ROTATING ACTION MOTION ASSESSMENT METHOD, SYSTEM, AND PROGRAM

Description

TECHNICAL FIELD

The present invention relates to an assessment method for a motion accompanied by a rotating action, and more particularly to, a rotating action motion assessment method and system for a motion accompanied by a rotating action at an acceleration equal to or higher than 9.8 m/sec², and a program.

BACKGROUND ART

A technology and a method for analyzing and assessing a motion, such as motion capture and skeleton estimation, are widely used.

In particular, in the field of sports, the above-mentioned technology and method serve as a tool very useful in performance assessment.

However, the above-mentioned technology and method are useful for the performance assessment, but a clear index does not exist for a body load of a subject. For example, in the baseball, the number of times of pitching is limited in the childhood and later, but the number of cases of troubles in the shoulder and the elbow does not decrease in the current situation.

For example, in Patent Literature 1, there is disclosed a physical action analysis/visualization device. In Patent Literature 1, as the description “the three-dimensional action measurement means generates . . . time-series data of three-dimensional coordinate values of a feature point of the body or the like in the three-dimensional space, that is, action data.” in paragraph [0010] indicates, the three-dimensional coordinate values at the plurality of feature points defined in advance in the human body, that is, a plurality of individual, independent and fixed local coordinates, are used (see FIG. 7 of Patent Literature 1). After that, optimization processing for each portion is executed through human body simulation.

However, as described in Patent Literature 1, when the plurality of individual, independent and fixed local coordinates in the human body are used to execute the optimization processing for each portion in the human body simulation, the device is excellent in the case in which performance assessment (for example, whether or not a pitching action which maximizes a pitching speed of a ball is achieved) for a movement of the human body and the like as observed from those plurality of fixed local coordinates is executed, but cannot make assessment in terms of the load on the body.

In the related-art body action analysis, the body action is considered in a rigid model, and hence the assessment in terms of the load on the body cannot be made.

CITATION LIST

Patent Literature

PTL 1

• • JP Hei 10-149445 A

PTL 2

• • JP 2022-155115 A

PTL 3

• • JP 2010-14712 A

SUMMARY OF INVENTION

Technical Problem

As a result of the inventor of the present invention continuing diligent research, the inventor of the present invention has found out the fact that, in a motion accompanied by a rotating action at an acceleration equal to or higher than 9.8 m/sec², a body load is particularly high and the fact that a degree of the body load can be assessed by treating this rotating action as a motion having reference at an origin (center coordinates of the rotation being unique local coordinates at each time) of a rotating coordinate system and relatively comparing and assessing, in the unique system, motions of all of joints with data on an own motion in a world coordinate system. Thus, the inventor of the present invention has conceived the present invention.

That is, the present invention has an object to provide a rotating action motion assessment method and system and a program with which a body load applied on a joint or the like of a body, performance and the like can be visualized and assessed by relatively comparing, in a motion accompanied by a rotating action at an acceleration equal to or higher than 9.8 m/sec², rotating coordinate system coordinate data on an own rotating action and world coordinate system data on the own rotating action with each other.

Solution to Problem

A rotating action motion assessment method according to one embodiment of the present invention is a rotating action motion assessment method for estimating and assessing performance and/or a body load in a motion accompanied by a rotating action at an acceleration exceeding 9.8 m/sec², the rotating action motion assessment method including: a rotating center definition step of defining a rotating center from at least one actually existing rotating center obtained from the group consisting of an actual action and a rotating action obtained through skeleton estimation and motion capture and/or an ideal rotating center; a step of obtaining, from the defined rotating center, world coordinate system coordinate data being coordinate data in a world coordinate system in the rotating action; a step of converting the world coordinate system coordinate data to rotating coordinate system local coordinate data being local coordinate data in a rotating coordinate system having, as an origin, a rotating center in a human body in the rotating action; and an assessment step of relatively comparing and assessing values of two pieces of data being the world coordinate system coordinate data and the rotating coordinate system local coordinate data on a predetermined position in the human body which are obtained from the same action in the rotating action.

It is preferred that the world coordinate system coordinate data be world coordinate data that indicates world coordinates of the predetermined position in the human body at each time, and that the rotating coordinate system local coordinate data be local coordinate data that indicates, at each time, local coordinates of the predetermined position in the human body having, as the origin, the rotating center in the human body in the rotating action.

It is preferred that the assessment step be a step of relatively comparing and assessing the values of the two pieces of data in terms of a speed or an acceleration indicated at each time of the predetermined position in the human body.

It is preferred that the assessment be assessment of a body load, that each of the two pieces of data being the world coordinate system coordinate data and the rotating coordinate system local coordinate data be data relating to the speed or the acceleration indicated at each time of the predetermined position in the human body, and that the body load be determined to be high when a maximum speed or a maximum acceleration of the rotating coordinate system local coordinate data is close to or equal to or higher than a maximum speed or a maximum acceleration of the world coordinate system coordinate data.

It is preferred that the assessment be assessment of a body load, that each of the two pieces of data being the world coordinate system coordinate data and the rotating coordinate system local coordinate data be data relating to an area of a graph of a speed indicated at each time of the predetermined position in the human body or a displacement of the predetermined position in the human body, and that the body load be determined to be high when the area of the graph of the speed indicated at each time of the predetermined position in the human body or the displacement of the predetermined position in the human body of the rotating coordinate system local coordinate data is close to or equal to or more than the area of the graph of the speed indicated at each time of the predetermined position in the human body or the displacement of the predetermined position in the human body of the world coordinate system coordinate data.

It is preferred that the rotating center definition step include a step of assessing a rotating center matching rate between the at least one actually existing rotating center and the ideal rotating center.

A conversion method for coordinate data in a rotating action motion according to one embodiment of the present invention is a conversion method for coordinate data in a rotating action motion, which is used for the above-mentioned rotating action motion assessment method, the conversion method including, in a motion accompanied by a rotating action at an acceleration exceeding 9.8 m/sec²: a rotating center definition step of defining a rotating center from at least one actually existing rotating center obtained from the group consisting of an actual action and a rotating action obtained through skeleton estimation and motion capture and/or an ideal rotating center; a step of obtaining, from the defined rotating center, world coordinate system coordinate data being coordinate data in a world coordinate system indicating world coordinates of a predetermined position in a human body at each time in the rotating action; a step of defining center coordinates of the world coordinate system coordinate data at each time; a step of obtaining Cartesian coordinate system data by matching one axis of a Cartesian coordinate system with a line segment connecting the center coordinates and a predetermined joint position; and a step of converting the Cartesian coordinate system data to local coordinate data that indicates, at each time, local coordinates of the predetermined position in the human body having, as an origin, the rotating center in the human body in the rotating action.

A rotating action motion assessment system according to one embodiment of the present invention is a rotating action motion assessment system for estimating and assessing performance and/or a body load in a motion accompanied by a rotating action at an acceleration exceeding 9.8 m/sec², the rotating action motion assessment system including: a rotating center definition device configured to define a rotating center from at least one actually existing rotating center obtained from the group consisting of an actual action and a rotating action obtained through skeleton estimation and motion capture and/or an ideal rotating center; a world coordinate system coordinate data obtaining device configured to obtain, from the defined rotating center, world coordinate system coordinate data being coordinate data in a world coordinate system in the rotating action; a conversion device configured to convert the world coordinate system coordinate data to rotating coordinate system local coordinate data being local coordinate data in a rotating coordinate system having, as an origin, a rotating center in a human body in the rotating action; and a relative comparison device configured to relatively compare values of two pieces of data being the world coordinate system coordinate data and the rotating coordinate system local coordinate data on a predetermined position in the human body which are obtained from the same action in the rotating action.

It is preferred that the world coordinate system coordinate data be world coordinate data that indicates world coordinates of the predetermined position in the human body at each time, and that the rotating coordinate system local coordinate data be local coordinate data that indicates, at each time, local coordinates of the predetermined position in the human body having, as the origin, the rotating center in the human body in the rotating action.

It is preferred that the assessment be assessment of a body load, that each of the two pieces of data being the world coordinate system coordinate data and the rotating coordinate system local coordinate data be data relating to a speed indicated at each time of the predetermined position in the human body, and that the body load be determined to be high when the speed in the rotating coordinate system local coordinate data is close to or equal to or higher than the speed in the world coordinate system coordinate data.

A conversion system for coordinate data in a rotating action motion according to one embodiment of the present invention is a conversion system for coordinate data in a rotating action motion, which is used for the above-mentioned rotating action motion assessment system, the conversion system including, in a motion accompanied by a rotating action at an acceleration exceeding 9.8 m/sec²: a rotating center definition device configured to define a rotating center from at least one actually existing rotating center obtained from the group consisting of an actual action and a rotating action obtained through skeleton estimation and motion capture and/or an ideal rotating center; a world coordinate system coordinate data obtaining device configured to obtain, from the defined rotating center, world coordinate system coordinate data being coordinate data in a world coordinate system indicating world coordinates of a predetermined position in a human body at each time in the rotating action; a device configured to define center coordinates of the world coordinate system coordinate data at each time; a device configured to obtain Cartesian coordinate system data by matching one axis of a Cartesian coordinate system with a line segment connecting the center coordinates and a predetermined joint position; and a conversion device configured to convert the Cartesian coordinate system data to local coordinate data that indicates, at each time, local coordinates of the predetermined position in the human body having, as an origin, the rotating center in the human body in the rotating action.

A first aspect of a program according to the present invention is a program for causing a computer to function as each device of the above-mentioned rotating action motion assessment system.

A second aspect of the program according to the present invention is a program for causing a computer to function as each device of the above-mentioned conversion system for coordinate data in a rotating action motion.

Advantageous Effects of Invention

According to the present invention, the following remarkable effect is achieved: it is possible to provide the rotating action motion assessment method and system and the program with which the body load applied on the joint or the like of the body, performance and the like can be visualized and assessed by relatively comparing, in the motion accompanied by the rotating action at an acceleration equal to or higher than 9.8 m/sec², the rotating coordinate system coordinate data on the own rotating action and the world coordinate system data on the own rotating action with each other.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 are schematic diagrams of a joint of a human, in which FIG. 1(a) is a diagram for illustrating a state of the joint in a usual state, FIG. 1(b) is a diagram for illustrating a state in which the joint is compressed and FIG. 1(c) is a diagram for illustrating a state in which the joint is pulled.

FIG. 2 is a diagram for illustrating coordinate system symbols of a world coordinate system and a rotating coordinate system.

FIG. 3 is a diagram for illustrating a model which does not deviate from a circle trajectory in the world coordinate system.

FIG. 4 is a diagram for illustrating a model which deviates from the circle trajectory in the world coordinate system.

FIG. 5 is a diagram for illustrating a model which does not deviate from a circle trajectory in the rotating coordinate system.

FIG. 6 is a diagram for illustrating a model which deviates from the circle trajectory in the rotating coordinate system.

FIG. 7 is a diagram for schematically illustrating rotating center calculation in a person who is conducting a pitching action of a ball of the baseball toward this side using the left arm as a rotating action motion.

FIG. 8 is a diagram for illustrating conversion of the action of FIG. 7 from the world coordinate system to the rotating coordinate system.

FIG. 9 is a diagram for illustrating the conversion of the action of FIG. 7 from the world coordinate system to the rotating coordinate system.

FIG. 10 is a diagram for illustrating the conversion of the action of FIG. 7 from the world coordinate system to the rotating coordinate system.

FIG. 11 is a diagram for illustrating the conversion of the action of FIG. 7 from the world coordinate system to the rotating coordinate system.

FIG. 12 is a diagram for illustrating the conversion of the action of FIG. 7 from the world coordinate system to the rotating coordinate system.

FIG. 13 is a diagram for illustrating the conversion of the action of FIG. 7 from the world coordinate system to the rotating coordinate system.

FIG. 14 is an explanatory diagram of an ideal rotating center.

FIG. 15 is a block diagram of a rotating action motion assessment system according to the present invention.

FIG. 16 is a flowchart of the rotating action motion assessment system according to the present invention.

FIG. 17 is a graph for showing an analysis example of a load on the elbow in the pitching action of a left handed pitcher in the world coordinate system in a case of low stress (low load).

FIG. 18 is a graph for showing an analysis example of the load on the elbow in the pitching action of the left-handed pitcher in the rotating coordinate system in the case of low stress (low load).

FIG. 19 is a graph of relative comparison of accelerations based on data of FIG. 17 and FIG. 18.

FIG. 20 is a graph of relative comparison of displacements based on the data of FIG. 17 and FIG. 18.

FIG. 21 is a graph for showing an analysis example of the load on the elbow in the pitching action of a right-handed pitcher in the world coordinate system in a case of huge stress (high load).

FIG. 22 is a graph for showing an analysis example of the load on the elbow in the pitching action of the right-handed pitcher in the rotating coordinate system in the case of huge stress (high load).

FIG. 23 is a graph of relative comparison of the accelerations based on data of FIG. 21 and FIG. 22.

FIG. 24 is a graph of relative comparison of the displacements based on the data of FIG. 21 and FIG. 22.

DESCRIPTION OF EMBODIMENTS

Now, an embodiment of the present invention is described. However, the embodiment is described only for illustrative purposes, and needless to say, the embodiment can be variously modified without departing from the technical concept of the present invention. In the illustrations, like members are denoted by like reference symbols.

A pitching action of a pitcher of the baseball is considered as an example of a motion accompanied by a rotating action at an acceleration equal to or higher than 9.8 m/sec². Causes for troubles of the shoulder and the elbow of the pitcher of the baseball include not only the number of times of pitching, but also a load at the time of the pitching, and hence it is required to additionally consider the load at the time of the pitching. That is, it is required to consider not only the number of times of the pitching, but also the load at the time of the motion (load of the pitching action).

Even when the pitcher throws in a form which is generally considered to be less likely to cause the trouble, it is not clarified whether or not this form applies an excessive load on the arm and the shoulder of this pitcher at the time of the motion even by assuming a rigid model and analyzing whether this model follows an ideal form of the pitching. In the present invention, the body of the human is considered as a semi-rigid model and the load on the joint at the time of the motion accompanied by the rotating action has successfully been clarified.

<About Joint>

FIG. 1 are schematic diagrams of a joint of the human. A joint 14 of FIG. 1(a) which connects a bone 10 and a bone 12 to each other is formed of a ligament, a cartilage, muscles and the like, can be recognized as an elastic body in terms of the dynamics and hence is a semi-rigid portion. The cause of the trouble (injury) of the joint is considered to be an excessive stress (mainly tensile force) applied to this elastic body. When the joint which connects the bone and the bone to each other is considered as the elastic body, in a case of a direction toward which the joint 14 is compressed as illustrated in FIG. 1(b), the bones interfere with each other, and hence the compression does not cause a problem unless the compression is equal to or higher than a limit of the Poisson's ratio. Meanwhile, a case of a direction toward which the joint 14 is pulled as illustrated in FIG. 1(c) is a problem, and it is particularly considered that a damage of the ligament surrounding a periphery of the joint to connect the joint is caused by an excessive tensile load applied to the joint.

1. <About Impulse>

An integral of a force F with respect to time “t” is an impulse. In the following expression, “m” is a mass, “a” is an acceleration, “v” is a speed and “n” is the number of times of a load (in the case of the pitcher, the number of times of the pitching).

[ Math . 1 ] ∑ i = 1 n ∫ F i ( t ) ⁢ dt ∵ F i ( t ) = m i ( t ) · a i ( t )

When it can be assumed that mi does not vary or the variation is negligible in this case, the following expressions are obtained.

[ Math . 2 ] ∵ F i ( t ) = m · a i ( t ) [ Math . 3 ] = ∑ i = 1 n m ⁢ ∫ a i ( t ) ⁢ dt ⁢ From ∵ dv i dt = a i ⁢ = ∑ i = 1 n ( m .   v i ( r ) + C ) ⁢ From ⁢ v i ( 0 ) = 0 ⁢ and ⁢ v i ( 0 ) + C = 0. C = 0. ⁢ = ∑ i = 1 n m · v i ( t )

[C is an integration constant]

2. <About Speed Component>

From the expressions given above, it is considered that, when the mass “m” does not vary or a change amount thereof is negligible during the motion, it is possible to assess the load on the body based on a speed component (v-t) at each time.

3-1. <About Relationship between Speed Component and Impulse>

[World Coordinate System Model]

When the speed component is perceived as a parameter of the impulse, it is considered that a speed component in the world coordinate system can be perceived as a parameter of the impulse with respect to the world coordinate system (earth). That is, a motion with respect to the earth as viewed in the world coordinate system is considered as the performance of the motion action. In FIG. 2, coordinate system symbols of the world coordinate system and a local rotating coordinate system described later are illustrated.

[World Coordinate System: Model without Deviation from Circle Trajectory]

As illustrated in FIG. 3, when a given object 16 accelerates on a circle trajectory from a position Pos. 1 (coordinates: x₁, y₁, z₁) to a position Pos. 2 (coordinates: x₂, y₂, z₂) between a time t₁ and a time t₂, accelerations a₁ and a₂ are indicated as differences in a speed v₂ and a speed v₁. Moreover, an average speed “v” at this time is given as follows.

[ Math . 4 ] v = ( x 2 - x 1 ) 2 + ( y 2 - y 1 ) 2 + ( z 2 - z 1 ) 2 ( t 2 - t 1 )

In FIG. 3, reference symbol 18 denotes the center of the circle of the circle trajectory.

[World Coordinate System: Model with Deviation from Circle Trajectory]

In contrast, as illustrated in FIG. 4, when another given object 16 accelerates while deviating from the circle trajectory, the acceleration is indicated as the difference in the speed vector as in the model without the deviation from the circle trajectory. Moreover, an average speed v′ at this time is given as follows.

[ Math . 5 ] v ′ = ( x 2 ′ - x 1 ′ ) 2 + ( y 2 ′ - y 1 ′ ) 2 + ( z 2 ′ - z 1 ′ ) 2 ( t 2 - t 1 )

As described above, even when the consideration is given in the world coordinate system, from an average speed obtained from the world coordinate system, it cannot be determined, based on this average speed, “whether or not the object deviates from the circle trajectory.” The model which does not deviate from the circle trajectory and the model which deviates from the circle trajectory sometimes indicate the same value (average speed).

3-2. <About Relationship between Speed Component and Impulse>

[Rotating Coordinate System Model]

A rotating axis in a rotating action motion varies depending on also an individual, and hence even when a form is considered in the world coordinate system, it can only be understood whether or not this form follows an ideal form. However, when the speed component is perceived as the parameter of the impulse, it is considered that a speed component in the rotating coordinate system in a case in which rotating center coordinates are defined in the body of a person who conducts the rotating action can be perceived as a parameter of an impulse with respect to the rotating coordinate system (body; torso). Moreover, the motion applied to the body can be considered as a body load.

[Rotating Coordinate System: Model without Deviation from Circle Trajectory]

As illustrated in FIG. 5, when an object associated with a given object (e.g., a connected object such as the shoulder with respect to the elbow) exists and is in motion in cooperation therewith, conversion to coordinates of the local rotating coordinate system is made by matching a line segment connecting this associated object and the center coordinates with one axis. The local rotating coordinate system is herein sometimes simply referred to as “rotating coordinate system.” That is, for example, the rotating coordinate system local coordinate data is sometimes simply referred to as “rotating coordinate system coordinate data.”

Through the conversion of data in the world coordinate system to data in the rotating coordinate system, the average speed in the rotating coordinate system can be calculated. An average speed v_R in the rotating coordinate system of an object in motion on the circle trajectory is given as follows.

[ Math . 6 ] v R = ( x R ⁢ 2 - x R ⁢ 1 ) 2 + ( y R ⁢ 2 - y R ⁢ 1 ) 2 + ( z R ⁢ 2 - z R ⁢ 1 ) 2 ( t 2 - t 1 )

A rotating direction of a rotating axis and a rotating direction of the motion match each other, and hence v>v_R. (v>>v_R)

The speed in the rotating coordinate system is lower than that in the world coordinate system, and hence the difference in the speed is also smaller. The acceleration is close to a centripetal force toward the center, and a compression load component of the force applied to the joint also increases.

[Rotating Coordinate System: Model with Deviation from Circle Trajectory]

FIG. 6 shows a model which deviates from the circle trajectory in the rotating coordinate system. Similarly to FIG. 5, when an object associated with a given object (e.g., a connected object such as the shoulder with respect to the elbow) exists and is in motion in cooperation therewith, conversion to coordinates of the rotating coordinate system is made by matching a line segment connecting this associated object and the center coordinates with one axis.

An average speed of the model deviating from the circle trajectory in the rotating coordinate system is as given below.

[ Math . 7 ] v R ′ = ( x R ⁢ 2 ′ - x R ⁢ 1 ′ ) 2 + ( y R ⁢ 2 ′ - y R ⁢ 1 ′ ) 2 + ( z R ⁢ 2 ′ - z R ⁢ 1 ′ ) 2 ( t 2 - t 1 )

Even when v′>v_R′, v_R′/v′ takes a larger value than v_R/v and when v′ and v_R′ are close to each other or when v′≤v_R′, a possibility of the deviation from the circle trajectory is high, and hence it can be determined that the object is deviating from the circle trajectory. It is considered that “the deviation from the circle trajectory is equal to application of an excessive tensile load,” and hence the determination of the load in the rotating action can be made.

• • 4. The two pieces of (impulse) data in the world coordinate system and in the local rotating coordinate system of the person in motion which are generated from the same motion are the same in dimensions (unit system) as described above, and hence can be relatively compared with each other.
  • 5. After that, when the speed of this person in motion in the local rotating coordinate system generated from the same motion is equal to or higher than or close to the speed in the world coordinate system, it is possible to determine that the person is in the motion which deviates from the circle trajectory. Moreover, various assessments can be made by relatively comparing the two pieces of (impulse) data in the world coordinate system and the local rotating coordinate system of the person in motion with each other.

[Calculation of Rotating Center]

Description is now given of a method of calculating the rotating center in the rotating coordinate system. FIG. 7 shows a diagram in which the spine of a person in a pitching action of a ball of the baseball toward this side using the left arm as a rotating action motion is represented by a straight line NW and a straight line connecting a shoulder LS of the left arm and a shoulder RS of the right arm, that is, a straight line R₁ and a straight line L1 connecting the left shoulder and the right shoulder, respectively, of the person in the rotating action motion is represented by a straight line LS·RS.

A rotating center coordinate point C (x_C, y_C, z_C) which is on the straight line NW of FIG. 7 and has the shortest distance to the straight line LS·RS is to be obtained.

A unit vector of the straight line LS·RS is represented as follows.

[ Math . 8 ] e → s

This unit vector is represented as follows.

[ Math . 9 ] e → s = ( x R - x L ( x R - x L ) 2 + ( y R - y L ) 2 + ( z R - z L ) 2 , y R - y L ( x R - x L ) 2 + ( y R - y L ) 2 + ( z R - z L ) 2 , z R - z L ( x R - x L ) 2 + ( y R - y L ) 2 + ( z R - z L ) 2 ) = ( N sx , N sy , N sz )

[Math. 10]

A unit vector

e → sp

of the straight line NW is represented as follows.

e → sp = ( x W - x N ( x W - x N ) 2 + ( y W - y N ) 2 + ( z W - z N ) 2 , y W - y N ( x W - x N ) 2 + ( y W - y N ) 2 + ( z W - z N ) 2 , z - z N ( x W - x N ) 2 + ( y W - y N ) 2 + ( z W - z N ) 2 ) = ( N spx , N spy , N spz )

[Math. 11]

A given point P (x_p, y_p, z_p) on the straight line LS·RS is given as follows.

( x p , y p , z p ) = ( x L + s ⁢ N s ⁢ x , y L + s ⁢ N s ⁢ y , z L + s ⁢ N sz ) ( 1 ) [ “ s ” ⁢ is ⁢ a ⁢ real ⁢ nu ⁢ mber ]

A given point Q (Xq, ya za) on the straight line NW is given as follows.

( x q , y q , z q ) = ( x N + t ⁢ N spx , y N + t ⁢ N spy , z N + t ⁢ N spz ) ⁢ [ “ t ” ⁢ is ⁢ a ⁢ real ⁢ number ] ( 2 )

[Math. 12]

Thus, a distance “d” between the point P and the point Q is given as follows.

d = ⁢ ( x p - x q ) 2 + ( y p - y q ) 2 + ( z p - z q ) 2

From the expression above, the following expression is obtained.

d 2 = ( x p - x q ) 2 + ( y p - y q ) 2 + ( z p - z q ) 2 ( 3 )

[Math. 13]

Expression (1) and Expression (2) are assigned to Expression (3) and d² is represented by f(s, t), d² is given as follows.

d 2 = f ⁡ ( s , t ) = ( N sx 2 + N sy 2 + N sz 2 ) ⁢ s 2 + 2 ⁢ { ( x L - x N ) ⁢ N sx + ( y L - y N ) ⁢ N sy + ( z L - z N ) ⁢ N sz } ⁢ s + ( N spx 2 + N spy 2 + N spz 2 ) ⁢ t 2 + 2 ⁢ { ( x L - x N ) ⁢ N spx + ( y L - y N ) ⁢ N spy + ( z L - z N ) ⁢ N spz } ⁢ t - 2 ⁢ ( N sx ⁢ N spx + N sy ⁢ N spy + N sz ⁢ N spz ) ⁢ st + ( x L - x N ) 2 + ( y L - y N ) 2 + ( z L - z N )

[Math. 14]

Conditions which minimize f(s, t) are:

∂ f ⁡ ( s · t ) ∂ s = 0 ⁢ and ⁢ ∂ f ⁡ ( s · t ) ∂ t = 0 ⁢ ∂ f ⁡ ( s · t ) ∂ t = 2 ⁢ ( N sx 2 + N sy 2 + N sz 2 ) ⁢ s + 2 { ( x L - x N ) ⁢ N sx + ( y L - y N ) ⁢ N sy + ( z L - z N ) ⁢ N sz } - 2 ⁢ ( N sx ⁢ N spx + N sy ⁢ N spy + N sz ⁢ N spz ) ⁢ t = 0

[ Math . 15 ] ∂ f ⁡ ( s · t ) ∂ t = 2 ⁢ ( N spx 2 + N spy 2 + N spz 2 ) ⁢ t - 2 { ( x L - x N ) ⁢ N spx + ( y L - y N ) ⁢ N spy + ( z L - z N ) ⁢ N spz } - 2 ⁢ ( N sx ⁢ N spx + N sy ⁢ N spy + N sz ⁢ N spz ) ⁢ s = 0

[Math. 16]

When the following notations are used,

α 1 = ( N sx 2 + N sy 2 + N sz 2 ) α 2 = { ( x L - x N ) ⁢ N sx + ( y L - y N ) ⁢ N sy + ( z L - z N ) ⁢ N sz } α 3 = ( N sx ⁢ N spx + N sy ⁢ N spy + N sz ⁢ N spz ) β 1 = ( N s ⁢ p ⁢ x 2 + N spy 2 + N spz 2 ) β 2 = { ( x L - x N ) ⁢ N spx + ( y L - y N ) ⁢ N spy + ( z L - z N ) ⁢ N spz }

[Math. 17]

• • the expressions given below are obtained.

∂ f ⁡ ( s · t ) ∂ s = 2 ⁢ α 1 ⁢ s + 2 ⁢ α 2 - 2 ⁢ α 3 ⁢ t = 0 ( 3 ) ∂ f ⁡ ( s · t ) ∂ t = 2 ⁢ β 1 ⁢ t + 2 ⁢ β 2 - 2 ⁢ a 3 ⁢ s = 0 ( 4 )

[Math. 18]

When “t” which satisfies Expression (3) and Expression (4) is represented by t₀, t₀ is given as follows.

t 0 = α 2 ⁢ α 3 - α 1 ⁢ β 2 α 3 2 - α 1 ⁢ β 1

Thus, the center coordinate point C (x_C, y_C, z_C) of the rotating motion is given as follows.

( x c , y c , z c ) = ( x N + t 0 ⁢ N spx , y N + t 0 ⁢ N spy , z N + t 0 ⁢ N spz )

As described above, the coordinates of the point C of the rotating center in the case in which the spine of the person in the rotating action motion is represented by the straight line NW and the left shoulder and the right shoulder of the person in the rotating action motion are represented by the straight line LS·RS are obtained. For positioning each part of the spine, the left shoulder and the right shoulder (that is, in the above-mentioned example, positioning of the straight line NW and the straight line LS·RS), the positioning may be executed based on an imaged actual rotating action or may be executed through use of a rotating action replaced by a rotating action obtained through skeleton estimation or motion capture. An example of the skeleton estimation is described in Patent Literature 2. An example of the motion capture is described in Patent Literature 3. Those technologies can be used to position each of the portions relating to the rotating axis of the rotating action such as the spine, the left arm and the right arm.

[Conversion from World Coordinate System to Rotating Coordinate System]

A method for the conversion from the world coordinate system to the rotating coordinate system is now described. FIG. 8 shows a diagram in which the spine of the person in the pitching action of the ball of the baseball toward this side using the left arm as the rotating action motion is represented by the straight line NW and the left arm and the right shoulder of the person in the rotating action motion are represented by the straight line LA and RS, respectively. Moreover, in FIG. 8, the shoulder of the left arm is represented by LS (coordinates: x_L, y_L, z_L) and the elbow of the left arm is represented by LE (coordinates: x_E, y_E, z_E). Further, the coordinates (x_C, y_C, z_C) of the point C on the spine having the shortest distance to the line connecting the left shoulder LS and the right shoulder RS obtained as described above are set as the rotating center. At this stage, the coordinates are in the world coordinate system.

After that, as illustrated in FIG. 9, the coordinate origin of the rotating coordinate system is moved to the rotating center coordinate point C, and the coordinates of each of the portions being the shoulder LS of the left arm and the elbow LE of the left arm are converted.

( x Ls , y Ls , z Ls ) = ( x L - x c , ⁢ y L - y c , ⁢ y L - z c ) [ Math . 19 ] ( x Es , y Es , z Es ) = ( x E - x c , ⁢ y E - y c , ⁢ z E - z c )

After that, a unit vector which directs from the rotating center coordinate point C to the left shoulder LS and is used for Y-axis rotation is obtained (see FIG. 10). Then, trigonometric functions of an expression of a conversion matrix are obtained from an Euler angle of the unit vector.

[ Math . 20 ] e → rcy = ( x LS x LS 2 + y LS 2 + z LS 2 , y LS x LS 2 + y LS 2 + z LS 2 , z LS x LS 2 + y LS 2 + z LS 2 ) = ( N rcyx , N rcyy , N rcyz )

When the Euler angle is represented as described above, the trigonometric functions for the Y-axis rotation conversion are given as follows.

cos ⁢ θ y = N rcyx N rcyx 2 + N rcyz 2 [ Math . 21 ] sin ⁢ θ y = N rcyz N rcyx 2 + N rcyz 2

After that, the coordinates are rotated about the Y axis in accordance with the obtained conversion matrix, to thereby convert the coordinates of each of the portions being the shoulder LS of the left arm and the elbow LE of the left arm (see FIG. 11).

( x Lry y Lry z Lry ) = ( cos ⁢ θ y 0 sin ⁢ θ y 0 1 0 - sin ⁢ θ y 0 cos ⁢ θ y ) ⁢ ( x LS y LS z LS ) [ Math . 22 ] ( x Ery y Ery z Ery ) = ( cos ⁢ θ y 0 sin ⁢ θ y 0 1 0 - sin ⁢ θ y 0 cos ⁢ θ y ) ⁢ ( x ES y ES z ES )

After that, a unit vector which directs from the rotating center coordinate point C to the left shoulder LS and is used for Z-axis rotation is obtained (see FIG. 12). Then, trigonometric functions of an expression of a conversion matrix are obtained from an Euler angle of the unit vector.

[ Math . 23 ] e → rcz = ( x Lry x Lry 2 + y Lry 2 + z Lry 2 , y Lry x Lry 2 + y Lry 2 + z Lry 2 , z Lry x Lry 2 + y Lry 2 + z Lry 2 ) = ( N rczx , N rczy , N rczz )

When the Euler angle is represented as described above, the trigonometric functions for the Z-axis rotation conversion are given as follows.

cos ⁢ θ z = N rczx N rczx 2 + N rczy 2 [ Math . 24 ] sin ⁢ θ z = N rcy N rczx 2 + N rczy 2 ( x LR y LR z LR ) = ( cos ⁢ θ z - sin ⁢ θ z 0 sin ⁢ θ z cos ⁢ θ z 0 0 0 1 ) ⁢ ( x Lry y Lry z Lry ) [ Math . 25 ] ( x ER y ER z ER ) = ( cos ⁢ θ z - sin ⁢ θ z 0 sin ⁢ θ z cos ⁢ θ z 0 0 0 1 ) ⁢ ( x Ery y Ery z Ery )

The conversion matrix is as given above, and the conversion to the coordinate axes with the axes being fixed in the body while the rotating center is set as the origin is completed. All records can be treated as the rotating coordinate system coordinates by converting all records through use of the same definition.

The coordinates are rotated about the Z axis in accordance with the obtained conversion matrix, to thereby convert the coordinates of each of the portions being the shoulder LS of the left arm and the elbow LE of the left arm. The straight line connecting the center coordinates of the rotating motion and the point LS and the X axis match each other (see FIG. 13). The above-mentioned conversion is executed at each time for each portion, to thereby convert the measured data to a coordinate group of the rotating coordinate system.

In the example of the pitching action, for each of portions being the neck, the hip, the right shoulder, the left shoulder, the right elbow and the left elbow, the above-mentioned conversion is executed at each time, to thereby convert the measured data to the coordinate group of the rotating coordinate system.

After that, a speed “v” at each time in the coordinate group in the rotating coordinate system is calculated based on the following expression.

v n = ( x n - x n - 1 ) 2 + ( y n - y n - 1 ) 2 + ( z n - z n - 1 ) 2 t n - t n - 1 [ Math . 26 ]

• • [“n” is a natural number]

There has been described the conversion from the definition of the rotating center in the case of, for example, the rotating action based on the moving image data obtained by imaging the actual action and the skeleton estimation or the motion capture based on the actual action. The definition of the rotating center in the above description is a so-called actually existing rotating center existing in the actual rotating action.

The actually existing rotating center based on the actual rotating action has been described above, but, for example, even in the case of the motion capture based on the actual action, the information on the spine of the person conducting the rotating action may not be obtained depending on the type of the motion capture. Without the information on the spine, the positioning of each of the portions being the above-mentioned spine, the left arm and the right arm cannot be achieved.

[Ideal Rotating Center]

Even in such a case without the information on the spine, it is possible to define the rotating center by considering an ideal rotating center.

An ideal rotating center coordinate point C_i illustrated in FIG. 14 is defined as follows.

( x ci , y ci , z ci ) = ( x R + x L 2 , y R + y L 2 , z R + z L 2 ) [ Math . 27 ]

For calculation of the rotating center in the rotating coordinate system model, it is also possible to use the above-mentioned ideal rotating center.

It is also possible to assess a matching rate between the ideal rotating center in a vicinity of the maximum speed and the actual rotating center, to thereby assess performance at this time point.

[Rotating Center Matching Rate]

When a distance from the origin O of the world coordinate system illustrated in FIG. 14 to the rotating center coordinate point C is set as follows:

OC → [ Math . 28 ]

and a distance from the origin O of the world coordinate system illustrated in FIG. 14 to the ideal rotating center coordinate point C_i is set as follows:

OC i → [ Math . 29 ]

the center coordinate matching rate between the rotating center coordinate point C and the ideal rotating center coordinate point C_i is as given below.

OC → OC i → [ Math . 30 ]

Rotating Center Matching Rate (1)

[Rotating Center Matching Rate in Terms of Rotating Center at Time of Occurrence of Maximum Speed and Rotating Center of Rotating Action at Each Time]

The rotating center matching rate in terms of the rotating center at the time of the occurrence of the maximum speed and the rotating center of the rotating action at each time can be used for performance assessment for the rotating action (for example, the pitching action of the baseball). By examining this rotating center matching rate, it is possible to use the rotating center matching rate to determine whether or not the body deviates at the time of the final acceleration (for example, at the time of ball release) of the rotating action. When the rotating center deviates, energy is used also for a translational motion, and hence it is considered that efficiency decreases. In this case, for example, in the case of the pitching action of the baseball, the assessment is made while the rotating center at the time of the occurrence of the maximum speed (at the time of ball release) of the elbow or the wrist is considered as the reference. When the data on the spine being the actually existing rotating center does not exist, it is possible to examine the rotating center matching rate in terms of the rotating center at the time of the occurrence of the maximum speed and the rotating center in the rotating action at each time by substituting the center coordinate of each time by the ideal rotating center. That is, by examining the rotating center matching rate in terms of the rotating center at the time of the occurrence of the maximum speed and the rotating center of the rotating action at each time, it is possible to assess the efficiency of the actual action.

Rotating Center Matching Rate (2)

[Rotating Center Matching Rate between Ideal Rotating Center and Actually Existing Rotating Center]

Moreover, for example, when the rotation of the torso in the rotating action such as the pitching action is considered, it is considered that the rotating center ideally exists at a middle point of a line connecting the right shoulder and the left shoulder. When the matching rate between the ideal rotating center in the vicinity of the maximum speed and the actually existing rotating center being the actual rotating center is assessed and the matching rate is not 100%, it is considered that there is still room for increasing the efficiency of the rotating motion of the person in motion (for example, pitcher). That is, by examining the rotating center matching rate between the ideal rotating center and the actually existing rotating center, it is possible to assess the efficiency of rotating motion mechanics. In summary, when the rotating center in the vicinity of the maximum speed is the ideal rotating center, it can be assessed that the motion mechanics of the torso of this pitcher is in the best state of the rotating motion. When it is required to analyze the motion which does not have the information data on the spine, it is not possible to assess the efficiency of the mechanics by examining the above-mentioned rotating center matching rate between the ideal rotating center and the actually existing rotating center. This is because the ideal rotation coordinates are used in place of the center axes of each piece of data.

One embodiment of a rotating action motion assessment system according to the present invention is now described. A block diagram of the one embodiment of the rotating action motion assessment system according to the present invention is illustrated in FIG. 15.

A rotating action motion assessment system 20 according to the one embodiment illustrated in FIG. 15 has a configuration including a server 30, a terminal device 32 and a communication network 34. A storage unit 22 and a control unit 26 are accommodated in the server 30 and are connected to the terminal device 32 via the communication network 34 such as the Internet or a company LAN (local area network).

The terminal device 32 is provided with an information input operation unit 24 and a display unit 28. Further, the terminal device 32 is provided with an input unit 36, a communication interface 38, a RAM/ROM 40, a CPU (control device/calculation device) 42, a memory (main storage device) 44 and a display interface 46. As the information input operation unit 24, a keyboard or a touch panel can be applied. As the display unit 28, for example, a liquid crystal display can be applied. As the terminal device 32, various computers can be used, and a computer of a mobile terminal type, such as a smartphone or a tablet computer, can also be used.

As the information input, at least one actually existing rotating center obtained from the group consisting of the actual action and the rotating action obtained through the skeleton estimation and the motion capture is input or the ideal rotating center is input. As another example, both of at least one actually existing rotating center obtained from the group consisting of the actual action and the rotating action obtained through the skeleton estimation and the motion capture and the ideal rotating center may be input, to thereby define the rotating center. The above-mentioned actual action includes various actual actions such as the actual action imaged as a moving image, the actual action recorded in a recording medium and a live view video. The input of the actual action is input of a taken image of the actual action. The taken image of the actual action includes a still image and a moving image. As the input of the rotating action obtained through the skeleton estimation, it is possible to input information on the skeleton estimation during the rotating action through use of, for example, an application that executes the skeleton estimation from the taken image of the actual action. Moreover, as the rotating action obtained through the motion capture, it is possible to input information on the motion capture during the rotating action through use of, for example, an application that executes the motion capture from the taken image of the actual action. As the information input, it is only required to obtain the actually existing rotating center from the group consisting of the actual action and the rotating action obtained through the skeleton estimation and the motion capture, and the actually existing rotating center can be obtained through calculation from at least one of the group thereof or can automatically be detected from at least one of the group thereof. In obtaining the actually existing rotating center, the actually existing rotating center may be obtained through any of the group thereof, for example, a combination of the actual taken image and the skeleton estimation. The information is input from the information input operation unit 24.

Based on the input information, the rotating action motion assessment is output from the display unit 28. An entire part from the input to the output can be executed through use of a program. When the entire part is executed on the system through use of the program, input of the user information is only input of an ID and the like (a name, a height, a registration number and the like), and the entire following part can automatically be executed.

Imaging of rotating action→Output of world coordinate system data group→Rotating center detection→Rotating coordinate system conversion→Verification

Moreover, when the rotating action is the motion of throwing the ball of the baseball, through detection of a direction of throwing the ball and the like, it is possible to automatically execute definition of left-handed pitching and right-handed pitching and the like. For example, when a camera is set in the information input operation unit 24, the entire part from the input to the output of the assessment can automatically be executed on the system by inputting the user information from the information input operation unit 24 and inputting the image from the information input operation unit 24.

Further, in the illustrated example, the example of the rotating action motion assessment system 20 is illustrated, but a conversion system for coordinate data in a rotating action motion which executes the processing up to the conversion of the coordinate data in the rotating action motion can be implemented by using the same configuration and changing only the program.

A first aspect of a program according to the present invention is a program for causing a computer to function as each device of the rotating action motion assessment system 20. That is, the first aspect of the program according to the present invention is a program for causing a computer to function as each device of the rotating action motion assessment system including: a rotating center definition device configured to define a rotating center from at least one actually existing rotating center obtained from the group consisting of an actual action and a rotating action obtained through skeleton estimation and motion capture and/or an ideal rotating center; a world coordinate system coordinate data obtaining device configured to obtain, from the defined rotating center, world coordinate system coordinate data being coordinate data in a world coordinate system in the rotating action; a conversion device configured to convert the world coordinate system coordinate data to rotating coordinate system local coordinate data being local coordinate data in a rotating coordinate system having, as an origin, a rotating center in a human body in the rotating action; and a relative comparison device configured to relatively compare values of two pieces of data being the world coordinate system coordinate data and the rotating coordinate system local coordinate data which are obtained from the same action in the rotating action.

Further, a second aspect of the program according to the present invention is a program for causing a computer to function as each device of the conversion system for coordinate data. That is, the second aspect of the program according to the present invention is a program for causing a computer to function as each device of the conversion system for coordinate data in a rotating action motion, the conversion system including: a rotating center definition device configured to define a rotating center from at least one actually existing rotating center obtained from the group consisting of an actual action and a rotating action obtained through skeleton estimation and motion capture and/or an ideal rotating center; a world coordinate system coordinate data obtaining device configured to obtain, from the defined rotating center, world coordinate system coordinate data being coordinate data in a world coordinate system indicating world coordinates of a predetermined position in a human body at each time in the rotating action; a device configured to define center coordinates of the world coordinate system coordinate data at each time; a device configured to obtain Cartesian coordinate system data by matching one axis of a Cartesian coordinate system with a line segment connecting the center coordinates and a predetermined joint position; and a conversion device configured to convert the Cartesian coordinate system data to local coordinate data that indicates, at each time, local coordinates of the predetermined position in the human body having, as an origin, the rotating center in the human body in the rotating action.

In the illustrated example, there is illustrated the example in which the terminal device 32 and the server 30 are connected to each other via the communication network 34. However, it is possible to avoid the use of the communication network 34 and to input the entire program in the terminal device 32, to thereby cause the terminal device 32 to function offline as the rotating action motion assessment system or to thereby cause the terminal device 32 to function offline as the conversion system for coordinate data.

A flowchart for illustrating one embodiment of a rotating action motion assessment method in the rotating action motion assessment system 20 according to the present invention is illustrated in FIG. 16. In FIG. 16, there is illustrated a pattern in which the skeleton estimation is used to define the rotating center from the actually existing rotating center. Moreover, an example illustrated in FIG. 16 is roughly divided into three parts of computer processing, which are a part which executes the skeleton estimation by the rotating action motion assessment system 20, an analysis part which executes the assessment by the rotating action motion assessment system 20 and a display part which indicates the assessment for the rotating action by the rotating action motion assessment system 20.

Each step of the flowchart of FIG. 16 is as described below. The flowchart of FIG. 16 is merely the one embodiment, and it should be understood that changes and the like such as a change in a sequence of each step and deletion and addition of a step can be executed by changing the program.

[Steps(S) Illustrated in FIG. 16]

Step S100: <Moving Image Taking Step> A moving image of an actual rotating action, for example, the pitching action of the baseball, is taken.

Step S102: <Skeleton Estimation Step> Skeleton estimation using a skeleton estimation technology is executed from the imaging data taken in Step S100. As the skeleton estimation, for example, in addition to the skeleton estimation technology as described in Patent Literature 2, publicly-known various skeleton estimation technologies can be applied.

Step S104: <Three-Dimensional Coordinates Detection Step> Three-dimensional coordinates are detected from the skeleton estimation in the rotating action.

Step S106: <Three-Dimensional Coordinate Data Extraction Step>

The detected three-dimensional coordinate data is extracted.

Step S108a: <Skeleton Image Insertion Step> A skeleton image is inserted. At this time, in Step S107, a skeleton definition file in a database is referred to (Step S107: skeleton definition file reference step).

Step S110: <Skeleton Estimation Moving Image Step> A skeleton estimation moving image is displayed. In this case, the assessment is not executed through relative comparison, but the skeleton estimation moving image is displayed for reference.

The subsequent steps include a step of converting coordinate data from the world coordinate system to the rotating coordinate system, which is a characteristic step of the present invention.

Step S108b: <Three-Dimensional Coordinate-Time Data Acquisition Step [World Coordinate System]> Data on the three-dimensional coordinates in the world coordinate system at each time is acquired.

Step S112: <Rotating Center Coordinate Calculation Step> Rotating center coordinates are calculated from the three-dimensional coordinate data in Step S108b. At this time, in Step S111, a rotating center coordinate calculation target skeleton definition file in the database is referred to (Step S111: rotating center coordinate calculation target skeleton definition file reference step).

Step S114: <Three-Dimensional Coordinate/Rotating Center Coordinate-Time Data Acquisition Step [World Coordinate System]>

Data at each time of the three-dimensional coordinate data in the world coordinate system is acquired.

Step S116a: <Unit Vector Calculation Step (During Rotating-Target Joint> A unit vector of a joint being an assessment target during the rotating action is calculated.

Step S118: <Unit Vector and Euler Angle Calculation Step> The unit vector and the Euler angle are calculated.

Step S120: <Coordinate Conversion Step> The coordinate axes are converted from the world coordinate system to the rotating coordinate system.

Step S122: <Three-Dimensional Coordinates-Time Data Acquisition Step [Rotating Coordinate System]> The three-dimensional coordinate data in the rotating coordinate system at each time is acquired.

Step S124: <Joint Portion Speed Calculation Step [Rotating Coordinate System]> The speed of the joint portion in the rotating coordinate system is calculated.

Step S125: <Joint Relative Position (Straight Line Matching Rate) Assessment Step [Rotating Coordinate System]> A joint relative position (straight line matching rate) of the joint portion being the assessment target in the rotating coordinate system is assessed and displayed. This step may be provided as required. For example, in terms of the rotating action of the pitching, a straight line matching rate between the line R1 from the spine to the right shoulder and the line L1 from the spine to the left shoulder illustrated in FIG. 7 may be assessed, or a straight line matching rate between the line R1 from the spine to the right shoulder and the line LA from the spine to the left arm may be assessed. It is possible to make such assessment that a higher straight line matching rate corresponds to execution of a rotating action closer to the ideal.

Step S126: <Speed-Time Graph Drawing Step [Rotating Coordinate System]> A graph indicating, at each time, the speed of the joint portion being the assessment target in the rotating coordinate system is drawn and displayed.

Step S127: <Acceleration-Time Graph Drawing Step [Rotating Coordinate System]> A graph indicating, at each time, the acceleration of the joint portion being the assessment target in the rotating coordinate system is drawn and displayed.

Meanwhile, the world coordinate system data for the relative comparison with the local coordinate data in the rotating coordinate system is also acquired as in the following steps.

Step S116b: <Joint Portion Speed Calculation Step [World Coordinate System]> The speed of the joint portion in the world coordinate system is calculated.

Step S128: <Step of Calculating Peak Speed (Vmax) of Target Joint [World Coordinate System]> A peak speed (Vmax) of the joint portion being the assessment target in the world coordinate system is calculated.

Step S130: <Ideal Rotating Center Calculation [World Coordinate System]> The ideal rotating center coordinates are calculated as required.

Step S131: <Rotating Center Coordinates Matching Rate [World Coordinate System]> The matching rate between the rotating center coordinates and the ideal rotating center coordinates of the joint porting being the assessment target in the world coordinate system is assessed and displayed. It is only required to provide this step as required.

Step S132: <Speed-Time Graph Drawing Step [World Coordinate System]> A graph indicating, at each time, the speed of the joint portion being the assessment target in the world coordinate system is drawn and displayed.

Step S133: <Acceleration-Time Graph Drawing Step [World Coordinate System]> A graph indicating, at each time, the acceleration of the joint portion being the assessment target in the world coordinate system is drawn and displayed.

After that, the obtained local coordinate data in the rotating coordinate system and the obtained coordinate data in the world coordinate system are relatively compared with each other and assessed.

Step S135: <Relative Comparison and Assessment Step> The obtained local coordinate data in the rotating coordinate system and the obtained coordinate data in the world coordinate system are relatively compared with each other and assessed. In this relative comparison, for example, a graph indicating the speed of a predetermined position, for example, the joint portion in the human body in the rotating coordinate system being the assessment target in Step S126 at each time and a graph indicating the speed of the joint portion in the world coordinate system being the assessment target in Step S132 at each time are compared with each other and are assessed.

As a criterion for the assessment through the relative comparison between the speeds in the rotating coordinate system and the world coordinate system, when the maximum speed of the rotating coordinate system local coordinate data is close to or equal to or higher than the maximum speed of the world coordinate system coordinate data, it is possible to determine that the body load is high. More specifically, for example, the determination is made as described below.

<Assessment: Low Load>

When the maximum speed of the joint portion being the assessment target in the world coordinate system is set as 100%, the maximum speed of the joint portion being the assessment target in the rotating coordinate system is 60% or lower.

The pitching action is a pitching action which has a low load on this joint portion and hence is less likely to cause the trouble even when this pitching action is continued.

<Assessment: Medium Load>

When the maximum speed of the joint portion being the assessment target in the world coordinate system is set as 100%, the maximum speed of the joint portion being the assessment target in the rotating coordinate system is higher than 60% and equal to or lower than 80%.

It is considered that the load on this joint portion has occurred to a significant degree, and hence this pitching action is a pitching action continuation of which requires attention.

<Assessment: High Load>

When the maximum speed of the joint portion being the assessment target in the world coordinate system is set as 100%, the maximum speed of the joint portion being the assessment target in the rotating coordinate system is higher than 80%.

This pitching action is a pitching action which has a high load on this joint portion and hence is highly likely to cause the trouble when this pitching action is continued.

Moreover, in the relative comparison assessment step of Step S135, for example, the maximum acceleration of the graph indicating the acceleration of the joint portion in the rotating coordinate system being the assessment target in Step S127 at each time and the maximum acceleration of the graph indicating the acceleration of the predetermined position in the human body, for example, the joint in the world coordinate system being the assessment target in Step S133 at each time are relatively compared with each other, and when the maximum acceleration of the rotating coordinate system is close to or equal to or higher than the maximum acceleration in the world coordinate system, it is possible to determine that the load on this joint portion is high. Moreover, areas of graphs indicating the speeds of the predetermined position in the human body at each time in the rotating coordinate system and the world coordinate system are relatively compared with each other, and when the area of the graph indicating the speed at each time in the rotating coordinate system is close to or equal to or more than the area of the graph indicating the speed at each time in the world coordinate system, it is possible to determine that the load on the predetermined position, for example, the joint portion in the human body is high.

Moreover, displacements of the predetermined position in the human body in the rotating coordinate system and the world coordinate system are relatively compared with each other, and when the displacement in the rotating coordinate system is close to or equal to or more than the displacement in the world coordinate system, it is also possible to determine that the load on the predetermined position, for example, the joint portion in the human body is high.

The present invention is characterized by the point that the comparison not with data on another person, but with the own data is made. Thus, although differences in body load such as the load on the joint caused by the rotating action exist among persons, the comparison with the own data is made, and hence it is possible to assess the body load by visualizing the body load, that is, quantifying the body load, which cannot have been achieved up to now. Moreover, in addition to assessing the body load such as the load on the joint caused by the rotating action, the rotating action motion assessment system and the rotating action motion assessment method according to the present invention can assess the performance in the rotating action by relatively comparing the data in the rotating coordinate system and the data in the world coordinate system with each other.

Example

Examples are now described. In the present invention, as the rotating center, at least one actually existing rotating center obtained from the group consisting of the actual action and the rotating action obtained through the skeleton estimation and the motion capture may be used, and/or the ideal rotating center may be used.

Example 1

A left-handed pitcher A actually threw a ball of the baseball with the left arm, and the person which conducted the pitching action with the left arm was imaged. From the moving image taken as described above, the rotating center was calculated based on the skeleton estimation. After that, for the elbow in the pitching action with the left arm, the speed at each time in each of the world coordinate system and the local rotating coordinate system was calculated. In FIG. 17, a graph of a result for the world coordinate system is shown. The maximum speed Vmax in the world coordinate system was 16.19 m/sec. In FIG. 18, a graph of a result for the speed at each time in the rotating coordinate system is shown. As a result of the relative comparison, the speed at each time in the rotating coordinate system, even the maximum speed Vmax of 8.67 m/sec, was much lower than the maximum speed Vmax of 16.19 m/sec in the world coordinate system (53.55% when the maximum speed in the world coordinate system is set as 100%). Thus, it can be determined that the load on the elbow in the pitching action with the left arm is low. Even when this pitching action is continued, the possibility of the trouble is low.

Moreover, in FIG. 19, a result obtained by calculating, for the elbow of the above-mentioned pitching action with the left arm, the acceleration at each time in each of the world coordinate system and the local rotating coordinate system and relatively comparing the accelerations with each other is shown. The maximum acceleration in the rotating coordinate system is neither close to nor higher than the maximum acceleration in the world coordinate system, and hence it can be determined that the load on the elbow being the joint portion is low.

Moreover, in FIG. 20, a result obtained by calculating, for the elbow of the above-mentioned pitching action with the left arm, a displacement with respect to the elbow in each of the world coordinate system and the local rotating coordinate system and comparing the displacements with each other is shown. The displacement with respect to the elbow in the rotating coordinate system is neither close to nor higher than the displacement with respect to the elbow in the world coordinate system, and hence it can be determined that the load on the elbow being the joint portion is low.

Example 2

After that, the rotating center was calculated, based on the skeleton estimation, from a recorded video of a right-handed pitcher B using the right arm to pitch a ball of the baseball. Then, for the elbow in the pitching action with the right arm, the speed at each time in each of the world coordinate system and the local rotating coordinate system was calculated. In FIG. 21, a graph of a result for the world coordinate system is shown. The maximum speed Vmax in the world coordinate system was 16.21 m/sec. In FIG. 22, a graph of a result for the speed at each time in the rotating coordinate system is shown. As a result of the relative comparison, the maximum speed Vmax of the speed at each time in the rotating coordinate system was 16.03 m/sec and reached a value close to the maximum speed Vmax of 16.21 m/sec in the world coordinate system (98.89% when the maximum speed in the world coordinate system is set as 100%). From this result, it can be determined that this pitching action is a pitching action having a high load on the elbow.

Moreover, in FIG. 23, a result obtained by calculating, for the elbow of the above-mentioned pitching action with the right arm, the acceleration at each time in each of the world coordinate system and the local rotating coordinate system and relatively comparing the accelerations with each other is shown. The maximum acceleration in the rotating coordinate system exceeds the maximum acceleration in the world coordinate system, and hence it can be determined that this pitching action is a pitching action having a high load on the elbow being the joint portion.

Moreover, in FIG. 24, a result obtained by calculating, for the elbow of the above-mentioned pitching action with the right arm, a displacement with respect to the elbow in each of the world coordinate system and the local rotating coordinate system and relatively comparing the displacements with each other is shown. The displacement with respect to the elbow in the rotating coordinate system exceeds the displacement with respect to the elbow in the world coordinate system, and hence it can be determined that this pitching action is a pitching action having a high load on the elbow being the joint portion.

In the above-mentioned Examples, the example of the pitching of the baseball has been described. The motion accompanied by the rotating action at the acceleration exceeding 9.8 m/sec² in the present invention refers to a motion accompanied by the rotating action at an acceleration exceeding 9.8 m/sec² in the world coordinate system. The motion accompanied by the rotating action at the acceleration exceeding 9.8 m/sec² in the present invention includes any motion accompanied by the rotating action having an acceleration exceeding 9.8 m/sec². The motion includes any one of motions accompanied by the rotating action in sports which handle a flying object or a sliding object, such as baseball, softball, soccer, tennis, golf, volleyball, basketball, cricket, hockey, rugby, American football, handball, water polo, bowling, lacrosse, ping-pong, squash, badminton and ice hockey as well as motions accompanied by the rotating action, such as dance and figure skate. Moreover, as long as track and field games, games such as swimming and diving, gymnastics, stunt, exercise and the like involve motions accompanied by the rotating action at an acceleration exceeding 9.8 m/sec², those motions are included in the motions accompanied by the rotating action in the present invention. In addition to the listed motions, it should be understood that as long as a motion is accompanied by the rotating action, the motion is included.

In the case of the pitching of the baseball, the rotating center of the body in the motion is any place on the spine. However, in a case of the rotating motion in another sport, for example, an action of kicking a ball in the soccer, the rotating center is at the hip joint or the like. As described above, the rotating center in the human body in the motion accompanied by the rotating action in the present invention varies in accordance with the type of motion, but it is only required to define the rotating center in the human body in accordance with the type of motion.

According to the present invention, it is possible to visualize and assess a body load applied on the joint or the like of the body, performance and the like by relatively comparing, in the above-mentioned various motions accompanied by the rotating action at an acceleration equal to or higher than 9.8 m/sec², the rotating coordinate system coordinate data on the own rotating action and the world coordinate system data on the own rotating action with each other.

REFERENCE SIGNS LIST

• • 10, 12: bone, 14: joint, 16: given object, 18: center, 20: rotating action motion assessment system, 22: storage unit, 24: information input operation unit, 26: control unit, 28: display unit, 30: server, 32: terminal device, 34: communication network, 36: input unit, 38: communication interface, 40: RAM/ROM, 42: CPU, 44: memory, 46: display interface.