U.S. patent application number 14/680311 was filed with the patent office on 2015-07-30 for motion analysis device and motion analysis method for analyzing deformation of measurement object.
The applicant listed for this patent is Seiko Epson Corporation. Invention is credited to Kazuo NOMURA, Masatoshi SATO, Toshiyasu TAKASUGI.
Application Number | 20150211970 14/680311 |
Document ID | / |
Family ID | 46455921 |
Filed Date | 2015-07-30 |
United States Patent
Application |
20150211970 |
Kind Code |
A1 |
TAKASUGI; Toshiyasu ; et
al. |
July 30, 2015 |
MOTION ANALYSIS DEVICE AND MOTION ANALYSIS METHOD FOR ANALYZING
DEFORMATION OF MEASUREMENT OBJECT
Abstract
A motion analysis device includes two posture angle sensors
attached to a measurement object at locations distant from each
other, a data acquisition section, a posture angle correction
section, and a deformation amount calculation section. The data
acquisition section acquires data of a first posture angle and a
second posture angle respectively detected by the posture angle
sensors. The posture angle correction section corrects a difference
between the first posture angle and the second posture angle after
starting a motion of the measurement object in accordance with a
difference between the first posture angle and the second posture
angle before starting the motion of the measurement object. The
deformation amount calculation section calculates a deformation
amount of the measurement object based on a difference between the
first posture angle and the second posture angle corrected by the
posture angle correction section.
Inventors: |
TAKASUGI; Toshiyasu;
(Hadano, JP) ; SATO; Masatoshi; (Hashima, JP)
; NOMURA; Kazuo; (Shiojiri, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Seiko Epson Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
46455921 |
Appl. No.: |
14/680311 |
Filed: |
April 7, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13347015 |
Jan 10, 2012 |
9026398 |
|
|
14680311 |
|
|
|
|
Current U.S.
Class: |
702/44 |
Current CPC
Class: |
G01B 21/22 20130101;
G01N 3/20 20130101; G01P 3/00 20130101; A63B 2225/50 20130101; A63B
69/36 20130101; A63B 24/0003 20130101; A63B 2220/34 20130101; A63B
2220/833 20130101; G01N 3/22 20130101; A63B 69/3611 20130101; A63B
2220/40 20130101 |
International
Class: |
G01N 3/20 20060101
G01N003/20; G01P 3/00 20060101 G01P003/00; G01B 21/22 20060101
G01B021/22; G01N 3/22 20060101 G01N003/22 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 2011 |
JP |
2011-003012 |
Claims
1. A central processing unit comprising: a data acquisition section
adapted to acquire data of a first posture angle outputted from a
first posture angle sensor attached a measurement object and a
second posture angle outputted from a second posture angle sensor
attached the measurement object; a posture angle correction section
adapted to correct a difference between the first posture angle and
the second posture angle after starting a motion of the measurement
object in accordance with a difference between the first posture
angle and the second posture angle before starting the motion of
the measurement object; and a deformation amount calculation
section adapted to calculate a deformation amount of the
measurement object based on a difference between the first posture
angle and the second posture angle corrected by the posture angle
correction section.
2. The central processing unit according to claim 1, wherein the
posture angle correction section performs the correction by
subtracting the difference between the first posture angle and the
second posture angle before starting the motion of the measurement
object from the difference between the first posture angle and the
second posture angle after starting the motion of the measurement
object.
3. A central processing unit comprising: a data acquisition section
adapted to acquire data of a first posture angle and a first
angular velocity outputted from a first posture angle sensor
attached a measurement object, a second posture angle and a second
angular velocity outputted from a second posture angle sensor
attached the measurement object; an angular velocity correction
section adapted to correct a difference between the first angular
velocity and the second angular velocity in accordance with a
difference between the first posture angle and the second posture
angle; and a deformation amount calculation section adapted to
calculate a deformation amount of the measurement object by
integrating the difference between the first angular velocity and
the second angular velocity corrected by the angular velocity
correction section.
4. The central processing unit according to claim 3, wherein the
angular velocity correction section corrects the difference between
the first angular velocity and the second angular velocity by
converting one of the first angular velocity and the second angular
velocity into an angular velocity with respect to a detection axis
of the other of the first angular velocity and the second angular
velocity in accordance with the difference between the first
posture angle and the second posture angle, and calculating a
difference between the first angular velocity and the second
angular velocity the one of which is converted.
5. The central processing unit according to claim 1, wherein the
measurement object is a golf club.
6. The central processing unit according to claim 3, wherein the
measurement object is a golf club.
7. The central processing unit according to claim 5, wherein the
first posture angle sensor is attached to one of a grip section and
a shaft section of the golf club, and the second posture angle
sensor is attached to a head section of the golf club.
8. The central processing unit according to claim 6, wherein the
first posture angle sensor is attached to one of a grip section and
a shaft section of the golf club, and the second posture angle
sensor is attached to a head section of the golf club.
9. A motion analysis method of a measurement object, comprising:
acquiring data of a first posture angle outputted from a first
posture angle sensor attached a measurement object and a second
posture angle outputted from a second posture angle sensor attached
the measurement object; correcting a difference between the first
posture angle and the second posture angle after starting a motion
of the measurement object in accordance with a difference between
the first posture angle and the second posture angle before
starting the motion of the measurement object; and calculating a
deformation amount of the measurement object based on a difference
between the first posture angle and the second posture angle
corrected in the correcting.
10. A motion analysis method of a measurement object, comprising:
acquiring data of a first posture angle and a first angular
velocity outputted from a first posture angle sensor attached a
measurement object, a second posture angle and a second angular
velocity outputted from a second posture angle sensor attached the
measurement object; correcting a difference between the first
angular velocity and the second angular velocity in accordance with
a difference between the first posture angle and the second posture
angle; and calculating a deformation amount of the measurement
object by integrating the difference between the first angular
velocity and the second angular velocity corrected in the
correcting.
Description
[0001] This is a continuation patent application of U.S.
application Ser. No. 13/347,015 filed Jan. 10, 2012 which claims
priority to Japanese Patent Application No. 2011-003012, filed Jan.
11, 2011 both of which are expressly incorporated by reference
herein in their entireties.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to a motion analysis device
and a motion analysis method.
[0004] 2. Related Art
[0005] In the characteristic evaluation of a golf club, analysis of
the deflection and the torsion thereof when making a swing is
performed. In the past, there has been known a method of shooting
the behavior of a golf club when making a swing with a camera, and
then analyzing the deflection and the torsion of the golf club
based on the shot image. However, since the image is analyzed in
this method, there is a disadvantage that it is difficult to
measure the deformation amount due to the deflection and the
torsion with high accuracy, and further, it takes time from the
measurement until the actual data is obtained.
[0006] On the other hand, in JP-A-2008-73210, there is proposed a
method of attaching gyro sensors respectively to a head portion and
a grip portion of a golf club to thereby evaluate the head speed of
a swing, the carry, and so on, and it is possible to apply this
method to the analysis of the deflection and the torsion of a golf
club. Specifically, the deflection amount and the torsion amount of
the golf club can be measured using the difference between the
angular velocities detected by the two gyro sensors attached
respectively to the head portion and the grip portion.
[0007] However, according to this method, since the error in the
installation angle of the gyro sensor attached to the grip portion
and the installation angle of the gyro sensor attached to the head
portion causes the error in the detection sensitivity of the
angular velocity, it is required to accurately conform the
installation angles to each other. However, since the grip portion
and the head portion are distant roughly 1 m from each other, it is
extremely difficult to accurately conform the installation angles
of the two gyro sensors to each other. If the error in the
installation angle can be measured, it is possible to correct the
angular velocities obtained from the gyro sensors. However, it is
also extremely difficult to accurately measure the error in the
installation angle. Therefore, in the case in which a high analysis
accuracy is required, the method using the gyro sensors is
applicable.
[0008] Such an analysis of the deformation amount due to the
deflection or the torsion is performed in a variety of fields
besides the golf club, and a new method realizing a high analysis
accuracy has been required.
SUMMARY
[0009] An advantage of some of the aspects of the invention is to
provide a motion analysis device and a motion analysis method
capable of analyzing a deformation amount of a measurement object
with high accuracy.
[0010] (1) An aspect of the invention is directed to a motion
analysis device including a first posture angle sensor attached to
a measurement object, and adapted to detect a first posture angle,
a second posture angle sensor attached to the measurement object at
a location distant from the first posture angle sensor, and adapted
to detect a second posture angle, a data acquisition section
adapted to acquire data of the first posture angle and the second
posture angle, a posture angle correction section adapted to
correct a difference between the first posture angle and the second
posture angle after starting a motion of the measurement object in
accordance with a difference between the first posture angle and
the second posture angle before starting the motion of the
measurement object, and a deformation amount calculation section
adapted to calculate a deformation amount of the measurement object
based on a difference between the first posture angle and the
second posture angle corrected by the posture angle correction
section.
[0011] Any object deformable in motion can be adopted as the
measurement object. Further, a motion of the measurement object
denotes a motion in which the measurement object changes at least
one of the position and the posture, and includes the case in which
the measurement object is provided with a motor, and voluntarily
causes a motion, and the case in which a motion is caused by an
external force applied to the measurement object.
[0012] The motion analysis device according to this aspect of the
invention uses the fact that the difference is caused between the
posture angles detected by two posture angle sensors in accordance
with the error in the installation angles of the two posture angle
sensors, measures the difference in the posture angle between the
two points of the measurement object as an offset before the motion
starts, and then calculates the difference in the posture angle
between the two points after the motion starts with the offset
correction. Thus, since the variation of the difference in the
posture angle between the two points caused by the motion of the
measurement object can accurately be calculated, the deformation
amount between the two points can be analyzed with high
accuracy.
[0013] (2) The motion analysis device of the aspect of the
invention may be configured such that the posture angle correction
section performs the correction by subtracting the difference
between the first posture angle and the second posture angle before
starting the motion of the measurement object from the difference
between the first posture angle and the second posture angle after
starting the motion of the measurement object.
[0014] (3) Another aspect of the invention is directed to a motion
analysis device including a first posture angle sensor attached to
a measurement object, and adapted to detect a first angular
velocity and a first posture angle, a second posture angle sensor
attached to the measurement object at a location distant from the
first posture angle sensor, and adapted to detect a second angular
velocity and a second posture angle, a data acquisition section
adapted to acquire data of the first posture angle, the first
angular velocity, the second posture angle, and the second angular
velocity, an angular velocity correction section adapted to correct
a difference between the first angular velocity and the second
angular velocity in accordance with a difference between the first
posture angle and the second posture angle, and a deformation
amount calculation section adapted to calculate a deformation
amount of the measurement object by integrating the difference
between the first angular velocity and the second angular velocity
corrected by the angular velocity correction section.
[0015] The motion analysis device according to this aspect of the
invention uses the fact that the difference is caused between the
posture angles detected by two posture angle sensors in accordance
with the error in the installation angles of the two posture angle
sensors, and corrects the difference in the angular velocity
between the two points of the measurement object in accordance with
the difference in the posture angle between the two points.
Further, since the variation of the difference in the posture angle
between the two points can accurately be calculated by integrating
the difference between the angular velocities after the correction,
the deformation amount between the two points can be analyzed with
high accuracy.
[0016] (4) The motion analysis device of the aspect of the
invention may be configured such that the angular velocity
correction section corrects the difference between the first
angular velocity and the second angular velocity by converting one
of the first angular velocity and the second angular velocity into
an angular velocity with respect to a detection axis of the other
of the first angular velocity and the second angular velocity in
accordance with the difference between the first posture angle and
the second posture angle, and calculating a difference between the
first angular velocity and the second angular velocity the one of
which is converted.
[0017] (5) The motion analysis device of the aspect of the
invention may be configured such that the measurement object is a
golf club.
[0018] According to the motion analysis device of this
configuration, since the variation of the difference in the posture
angle between the two points caused by the swing of the golf club
can accurately be calculated, the deformation amount of the golf
club during the swing can be analyzed with high accuracy.
[0019] (6) The motion analysis device of the aspect of the
invention may be configured such that the first posture angle
sensor is attached to one of a grip section and a shaft section of
the golf club, and the second posture angle sensor is attached to a
head section of the golf club.
[0020] According to this configuration, the deflection amount of
the shaft section of the golf club and the torsion amount of the
head section can be analyzed with high accuracy.
[0021] (7) Yet another aspect of the invention is directed to a
motion analysis method of a measurement object including: attaching
a first posture angle sensor adapted to detect a first posture
angle and a second posture angle sensor adapted to detect a second
posture angle to the measurement object at locations distant from
each other, acquiring data of the first posture angle and the
second posture angle, correcting a difference between the first
posture angle and the second posture angle after starting a motion
of the measurement object in accordance with a difference between
the first posture angle and the second posture angle before
starting the motion of the measurement object, and calculating a
deformation amount of the measurement object based on a difference
between the first posture angle and the second posture angle
corrected in the correcting.
[0022] The motion analysis method of this configuration uses the
fact that the difference is caused between the posture angles
detected by two posture angle sensors in accordance with the error
in the installation angles of the two posture angle sensors,
measures the difference in the posture angle between two points of
the measurement object as an offset before the motion starts, and
then calculates the difference in the posture angle between the two
points after the motion starts with the offset correction. Thus,
since the variation of the difference in the posture angle between
the two points caused by the motion of the measurement object can
accurately be calculated, the deformation amount between the two
points can be analyzed with high accuracy.
[0023] (8) Still yet another aspect of the invention is directed to
a motion analysis method of a measurement object including:
attaching a first posture angle sensor adapted to detect a first
angular velocity and a first posture angle and a second posture
angle sensor adapted to detect a second angular velocity and a
second posture angle to the measurement object at locations distant
from each other, acquiring data of the first posture angle, the
first angular velocity, the second posture angle, and the second
angular velocity, correcting a difference between the first angular
velocity and the second angular velocity in accordance with a
difference between the first posture angle and the second posture
angle, and calculating a deformation amount of the measurement
object by integrating the difference between the first angular
velocity and the second angular velocity corrected in the
correcting.
[0024] The motion analysis method of this configuration uses the
fact that the difference is caused between the posture angles
detected by two posture angle sensors in accordance with the error
in the installation angles of the two posture angle sensors, and
corrects the difference in the angular velocity between the two
points of the measurement object in accordance with the difference
in the posture angle between the two points. Further, since the
variation of the difference in the posture angle between the two
points can accurately be calculated by integrating the difference
between the angular velocities after the correction, the
deformation amount between the two points can be analyzed with high
accuracy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The invention will be described with reference to the
accompanying drawings, wherein like numbers reference like
elements.
[0026] FIG. 1 is a diagram showing a configuration of a motion
analysis device according to a first embodiment of the
invention.
[0027] FIG. 2 is a flowchart showing an example of a method of
calculating the deformation amount of a measurement object in the
first embodiment.
[0028] FIG. 3 is an explanatory diagram of a golf swing analysis
device.
[0029] FIGS. 4A and 4B are diagrams showing an example of a shape
of an initial posture of a golf club.
[0030] FIGS. 5A and 5B are diagrams showing an example of a shape
of the golf club during a swing.
[0031] FIG. 6A is a diagram showing an example of the initial
postures of two posture angle sensors, and FIG. 6B is a diagram
showing an example of the postures of the two posture angle sensors
during a swing.
[0032] FIG. 7 is a flowchart showing an example of a calculation
process of the deformation amount of a golf club in the first
embodiment.
[0033] FIGS. 8A through 8C are explanatory diagrams of the
difference between the posture angles of the two posture angle
sensors.
[0034] FIG. 9 is a diagram showing a configuration of a motion
analysis device according to a second embodiment of the
invention.
[0035] FIG. 10 is a flowchart showing an example of a method of
calculating the deformation amount of a measurement object in the
second embodiment.
[0036] FIG. 11 is a flowchart showing an example of a calculation
process of the deformation amount of a golf club in the second
embodiment.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0037] Hereinafter, preferred embodiments of the invention will be
described in detail with reference to the accompanying drawings. It
should be noted that the embodiments described below do not
unreasonably limit the content of the invention as set forth in the
appended claims. Further, all of the constituents described below
are not necessarily essential elements of the invention.
1. First Embodiment
[0038] FIG. 1 is a diagram showing a configuration of a motion
analysis device according to a first embodiment. The motion
analysis device 1 according to the present embodiment is configured
including two posture angle sensors 10a, 10b, and a host terminal
20. The posture angle sensors 10a, 10b and the host terminal 20 are
connected to each other in a wired or wireless manner. The posture
angle sensors 10a, 10b are attached to a measurement object to be
the object of the motion analysis at respective locations distant
from each other.
[0039] The posture angle sensor 10a includes, for example, a
triaxial angular velocity sensor 100a, a triaxial acceleration
sensor 102a, a triaxial geomagnetic sensor 104a, a data processing
section 110a, and a communication section 120a.
[0040] The triaxial angular velocity sensor 100a detects the
angular velocities around three axes (an x.sub.1 axis, a y.sub.1
axis, and a z.sub.1 axis) perpendicular to each other, and then
outputs a signal (triaxial angular velocity data) corresponding to
the levels of the triaxial angular velocities thus detected.
[0041] The triaxial acceleration sensor 102a detects the
acceleration in each of the three axial directions perpendicular to
each other, and then outputs a signal (triaxial acceleration data)
corresponding to the level of the triaxial acceleration thus
detected.
[0042] The triaxial geomagnetic sensor 104a detects the
geomagnetism in each of the three axial directions perpendicular to
each other, and then outputs a signal (triaxial geomagnetic data)
corresponding to the intensity of the triaxial geomagnetism thus
detected.
[0043] It should be noted that the triaxial angular velocity sensor
100a, the triaxial acceleration sensor 102a, and the triaxial
geomagnetic sensor 104a are attached so that the three axes of the
sensors match each other. Alternatively, in the case in which the
three axes of the triaxial angular velocity sensor 100a, the
triaxial acceleration sensor 102a, and the triaxial geomagnetic
sensor 104a do not match each other, and the error in the
installation angles exists, the data processing section 110a
converts, for example, the triaxial acceleration data output by the
triaxial acceleration sensor 102a and the triaxial geomagnetic data
output by the triaxial geomagnetic sensor 104a into the
acceleration data and the geomagnetic data in the three axes (the
x.sub.1 axis, the y.sub.1 axis, and the z.sub.1 axis) directions of
the triaxial angular velocity sensor 100a by the coordinate
conversion using the correction parameter generated by the data
processing section 111a and then stored in a storage section, not
shown, in advance.
[0044] The data processing section 110a performs a process of
calculating the posture angle of the posture angle sensor 10a in
addition to the coordinate conversion process of the triaxial
acceleration data and the triaxial geomagnetic data, if necessary.
It is also possible to define, for example, an absolute coordinate
system (an XYZ coordinate system) having a northern direction and
an eastern direction in a horizontal plane as X and Y axes, and a
vertically upward direction (the direction opposite to the
direction of gravitational force) as a Z axis, and calculate the
posture angles of the posture angle sensors 10a, 10b in the
absolute coordinate system (the XYZ coordinate system). For
example, it is possible to set the measurement object to a resting
state, and identify the directions of the x.sub.1 axis, the y.sub.1
axis, and the z.sub.1 axis in the XYZ coordinate system based on
the gravitational direction obtained from the triaxial acceleration
data and the northern direction obtained from the geomagnetic data
to thereby calculate the posture angle (an initial posture angle)
of the posture angle sensor 10a in an initial state (a resting
state). Further, after the measurement object starts the motion,
the posture angle of the posture sensor 10a in the XYZ coordinate
system can be calculated using the triaxial angular velocity data.
The posture angle can be expressed using, for example, rotational
angles (a roll angle .psi., a pitch angle .theta., and a yaw angle
.phi.) around the X axis, the Y axis, and the Z axis, an Euler
angle, and a quaternion.
[0045] Further, the data processing section 110a performs a process
of outputting a packet formed by combining the posture angle data
thus calculated with time information and so on to the
communication section 120. The packet data can be arranged to
include the triaxial angular velocity data, the triaxial
acceleration data, the triaxial geomagnetic data, and so on besides
the posture angle data. Further, the data processing section 110a
can be arranged to perform processes of the bias correction and the
temperature correction of the triaxial angular velocity sensor
100a, the triaxial acceleration sensor 102a, and the triaxial
geomagnetic sensor 104a. It should be noted that it is possible to
incorporate the functions of the bias correction and the
temperature correction into the triaxial angular velocity sensor
100a, the triaxial acceleration sensor 102a, and the triaxial
geomagnetic sensor 104a.
[0046] The communication section 120a performs a process of
transmitting the packet data, which is received from the data
processing section 110a, to the host terminal 20.
[0047] Similarly to the posture angle sensor 10a, the posture angle
sensor 10b includes a triaxial angular velocity sensor 100b, a
triaxial acceleration sensor 102b, a triaxial geomagnetic sensor
104b, a data processing section 110b, and a communication section
120b. Since the processes of the respective constituents thereof
are the same as those in the posture angle sensor 10a, the
explanation will be omitted.
[0048] The host terminal 20 is configured including a processing
section (CPU) 200, a communication section 210, an operation
section 220, a ROM 230, a RAM 240, a nonvolatile memory 250, and a
display section 260. The host terminal 20 can be realized using a
personal computer (PC) or a portable device such as a
smartphone.
[0049] The communication section 210 performs a process of
receiving the data transmitted from the posture angle sensors 10a,
10b, and then transmitting them to the processing section 200.
[0050] The operation section 220 performs a process of obtaining
operation data from the user, and then transmitting it to the
processing section 200. The operation section 220 corresponds to,
for example, a touch panel display, a button, a key, and a
microphone.
[0051] The ROM 230 stores a program for the processing section 200
to perform a variety of calculation processes and control
processes, various programs and data for realizing application
functions, and so on.
[0052] The RAM 240 is a storage section used as a working area of
the processing section 200, and temporarily storing, for example,
the program and data retrieved from the ROM 230, the data input
from the operation section 220, and the calculation result obtained
by the processing section 200 performing operations with the
various programs.
[0053] The nonvolatile memory 250 is a recording section for
storing the data required to be stored for a long period of time
out of the data generated by the processing of the processing
section 200.
[0054] The display section 260 is for displaying the processing
result of the processing section 200 as letters, graphs, or other
images. The display section 260 corresponds to, for example, a CRT,
an LCD, a touch panel display, and a head-mount display (HMD). It
should be noted that it is also possible to arrange that the
functions of the operation section 220 and the display section 260
are realized by a single touch panel display.
[0055] The processing section 200 performs various calculation
processes on the data received from the posture angle sensors 10a,
10b via the communication section 210, and various control
processes (e.g., display control on the display section 260) in
accordance with the programs stored in the ROM 240.
[0056] In particular, in the present embodiment, the processing
section 200 functions as a data acquisition section 201, a posture
angle correction section 202, and a deformation amount calculation
section 203. It should be noted that it is also possible for the
processing section 200 of the present embodiment to have a
configuration in which some of the functions are eliminated.
[0057] The data acquisition section 201 performs a process of
acquiring the output data (the posture angle data) of the posture
angle sensors 10a, 10b, which is received vie the communication
section 210, at a constant period .DELTA.t. The data thus acquired
is stored in, for example, the RAM 240.
[0058] The posture angle correction section 202 performs a process
of correcting the difference between the posture angle (a first
posture angle) of the posture angle sensor 10a and the posture
angle (a second posture angle) of the posture angle sensor 10b
after the measurement object starts the motion in accordance with
the difference between the posture angle of the posture angle
sensor 10a and the posture angle of the posture angle sensor 10b
before the measurement object starts the motion. For example, the
posture angle correction section 202 can be arranged to perform the
correction by subtracting the difference between the posture angle
of the posture angle sensor 10a and the posture angle of the
posture angle sensor 10b before the measurement object starts the
motion from the difference between the posture angle of the posture
angle sensor 10a and the posture angle of the posture angle sensor
10b after the measurement object starts the motion.
[0059] The deformation amount calculation section 203 performs a
process of calculating the deformation amount of the measurement
object based on the difference between the posture angle of the
posture angle sensor 10a and the posture angle of the posture angle
sensor 10b thus corrected by the posture angle correction section
202.
[0060] FIG. 2 is a flowchart showing an example of a method of
calculating the deformation amount of the measurement object using
the motion analysis device according to the first embodiment.
[0061] Firstly, the posture angle sensors 10a, 10b are attached
(S10, a sensor attaching process) to the measurement object at
locations distant from each other.
[0062] Subsequently, the processing section 200 functions as the
data acquisition section 201, and starts (S20, a data acquisition
process) the process of continuously acquiring the respective
posture angle data of the posture angle sensors 10a, 10b prior to
the measurement object starting the motion.
[0063] Subsequently, the processing section 200 functions as the
posture angle correction section 202, and corrects (S30, a posture
angle correction process) the difference between the two posture
angle data acquired in S20 after the measurement object starts the
motion in accordance with the two posture angle data acquired in
S20 before the measurement object starts the motion.
[0064] Finally, the processing section 200 functions as the
deformation amount calculation section 203, and calculates (S40, a
deformation amount calculation process) the deformation amount of
the measurement object based on the difference between the two
posture angle data thus corrected in S30. Thus, the deformation
amount of the measurement object can be calculated taking the
initial state before the measurement object starts the motion as a
reference (no deformation).
Specific Example
[0065] Then, the method according to the present embodiment will be
explained citing an example of calculating the deformation amounts
(a deflection amount and a torsion amount) of a golf club in a
swing of the golf club. In this example, the golf club corresponds
to the measurement object, the posture angle sensor 10a and the
posture angle sensor 10b are attached to the golf club at the
locations distant from each other, and the motion analysis device 1
functions as a golf swing analysis device. In particular, the
posture angle correction section 202 performs a process of
correcting the difference between the posture angle of the posture
angle sensor 10a and the posture angle of the posture angle sensor
10b after a swing of the golf club is started in accordance with
the difference between the posture angle of the posture angle
sensor 10a and the posture angle of the posture angle sensor 10b
before the swing of the golf club is started. Further, the
deformation amount calculation section 203 performs a process of
calculating the deformation amount of the golf club based on the
difference between the posture angle of the posture angle sensor
10a and the posture angle of the posture angle sensor 10b thus
corrected by the posture angle correction section 202.
[0066] For example, as shown in FIG. 3, the posture angle sensor
10a is attached to a shaft section 4 of the golf club 2 at a
position in the vicinity of the base thereof near to a grip section
5, and the posture angle sensor 10b is attached to a head section 3
of the golf club 2. The posture angle sensor 10a can be attached to
the grip section 5, and the posture angle sensor 10b can be
attached to the shaft section 4 at a position in the vicinity of
the tip thereof near to the head section 3. The posture angle
sensors 10a, 10b wirelessly transmit the respective posture angle
data to the host terminal 20 (personal computer) at a constant
period.
[0067] For example, after setting the golf club 2 in a resting
state with an initial posture in which the long axis of the shaft
section 4 conforms with the gravitational direction so as to
minimize the deformation of the golf club 2, the subject grips the
golf club 2, and makes a swing. The host terminal 20 acquires the
respective posture angle data from the posture angle sensors 10a,
10b, corrects the difference between the two posture angles after
the swing is started based on the difference between the two
posture angles in the initial posture, and calculates the
deformation amount of the golf club 2 due to the deflection of the
shaft section 4 and the torsion of the head section 3.
[0068] FIGS. 4A and 4B are diagrams showing an example of a shape
of the initial posture of the golf club 2. In contrast, FIGS. 5A
and 5B are diagrams showing an example of a shape of the golf club
2 during the swing. FIGS. 4A and 5A are diagrams showing a side of
the golf club, and FIGS. 4B and 5B are diagrams of the golf club
viewed from the grip side. It should be noted that in FIGS. 4B and
5B, the grip section 5 is omitted from the drawings.
[0069] As shown in FIGS. 4A and 4B, the posture angle sensor 10a is
attached so that the x.sub.1 axis is roughly perpendicular to the
long axis direction of the shaft section 4 and roughly parallel to
the swing direction, the y.sub.1 axis is roughly perpendicular to
the long axis direction of the shaft section 4 and roughly
perpendicular to the swing direction, and the z.sub.1 axis is
roughly parallel to the long axis direction of the shaft section 4.
Similarly, the posture angle sensor 10b is attached so that an
x.sub.2 axis is roughly perpendicular to the long axis direction of
the shaft section 4 and roughly parallel to the swing direction, a
y.sub.2 axis is roughly perpendicular to the long axis direction of
the shaft section 4 and roughly perpendicular to the swing
direction, and a z.sub.2 axis is roughly parallel to the long axis
direction of the shaft section 4. In other words, in the initial
posture, the x.sub.1 axis, the y.sub.1 axis, and the z.sub.1 axis
conform with the x.sub.2 axis, the y.sub.2 axis, and the z.sub.2
axis, respectively, and the posture angle of the posture angle
sensor 10a and the posture angle of the posture angle sensor 10b
roughly conform with each other.
[0070] In contrast, during the swing, since the shaft section 4
deflects to a direction opposite to the swing direction, the
x.sub.1 axis and the x.sub.2 axis are shifted from each other, and
at the same time, the z.sub.1 axis and the z.sub.2 axis are shifted
from each other as shown in FIG. 5A. Further, as shown in FIG. 5B,
since the head section 3 is twisted around the long axis of the
shaft section 4, the x.sub.1 axis and the x.sub.2 axis are shifted
from each other, and at the same time, the y.sub.1 axis and the
y.sub.2 axis are shifted from each other. In other words, during
the swing, the posture angle of the posture angle sensor 10a and
the posture angle of the posture angle sensor 10b fail to conform
with each other. Therefore, in principle, the deformation amount of
the golf club 2 can be calculated based on the difference between
the posture angle of the posture angle sensor 10a and the posture
angle of the posture angle sensor 10b during the swing. It can be
said that the larger the difference is, the larger the deformation
amount of the golf club 2 is.
[0071] However, in reality, since there is an error in the
installation angles of the posture angle sensors 10a, 10b, the
posture angle of the posture angle sensor 10a and the posture angle
of the posture angle sensor 10b fail to conform with each other in
the initial posture. FIG. 6A is a diagram showing an example of the
initial postures of the posture angle sensors 10a, 10b, and FIG. 6B
is a diagram showing an example of the postures of the posture
angle sensors 10a, 10b during the swing. In FIGS. 6A and 6B, the
posture angle sensors 10a, 10b are illustrated with the respective
centroids (origins) conformed with each other. As shown in FIG. 6A,
in the initial posture, the x.sub.1 axis, the y.sub.1 axis, and the
z.sub.1 axis are slightly shifted from the x.sub.2 axis, the
y.sub.2 axis, and the z.sub.2 axis, respectively, due to the error
in the installation angles. Therefore, as shown in FIG. 6B,
although the x.sub.1 axis, the y.sub.1 axis, and the z.sub.1 axis
are more significantly shifted from the x.sub.2 axis, the y.sub.2
axis, and the z.sub.2 axis during the swing due to the deflection
of the shaft section 4 and the torsion of the head section 3, since
an offset corresponding to the difference in the posture angle in
the initial posture is caused, it is not achievable to accurately
calculate the deformation amount of the golf club 2 only by the
information of the difference in the posture angle during the
swing.
[0072] Therefore, in the first embodiment, there is performed a
correction calculation of subtracting the difference (the offset)
between the posture angle of the posture angle sensor 10a and the
posture angle of the posture angle sensor 10b in the initial
posture from the difference between the posture angle of the
posture angle sensor 10a and the posture angle of the posture angle
sensor 10b during the swing. Then, the accurate deformation amount
of the golf club 2 is calculated based on the difference in the
posture angle after the correction.
[0073] FIG. 7 shows an example of a flowchart of a calculation
process of the deformation amount of the golf club 2 in the first
embodiment.
[0074] Firstly, the subject sets (S110) the golf club to the
initial posture, then the two initial posture angles are acquired
from the posture angle sensors 10a, 10b, and then the difference
therebetween is calculated (S120).
[0075] Then, the time t is reset (S130) to 0, and then the subject
starts (S140) the swing of the golf club.
[0076] Then, the two posture angles are acquired from the posture
angle sensors 10a, 10b, and then the difference therebetween is
calculated (S150).
[0077] Then, the correction calculation of subtracting the
difference between the two initial posture angles calculated in
S120 from the difference between the two posture angles calculated
in S150 is performed (S160).
[0078] Then, the difference (in the XYZ coordinate system) between
the two posture angles after the correction obtained in S160 is
converted into the x.sub.1y.sub.1z.sub.1 coordinate system, and the
deformation amount of the golf club is calculated (S170).
[0079] In the case of, for example, expressing the posture angle
with the roll angle, the pitch angle, and the yaw angle, the
difference between the two posture angles after the correction,
which is converted into the x.sub.1y.sub.1z.sub.1 coordinate
system, is represented by the roll angle .DELTA..psi. (the
rotational angle around the x.sub.1 axis), the pitch angle
.DELTA..theta. (the rotational angle around the y.sub.1 axis), and
the yaw angle .DELTA..phi. (the rotational angle around the z.sub.1
axis) as shown in FIG. 8A, FIG. 8B and FIG. 8C. Specifically, the
roll angle .DELTA..psi. corresponds to the deformation amount
(mainly the torsion amount of the head section 3) of the golf club
2 on the y.sub.1z.sub.1 plane, the pitch angle .DELTA..theta.
corresponds to the deformation amount (mainly the deflection amount
of the shaft section 4) of the golf club 2 on the z.sub.1x.sub.1
plane, and the yaw angle .DELTA..phi. corresponds to the
deformation amount (mainly the deflection amount of the head
section 3) of the golf club 2 on the x.sub.1y.sub.1 plane. In the
case of expressing the posture angle with an Euler angle or a
quaternion, the roll angle .DELTA..psi., the pitch angle
.DELTA..theta., and the yaw angle .DELTA..phi. can be calculated by
performing a known appropriate calculation.
[0080] Then, if the analysis is not terminated (N in S180), the
time t is increased (S190) by .DELTA.t, and then the processes
corresponding to S150 through S170 are performed again.
[0081] The motion analysis device according to the first embodiment
described hereinabove uses the fact that the difference between the
posture angles detected by the posture angle sensors 10a, 10b
occurs in accordance with the error in the installation angles of
the posture angle sensors 10a, 10b, measures the difference in the
posture angle between two points of the measurement object before
the motion starts as an offset, and then calculates the difference
in the posture angle between the two points after the motion starts
with the offset correction. Thus, since the variation of the
difference in the posture angle between the two points caused by
the motion of the measurement object can accurately be calculated,
the deformation amount between the two points can be analyzed with
high accuracy.
[0082] Further, since the deformation amount of the measurement
object can be calculated irrespective of the error in the
installation angles of the posture angle sensors 10a, 10b, it is
possible to attach the posture angle sensors 10a, 10b independently
from each other to the measurement object at arbitrary positions
and arbitrary angles. Therefore, according to the present
embodiment, the motion analysis device easy to set and easy to deal
with can be provided.
2. Second Embodiment
[0083] FIG. 9 is a diagram showing a configuration of a motion
analysis device according to a second embodiment. In the motion
analysis device according to the second embodiment, the posture
angle sensor 10a transmits the angular velocity data
(.omega..sub.x1, .omega..sub.y1, .omega..sub.z1) around the three
axes, namely the x.sub.1 axis, the y.sub.1 axis, and the z.sub.1
axis, to the host terminal 20 at a constant period in addition to
the posture angle data in the XYZ coordinate system. Further, the
posture angle sensor 10b also transmits the angular velocity data
(.omega..sub.x2, .omega..sub.y2, .omega..sub.z2) around the three
axes, namely the x.sub.2 axis, the y.sub.2 axis, and the z.sub.2
axis, to the host terminal 20 at a constant period in addition to
the posture angle data in the XYZ coordinate system. It should be
noted that the posture angle sensors 10a, 10b are not necessarily
required to output the angular velocity data around the three axes,
but are required to output the angular velocity data around the
axes necessary for the analysis.
[0084] Further, in the second embodiment, the processing section
200 functions as the data acquisition section 201, an angular
velocity correction section 204, and the deformation amount
calculation section 203. It should be noted that it is also
possible for the processing section 200 of the present embodiment
to have a configuration in which some of the functions are
eliminated.
[0085] The data acquisition section 201 performs a process of
acquiring the respective posture angle data and the triaxial
angular velocity data from the posture angle sensors 10a, 10b at a
constant period .DELTA.t.
[0086] The angular velocity correction section 204 performs a
process of correcting the difference between the angular velocity
(a first angular velocity) from the posture angle sensor 10a and
the angular velocity (a second angular velocity) from the posture
angle sensor 10b in accordance with the difference between the
posture angle (the first posture angle) of the posture angle sensor
10a and the posture angle (the second posture angle) of the posture
angle sensor 10b. For example, it is possible for the angular
velocity correction section 204 to perform the process of
correcting the difference between the angular velocities by
converting one of the angular velocity from the posture angle
sensor 10a and the angular velocity from the posture angle sensor
10b into the angular velocity with respect to the detection axis of
the other of the angular velocities in accordance with the
difference between the posture angle of the posture angle sensor
10a and the posture angle of the posture angle sensor 10b, and then
calculating the difference between the two angular velocities after
the conversion.
[0087] The deformation amount calculation section 203 performs the
process of calculating the deformation amount of the measurement
object by integrating the difference between the two angular
velocities thus corrected by the angular velocity correction
section 204.
[0088] The other constituents shown in FIG. 9 are the same as shown
in FIG. 1, and are therefore denoted by the same reference symbols,
and the explanation therefor will be omitted.
[0089] FIG. 10 is a flowchart showing an example of a method of
calculating the deformation amount of the measurement object in
motion using the motion analysis device according to the second
embodiment.
[0090] Firstly, the posture angle sensors 10a, 10b are attached
(S12, a sensor attaching process) to the measurement object at
locations distant from each other.
[0091] Subsequently, the processing section 200 functions as the
data acquisition section 201, and starts (S22, a data acquisition
process) the process of continuously acquiring the posture angle
data and the angular velocity data from the posture angle sensors
10a, 10b prior to the measurement object starting the motion.
[0092] Subsequently, the processing section 200 functions as the
angular velocity correction section 204, and corrects (S32, an
angular velocity correction process) the difference between the two
angular velocities acquired in S22 in accordance with the
difference between the two posture angles acquired in S22.
[0093] Finally, the processing section 200 functions as the
deformation amount calculation section 203, and calculates (S42, a
deformation amount calculation process) the deformation amount of
the measurement object by integrating the difference between the
two angular velocities thus corrected in S32.
Specific Example
[0094] Then, the method according to the second embodiment will be
explained citing an example of calculating the deformation amounts
(a deflection amount and a torsion amount) of a golf club in a
swing of the golf club similarly to the first embodiment. Similarly
to the case explained in the first embodiment, also in this
example, the golf club corresponds to the measurement object, the
posture angle sensor 10a and the posture angle sensor 10b are
attached to the golf club at the locations distant from each other,
and the motion analysis device 1 functions as a golf swing analysis
device.
[0095] In particular, the angular velocity correction section 204
calculates the difference in the posture angle between the posture
angle sensors 10a, 10b every period .DELTA.t, and corrects
(converts) the triaxial angular velocities .omega..sub.x2,
.omega..sub.y2, and .omega..sub.z2 acquired from the posture angle
sensor 10b respectively to the angular velocities .omega..sub.x2',
.omega..sub.y2', and .omega..sub.z2' around the three axes, namely
the x.sub.1 axis, the y.sub.1 axis, and the z.sub.1 axis after
starting the swing of the golf club in accordance with the
calculation result. For example, at time t, the angle
.DELTA..psi..sub.E(t) formed between the x.sub.1 axis and the
x.sub.2 axis, the angle .DELTA..theta..sub.E(t) formed between the
y.sub.1 axis and the y.sub.2 axis, and the angle
.DELTA..phi..sub.E(t) formed between the z.sub.1 axis and the
z.sub.2 axis are calculated from the posture angle difference of
the posture angle sensors 10a, 10b, and the angular velocities
.omega..sub.x2(t), .omega..sub.y2(t), and .omega..sub.z2(t) are
corrected to the angular velocities .omega..sub.x2'(t),
.omega..sub.y2'(t), and .omega..sub.z2'(t) using the formulas 1, 2,
and 3 below, respectively
.omega. x 2 ' ( t ) = .omega. x 2 ( t ) cos .DELTA..PSI. E ( 1 )
.omega. y 2 ' ( t ) = .omega. y 2 ( t ) cos .DELTA..theta. E ( t )
( 2 ) .omega. z 2 ' ( t ) = .omega. z 2 ( t ) cos .DELTA..phi. E (
t ) ( 3 ) ##EQU00001##
[0096] Further, in theory, the integral value .DELTA..psi.(T) of
the difference between the angular velocities .omega..sub.x1,
.omega..sub.x2' from the time t=0 to the time t=T, the integral
value .DELTA..theta.(T) of the difference between the angular
velocities .omega..sub.y1, .omega..sub.y2' from the time t=0 to the
time t=T, and the integral value .DELTA..phi.(T) of the difference
between the angular velocities .omega..sub.z1, .omega..sub.z2' from
the time t=0 to the time t=T can be calculated using the formulas
4, 5, and 6 below, respectively.
.DELTA..psi.(T)=.intg..sub.0.sup.T{.omega..sub.x1(t)-.omega..sub.x2'(t)}-
dt (4)
.DELTA..theta.(T)=.intg..sub.0.sup.T{.omega..sub.y1(t)-.omega..sub.y2'(t-
)}dt (5)
.DELTA..phi.(T)=.intg..sub.0.sup.T{.omega..sub.z1(t)-.omega..sub.z2'(t)}-
dt (6)
[0097] These integral values .DELTA..psi.(T), .DELTA..theta.(T),
and .DELTA..phi.(T) correspond to the values .DELTA..psi.,
.DELTA..theta., and .DELTA..phi. shown in FIGS. 8A, 8B, and 8C,
respectively. Therefore, by calculating the integral values
.DELTA..omega.(T), .DELTA..theta.(T), and .DELTA..phi.(T), the
deformation amount of the golf club 2 can be obtained.
[0098] It should be noted that in the practical process, the
discrete integration of calculating .DELTA..psi.(t+.DELTA.t),
.DELTA..theta.(t+.DELTA.t), and .DELTA..phi.(t+.DELTA.t) by adding
.omega..sub.x1(t)-.omega..sub.x2'(t),
.omega..sub.y1(t)-.omega..sub.y2'(t), and
.omega..sub.z1(t)-.omega..sub.z2'(t) to .DELTA..psi.(t),
.DELTA..theta.(t), and .DELTA..phi.(t), respectively, is repeatedly
performed until t+.DELTA.t=T is reached. Thus, the integral values
.DELTA..psi.(T), .DELTA..theta.(T), and .DELTA..phi.(T) are
approximated. By setting .DELTA.t to a small value, the accuracy of
approximation can be enhanced.
[0099] FIG. 11 shows an example of a flowchart of a calculation
process of the deformation amount of the golf club 2 in the second
embodiment.
[0100] Firstly, the time t, and the integral values
.DELTA..psi.(0), .DELTA..theta.(0), and .DELTA..phi.(0) are reset
(S210) to 0, and then the subject starts (S220) the swing of the
golf club.
[0101] Subsequently, the posture angle and the triaxial angular
velocities .omega..sub.x1, .omega..sub.y1, and .omega..sub.z1 are
acquired (S230) from the posture angle sensor 10a, and at the same
time, the posture angle and the triaxial angular velocities
.omega..sub.x2, .omega..sub.y2, and .omega..sub.z2 are acquired
(S230) from the posture angle sensor 10b.
[0102] Then, the difference between the posture angle of the
posture angle sensor 10a acquired in S230 and the posture angle of
the posture angle sensor 10b acquired in S230 is calculated
(S240).
[0103] Subsequently, based on the difference between the two
posture angles calculated in S240, the triaxial angular velocities
.omega..sub.x2(t), .omega..sub.y2 (t), and .omega..sub.z2(t) are
corrected (S250) to the triaxial angular velocities
.omega..sub.x2'(t), .omega..sub.y2'(t), and .omega..sub.z2'(t)
around the x.sub.1 axis, the y.sub.1 axis, and the z.sub.1 axis,
respectively.
[0104] Subsequently, {.omega..sub.x1(t)-.omega..sub.x2'(t)} is
added to .DELTA..psi.(t) and is then substituted in
.DELTA..psi.(t+.DELTA.t), {.omega..sub.y1(t)-.omega..sub.y2'(t)} is
added to .DELTA..theta.(t) and is then substituted in
.DELTA..theta.(t+.DELTA.t), and
{.omega..sub.z1(t)-.omega..sub.z2'(t)} is added to .DELTA..phi.(t)
and is then substituted (S260) in .DELTA..phi.(t+.DELTA.t).
[0105] Then, if the analysis is not terminated (N in S270), the
time t is increased (S280) by .DELTA.t, and then the processes
corresponding to S230 through S260 are performed again.
[0106] The values .DELTA..psi.(t), .DELTA..theta.(t), and
.DELTA..phi.(t) thus obtained correspond respectively to the
deformation amount of the golf club 2 on the y.sub.1z.sub.1 plane
at the time t, the deformation amount thereof on the z.sub.1x.sub.1
plane, and the deformation amount thereof on the x.sub.1y.sub.1
plane.
[0107] The motion analysis device according to the second
embodiment described hereinabove uses the fact that the difference
between the posture angles detected by the posture angle sensors
10a, 10b occurs in accordance with the error in the installation
angles of the posture angle sensors 10a, 10b, and corrects the
difference in the angular velocity between two points of the
measurement object before the motion starts in accordance with the
difference in the posture angle between the two points. Further,
since the variation of the difference in the posture angle between
the two points can accurately be calculated by integrating the
difference between the angular velocities after the correction, the
deformation amount between the two points can be analyzed with high
accuracy.
[0108] Further, since the deformation amount of the measurement
object can be calculated irrespective of the error in the
installation angles of the posture angle sensors 10a, 10b, it is
possible to attach the posture angle sensors 10a, 10b independently
from each other to the measurement object at arbitrary positions
and arbitrary angles. Therefore, according to the present
embodiment, the motion analysis device easy to set and easy to deal
with can be provided.
[0109] The invention is not limited to the embodiments described
above, but can be put into practice with various modifications
within the scope or the spirit of the invention.
[0110] For example, although in the present embodiment the
calculation process of the deformation amount of the measurement
object is performed in real time, it is not necessarily required to
perform the calculation process of the deformation amount of the
measurement object in real time. It is also possible to arrange,
for example, that the posture angle sensors 10a, 10b and the host
terminal 20 are each provided with a memory card interface section
instead of connecting the posture angle sensors 10a, 10b and the
host terminal 20 to each other in a wireless or wired manner, and
the posture angle sensors 10a, 10b write the posture angle data and
so on in the memory card, and then the host terminal 20 reads out
the data from the memory card to perform the calculation process of
the deformation amount of the measurement object.
[0111] Further, although in the first embodiment, the processing
section 200 (the data acquisition section 201) continuously
acquires the posture angle data at a constant period and then
calculates the deformation amount of the measurement object every
time, if, for example, it is attempted to analyze only the
deformation amount of the golf club at the maximum speed of the
swing of the golf club, it is also possible to arrange that only
the posture angle data in the initial posture and the posture angle
data at the analysis timing are acquired, and then the deformation
amount at the analysis timing is calculated.
[0112] Further, although in the embodiments described above the
explanation is presented citing the example of attaching the two
posture angle sensors to the measurement object and then
calculating the deformation amount between the two points, it is
also possible to arrange that three or more posture angle sensors
are attached to the measurement object at locations distant from
each other, and the deformation amount between any two of the
points is calculated. According to this configuration, the
deformation of the measurement object can more accurately be
analyzed.
[0113] Further, although in the embodiments described above the
explanation is presented citing the swing analysis of the golf club
as an example, the invention can also be applied to a swing
analysis of other exercise equipment, and further various
applications such as an analysis of the deformation amount of a
vehicle by attaching the posture angle sensors to the front, back,
right, and left of the vehicle, or an analysis of the deformation
amount of a tall building by attaching the posture angle sensor to
a plurality of floors of the tall building.
[0114] The invention includes configurations (e.g., configurations
having the same function, the same way, and the same result, or
configurations having the same object and the same advantages)
substantially the same as those described in the embodiment
section. Further, the invention includes configurations obtained by
replacing a non-essential part of the configurations described in
the embodiment section. Further, the invention includes
configurations exerting the same advantages or configurations
capable of achieving the same object as the configurations
described in the embodiment section. Further, the invention
includes configurations obtained by adding technologies known to
the public to the configurations described in the embodiment
section.
* * * * *