part of the sporting equipment at the checkpoint on the
swing movement path, it is possible to visually evaluate the
checkpoint.
[0018] (6) The movement analysis method according to the aspect of
the invention may further include displaying a mark which changes
direction according to a change in the state of the posture of the
interest part of the sporting equipment.
[0019] When the mark is displayed, it is possible to display, for
example, a wrist twisting state or the change in the angle of the
hitting surface as the posture of the interest part of the sporting
equipment such that the examinee easily understands the
posture.
[0020] (7) The movement analysis method according to the aspect of
the invention may further include displaying the state of the
posture of the interest part in a direction in which an examinee
gazes at the interest part of the sporting equipment. When the
direction in which the examinee faces the checkpoint from the view
point is set to the gaze direction, it is possible to display the
posture of the interest part which is viewed from the eyes of the
examinee.
[0021] (8) In the movement analysis method according the aspect of
the invention, the movement path may be calculated based on output
of an inertial sensor which is mounted on at least one of the
sporting equipment and an examinee.
[0022] (9) In the movement analysis method according the aspect of
the invention, the rotation angle may be calculated based on output
of an inertial sensor which is mounted on the sporting
equipment.
[0023] (10) Another aspect of the invention provides a movement
analysis apparatus including: a designation unit that designates a
checkpoint of sporting equipment on which a swing motion is being
performed; a first calculation unit that calculates a movement path
of the sporting equipment using an output of an inertial sensor; a
second calculation unit that calculates a state of a posture of an
interest part of the sporting equipment at the checkpoint in the
movement path of the sporting equipment; and a display unit that
outputs and displays the posture of the interest part of the
sporting equipment at the checkpoint.
[0024] (11) Still another aspect of the invention provides a
movement analysis program causing a computer to perform: acquiring
information about movement path of sporting equipment, which is
being swung, and information about calculation of a posture of an
interest part of the sporting equipment using an output of an
inertial sensor; designating a checkpoint in the movement path of
the sporting equipment; and outputting and displaying a state of
the posture of the interest part of the sporting equipment at the
designated checkpoint.
[0025] In the movement analysis program according to the aspect, it
is possible to cause the computer to perform operations of the
movement analysis apparatus according to another aspect. The
program may be stored in the movement analysis apparatus from the
beginning, may be stored in a storage medium and then installed in
the movement analysis apparatus, and may be downloaded in a
communication terminal of the movement analysis apparatus from a
server through a network.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0027] FIG. 1 is a schematic diagram schematically illustrating the
configuration of a golf swing analysis apparatus according to an
embodiment of the invention.
[0028] FIG. 2 is a schematic diagram schematically illustrating the
relationship between a movement analysis model, and a golfer and a
golf club.
[0029] FIG. 3 is a block diagram schematically illustrating the
configuration of an arithmetic processing circuit according to the
embodiment.
[0030] FIG. 4 is a diagram illustrating an example of a
checkpoint.
[0031] FIG. 5 is a diagram illustrating an output of an inertial
sensor which is managed for each unit time.
[0032] FIG. 6 is a diagram illustrating a front image on which a
normal view coordinate conversion is performed.
[0033] FIG. 7 is a diagram illustrating a side image on which the
normal view coordinate conversion is performed.
[0034] FIG. 8 is a diagram illustrating an example of display for
an image which visually expresses the movement path of a golf club
and the posture of the golf club at the checkpoint.
[0035] FIG. 9 is a diagram illustrating another example of display
in which view coordinates are different from those in FIG. 8.
[0036] FIG. 10 is a diagram illustrating further another example of
display in which view coordinates are different from those in FIGS.
8 and 9.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0037] Hereinafter, an embodiment of the invention will be
described with reference to the accompanying drawings. Meanwhile,
the embodiment which will be described below does not
inappropriately limit the content of the invention described in the
appended claims, and all of the configurations, which are described
in the embodiment, are not essential for the solution of the
invention.
1. Configuration of Golf Club Analysis Apparatus
[0038] FIG. 1 schematically illustrates the configuration of a golf
swing analysis apparatus (movement analysis apparatus) 11 according
to an embodiment of the invention. The golf swing analysis
apparatus 11 includes, for example, an inertial sensor 12. The
inertial sensor 12 is provided with, for example, an acceleration
sensor and a gyro sensor. The acceleration sensor is capable of
detecting respective accelerations in triaxial directions which are
perpendicular to each other. The gyro sensor is capable of
individually detecting respective angular velocities around the
respective axes of the three axes which are perpendicular to each
other. The inertial sensor 12 outputs a detection signal. In the
detection signal, an acceleration and an angular velocity are
specified for each axis. The acceleration sensor and the gyro
sensor relatively accurately detect information about the
acceleration and the angular velocity.
[0039] The inertial sensor 12 is attached to a golf club (sporting
equipment) 13. The golf club 13 includes a shaft 13a and a grip
13b. The grip 13b is gripped by the hands. The grip 13b is formed
on the same axis as the shaft 13a. The tip end of the shaft 13a is
coupled with a club head 13c. Preferably, the inertial sensor 12 is
attached to the shaft 13a or the grip 13b of the golf club 13. The
shaft 13a indicates a bar-shaped portion which includes the grip
13b and reaches the club head 13c. The inertial sensor 12 may be
relatively unmovably fixed to the golf club 13. Here, in the
attachment of the inertial sensor 12, one detection axis of the
inertial sensor 12 is aligned on the axis of the shaft 13a. One
more detection axis of the inertial sensor 12 is aligned in a
direction of the face (hitting surface) of the club head 13c.
[0040] The golf swing analysis apparatus 11 includes an arithmetic
processing circuit 14. The inertial sensor 12 is connected to the
arithmetic processing circuit 14. In the connection, a
predetermined interface circuit 15 is connected to the arithmetic
processing circuit 14. The interface circuit 15 may be connected to
the inertial sensor 12 in a wired or wireless manner. A detection
signal is supplied to the arithmetic processing circuit 14 from the
inertial sensor 12.
[0041] A storage device 16 is connected to the arithmetic
processing circuit 14. For example, a golf swing analysis software
program (movement analysis program) 17 and the relative data
thereof can be stored in the storage device 16. The arithmetic
processing circuit 14 executes the golf swing analysis software
program 17 and implements a golf swing analysis method. A Dynamic
Random Access Memory (DRAM), a high-capacity storage device unit, a
nonvolatile memory, or the like can be included in the storage
device 16. For example, the golf swing analysis software program 17
is temporally held in the DRAM when the golf swing analysis method
is performed. The golf swing analysis software program 17 and data
are held in the high capacity storage device unit such as a Hard
Disk Drive (HDD). A relatively small capacity program, such as a
Basic Input/Output System (BIOS), or data is stored in the
nonvolatile memory.
[0042] An image processing circuit 18 is connected to the
arithmetic processing circuit 14. The arithmetic processing circuit
14 transmits predetermined image data to the image processing
circuit 18. A display device (display unit) 19 is connected to the
image processing circuit 18. The image processing circuit 18 is
provided with a view coordinate conversion unit 18A. As will be
described in detail, the view coordinate conversion unit 18A
performs conversion on the viewpoint and gaze direction of an image
which is displayed on the display device 19. In the connection, a
predetermined interface circuit (not shown in the drawing) is
connected to the image processing circuit 18. The image processing
circuit 18 transmits an image signal to the display device 19 in
accordance with input image data. An image which is specified based
on the image signal is displayed on the screen of the display
device 19. A liquid crystal display or another flat panel display
is used for the display device 19.
[0043] A designation unit 20 is connected to the arithmetic
processing circuit 14. The designation unit 20 designates the
checkpoint of the golf club 13, on which the swing motion is
performed, for the arithmetic processing circuit 14. The arithmetic
processing circuit 14 calculates the movement path of the interest
part of the golf club 13, and calculates a rotation angle which is
generated around the axis of the shaft 13a at the checkpoint based
on the output of the inertial sensor 12 up to the checkpoint on the
movement path. Here, the arithmetic processing circuit 14, the
storage device 16, the image processing circuit 18, and the
designation unit 20 are provided as, for example, a computer
apparatus.
[0044] An input device 21 is connected to the arithmetic processing
circuit 14 and the designation unit 20. The input device 21
includes at least alphabet keys and numeric keys. Character
information or numerical value information is input to the
arithmetic processing circuit 14 from the input device 21. The
input device 21 may include, for example, a keyboard. The
combination of the computer apparatus and the keyboard may be
replaced by, for example, a smart phone, a mobile phone terminal, a
tablet Personal Computer (PC), or the like.
[0045] Here, a checkpoint which is designated by the designation
unit 20 may be set based on external input data (for example, data
of the height of the examinee) which is input by the input device
21. In addition, the view coordinate conversion unit 18A may be
connected to the designation unit 20. If so, the view point can be
set based on the data of the height of the examinee and a direction
which faces the checkpoint from the viewpoint can be set to the
gaze direction.
2. Movement Analysis Model
[0046] The arithmetic processing circuit 14 defines a virtual
space. The virtual space is formed in a 3-dimensional space. The
3-dimensional space specifies an actual space. As shown in FIG. 2,
the 3-dimensional space includes an absolute reference coordinate
system (world coordinate system) .SIGMA.xyz. In the 3-dimensional
space, a 3-dimensional movement analysis model 26 is constructed
along the absolute reference coordinate system .SIGMA.xyz. A bar 27
of the 3-dimensional movement analysis model 26 is point restrained
by a fulcrum 28 (coordinate x). The bar 27 3-dimensionally operates
as a pendulum around the fulcrum 28. It is possible to move the
position of the fulcrum 28. Here, the position of the tip end of
the club head 13c is specified by a coordinate xh along the
absolute reference coordinate system .SIGMA.xyz.
[0047] The 3-dimensional movement analysis model 26 corresponds to
a model of the golf club 13 when a swing is performed. The shaft
13a of the golf club 13 is projected as the bar 27 of the pendulum.
The grip 13b is projected as the fulcrum 28 of the bar 27. The
inertial sensor 12 is fixed to the shaft 13a. The inertial sensor
12 outputs an acceleration signal and an angular velocity signal.
In the acceleration signal, an acceleration signal which includes a
gravity acceleration g is output.
[0048] Similarly, the arithmetic processing circuit 14 fixes a
local coordinate system (sensor coordinate system) .SIGMA.s to the
inertial sensor 12. The origin of the local coordinate system
.SIGMA.s is set to the origin of the detection axis of the inertial
sensor 12. The Y axis of the local coordinate system .SIGMA.s
coincides with the long axis of the shaft 13a as shown in FIG. 1.
The x axis of the local coordinate system .SIGMA.s coincides with a
struck ball direction which is specified as a direction of a face
as shown in FIG. 1. Therefore, based on the local coordinate system
.SIGMA.s, a fulcrum position l.sub.sj is specified as (0,
l.sub.sjy, 0) as shown in FIG. 2. Similarly, the position l.sub.sh
of the club head 13c is specified as (0, l.sub.shy, 0).
3. Swing Trace Calculation
[0049] FIG. 3 schematically illustrates the configuration of the
arithmetic processing circuit 14 according to the embodiment. The
arithmetic processing circuit 14 includes a swing trace calculation
unit 31 as a first calculation unit and a rotation angle
calculation unit 32 as a second calculation unit. The swing trace
calculation unit 31 is connected to the inertial sensor 12. An
output signal is supplied to the swing trace calculation unit 31
from the inertial sensor 12. Here, the output of the inertial
sensor 12 includes accelerations which are respectively detected
along the perpendicular three axes, and angular velocities which
are respectively detected around the perpendicular three axes. The
swing trace calculation unit 31 detects the position and the
posture of the golf club 13 based on the output of the inertial
sensor 12. The swing trace calculation unit 31 detects, for
example, the positions of the grip 13b and the club head 13c which
are moving. In the detection, the swing trace calculation unit 31
calculates the acceleration of the grip 13b according to, for
example, subsequent Expression (1). In the calculation of the
acceleration, the swing trace calculation unit 31 specifies the
position l.sub.sj of the grip 13b according to the unique local
coordinate system .SIGMA.s of the inertial sensor 12. In the
specification, the swing trace calculation unit 31 acquires
positional information from the storage device 16. The position
l.sub.sj of the grip 13b is stored in the storage device in
advance. The position l.sub.sj of the grip 13b may be designated
through, for example, the input device 21. In Expression (1),
.alpha..sub.sj indicates the acceleration of the grip, as indicates
the acceleration which is measured by the inertial sensor 12, and
.omega.s indicates the angular velocity which is measured by the
inertial sensor 12.
.alpha..sub.sj=.alpha..sub.s+{dot over
(.omega.)}.sub.s.times.l.sub.sj+.omega..sub.s.times.(.omega..sub.s.times.-
l.sub.sj)+g (1)
[0050] The swing trace calculation unit 31 calculates the moving
velocity of the grip 13b based on the calculated acceleration.
Here, an integration process is performed on the acceleration with
a prescribed sampling interval dt according to subsequent
Expression (2). N indicates the number of samples (hereinafter, the
same).
V sj ( 0 ) = 0 V sj ( t ) = n = 1 t .alpha. sj ( n ) t ( t - 1 , ,
N ) ( 2 ) ##EQU00001##
[0051] Further, the swing trace calculation unit 31 calculates the
position of the grip 13b based on the calculated velocity. Here,
the integration process is performed on the velocity with the
prescribed sampling interval dt according to subsequent Expression
(3).
P sj ( t ) = n = 1 t V sj ( n ) t ( t = 1 , , N ) ( 3 )
##EQU00002##
[0052] The swing trace calculation unit 31 specifies the position
of the local coordinate system .SIGMA.s (or the position of the
grip 13b) in a virtual 3-dimensional space in advance. When the
displacement of the local coordinate system .SIGMA.s or the
displacement of the grip 13b is converted into a coordinate system
in the virtual 3-dimensional space, the position of the golf club
13 is specified.
[0053] Similarly, the swing trace calculation unit 31 detects the
position of the club head 13c according to subsequent Expressions
(4) to (6). In the detection of the position, the swing trace
calculation unit 31 specifies the position l.sub.sh of the club
head 13c according to the unique local coordinate system .SIGMA.s
of the inertial sensor 12. In the specification, the swing trace
calculation unit 31 acquires the positional information from the
storage device 16. The position l.sub.sh of the club head 13c is
stored in the storage device 16 in advance. The position l.sub.sh
of the club head 13c may be designated through, for example, the
input device 21.
.alpha. sh = a s + .omega. s .times. sh + .omega. s .times. (
.omega. s .times. sh ) + g V sh ( 0 ) = 0 ( 4 ) V sh ( t ) = n = 1
t .alpha. sh ( n ) t ( t = 1 , , N ) ( 5 ) P sh ( t ) = n = 1 t V
sh ( n ) t ( t = 1 , , N ) ( 6 ) ##EQU00003##
[0054] The swing trace calculation unit 31 specifies the position
l.sub.sh of the club head 13c according to the unique local
coordinate system .SIGMA.s of the inertial sensor 12 as described
above, and then converts the position l.sub.sh of the club head 13c
into the coordinate system in the virtual 3-dimensional space. That
is, the position P.sub.sh(t) of the club head 13c is shown by
coordinates (x, y, z) in the virtual 3-dimensional space shown in
FIG. 1.
4. Calculation of Rotation Angle Around Axis of Shaft
[0055] The rotation angle calculation unit 32 is connected to the
inertial sensor 12 and the designation unit 20. An output from the
inertial sensor 12 is supplied to the rotation angle calculation
unit 32. The rotation angle calculation unit 32 detects the
rotation angle .theta..sub.m (m=1, . . . , N) of the grip 13b
around the axis from the initial position of an angular position
"0.degree." to the checkpoint based on the output of the inertial
sensor 12. In the detection, the rotation angle calculation unit 32
integrates the amount of change in the rotation angle per unit time
(angular velocity .omega..sub.n) as shown in subsequent Expression
(7).
.theta. 0 = 0 .theta. m = n = 1 m .omega. n t ( 1 .ltoreq. m < N
) ( 17 ) ##EQU00004##
[0056] An integration period in Expression (7) ranges from the
initial position n=1 to the checkpoint n=m, and integration is
performed on the angular velocity .omega..sub.n which is output
from the inertial sensor (here, a gyro sensor) 12 during the
period. In this manner, the rotation angle .theta..sub.n, is
calculated at the checkpoint of the grip 13b.
[0057] In the detection of the rotation angle .theta..sub.m, at the
checkpoint, the rotation angle calculation unit 32 detects the
initial position of the grip 13b around the axis of the grip 13b
(the same axis of the shaft 13a) based on the output of the
inertial sensor 12. In the detection, the rotation angle
calculation unit 32 acquires the angular velocity at address around
a first detection axis (here, around the y axis) which is parallel
to the shaft 13a by the inertial sensor 12. The rotation angle
calculation unit 32 sets the acquired angular velocity to an
initial value. The angular velocity is not generated around the y
axis at address. Therefore, when the grip 13b stops at an angular
velocity of "0 (zero)", the angular position is set to "0.degree.
(zero degree)" (=initial position).
[0058] The angular velocity .omega..sub.n is sequentially input to
the rotation angle calculation unit 32 from the inertial sensor
(gyro sensor) 12. Therefore, a checkpoint is designated to the
rotation angle calculation unit 32. If the end of the integration
period is acquired, the rotation angle calculation unit 32 can
calculate the rotation angle .theta..sub.m of the grip 13b at the
checkpoint.
5. Designation of Checkpoint
[0059] Although the checkpoint can be designated as positional
information or time information in the movement path of the golf
club 13, a case in which designation is performed using the
positional information will be described below.
[0060] FIG. 4 is a diagram illustrating an example of the
checkpoint. In the golf driving range, there is a case in which the
golf club 13 is stopped during downswing facing the impact from the
top, and the direction of the face of the club head 13c at that
time is recognized as a checkpoint. In the example, the club head
13c is stopped at, for example, the height of the eyes of a golfer.
The checkpoint is a height H1 up to the club head 13c. The
checkpoint (height) H1 can be designated in such a way that the
golf swing analysis apparatus 11 acquires a height H2 of the
golfer. In the embodiment, height data H2 of an examinee is input
by the input device 21. The designation unit 20 can designate the
checkpoint (height) H1 by performing an operation of
H1=H2.times..alpha. using, for example, a coefficient .alpha.
(.alpha.<1) It is possible to set the coefficient .alpha. to,
for example, .alpha.=0.8 as the coefficient of the height of eyes
of the examinee, who is a little bent.
[0061] FIG. 5 illustrates an example of data which is detected by
the inertial sensor 12. For example, a sampling counter number t
(t=1 to N) is attached to a top bit of the data of the acceleration
and the angular velocity of three axes, which are transmitted from
the inertial sensor 12, as shown in FIG. 5. Meanwhile, the data may
be stored in the storage device 16 or a storage unit inside the
arithmetic processing circuit 14. The sampling counter number t
coincides with a symbol t in Expression (7) which is used when the
swing trace calculation unit 31 calculates the position P.sub.sh(t)
of the club head 13c. That is, the position P.sub.sh(t) of the club
head 13c, which is calculated by the swing trace calculation unit
31 based on Expression (7), is calculated per the sampling counter
number t.
[0062] The position P.sub.sh(t) of the club head 13c, which is
calculated per the sampling counter number t, is input to the
designation unit 20 from the swing trace calculation unit 31. The
designation unit 20 determines whether or not the height (z
coordinate) of the position P.sub.sh(t) of the club head 13c
coincides with the checkpoint (height) H1, or acquires the sampling
counter number t=m which is the closest value.
[0063] In this manner, the designation unit 20 designates the
sampling counter number t=m, which corresponds to the checkpoint
(height) H1, for the rotation angle calculation unit 32. Based on
Expression (7), the rotation angle calculation unit 32 calculates
the rotation angle .theta..sub.m which is generated around the axis
of the shaft 13a at the checkpoint H1 on the movement path of the
club head 13c based on the output (t=1 to m) of the inertial sensor
12 up to the checkpoint H1.
6. Display
[0064] The arithmetic processing circuit 14 includes an image data
generation unit 34. The image data generation unit 34 is connected
to the swing trace calculation unit 31 and the rotation angle
calculation unit 32. An output signal is supplied to the image data
generation unit 34 from the swing trace calculation unit 31 and the
rotation angle calculation unit 32. The image data generation unit
34 includes a movement trace image generation unit 35, a surface
rotation image generation unit 36, and a cube image generation unit
37. The movement trace image generation unit 35 generates images
(R1 and R2 shown in FIGS. 8 to 10 which will be described later) to
visually display the movement path of the golf club 13 based on the
position and the posture of the golf club 13. The surface rotation
image generation unit 36 generates an object image (image 41 shown
in FIGS. 8 to 10) for displaying a face which is prescribed on the
golf club 13 and rotates around the axis of the shaft 13a. The cube
image generation unit 37 generates an image of a cube (a mark 42
shown in FIGS. 8 and 9) which has a ridgeline parallel to the axis
of the grip 13b. In the cube, one plane, which extends parallel to
the axis of the grip 13b and has a geometric-shaped outline (here,
a quadrate outline), is prescribed. The object image 41 of the face
surface and the plane 43 of the cube 42 change directions around
the axis of the grip 13b according to the rotation angle
.theta..sub.m of the grip 13b when the club head 13c is at the
checkpoint. Images, acquired when the club head 13c is at the
checkpoint, are associated with each other, and output from the
image data generation unit 34 as a single piece of image data.
Meanwhile, the mark can have a three-dimensional shape, such as a
curved surface or a sphere other than a cube, in addition to the
plane or cube.
[0065] The arithmetic processing circuit 14 includes a drawing unit
38. The drawing unit 38 is connected to the image data generation
unit 34. Image data is supplied to the drawing unit 38 from the
image data generation unit 34. The drawing unit 38 draws an image
which visually displays the movement path of the golf club 13 based
on the output signal of the movement trace image generation unit
35, and displays the image on the display device 19. The drawing
unit 38 overlaps the face image (object) 41 and the cube image
(mark) 42 on the image of the movement path of the golf club 13 for
each position. As a result, in the virtual 3-dimensional space, an
image which is acquired by associating the movement path of the
golf club 13 with the rotation angle of the face and the rotation
angle of the cube at the checkpoint and which is visually
displayed, is generated.
7. Operation of Golf Swing Analysis Apparatus
[0066] An operation of the golf swing analysis apparatus 11 will be
simply described. First, a golf swing of a golfer is measured.
Prior to the measurement, necessary information is input to the
arithmetic processing circuit 14 from the input device 21. Here,
according to the 3-dimensional movement analysis model 26, the
position l.sub.sj of the fulcrum 28 according to the local
coordinate system .SIGMA.s and the rotation matrix R0 of an initial
posture of the inertial sensor 12 are prompted to be input. In
addition, data of the height of the golfer is input to the
designation unit 20 from the input device 21. The input information
is managed, for example, under a specific identifier. The
identifier may identify a specific golfer.
[0067] Prior to the measurement, the inertial sensor 12 is attached
to the shaft 13a of the golf club 13. The inertial sensor 12 is
fixed to the golf club 13 such that relative displacement is not
possible. Here, one detection axis of the inertial sensor 12 is
aligned on the axis of the shaft 13a. One detection axis of the
inertial sensor 12 is aligned in a struck ball direction which is
specified as the direction of the face (hitting surface).
[0068] Prior to the execution of golf swing, measurement performed
by the inertial sensor 12 starts. When a motion starts, the
inertial sensor 12 is set to a predetermined position and posture.
The position and the posture are specified in a rotation matrix R0
of the initial posture. The inertial sensor 12 continuously
measures the acceleration and the angular velocity at a specific
sampling interval. The sampling interval prescribes a measurement
resolution. The detection signal of the inertial sensor 12 is
transmitted to the arithmetic processing circuit 14 in real time.
The arithmetic processing circuit 14 receives a signal which
specifies the output of the inertial sensor 12.
[0069] The golf swing starts from address and reaches the
follow-through and the finish through take back, half way back, top
to downswing, and impact. If the golf club 13 is swung, the posture
of the golf club 13 changes according to a time axis. The inertial
sensor 12 outputs the detection signal according to the posture of
the golf club 13. At this time, the swing trace calculation unit 31
detects the position of the golf club 13, in particular, the club
head 13c based on the output of the inertial sensor 12. The
designation unit 20, to which the position of the club head 13c is
input from the swing trace calculation unit 31, compares the
position and the checkpoint. The designation unit 20 acquires the
sampling counter number t=m when the swing trace calculation unit
31 calculates the position corresponding to the checkpoint, and
instructs the rotation angle calculation unit 32. The rotation
angle calculation unit 32 calculates the angular position of the
grip 13b around the axis of the grip 13b at the checkpoint
according to Expression (7) based on the output of the inertial
sensor 12 up to the checkpoint H1 on the movement path of the club
head 13c. The image data generation unit 34 generates 3-dimensional
image data (for example, polygon data) which specifies an image of
the face and an image of the cube at the checkpoint in association
with the movement path of the golf club 13. The drawing unit 38
draws the image of the face 41 and the image of the cube 42 in
association with the movement path T of the golf club 13 based on
the 3-dimensional image data.
[0070] The drawing data is transmitted to the image processing
circuit 18, and an image is displayed on the screen of the display
device 19 according to the drawing data. The image processing
circuit 18 includes a view coordinate conversion unit 18A. The view
coordinate conversion unit 18A has a well-known function to perform
view coordinate conversion such that an image, viewed from the view
point toward the gaze direction, is displayed on the display device
19. For example, the view point is set on the z axis by the
absolute reference coordinate system (x, y, z) shown in FIG. 1, and
a front image, which is acquired by performing normal view
coordinate conversion such that the gaze direction from the view
point is set to the z direction, is shown in FIG. 6. Similarly, the
view point is set on the x axis, a side image, which is acquired by
performing the normal view coordinate conversion such that the gaze
direction from the viewpoint is set to the x direction, is shown in
FIG. 7. Meanwhile, in FIGS. 6 and 7, a backswing movement path is
R1, and a downswing movement path is R2.
[0071] In the embodiment, the front image or the side image shown
in FIGS. 6 and 7 may be used. FIG. 8 illustrates the posture of the
face of the club head 13c at the checkpoint, which is displayed in,
for example, the front image which is the same as in FIG. 6.
Furthermore, for example, view coordinate conversion, in which the
vicinity of the eyes of a golfer is set to a view point 1 and which
includes a gaze direction 1 toward the checkpoint from the view
point 1 in FIG. 7, can be illustrated in FIG. 9. The gaze direction
1 is the same as the gaze direction S from the view point P shown
in FIG. 4. That is, in FIG. 9, the posture of the face of the club
head 13c at the checkpoint viewed from the eyes of the golfer is
displayed by the movement analysis apparatus 11, similarly to FIG.
4 when the golf club 13 is swung at the checkpoint without
stopping. According to the display example in FIG. 9, it is
excellent in that the checkpoint acquired when exercise, which is
used as in FIG. 4, is performed (when the golf club is stopped) can
be compared with the checkpoint when the golf club is swung without
stopping. As further another example, in FIG. 7, view coordinate
conversion, in which a view point 2 is set obliquely above and
behind the golfer and which includes a gaze direction 2 toward the
golfer from the view point 2 in FIG. 7, can be illustrated in FIG.
10.
[0072] FIGS. 8 to 10 illustrate the backswing movement path R1 and
the downswing movement path R2. In addition, FIGS. 8 to 10
illustrate an object 41 which indicates the face of the club head
13c which rotates around the axis of the shaft 13a. In addition,
FIGS. 8 and 9 illustrate a cube 42 which is a mark. Since the shaft
13a of the sporting equipment 13 has a bar shape, it is difficult
for the examinee to grasp the amount of rotation even though the
rotation around the axis of the shaft 13a is displayed as the
object 41. Therefore, when the mark 42 (FIGS. 8 and 9) which
indicates the change in rotation angle generated around the axis of
the shaft 13a of the sporting equipment 13 is displayed in
conjunction with the movement path of the sporting equipment 13, it
is possible to display the wrist twisting state and the change in
the angle of the struck ball surface for easy understanding by the
examinee.
[0073] The plane 43 of the cube 42 in the image changes the
direction according to the rotation of the grip 13b and the shaft
13a. The rotation of the grip 13b, that is, the rotation of the
wrist is expressed through the rotation of the plane 43. In this
manner, the examinee can clearly grasp the rotation of the wrist at
the checkpoint based on the image. The examinee can improve a swing
posture according to such a grasp. In particular, the cube 42
reflects the perpendicular three axes of the grip 13b. As a result,
the examinee can ideally recognize the behavior of the wrist at the
checkpoint clearly.
[0074] In the representation of the swing motion, the face 41 at
the checkpoint is specified in the image. In this manner, the
rotation of the wrist at the checkpoint with the golf club 13
itself is represented. The examinee can visually recognize the
behavior of the golf club 13. The examinee can improve the swing
posture through the recognition. Meanwhile, the first image and the
second image may be displayed in parallel or overlapping on the
display device 19. In this manner, it is possible to compare
different swings of the same golfer. Further, it is possible to
compare the swing of a person with the swing of an advanced
learner.
[0075] Meanwhile, in the above embodiment, the individual
functional block of the arithmetic processing circuit 14 is
realized by executing the golf swing analysis software program 17.
However, the individual functional block may be realized by
hardware without resorting to software processing. In addition, the
golf swing analysis apparatus 11 may be applied for analysis of
swing of sporting equipment (for example, a tennis racket, a table
tennis racket, or a baseball bat) which is gripped and swung by
hand. In addition, although the swing trace calculation unit 31 and
the rotation angle calculation unit 32 in FIG. 3 are separately
described, the swing trace calculation unit 31 and the rotation
angle calculation unit 32 may collectively function as a single
calculation unit.
[0076] Although the embodiment has been described in detail as
above, those skilled in the art can easily understand that various
modifications are possible without substantially departing from the
novelty and advantages of the invention. Therefore, all of such
modification examples are included in the scope of the invention.
For example, in the specification or drawings, a term, which is
described at least once with a different term having wider or
synonymous meaning, can be replaced with the different term at any
place of the specification or the drawings. In addition, the
configurations and operations of the inertial sensor 12, the golf
club 13, the arithmetic processing circuit 14, the designation unit
20, the 3-dimensional movement analysis model 26, the swing trace
calculation unit 31, the rotation angle calculation unit 32, and
the like are not limited to the description of the embodiment, and
various modifications are possible. For example, the arithmetic
processing circuit 14, the image processing circuit 18, the swing
trace calculation unit 31, and the rotation angle calculation unit
32 may be embodied by a single processing unit, such as a central
processing unit (CPU), more than one processing unit, or may be
embodied by one or more special purpose circuits. The processing
units are not limited to CPUs, and may be provided by any other
type of processing unit. In addition, it is possible to apply the
invention to sports, such as tennis or baseball, in which a swing
motion is used, in addition to golf.
* * * * *