JP2019141262A - Method for analyzing motion of martial art - Google Patents

Abstract

To highly accurately measure a motion of a player of a martial art.SOLUTION: The method for analyzing a motion of a martial art takes an image of the body of a player wearing color markers of four colors or less and thereby analyzes the motion of the player regardless of the color of clothing or an illumination environment.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a martial arts motion analysis method.

  Conventionally, techniques as disclosed in Patent Document 1 to Patent Document 4 have been disclosed.

JP 2007-61121 A Japanese Patent Laid-Open No. 2006-6415 JP 2002-65641 A Registered Utility Model No. 3214455

Patent Document 1 uses a multi-link model in which a predetermined part of the body is used as a reference point, a plurality of joint portions are marked with markers, and each of the links connecting the markers is connected in order. A three-dimensional motion measurement technique for analyzing motion is described. According to the prior art described in Patent Document 1, approximately the same number of markers as the human body joints are required, and the labor required for marking becomes enormous. In addition, although the type of marker is not specified, a multi-link model in which the links connecting the markers are connected in order is used, so part of the marker is shielded by the lighting environment and the clothes of the measurement subject. There is a problem that the estimation accuracy is extremely lowered.
Japanese Patent Application Laid-Open No. 2004-260260 describes a technique that enables the position of an optical marker to be estimated by using a three-axis gyro sensor even when the optical marker is hidden from the camera. According to the prior art described in Patent Document 2, both an optical motion capture and at least a three-axis gyro sensor must be used, and there is a problem that a large cost is required for use.
Patent Document 3 describes that an LED light source is used as a marker to measure a three-dimensional movement of a finger. Patent Document 4 describes an optical marker that uses a magnet and is detachable from a pedestal. According to the prior art described in Patent Document 4, there is a problem that the marker becomes expensive and the cost cannot be reduced.

  One embodiment of the present invention is a martial arts motion analysis method for performing motion analysis of the athlete by imaging the athlete's body equipped with four or less color markers, regardless of the color of the clothing or the lighting environment. It is.

  In one embodiment of the present invention, an imaging step of imaging a player's body equipped with color markers of four colors or less and outputting an RGB color system image, and a color specification of the video output in the imaging step A conversion step of converting the color system from the RGB color system to a color system including hue, saturation, and brightness, and setting a threshold value for the image in which the color system is converted in the conversion step Is a martial arts motion analysis method including a background removal step of removing a background included in an image.

  In one embodiment of the present invention, in the above-described martial arts motion analysis method, a mounting position at which the color marker is mounted on a player's body is determined in advance, and based on the image captured in the imaging step, A joint angle estimating step of estimating the joint angle of the person.

  In one embodiment of the present invention, in the martial arts motion analysis method described above, in the imaging step, the video is captured by a single camera.

  In one embodiment of the present invention, in the above-described martial arts motion analysis method, the color marker includes a first type of color marker that is fixed in advance to a stretchable belt, and a belt that is previously attached to the body of the athlete. There is a second type of color marker that is attached to the attachment part during measurement.

  According to the present invention, the movement of a martial arts player can be measured with high accuracy.

It is a figure which shows an example of the body part (side view) which mounts the color marker of this embodiment. It is a figure which shows an example of the body part (back view) which mounts the color marker of this embodiment. It is a figure which shows an example of a response | compatibility with the color marker number of this embodiment, and an anatomical mounting site | part. It is a figure which shows an example of the mounting rule of the color marker of this embodiment. It is a figure which shows an example of how to obtain | require the human body joint angle of this embodiment. It is a figure which shows an example of the form of the color marker of this embodiment. It is a figure which shows an example of the angle of view of the imaging part (camera) of this embodiment. It is a figure which shows the operation example of the calibration before measurement of this embodiment. It is a figure which shows an example of the process sequence of the martial arts movement analysis method of this embodiment. It is a figure which shows an example of the analysis result of the body gravity center by the martial arts movement analysis method of this embodiment. It is a figure which shows an example of the analysis result of the motion of the upper body by the martial arts movement analysis method of this embodiment. It is a figure which shows an example of the analysis result of the time required for the impact by the martial arts movement analysis method of this embodiment. It is a figure which shows an example of the analysis result of the attraction time of a crossing foot by the martial arts action analysis method of this embodiment. It is a figure which shows an example of the analysis result of the angle of the lower leg at the time of depressing by the martial arts action analysis method of this embodiment. It is a figure which shows an example of the analysis result of the jump distance (distance of a left foot from a left foot) by the martial arts movement analysis method of this embodiment. It is a figure which shows an example of the analysis result of the movement of the head by the martial arts movement analysis method of this embodiment.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(1) Mounting of color markers of 4 colors or less to the body Prepare 4 color markers. The marker may be a spherical color marker, which will be described later, or a colored tape. The marker may use a small light source such as an LED.
For example, the color marker colors are green (R), yellow (Y), orange (O), and pink (P). These four colors are the colors that stand out well even in the dark, and are the types of light reflecting tapes that are easily available even when wrapped around a spherical marker.
However, the four types of color marker colors are preferably different from the floor of the measurement location.

  That is, in the martial arts motion analysis method, the athlete's motion analysis is performed regardless of the color of the clothing or the lighting environment by capturing an image of the athlete's body with four or less color markers.

For example, the color marker is a four-color reflective tape wound around a spherical foamed polystyrene having a diameter of about 2 to 4 cm. The bottom is fixed to a flat plate such as a cap of a plastic bottle as a base.
There are two methods for fixing the color marker to the body. In one type, the color marker is fixed in advance to a stretchable belt with a hook-and-loop fastener, and the color marker is attached to the specified body part by winding the belt around a body part that is difficult to reach such as the back of the human body. To do. In the other type, the color marker and the belt are not fixed. When the marker is mounted, the belt is first wound around the body part, and then the color marker is adhered to the belt with a double-sided tape or the like.

(2) Mounting position of color marker FIG. 1 is a diagram illustrating an example of a body part (side view) to which the color marker of this embodiment is mounted.
FIG. 2 is a diagram illustrating an example of a body part (back view) to which the color marker of this embodiment is attached.
FIG. 3 is a diagram illustrating an example of the correspondence between the color marker number and the anatomical attachment site of the present embodiment.
When measuring movements of kendo martial arts and sports (kendo, short kendo, bayonet, naginata, fencing, etc.) in the sagittal plane as described above, for example, color the body parts shown in FIGS. A marker should be attached.

There are two types of color markers attached to the human body, and one type is fixed to the elastic belt in advance and is used mainly for mounting on the back of the human body. The other type is a color marker to be attached to a body part other than the back surface, which is not fixed to the belt in advance, and is attached to the belt with a double-sided tape or the like when the marker is attached.
The color markers previously fixed to the belt are marker numbers 1, 6, and 7 in the example illustrated in FIG.
The belt fixing type color marker mounting method is as follows. The user holds both ends of the belt to which the color marker 1 is fixed, and places the color marker 1 directly below the bone at the center of the back of the head. Next, fix the belt according to the size of the head so that it passes over both ears. Finally, the color marker 2 is affixed to a position on the right ear of the belt, and the color marker 3 is affixed to the center of the forehead.
The belt on which the color marker 6 is fixed in advance is passed through the base of the armpits (armpits), and the belt is mounted so that the color marker 6 is positioned on the spine.
The belt on which the color marker 7 is fixed in advance is first applied to the height of the left and right greater trochanters, and the belt is mounted so that the marker 7 is positioned on the spine. Then, the color marker 8 is attached to the position of the right greater trochanter. It is good to confirm whether the height of the color marker 7 and the color marker 8 is the same with a mirror.
For color markers other than color markers 1, 2, 3, 6, 7, and 8, attach double-sided tape or the like on the body position shown in Table 1 from the belt wrapped around the body or from the top of the clothing. Paste the color marker.

(3) Method for Determining Color Marker Color FIG. 4 is a diagram showing an example of a color marker mounting rule according to this embodiment.
Step 1: Captured image of user's outerwear (area A1), pants (area A2), background (area A3), user's head (area A4), upper right limb and weapon (area) Divide into A5). The pants are subdivided into a left leg (region A21), a left foot (region A22), a right leg (region A23), and a right foot (region A24).

  Step 2: Check whether the area A1 includes a color similar to any of the four color marker colors. If it is included, a color marker of one type different from the similar color is attached to all of the color markers 4, 5, 6, 7, and 8 attached to the area A1. On the contrary, if the area A1 does not include a color similar to the four types of color marker colors, any one of the four colors is selected and the color markers 4, 5,. The color markers of the color are attached to all positions 6, 7, and 8.

  Step 3: Check whether or not the region A2 includes a color similar to any of the four types of color marker colors. If it is included, any two of the three different colors are selected, and the positions of the color markers 9 and 10 to be attached to the area A21 and the positions of the color markers 10 and 12 to be attached to the area A23, Attach color markers of different colors. Conversely, if the area A2 does not contain a color similar to any of the four color markers, select any two of the four colors and select one color marker. The color marker of the other color is attached to the area A21 in the area A21.

Step 4: In the areas A22 and A24, two types of colors different from the colors selected in the areas A21 and A23 are mounted at the positions of the color markers 13 and 14, respectively.
Step 5: It is confirmed whether or not a color similar to any of the four color marker colors is included in the background area A3. If it is included, the color markers 1 and 3 to be mounted in the area A4 are mounted with a color marker color different from that color and different from the color used in the area A1. On the contrary, if it is not included, a color different from the color used in the area A1 is attached to the color markers 1 and 3. The color marker 2 is attached with the color used in the area A1 and a color different from the color markers 1 and 3.

Step 6: The color markers 15, 16, 17, 18, and 19 included in the region A5 are alternately mounted with two types of color marker colors different from the region A1 and the color marker 3. This prevents color markers of the same color from adjoining or crossing even when the upper right limb or weapon is swung up near the forehead, such as when hitting a kendo or short kendo. be able to.
As described above, the four types of color marker colors are preferably different from the floor of the measurement location.

(4) Color system conversion from RGB color system to HSV, etc. As described above, the color marker colors of the same body part are the same while there are no similar colors in the vicinity, and multiple markers can cross or approach. If different colors are arranged for the characteristic parts, the background can be removed and only the color markers can be extracted by simple image processing.
The general flow of image processing is described below.
Step 1: Specify the position of the color marker in the captured image.
Procedure 2: The captured image is converted from the RGB color system to an HSV color system (or HSB color system) that expresses colors in three of hue, saturation, and brightness. Then, the HSV value of each color marker color is stored.
Procedure 3: Set the upper and lower limits of the HSV value. Each is as follows.
H: ± 10/180 from the value acquired by clicking
S: 0 to 255, lower limit is 80, upper limit is 255
V: 0 to 255, lower limit is 50, upper limit is 255
Here, the reason why the low value of V (luminance value) is excluded is to remove pixels that are too black (too dark) due to the influence of illumination light or the like. The reason why the low value of S (saturation) is excluded is to remove pixels that are too white (too bright) due to the influence of sunlight or the like.
Procedure 4: The barycentric pixel of each color marker is recorded as the marker position.
Procedure 5: Estimate the human body joint angle and convert from the image coordinate system to the physical coordinate system from the center-of-gravity pixel and the horizontal reference line placed so as to appear in the image.
Procedure 6: The processing is transferred to the next frame, and the color system conversion from the RGB color system to HSV (or HSB) is performed.
Procedure 7: In the vicinity of the marker position stored in the previous frame, the pixels within the range of the set value of 3 described above are extracted, and each centroid pixel is recorded as the marker position.
Procedure 8: The processing is moved to the above-mentioned 5 and the same processing is repeated until the final frame.
Through the above processing, the position coordinates of each color marker are obtained.

  That is, the martial arts motion analysis method of the present embodiment captures an image of a player wearing a color marker of four colors or less and outputs an RGB color system image, and an image output in the imaging step Conversion step to convert the color system from the RGB color system to a color system including hue, saturation, and lightness, and a threshold is set for the image in which the color system was converted in the conversion step And a background removal step of removing the background included in the video.

FIG. 5 is a diagram illustrating an example of how to obtain the human body joint angle according to the present embodiment.
There are two types of methods for obtaining the human body joint angle from the marker position coordinates. The image is picked up in advance including an image clue such as a curved scale, a ruler, or a horizontal plane such as a floor plane. Then, as illustrated in FIG. 5, for example, the inclination of the head includes a horizontal vector a ₀ (in the figure, an arrow above a ₀ ) and two color marker vectors a ₁ (in the figure, a ₁ Calculate from the angle formed by the arrow at the top. In addition, for example, the elbow joint angle is determined by two vectors a ₂ (arrows above a _{2 in} the figure) and vectors a ₃ (arrows above a _{3 in} the figure) of three adjacent color markers. Find from the corner to make.

  That is, in the martial arts motion analysis method of the present embodiment, the mounting position at which the color marker is mounted on the athlete's body is determined in advance, and the joint angle of the athlete is determined based on the image captured in the imaging step. The method further includes a joint angle estimation step for performing estimation.

(5) Three-dimensional motion measurement by one camera As described above, the color marker mounting position is generally bilaterally symmetric with respect to the human body. However, by attaching the color markers 4 and 5 to the left and right shoulder ridges (shoulder joint positions), not only the three-dimensional motion measurement in the sagittal plane (y-axis direction) can be performed with one camera. The upper body twist (rotation around the y-axis) can also be measured.

  That is, in the martial arts motion analysis method of the present embodiment, an image is captured by one camera in the imaging step.

(6) Manufacture of color marker A color marker is obtained by wrapping a four-color light reflecting tape around a spherical foam polystyrene having a diameter of about 2 to 4 cm. Fix it to the cap of the plastic bottle as the base. Since the base is flat, it can be easily attached to the elastic belt with ordinary double-sided tape. At the time of wearing on the human body, since the marker portion can be easily attached at an arbitrary position on the belt after the belt is first attached, the position hardly moves during the attaching operation. It is lightweight and it is difficult for the marker to come off even when it comes into contact with the human body.

(7) Two types of color markers FIG. 6 is a diagram illustrating an example of a color marker according to the present embodiment. Two types of color markers are preferably prepared. In one type, the color marker is fixed in advance to a stretchable belt with a hook-and-loop fastener. For example, as shown in the color markers 1, 6, and 7 in FIG. By wrapping a belt with a color marker around a body part that is difficult to reach, the color marker is accurately attached to the designated body part.
In the other type, the color marker and the belt are not fixed in advance, and when the marker is mounted, the belt is first wound around the body part, and then the color marker is bonded to the belt with a double-sided tape or the like. In FIG. 1, colors other than color markers 1, 6, and 7 are applicable.
It should be noted that in the measurement of sword martial arts and sports (kendo, short kendo, bayonet, naginata, fencing, etc.), weapons such as bamboo swords do not have to be color markers attached to the body. You can just wrap the color tape around your weapon.

  In other words, in the martial arts motion analysis method of the present embodiment, the color marker includes a first type color marker that is fixed in advance to the stretchable belt and a belt mounting portion that is previously attached to the athlete's body. There is a second type of color marker that is attached during measurement.

Next, the implementation procedure of the martial arts movement analysis method of this embodiment is demonstrated.
FIG. 7 is a diagram illustrating an example of an angle of view of the imaging unit (camera) of the present embodiment.
(Procedure 1) The camera is installed at the position shown in FIG. FIG. 7 shows an example of short kendo movement measurement. A high-measured person installs a camera at a position where neither a body part nor a bamboo sword protrudes from an image by a single hitting action. As a camera, a normal smartphone is used and a high-speed imaging function (motion video) is used.

FIG. 8 is a diagram illustrating an operation example of calibration before measurement according to the present embodiment.
(Procedure 2) In order to perform conversion from the image coordinate system to the physical coordinate system, the measurement subject performs calibration operation prior to measurement. Specifically, the following operations a to e are performed, the user is stopped and images are taken.
Action a: The posture is “careful” in the horizontal direction.
Action b: “Face Forward” posture with only one arm close to the camera.
Operation c: One arm extended horizontally is bent 90 degrees vertically from the elbow.
Action d: After “straight”, one leg close to the camera is bent horizontally at the thigh and the lower leg is lowered vertically.
Action e: After “fixed”, the camera faces backwards and is in a “careful” position.
By photographing the calibration operation, even if the color marker is not attached to the center of the joint, the joint can be imaged at 90 degrees and 180 degrees, so that the joint angle can be appropriately interpolated thereafter.

The purpose of the pre-measurement calibration is, first of all, because there is no guarantee that the color marker is placed at the center of joint rotation of the body, so a known joint angle such as 90 degrees, 120 degrees, 150 degrees, 180 degrees, for example, The output value is corrected so that the joint angle value calculated by the color marker at that time becomes a known angle.
The second purpose of the pre-measurement calibration is that the estimated value may be output differently even if the user is taking a specific posture due to the characteristics of the body posture such as the back of the cat. When the user on the back is standing vertically, the estimated value is corrected so as to output 90 degrees.

  (Procedure 3) Have the person to be measured perform a measurement operation and take an image with a camera.

(Procedure 4) Color markers are extracted by the processing procedure shown in FIG.
FIG. 9 is a diagram illustrating an example of a processing procedure of the martial arts motion analysis method of the present embodiment.
(Step S10) The position of the color marker in the image is designated.
(Step S20) The captured image is converted from the RGB color system to the HSV color system.
(Step S30) The HSV value of each color marker color is stored.
(Step S40) The upper and lower limits of the HSV value are set.
(Step S50) The barycentric pixel of each color marker is recorded as the marker position.
(Step S60) A human body joint angle and physical coordinates are estimated.
(Step S70) It is determined whether it is the last frame.
(Step S80) The RGB color system is converted to the HSV color system in the next frame.
(Step S90) Pixels within the set value range are extracted near the marker position in the previous frame.
(Step S100) Each center-of-gravity pixel is recorded as a marker position.

  (Procedure 5) An object having a known physical length, such as a music scale or a ruler, is included in the captured image in advance, and the relationship between the number of pixels and the physical distance is obtained. Thereby, conversion from the image coordinate system to the physical coordinate system is performed.

Based on (Step 6) (1), horizontal vector a ₀ and the vector a ₁ of two color markers shown in FIG. 5 from an angle, to estimate the joint angle.

Alternatively, based on Equation (2), the joint angle is estimated from the angle formed by the _two vectors a ₂ and a _{3 of the} three adjacent color markers shown in FIG.

  The color marker to be used may be a spherical reflection marker as in the best embodiment, or a small light source such as an LED.

As described above, according to the martial arts motion analysis method of the present embodiment, the following effects can be obtained.
(1) Realize high-precision motion analysis even when martial arts and sports athletes wear clothing of various colors or when practicing or playing games in various lighting environments.
(2) Background can be removed from captured images by simple threshold settings for the color system, and markers can be stably extracted even in dimly lit imaging environments or in direct sunlight. It becomes.
(3) With a small number of markers, the main joint angles of the human body can be estimated.
(4) It is possible to measure the three-dimensional movement of the human body with only one camera, and no special camera is required.
(5) A color marker that is inexpensive and difficult to be detached from the human body can be used.

In other words, according to the martial arts motion analysis method of the present embodiment, the motion of the martial arts player can be measured with high accuracy.
Specifically, the martial arts motion analysis method of this embodiment arranges color markers having a maximum of four types of colors on the human body according to a predetermined rule, so that the person to be measured wears any color. Even in this case, the marker should not be shielded.
Also, the martial arts motion analysis method of the present embodiment converts an image captured by a camera from an RGB color system to an HSV color system so that, for example, the illumination is dark and part of the marker is difficult to see. Even in the environment, only a color marker can be extracted with high accuracy by simple threshold setting.
Furthermore, the martial arts motion analysis method of the present embodiment can perform highly accurate motion measurement with a relatively small number of markers by attaching four or less types of color markers to a predetermined body part.
In the martial arts motion analysis method of this embodiment, the sagittal plane including the upper body twist (rotation about the y-axis) is obtained by one camera by making the color marker mounting position generally symmetrical with respect to the human body. Enables three-dimensional motion measurement in the (y-axis direction).
In the martial arts motion analysis method of the present embodiment, a reflective tape of four colors or less is wound around a foamed sphere, and this is adhered to a base such as a cap of a plastic bottle. Since it is attached to the human body with an elastic belt, it is a very inexpensive marker. In addition, since the main body is lightweight and the pedestal is flat, it can be easily attached to the belt with double-sided tape, so it can be attached to any position on the belt. In addition, the marker is unlikely to come off even if it comes into contact with the human body.

Further, according to the martial arts motion analysis method of the present embodiment,
(1) The difference in movement of martial arts and sports athletes can be achieved with just 2-4 color markers, elastic belts with hook-and-loop fasteners, smartphone cameras that everyone has, and lightweight apps. It can be quantified.
(2) Efficient single practice / single practice.
(3) You can improve the competition without a leader.
(4) For example, in the case of short kendo, it becomes possible to quantify the proficiency level of competition as shown in FIGS.
FIG. 10 is a diagram illustrating an example of the analysis result of the center of gravity of the body by the martial arts motion analysis method of the present embodiment.
FIG. 11 is a diagram illustrating an example of the analysis result of the upper body movement by the martial arts motion analysis method of the present embodiment.
FIG. 12 is a diagram illustrating an example of the analysis result of the time required for hitting by the martial arts motion analysis method of the present embodiment.
FIG. 13 is a diagram illustrating an example of an analysis result of a crossing foot attracting time according to the martial arts motion analysis method of the present embodiment.
FIG. 14 is a diagram showing an example of the analysis result of the angle of the lower leg when stepped on by the martial arts motion analysis method of the present embodiment.
FIG. 15 is a diagram illustrating an example of the analysis result of the jump distance (the distance from the left foot to the left foot) by the martial arts motion analysis method of the present embodiment.
FIG. 16 is a diagram illustrating an example of the analysis result of the head movement by the martial arts motion analysis method of the present embodiment.
(5) By obtaining a database of many people using the present invention, a “computer trainer”, a “martial arts app”, and the like can be realized.
(6) Not only sword martial arts such as kendo, short kendo, gun kendo, naginata, fencing, but also sports with a focus on sagittal movements such as golf, It can be used to improve skills based on it.
(7) It can be applied to the quantification of usability of cosmetics, etc., by analyzing the operation of eyeliner and mascara.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and appropriate modifications may be made without departing from the spirit of the present invention. it can.

  Each of the above devices has a computer inside. The process of each device described above is stored in a computer-readable recording medium in the form of a program, and the above-described processing is performed by the computer reading and executing the program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

The program may be for realizing a part of the functions described above.
Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

  DESCRIPTION OF SYMBOLS 1-19 ... Color marker, A ... Area | region, 100 ... Small ball which wound light reflection tape, 200 ... Base, 300 ... Elastic belt with hook-and-loop fastener

Claims (5)

A martial arts motion analysis method for performing motion analysis of the athlete regardless of the color of the clothing or the lighting environment by capturing an image of the athlete's body on which color markers of four colors or less are attached. An imaging step of imaging an athlete's body equipped with four or less color markers and outputting an RGB color system image;
A conversion step of converting the color system of the video output in the imaging step from the RGB color system to a color system including hue, saturation, and brightness;
A background removal step of removing a background included in the video by setting a threshold for the video in which the color system is converted in the conversion step;
A martial arts motion analysis method comprising: The mounting position where the color marker is mounted on the athlete's body is predetermined,
The martial arts movement analysis method according to claim 2, further comprising: a joint angle estimation step of estimating a joint angle of the athlete based on the video imaged in the imaging step. The martial arts motion analysis method according to claim 2 or 3, wherein in the imaging step, the video is captured by a single camera. The color marker includes a first type of color marker that is fixed in advance to the stretchable belt and a second type of color that is attached to the belt mounting part that is previously attached to the athlete's body at the time of measurement. The martial arts movement analysis method according to any one of claims 2 to 4, wherein there is a marker.

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