JP6700546B2 - Load detection method, load detection device, and load detection program - Google Patents

Description

  The present invention relates to a load detection method, a load detection device, and a load detection program.

Back pain is known as one of occupational diseases. For example, low back pain is said to occur when a heavy load is lifted and a sudden force is applied to the intervertebral disc and muscles to damage them.
Further, a technique for measuring a load applied to a specific part of the human body has been proposed. For example, based on the information detected by the angle sensor mounted on the trunk of the worker and the load sensor mounted on the sole of the worker, a low back pain prevention device that calculates the load applied to the lumbar region has been proposed. There is. In addition, a technique is proposed in which a 3-axis accelerometer is attached to the knee and the heel to measure the load applied to the knee and the heel from the impulse calculated based on the acceleration measured from the 3-axis accelerometer. Has been done.

JP2012-183291A JP, 2012-183294, A

The above technique has a problem in that it is only possible to measure the load applied to specific parts of the human body such as the waist, knees, and heels.
In one aspect, an object of the present invention is to provide a load detection method, a load detection device, and a load detection program capable of detecting the presence or absence of a load on any part of the human body.

  In one aspect, a load detection method is provided. In this load detection method, the computer calculates a first angle indicating the inclination of a part of the human body based on the first measurement result by the acceleration sensor attached to the human body, and the computer calculates another angle different from the acceleration sensor. A second angle indicating the inclination of the body part is calculated based on the second measurement result of the human body by the sensor, and the presence or absence of the load applied to the body part is determined based on the difference between the first angle and the second angle. To do.

  Further, in one aspect, a load detection device is provided. This load detection device has a first calculation unit, a second calculation unit, and a determination unit. The first calculation unit calculates a first angle indicating the inclination of the part of the human body based on the first measurement result by the acceleration sensor attached to the human body. The second calculation unit calculates the second angle indicating the inclination of the body part based on the second measurement result of the human body by another sensor of a type different from the acceleration sensor. The determination unit determines whether or not there is a load applied to the site based on the difference between the first angle and the second angle.

  Further, in one aspect, a load detection program is provided. This load detection program calculates, on the computer, a first angle indicating the inclination of a part of the human body based on the first measurement result by the acceleration sensor attached to the human body, and the load sensor is of another type different from the acceleration sensor. A second angle indicating the inclination of the body part is calculated based on the second measurement result of the human body by the sensor, and the presence or absence of the load applied to the body part is determined based on the difference between the first angle and the second angle. Yes, execute the process.

  In one aspect, the presence or absence of a load can be detected at any part of the human body.

It is a figure which shows the load detection apparatus of 1st Embodiment. It is a figure which shows the load detection system of 2nd Embodiment. It is a figure which shows the hardware example of a load detection apparatus. It is a figure which shows the state which has attached|subjected the acceleration sensor and the reflection marker to a test subject. It is a figure which shows the function example of a load detection apparatus. It is a figure which shows about calculation of a sensor angle. It is a figure which shows the outline of a load determination process. It is a figure showing about processing which specifies a generation place of load. It is a flow chart which shows an example of load judgment processing. It is a figure shown about calculation of the direction and magnitude of load. It is a figure for demonstrating the 1st method of converting into a two-dimensional coordinate. It is a figure for demonstrating the 2nd method of transforming into two-dimensional coordinate. It is a figure which shows the example of a function of the load detection apparatus of 3rd Embodiment.

Hereinafter, the present embodiment will be described with reference to the drawings.
[First Embodiment]
FIG. 1 is a diagram showing a load detection device according to the first embodiment. The load detection device 1 includes a first calculation unit 1a, a second calculation unit 1b, a determination unit 1c, and a calculation unit 1d. The first calculation unit 1a, the second calculation unit 1b, the determination unit 1c, and the calculation unit 1d include a CPU (Central Processing Unit), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), and an FPGA (Field Programmable Gate). Array) and the like. The “processor” may also include a set of multiple processors (multiprocessor).

  The load detection device 1 is a device that detects the presence or absence of a load applied to the body part 2a of the subject 2. The part 2a can be an arbitrary part of the body of the subject 2, such as the back or shoulder of the subject 2.

  The subject 2 wears the acceleration sensor 3. The acceleration sensor 3 is, for example, a triaxial acceleration sensor. In this case, the acceleration sensor 3 measures acceleration values in the three axis directions. Further, for example, the acceleration sensor 3 may be attached to the part 2a, or the acceleration sensor 3 may be attached to a plurality of places around the part 2a. The load detection device 1 can acquire the measurement result of the acceleration sensor 3.

  Further, the load detection device 1 can acquire the measurement result of the body of the subject 2 by motion capture. In FIG. 1, an optical motion capture system 5 including an imaging device 4 and a calculation unit 1d is illustrated. The imaging device 4 images the subject 2. The calculation unit 1d outputs the measurement result regarding the body of the subject 2 based on the measurement value obtained by the imaging device 4.

  For example, a plurality of markers are attached to the site 2a of the subject 2 and its surroundings, and the imaging device 4 images these markers. Note that each marker may be imaged from different positions by the plurality of imaging devices 4. The calculation unit 1d measures the position of each marker in the three-dimensional space based on the imaging result of the imaging device 4.

  The function of the calculation unit 1d may be implemented in a device other than the load detection device 1. Further, as the image pickup device 4, for example, a device for picking up a visible region, a device for picking up an infrared region, or a composite device combining these may be used. Further, the motion capture system 5 is not limited to the optical type, but a system using another method such as a magnetic type using a magnetic sensor can also be used.

  The first calculation unit 1a acquires the measurement result of the acceleration sensor 3. The second calculator 1b acquires the measurement result by the motion capture system 5. These measurement results are measured at the same time. The first calculation unit 1a and the second calculation unit 1b may obtain these measurement results in real time, or they may be obtained from the measurement results stored in a storage device (not shown). The measurement result of may be acquired.

  The first calculator 1a calculates a first angle indicating the inclination of the part 2a based on the measurement result of the acceleration sensor 3. For example, the first calculator 1a calculates a first angle based on the direction of gravity based on the measurement values of the x-direction, the y-direction, and the z-direction measured by the acceleration sensor 3. The second calculator 1b calculates a second angle indicating the inclination of the part 2a based on the measurement result by the motion capture system 5. The first angle and the second angle may be angles in a three-dimensional space or may be angles on a predetermined reference plane.

  Here, when the part 2a is not moving, the measurement result of the acceleration sensor 3 includes only the gravitational acceleration component and does not include the motion acceleration component. In such a state, an error is unlikely to occur in the first angle based on the measurement result of the acceleration sensor 3. However, when the part 2a moves with acceleration, the measurement result of the acceleration sensor 3 includes the motion acceleration component in addition to the gravity acceleration component. In such a state, an error occurs due to the motion acceleration component at the first angle.

  On the other hand, an error is unlikely to occur at the second angle based on the measurement result by the motion capture system 5, regardless of whether or not the part 2a is moving. Therefore, when the difference between the first angle and the second angle is not 0, it is estimated that the part 2a is moving and the error due to the motion acceleration component occurs in the first angle.

  The determining unit 1c determines whether or not the load is applied to the portion 2a by using the error that may occur in the first angle. That is, the determination unit 1c determines the presence/absence of the load applied to the part 2a based on the difference between the first angle and the second angle. When there is a difference between the first angle and the second angle, the cause is due to the motion acceleration component. The second law of motion (F=ma: F is force, m is mass, a is motion acceleration) because the motion acceleration is applied to the part 2a where there is a difference between the first angle and the second angle. Therefore, it can be said that the portion 2a is under load. In this way, the determination unit 1c determines that the part 2a is under load when there is a difference between the first angle and the second angle. The part 2a that is determined to be loaded may be limited to a specific area of the body or may be a wide area.

  According to the first embodiment described above, the load detection device 1 can accurately determine the presence/absence of the load applied to the part 2a by using the angle calculation error based on the acceleration sensor 3. Further, the inclination based on the measurement value of the acceleration sensor 3 and the inclination based on the measurement value by the motion capture can be detected at any part of the body of the subject 2. Therefore, the load detecting device 1 can determine the presence/absence of a load in any part of the body of the subject 2 as long as the part can detect the inclination in this way.

  Note that, in the above example, the second angle is calculated based on the measurement result by the motion capture system 5, but the second angle may be calculated based on the measurement result measured by a sensor such as an inclinometer. ..

[Second Embodiment]
FIG. 2 is a diagram showing a load detection system according to the second embodiment. The load detection system includes a load detection device 100, acceleration sensors 200a, 200b,... And cameras 300a to 300d. The load detection device 100, the acceleration sensors 200a, 200b,... And the cameras 300a to 300d are connected via a network. The number of acceleration sensors is not limited to two. The number of cameras is not limited to four.

  The load detection device 100 is an example of the load detection device 1 of FIG. 1, the acceleration sensors 200a, 200b,... Are examples of the acceleration sensor 3 of FIG. 1, and the cameras 300a to 300d are the imaging devices of FIG. It is an example of the device 4.

  The load detection device 100 is a device that analyzes the information acquired from the acceleration sensors 200a, 200b,... And the cameras 300a to 300d to detect the load applied to the body part.

  The acceleration sensors 200a, 200b,... Are so-called “wearable sensors” worn on the subject. Further, the acceleration sensors 200a, 200b,... Are three-axis acceleration sensors that detect acceleration in the three-axis directions based on the gravity direction. Note that how the three axis directions are defined will be described later.

  An optical motion capture system is constructed by the load detection device 100 and the cameras 300a to 300d. In the optical motion capture system, a subject is equipped with a reflective marker (hereinafter, also referred to as a marker). The cameras 300a to 300d capture images of the light reflected by the reflective marker by applying light to the reflective marker. The load detection device 100 calculates the position (three-dimensional coordinate) of the reflection marker in the three-dimensional space using the principle of triangulation based on the information captured by the cameras 300a to 300d.

  FIG. 3 is a diagram illustrating a hardware example of the load detection device. The load detection device 100 includes a processor 101, a RAM (Random Access Memory) 102, an HDD (Hard Disk Drive) 103, an image signal processing unit 104, an input signal processing unit 105, a reading device 106, and communication interfaces 107 and 107a.

  The processor 101 controls the entire load detection device 100. The processor 101 may be a multiprocessor including a plurality of processing elements. The processor 101 is, for example, a CPU, DSP, ASIC, FPGA, or the like. Moreover, the processor 101 may be a combination of two or more elements of a CPU, a DSP, an ASIC, an FPGA, and the like.

  The RAM 102 is a main storage device of the load detection device 100. The RAM 102 temporarily stores at least a part of an OS program and an application program executed by the processor 101. The RAM 102 also stores various data used for processing by the processor 101.

  The HDD 103 is an auxiliary storage device of the load detection device 100. The HDD 103 magnetically writes and reads data with respect to a built-in magnetic disk. The HDD 103 stores the OS program, application programs, and various data. The load detection device 100 may include another type of auxiliary storage device such as a flash memory or an SSD (Solid State Drive), or may include a plurality of auxiliary storage devices.

  The image signal processing unit 104 outputs an image to the display 11 connected to the load detection device 100 according to an instruction from the processor 101. As the display 11, various displays such as a CRT (Cathode Ray Tube) display, a liquid crystal display (LCD: Liquid Crystal Display), and an organic EL (Electro-Luminescence) display can be used. The load detection device 100 may integrally include the display 11.

  The input signal processing unit 105 acquires an input signal from the input device 12 connected to the load detection device 100 and outputs the input signal to the processor 101. As the input device 12, various input devices such as a pointing device such as a mouse and a touch panel and a keyboard can be used. A plurality of types of input devices may be connected to the load detection device 100. The load detection device 100 may integrally include the input device 12.

  The reading device 106 is a device that reads a program or data recorded in the portable recording medium 13. As the recording medium 13, for example, a magnetic disk such as a flexible disk (FD: Flexible Disk) or HDD, an optical disk such as a CD (Compact Disc) or a DVD (Digital Versatile Disc), or a magneto-optical disk (MO: Magneto-Optical disk). Can be used. Further, as the recording medium 13, for example, a non-volatile semiconductor memory such as a flash memory card can be used. The reading device 106 stores the program or data read from the recording medium 13 in the RAM 102 or the HDD 103 according to an instruction from the processor 101, for example.

  The communication interface 107 communicates with the acceleration sensors 200a, 200b,... Via the network. The communication interface 107a communicates with the cameras 300a to 300d via the network. The communication interfaces 107 and 107a may be wired communication interfaces or wireless communication interfaces.

  FIG. 4 is a diagram showing a state in which the subject is wearing the acceleration sensor and the reflection marker. On the back of the subject 900, an acceleration sensor and a reflection marker are alternately mounted on a straight line along the spine. For example, the acceleration sensor 200a, the reflection marker 400a, the acceleration sensor 200b, and the reflection marker 400b are sequentially mounted on the back of the subject 900 from the upper side. The reflective markers are attached at predetermined intervals. For example, the predetermined interval is 6 cm. Further, at least one reflection marker may be attached to the boundary of each of the five regions such as the lumbar spine. The acceleration sensor is mounted at an intermediate position between the reflective markers on both sides. As will be described later, in the present embodiment, the position of the reflection marker is the target site where the presence or absence of load is detected.

  The subject 900 performs some operation while wearing the acceleration sensor and the reflection marker. The load detection device 100 acquires, via the network, the measurement values measured by the respective acceleration sensors mounted on the back of the subject 900 who is operating.

  Although the acceleration sensor and the reflection marker are attached to the back in FIG. 4, they may be attached to other parts. For example, the acceleration sensor and the reflection marker may be alternately mounted on a straight line along the flank.

  FIG. 5 is a diagram illustrating an example of functions of the load detection device. The load detection device 100 includes an acquisition unit 110, a sensor angle calculation unit 120, a motion capture processing unit 130, a coordinate conversion unit 140, a marker angle calculation unit 150, a load determination unit 160, a load information calculation unit 170, and a history storage unit 180. ..

  The acquisition unit 110, the sensor angle calculation unit 120, the motion capture processing unit 130, the coordinate conversion unit 140, the marker angle calculation unit 150, the load determination unit 160, and the load information calculation unit 170 are, for example, modules of a program executed by the processor 101. To be implemented. The history storage unit 180 is implemented as a storage area secured in the RAM 102 or the HDD 103, for example.

  The acquisition unit 110 acquires the measurement values measured at the same time from the acceleration sensor 200 and the camera 300. The acceleration sensor 200 of FIG. 5 is a combination of the acceleration sensors 200a, 200b,... The camera 300 of FIG. 5 shows the cameras 300a to 300d collectively.

  The acquisition unit 110 does not have to acquire measurement values from the acceleration sensor 200 and the camera 300 in real time. For example, once the measurement values output from the acceleration sensor 200 and the camera 300 are stored in the HDD 103, the acquisition unit 110 acquires the measurement values of the acceleration sensor 200 and the camera 300 measured from the HDD 103 at the same time. To do.

  The measurement values acquired by the acquisition unit 110 from the acceleration sensor 200 are accelerations in the x-direction, the y-direction, and the z-direction for each acceleration sensor. The information acquired by the acquisition unit 110 from the camera 300 is information obtained by imaging each reflection marker.

  The sensor angle calculation unit 120 calculates, based on the measurement value measured by each acceleration sensor, the tilt angle of each of the left and right directions and the front-rear direction of the place where each acceleration sensor is mounted when viewed from the subject. Hereinafter, the inclination angle of the mounting location of the acceleration sensor may be referred to as a “sensor angle”. In the present embodiment, the sensor angle indicates the inclination angle of the back at the position where the acceleration sensor is mounted, and when the sensor is stationary, this is equivalent to the inclination angle of the acceleration sensor itself.

  When the acceleration sensor is attached to the subject in a tilted state, the sensor angle calculation unit 120 calculates the sensor angle by correcting the tilt angle in the left-right direction. When the acceleration sensor is not attached to the subject in a tilted state, the sensor angle calculation unit 120 sets the calculated tilt angle as the sensor angle as it is.

  The motion capture processing unit 130 calculates the position (three-dimensional coordinate) of each reflection marker using the principle of triangulation based on the information acquired from the camera 300. Note that, hereinafter, the position of the reflection marker may be simply referred to as “marker position”.

  The coordinate conversion unit 140 converts the three-dimensional coordinates of each marker position calculated by the motion capture processing unit 130 into two-dimensional coordinates. Specifically, the coordinate conversion unit 140 converts the three-dimensional coordinates of the marker position into two-dimensional coordinates on a vertical plane along the front-back direction of the subject and two-dimensional coordinates on a horizontal plane along the left-right direction of the subject. Convert to and.

  The marker angle calculation unit 150 individually calculates the tilt angle of the marker position from both the sensor angle calculated by the sensor angle calculation unit 120 and the two-dimensional coordinate of the marker position calculated by the coordinate conversion unit 140. Hereinafter, the tilt angle of the marker position may be referred to as a “marker angle”. In the present embodiment, the marker angle indicates the inclination angle of the back at the position where the reflection marker is attached, which is equivalent to the inclination angle of the reflection marker itself.

  The marker angle calculation unit 150 interpolates the sensor angle and calculates the angle of the marker position (marker angle). Specifically, since the reflection marker exists between the two acceleration sensors, the marker angle calculation unit 150 regards the average of the sensor angles at the positions of the two acceleration sensors as the marker position angle, for example.

  In addition, the marker angle calculation unit 150 calculates the angle of the marker position (marker angle) based on the two-dimensional coordinates of each marker position. For example, the marker angle calculation unit 150 calculates the marker angle from the two-dimensional coordinates of the reflection marker at the marker position to be calculated and the reflection marker adjacent to the reflection marker.

  In some cases, the inclination of each marker position can be directly calculated by the motion capture processing unit 130. In this case, for example, the marker angle calculation unit 150 separates the calculated inclination of the marker position into each component in the left-right direction and the front-back direction. The marker angle calculation unit 150 outputs each of the separated components instead of the inclination in the left-right direction and the front-back direction based on the above two-dimensional coordinates.

  The load determination unit 160 determines, for each marker position, whether or not there is a difference between the marker angle calculated based on the sensor angle and the marker angle calculated based on the two-dimensional coordinates. If there is a difference in angle, the cause is due to the former marker angle error caused by the motion acceleration component. Since the motion acceleration is applied to the marker position having a difference in angle, a load is applied to the marker position from the second law of motion (F=ma: F is force, m is mass, and a is motion acceleration). Can be said. Therefore, the load determination unit 160 determines that the marker position having the difference in angle is the position where the load is applied. The load determination unit 160 stores, in the history storage unit 180, information (marker number or the like) on the place where the load is applied. If there is no difference between the angles, the load determining unit 160 determines that the load is not applied to the corresponding marker position.

  Although the load measurement point is the marker position in the present embodiment, it may be the sensor position. Specifically, the marker angle calculation unit 150 interpolates the marker angle calculated based on the two-dimensional coordinates of each marker position to calculate the angle at the sensor position. Then, it may be determined for each sensor position whether or not there is a difference between the sensor angle and the sensor angle calculated based on the marker angle.

  The load information calculation unit 170 calculates the direction and magnitude of the load for the marker position that is determined to be loaded. Since the direction in which the load is applied is the direction of the motion acceleration, the load information calculation unit 170 calculates the direction and magnitude of the motion acceleration based on the measurement value of the acceleration sensor mounted around the marker position. The direction of the motion acceleration is output as the direction of the load applied to the marker position. Further, from the second law of motion, the magnitude of motion acceleration is output as an index indicating the magnitude of load.

  In addition, the load information calculation unit 170 determines the magnitude of the load with respect to the load at the time of past measurement, based on the ratio of the magnitude of the motion acceleration measured at the present time to the magnitude of the motion acceleration measured at the same marker position in the past. It may be output as a relative size. In this case, the load information calculation unit 170 acquires the exercise acceleration measured in the past from the history storage unit 180.

  The history storage unit 180 stores information on the load measurement result at each marker position. For example, the information includes a marker number, presence/absence of load, direction of load, motion acceleration, or magnitude of load.

  It should be noted that the load detection device 100 measures the load at each sensor position at each measurement time set at regular intervals. The history storage unit 180 stores information on the load measurement result at each measurement time. The accumulated information is used when the load information calculation unit 170 calculates the magnitude of the load as a relative value.

FIG. 6 is a diagram showing calculation of the sensor angle. The upper right side of FIG. 6 shows that the acceleration sensor 200a is attached to the back of the subject 900.
As shown on the upper left side of FIG. 6, the acceleration sensor 200a measures acceleration in each of the x direction, the y direction, and the z direction. The x direction, the y direction, and the z direction are detected as relative directions with respect to the direction of the gravity g.

  The x direction indicates a direction orthogonal to the front-back direction with respect to the back of the subject 900, and the y direction indicates a direction orthogonal to the left-right direction with respect to the back of the subject 900. In the present embodiment, as shown in FIG. 6, the rearward direction of the subject 900 is the positive direction for the x direction, and the rightward direction of the subject 900 is the positive direction for the y direction. The z direction indicates the direction along the back of the subject 900. In the present embodiment, as shown in FIG. 6, the upper direction of subject 900 is the positive direction in the z direction.

The sensor angle calculation unit 120 calculates the sensor angle based on the above-mentioned measurement value obtained by the acceleration sensor. The sensor angle of the i-th sensor position from above, the sensor angle theta _IS01 in the left-and-right direction of the subject 900, and a sensor angle theta _IS02 respect the longitudinal direction of the subject 900 is calculated. Note that i is an integer of 1 or more, and its maximum value is the number of acceleration sensors.

Specifically, as shown in the lower side of FIG. 6, the sensor angle θ _iS02 with respect to the front-back direction is calculated as an angle with respect to the vertically upward direction on a vertical plane including the front-back direction of the subject 900. Although not shown, the sensor angle θ _iS01 with respect to the left-right direction is calculated as an angle with respect to the vertically upward direction on a vertical plane including the left-right direction of the subject 900. If the mounting location of the acceleration sensor is not tilted with respect to the left-right direction, the angle shift with respect to the left-right direction is 0°.

  FIG. 7 is a diagram showing an outline of the load determination processing. FIG. 7I shows an example of the sensor position and the marker position. As shown in FIG. 7(i), the subject 900 is alternately equipped with the acceleration sensor and the reflection marker. In the present embodiment, the acceleration sensor and the reflection marker are attached along the spine.

  The sensor angle calculation unit 120 calculates the tilt angle (sensor angle) at each sensor position based on the measurement result obtained from the acceleration sensor corresponding to each sensor position. FIG. 7(ii) shows that the sensor angle is calculated based on the measurement value measured by the acceleration sensor at each sensor position.

Since the load measurement point is the marker position, the marker angle calculation unit 150 calculates the marker angle at each marker position by interpolation calculation based on the calculated sensor angle at each sensor position. FIG. 7(iii) shows that the marker angle at the marker position is calculated by performing interpolation calculation of the sensor angle. The marker angle is, for example, an angle obtained by averaging the respective sensor angles at the positions of the two acceleration sensors existing above and below the corresponding reflection marker. In practice, as a marker angle of the i-th marker position from the top, the marker angle theta _iS1 in the left-and-right direction, and the marker angle theta _IS2 for the longitudinal direction it is calculated.

In addition to this, the marker angle calculation unit 150 calculates the marker angle at each marker position using the two-dimensional coordinates of each marker position based on the measurement result by motion capture. FIG. 7( v) shows only the position of the reflection marker attached to the subject 900. FIG. 7( iv) shows that the marker angle calculation unit 150 calculates the marker angle at the marker position based on the two-dimensional coordinates of each marker position. In practice, as a marker angle of the i-th marker position from the top, the marker angle theta _IM1 in the left-and-right direction, and the marker angle theta _iM2 against the longitudinal direction is calculated.

  The load determination unit 160 compares the marker angle calculated as shown in FIG. 7(iii) with the marker angle at the same marker position calculated as shown in FIG. 7(iv), and whether there is a difference in angle. Determine whether or not. The load determination unit 160 determines that a marker position having a difference in marker angle is a position where a load is applied.

FIG. 8 is a diagram illustrating a process of identifying a load occurrence point. In FIG. 8, only the marker angle with respect to the front-back direction is shown as an example.
Reflection markers 400a, 400b, 400c, and 400d are attached to the back of the subject in order from the top. FIG. _8A shows the marker angle θ _iS2 calculated from the sensor angle. For example, the marker angle with respect to the front-back direction at the position of the first reflective marker 400a from the top is expressed as “θ _1S2 ”. FIG. _8B shows the marker angle θ _iM2 calculated based on the two-dimensional coordinates. For example, the marker angle with respect to the front-back direction at the position of the first reflective marker 400a from the top is expressed as “θ _1M2 ”.

Here, when a load is applied to the i-th marker position, the marker angle θ _iS2 based on the sensor angle includes an error caused by the movement. This error occurs because the (virtual) measurement value by the acceleration sensor at the i-th marker position includes not only the gravity acceleration component but also the motion acceleration component. On the other hand, the marker angle θ _iM2 based on the two-dimensional coordinates for the i-th marker position has no error due to whether the marker position is moving.

Therefore, the load determining unit 160 calculates the difference between the marker angle theta _IS2 and the marker angle theta _iM2 at the same marker position. If the difference is not 0, it can be estimated that a load is applied to the i-th marker position. For example, the load determining unit 160 calculates the difference between the first position of the reflective markers 400a of the marker angle theta _1S2 and the marker angle theta _1M2. When the calculated difference is not 0, the load determination unit 160 identifies the position of the reflection marker 400a as the place where the load is applied.

  In this way, the load determination unit 160 identifies a marker position where the difference between the marker angles is not 0 as the point where the load is applied. If there is no difference between the marker angles, the load determination unit 160 determines that the corresponding marker position is not loaded.

Next, details of the processing of the load detection device 100 will be described using a flowchart.
FIG. 9 is a flowchart showing an example of the load determination process. Hereinafter, the process illustrated in FIG. 9 will be described in order of step number.

  (S11) The acquisition unit 110 acquires the measurement values in the x direction, the y direction, and the z direction measured by each acceleration sensor at time t. In addition, the acquisition unit 110 acquires information that each camera captured the reflection marker at time t.

(S12) The sensor angle calculation unit 120 calculates the tilt angle in each of the left-right direction and the front-back direction with respect to the sensor position where each acceleration sensor is attached, based on the measurement value of each acceleration sensor acquired in step S11. The calculated tilt angle is represented as an angle with the direction of gravity as a reference. Inclination angle phi _iS1 in the horizontal direction in the i-th sensor position from above, the front-rear direction of the inclination angle phi _IS2, the following formula, respectively (1-1) is calculated according to (1-2). It should be noted that X _iS , Y _iS , and Z _iS represent measured values of acceleration in the x direction, y direction, and z direction by the i-th acceleration sensor, respectively.

(S13) The sensor angle calculation unit 120 calculates the sensor angles θ _iS01 and θ _iS02 by correcting the tilt angles φ _iS1 and φ _iS2 . This correction is for reducing an error caused when the acceleration sensor is attached to the subject in a tilted state. Here, assuming that the acceleration sensor is tilted in the y direction, that is, the acceleration sensor is mounted in a state where the acceleration sensor is tilted in the left-right direction when viewed from the rear side of the subject, the left-right tilt angle φ _iS1 To correct.

If the left and right inclination angles of the acceleration sensor in the reference posture (that is, when the acceleration sensor is worn in a state in which the subject is not tilted) are represented by φ _i01 , the sensor angles θ _iS01 and θ _iS02 in the left and right directions are as _follows : , Is calculated according to the following equation (2).
(Θ _iS01 , θ _iS02 )=(φ _iS1 −φ _i01 , φ _iS2 ) (2)
Since it is assumed that the sensor plane and the surface in the left-right direction are parallel, the sensor angle θ _iS02 and the inclination angle φ _iS2 are the same angle.

(S14) The marker angle calculation unit 150 interpolates the sensor angle and calculates the marker angles θ _iS1 and θ _iS2 in the left-right direction and the front-back direction at each marker position. Marker angles θ _iS1 , θ _i
S2 is calculated according to the following equations (3-1) and (3-2).
θ _iS1 = (θ _iS01 + θ _(i+1)S01 )/2 (3-1)
θ _iS2 = (θ _iS02 + θ _(i+1)S02 )/2 (3-2)
In this way, the marker angle at the marker position is calculated based on the sensor angles at the two sensor positions. For example, when i=1, the marker angle calculation unit 150 determines that the acceleration sensor 2
The marker angle at the position of the reflection marker 400a is calculated using the sensor angles at the positions of 00a and 200b. Since the marker angle is calculated from the two sensor angles, the number of reflection markers is one less than the number of acceleration sensors.

As another method, the marker angle calculation unit 150 may approximate the change in each sensor angle by a function and calculate the marker angles θ _iS1 and θ _iS2 using the function.
For example, the marker angle calculation unit 150 approximates the relationship between the sensor position and the sensor angle in each of the left-right direction and the front-back direction by a quadratic function, and uses the quadratic function to calculate the marker angles θ _iS1 and θ _iS2 . ..

  (S15) The motion capture processing unit 130 calculates the three-dimensional coordinates indicating the marker position using the principle of triangulation based on the information obtained by capturing the reflection marker acquired in step S11.

(S16) The coordinate conversion unit 140 converts the calculated three-dimensional coordinates of each marker position into two-dimensional coordinates corresponding to the left-right direction and the front-back direction of the subject.
The processes of steps S15 and S16 are performed as follows, for example. When taken by the camera, the subject is placed so as to face a specific direction in the three-dimensional coordinate system (marker coordinate system) defined in the motion capture. For example, in this three-dimensional coordinate system, it is assumed that the x axis and the y axis are set on the horizontal plane and the z axis is set in the vertical direction. Then, the subject is arranged so as to face the direction of the x-axis. In this case, the y-axis extends in the left-right direction of the subject.

In step S15, the three-dimensional coordinates (X _iM , Y _iM , Z _iM ) of the i-th marker position are calculated. In step S16, the coordinate converter 140, two-dimensional coordinates corresponding to the left-right direction (X _iC1, Y _iC1) as (Y _iM, Z _iM) to calculate the two-dimensional coordinates corresponding to the longitudinal direction (X _Ic2, Y (X _iM , Z _iM ) is calculated as _iC2 ).

Note that in steps S15 and S16, the method described later in FIG. 11 or 12 may be used.
(S17) The marker angle calculation unit 150 calculates the marker angles θ _iM1 and θ _iM2 of each marker position based on the two-dimensional coordinates of each marker position converted in step S16.

For example, the marker angle θ _iM2 in the front-back direction at the i-th marker position is calculated according to the following equations (4-1) and (4-2). The expression (4-1) is a calculation expression when i is 2 or more, and the expression (4-2) is a calculation expression when i=1.

As shown in Expression (4-2), the marker angle calculation unit 150 regards the marker angle at the uppermost (first) marker position as the same as the marker angle at the second marker position.
Further, the marker angle calculation unit 150 may calculate the marker angle θ _iM2 at the marker position _according to the following equations (5-1), (5-2), (5-3). The equation (5-1) is a calculation equation when i=the number of markers, the equation (5-2) is a calculation equation when 2≦i<the number of markers, and the equation (5-3) is a calculation equation when i=1.

It should be _noted that the marker angle θ _iM1 in the left-right direction at the i-th marker position is expressed by equations (4-1), (4-2), (5-1), (5-2), and (5-3). , Θ _iM2 in place of θ _iM2 , and (X _iC1 , Y _iC1 ) in place of (X _iC2 , Y _iC2 ).

(S18) The load determination unit 160 calculates the difference between the marker angle based on the sensor angle and the marker angle based on the two-dimensional coordinates for each marker position. Specifically, the load determination unit 160 calculates (θ _iS1 −θ _iM1 ) and (θ _iS2 −θ _iM2 ).

(S19) The load determination unit 160 identifies a marker position having a difference in angle as a location where a load is applied.
As an actual process, for example, the load determining unit 160 calculates the absolute value of the difference between the marker angles in the left-right direction and the front-rear direction in step S18, and calculates the calculated absolute value in step S19 as a predetermined threshold value. Compare with. The threshold value is set to a value larger than 0. The load determination unit 160 determines that the load is applied to the corresponding marker position when the absolute value of the difference exceeds the threshold value in at least one of the left-right direction and the front-back direction.

The value compared with the predetermined threshold value in step S19 may be a value considering the acceleration vector at the marker position. For example, the load determination unit 160 uses the gravity acceleration vector G _e at the marker position and the acceleration vector A _r at the marker position calculated from the sensor as “G _e ·A _r /(||G _e |||| |A _r ||)” is calculated. The acceleration vector A _r at the marker position is calculated, for example, by averaging the acceleration vectors based on the measured acceleration values at the sensor positions on both sides of the marker position. ||G _e || and ||A _r || respectively indicate the magnitude (norm) of the gravity acceleration vector G _e and the acceleration vector A _r . In step S19, the load determining unit 160 compares the marker position by comparing, for example, a value obtained by multiplying the value H by a predetermined weighting coefficient with the absolute value of the difference, and the threshold value. It is determined whether the load is applied to.

(S20) The load information calculation unit 170 calculates the direction and magnitude of the load for the marker position identified as being loaded in each step S19.
When the past information in the history storage unit 180 is referred to in order to calculate the relative magnitude of the load in step S20, the following process is further performed in step S20. The load information calculation unit 170 registers the value of the motion acceleration obtained in the process of calculating the relative magnitude of the load in the history storage unit 180 in association with the identification information indicating the marker position and the measurement time. The load information calculation unit 170 registers the values of motion acceleration for all marker positions in the history storage unit 180. The motion acceleration=0 is registered for the marker position for which it is determined that the load is not applied in step S19.

  Note that in FIG. 9 described above, the process is executed using both the left and right direction and the front-rear direction marker angle. However, for example, even if the process is executed using the left and right direction and the front-rear direction marker angle. Good. In this case, it is possible to detect the presence or absence of a load in one of the left-right direction and the front-back direction.

Here, a specific example of the process of step S20 will be described with reference to FIG.
FIG. 10 is a diagram showing calculation of the direction and magnitude of the load. First, since the direction in which the load is applied is the direction of the motion acceleration, the load information calculation unit 170 calculates the motion acceleration at the marker position. The motion acceleration is calculated based on the measurement value of the acceleration sensor.

For example, it is assumed that the i-th reflective marker 400_i from the top is specified as the place where the load is applied. Here, in reality, no acceleration sensor is mounted at the position of the reflection marker 400_i. Therefore, the load information calculation unit 170 measures virtual measurement values (b _x , b _y , b _z ) of acceleration by the acceleration sensor at the position of the reflection marker 400 — i by measuring a plurality of acceleration sensors around the marker position. The value is calculated by interpolation. For example, the measured value _{(b x, b y, b} z) is, i-th measured value of the acceleration sensor _{(X iS, Y iS, Z} iS) and, (i + 1) th measurement value of the acceleration sensor (X _{(i +1)S} , Y _(i+1)S , Z _(i+1)S ) for each of the x component, the y component, and the z component.

In FIG. 10A, the x-axis, the y-axis, and the z-axis of the coordinate system (sensor coordinate system) for the measurement values of the acceleration sensor are represented by X _S , Y _S , and Z _S , respectively. Also, the x-axis, y-axis, and z-axis of the coordinate system (marker coordinate system) for the three-dimensional coordinates of the reflection marker are represented by X _M , Y _M , and Z _M , respectively. The marker coordinate system is a three-dimensional coordinate system defined in motion capture as described above. Here, as an example, it is assumed that the direction of the X _M axis of the marker coordinate system is the forward direction of the subject, the direction of the Y _M axis is the right direction of the subject, and the direction of the Z _M axis is the vertically upward direction.

In addition, b shown in FIG. 10A is the total acceleration vector indicated by the measured acceleration values (b _x , b _y , b _z ) at the position of the reflection marker 400 — _i . Since the total acceleration vector b includes the component of the gravitational acceleration vector g and the component of the motion acceleration vector a′, it can be expressed by the equation b=g+a′. Since the direction and magnitude of the gravitational acceleration g are known in advance, the load information calculation unit 170 uses the equation a′=b−g based on the respective directions and magnitudes of the total acceleration vector b and the gravitational acceleration vector g. The direction and magnitude of the motion acceleration a can be calculated.

However, since the sensor coordinate system and the marker coordinate system are different as shown in FIG. 10A, the load information calculation unit 170 uses the measured values (b _x , b _y , b _z ) that are the values of the sensor coordinate system as It is converted into a measured value (b _xM , b _yM , b _zM ) in the marker coordinate system. Here, it is assumed that the reflection marker 400 — i is inclined by the angle θ _iM2 about the Y _S axis. In this case, the Y _M axis coincides with the Y _S axis. The angle θ _iM2 is a marker angle calculated based on the two-dimensional coordinates of the reflective marker 400 — i.

FIG. 10B shows the relationship between the sensor coordinate system and the marker coordinate system when viewed from the left and right direction of the subject. The measured values (b _xM , by _M , b _zM ) in the marker coordinate system are represented by the following equations (6-1), (6-2), (6-3).

The load information calculation unit 170 calculates the motion acceleration vector a′ according to the following equation (7) using the converted measurement values (b _xM , by _M , b _zM ). The gravitational acceleration vector g is expressed as (0,0,G).

  From the equation (7), the direction and magnitude of the motion acceleration a can be calculated as the direction and size of the motion acceleration vector a'. Since the direction to which the load is applied is the same as the direction to which the motion acceleration is applied, the load information calculation unit 170 outputs the direction of the vector represented by Expression (7) as the direction to which the load is applied.

  In addition, the magnitude of the load is calculated as a product of the motion acceleration and the mass. The mass of the detection target portion is a predetermined constant, and if the mass at each marker position is considered to be the same, the load information calculation unit 170 uses the motion acceleration calculated from the equation (7) as an index indicating the magnitude of the load. The size of a can be output.

As another method, the load information calculation unit 170 may output an index indicating the magnitude of the load as a relative magnitude between the previous measurement time and the current measurement time. Specifically, the load information calculation unit 170 refers to the history storage unit 180, and the magnitude of the motion acceleration at the time (t-1) for the marker position specified in step S19 ||a(t-1). ) || The magnitude of the load at the marker position at time (t-1) is expressed by the following equation (8-1).
||F(t-1)||=m·||a(t-1)|| (8-1)
Further, using the magnitude ||a(t)|| of the motion acceleration at the time t of the load detection target, the load at the time t at the marker position specified in step S19 is expressed by the following equation (8-2) Represented by
||F(t)||=m·||a(t)|| (8-2)
The load information calculation unit 170 uses the following expression (8-3) as an index indicating the magnitude of the load at time t, and the relative magnitude of the load ||F(t)||||F( t-1) || is calculated.

The load information calculation unit 170 may use impulse or exercise amount as an index indicating the magnitude of load, instead of exercise acceleration.
By the way, the process of converting the three-dimensional coordinates indicating each marker position in step S16 into two-dimensional coordinates may be executed using the following two methods. The first method will be described with reference to FIG.

FIG. 11 is a diagram for explaining the first method of converting into two-dimensional coordinates. In FIG. 11, it is assumed that the coordinates of each reflection marker in the three-dimensional space represented by the X _p , Y _p , and Z _p axes are specified by motion capture. The X _p axis and the Y _p axis are along the horizontal plane, and the direction of the Z _p axis is the vertical direction.

The coordinate conversion unit 140 calculates the eigenvector that maximizes the variance of the values (coordinates) of X _p and Y _p of each reflection marker by using the principal component analysis. In FIG. 11, the eigenvector is represented by q ₁ . For example, in FIG. 11, since the subject bends forward in the direction of the vector q ₁ , the direction in which the variance of the values of X _p and Y _p of each reflection marker is maximum is the direction of the vector q ₁ . In this case, each reflective markers are present in the q ₁ -Z _p plane.

However, it is not known if the subject's movement is in the front-back direction. Therefore, for example, when it is determined that the acceleration change detected by the acceleration sensor is only in the front-rear direction, the coordinate conversion unit 140 determines that each reflective marker is present on the q ₁ -Z _p plane. As another method, the subject may be instructed to move only in the front-back direction.

The coordinate conversion unit 140 calculates the inner product of the values of X _p and Y _p of the reflection marker and the direction q ₁ for each reflection marker. As a result, the values (coordinates) of X _p and Y _p are projected onto the vector q ₁ . Coordinate conversion unit 140, the three-dimensional coordinates representing the respective reflective markers, and converts the calculated value of the inner product values of X _Ic2, Z _p to 2-dimensional coordinates set on the _{Y iC2 (X iC2, Y iC2} ).
In the above description, the case where the subject moves in the front-rear direction has been shown, but even when the subject moves in the left-right direction, the same process can be performed to convert into two-dimensional coordinates. However, the first method described above can convert only two-dimensional coordinates corresponding to one of the left-right direction and the front-back direction.

Next, the second method will be described with reference to FIG. FIG. 12 is a diagram for explaining the second method of converting into two-dimensional coordinates. In FIG. 12, it is assumed that the coordinates of each reflection marker in the three-dimensional space represented by the X _r , Y _r , and Z _r axes are specified by motion capture. The X _r axis and the Y _r axis are along the horizontal plane, and the Z _r axis is in the vertical direction.

  In FIG. 12, the reflection markers 401a and 401b are attached to both shoulders of the subject in addition to the back. Further, the reflection markers 401a and 401b may be attached to a place other than both shoulders. For example, the reflection markers 401a and 401b are attached to both arms of the subject. The reflection markers 401a and 401b are attached at positions displaced in the left-right direction from the position of the spine.

Coordinate conversion unit 140, projecting reflective markers 401a, the 401b to X _r -Y _r plane. The positions of the projected reflection markers 401a and 401b are defined as points R ₁ and R ₂ , respectively. The coordinate conversion unit 140 calculates a vector q ₂ orthogonal to a straight line including the points R ₁ and R ₂ from the origin Q. The coordinate conversion unit 140 calculates, for each reflection marker, the inner product of the value of each component of X _r and Y _r of the reflection marker and the vector q ₂ . As a result, the values (coordinates) of X _r and Y _r are projected onto the vector q ₂ . The coordinate conversion unit 140 sets the calculated inner product value to X _iC2 and the calculated value of Z _r to Y _iC2 with respect to the three-dimensional coordinates representing each reflection marker, and the two-dimensional coordinates (X _iC2 , Y _iC2 ).

The coordinate transformation unit 140 calculates the vector q ₃ orthogonal to the vector q ₂ in X _r -Y _r plane. The coordinate conversion unit 140 calculates the inner product of the values of X _r and Y _r of the reflection marker and the vector q ₃ for each reflection marker. As a result, the values (coordinates) of X _r and Y _r are projected onto the vector q ₃ . The coordinate conversion unit 140 sets the calculated inner product value to X _iC1 and the calculated value of Z _r to Y _iC1 for the three-dimensional coordinates representing each reflection marker, and sets two-dimensional coordinates (X _iC1 , Y _iC1 ).

As described above, it is possible to convert three-dimensional coordinates indicating each marker position into two-dimensional coordinates using two methods.
According to the second embodiment, the location of the load applied to the subject can be specified using the acceleration sensor and the motion capture. Then, the direction and magnitude of the load applied to the specified location can be specified. The load detection location can be set to any location on the subject's body as long as the inclination can be calculated.

[Third Embodiment]
Next, a third embodiment will be described. Items that differ from the above-described second embodiment will be mainly described, and descriptions of common items will be omitted.

  In the second embodiment, the acceleration sensor and the motion capture are used to identify the location of the load applied to the subject. The third embodiment provides a function of specifying the location of the load applied to the subject by using the acceleration sensor and the inclinometer.

  In the third embodiment, the subject is equipped with the acceleration sensor and the inclinometer. For example, as shown in FIG. 4, a plurality of acceleration sensors are attached to the back of the subject 900, and an inclinometer is attached instead of the reflection marker. That is, the acceleration sensor and the inclinometer are mounted alternately.

  FIG. 13 is a diagram illustrating an example of functions of the load detection device according to the third embodiment. The load detection device 100a includes an acquisition unit 110a, a sensor angle calculation unit 120, a load determination unit 160a, a load information calculation unit 170a, a history storage unit 180a, and an angle calculation unit 190. The load detection device 100a is realized by the same hardware configuration as the load detection device 100 of FIG. Further, the communication interface 107a of the load detection device 100a communicates with the inclinometer via the network. The acquisition unit 110a, the sensor angle calculation unit 120, the load determination unit 160a, the load information calculation unit 170a, and the angle calculation unit 190 are implemented, for example, as modules of a program executed by the processor 101 included in the load detection device 100a.

  The acquisition unit 110a acquires the measurement values measured at the same time from the acceleration sensor 200 and the inclinometer 500. The inclinometer 500 is a collection of a plurality of inclinometers attached to the subject. Here, the inclinometer 500 may be a two-axis inclinometer or a three-axis inclinometer. When the inclinometer 500 is a two-axis inclinometer, the acquisition unit 110a acquires, for each inclinometer, a measurement value indicating the inclination in the left-right direction or the front-rear direction of the mounting position of each inclinometer. When the inclinometer 500 is a three-axis inclinometer, the acquisition unit 110 acquires measurement values in the x direction, y direction, and z direction for each inclinometer.

  Similar to the second embodiment, the sensor angle calculation unit 120 calculates the tilt angles in the left-right direction and the front-back direction at each sensor position based on the measurement values acquired for each acceleration sensor. The sensor angle calculation unit 120 calculates the sensor angle in each of the left-right direction and the front-back direction at each sensor position by correcting the inclination angle in the left-right direction among these.

  The angle calculation unit 190 calculates the angle at the position of the inclinometer 500 (hereinafter, also referred to as “inclinometer position”) based on each of the sensor angle and the measurement value of the inclinometer 500. Specifically, the angle calculation unit 190 interpolates the respective angles in the left-right direction and the front-back direction at the inclinometer position by interpolating each sensor angle by the same procedure as the marker angle calculation unit 150 of the second embodiment. Calculate by Further, when the inclinometer 500 is a three-axis inclinometer, the angle calculation unit 190 calculates each angle in the left-right direction and the front-back direction at each inclinometer position based on the measurement value acquired for each inclinometer. When the inclinometer directly outputs the respective angles in the left-right direction and the front-back direction, the angle calculation unit 190 outputs the angles acquired by the acquisition unit 110a as they are to the load determination unit 160a.

  Here, the angle based on the measurement value of the inclinometer does not cause an error due to movement of the mounting position of the inclinometer. Therefore, the load determination unit 160a determines, for each inclinometer position, whether or not there is a difference between the angle of the inclinometer position based on the sensor angle and the angle of the inclinometer position based on the measurement value of the inclinometer. If there is a difference in angle, the cause is due to the former angle error caused by the motion acceleration component. Since motion acceleration is applied to the inclinometer position where there is a difference in angle, a load is applied to the inclinometer position from the second law of motion (F=ma: F is force, m is mass, and a is motion acceleration). It can be said that it has been added. Therefore, the load determination unit 160a determines that the position of the inclinometer having a difference in angle is the place where the load is applied. The load determination unit 160a stores information (such as an inclinometer number) on the place where the load is applied in the history storage unit 180.

  The load information calculation unit 170a calculates the direction and size of the load applied. As mentioned above, the angle of the inclinometer position based on the measured value of the inclinometer does not include the error due to the motion acceleration, so this angle shows the accurate angle with respect to the vertical direction of the ground coordinate system. Can be said. That is, the angle based on the measurement value of the inclinometer indicates the rotation angle of the three-dimensional coordinate system of the acceleration sensor at the inclinometer position with respect to the ground coordinate system.

  Therefore, the load information calculation unit 170a uses an angle based on the measurement value of the inclinometer by the same procedure as the conversion of the sensor coordinate system into the marker coordinate system by the load information calculation unit 170 according to the second embodiment. Convert the sensor coordinate system to the ground coordinate system. As a result, the load information calculation unit 170a uses the same procedure as in the second embodiment to determine the direction and magnitude of the motion acceleration at the inclinometer position based on the virtual measurement value of the acceleration sensor at the inclinometer position. Can be calculated. The load information calculation unit 170a indicates the load direction at the inclinometer position and the load magnitude from the direction and magnitude of the motion acceleration in the same procedure as the load information calculation unit 170 of the second embodiment. Output the index and.

  The history storage unit 180a stores the magnitude of the motion acceleration at each inclinometer position at each measurement time. The magnitude of the stored motion acceleration is referred to when the load information calculation unit 170a calculates the relative magnitude of the load.

  As described above, according to the third embodiment, the location of the load applied to the subject can be specified by using the acceleration sensor and the inclinometer. Then, the direction and magnitude of the load applied to the specified location can be specified. Similar to the second embodiment, the load detection location can be set to any location on the body of the subject as long as the inclination can be calculated.

  The information processing according to the first embodiment can be realized by causing a processor used in the load detection device 1 to execute a program. The information processing of the second and third embodiments can be realized by causing the processor 101 to execute a program. The program can be recorded in a computer-readable recording medium.

  For example, the program can be distributed by distributing a recording medium recording the program. In addition, a program that implements functions corresponding to the acquisition unit 110, the sensor angle calculation unit 120, the motion capture processing unit 130, the coordinate conversion unit 140, the marker angle calculation unit 150, the load determination unit 160, and the load information calculation unit 170 is separately provided. Each program may be separately distributed as a program. The functions of the acquisition unit 110, the sensor angle calculation unit 120, the motion capture processing unit 130, the coordinate conversion unit 140, the marker angle calculation unit 150, the load determination unit 160, and the load information calculation unit 170 may be realized by separate computers. The same applies to the acquisition unit 110a, the sensor angle calculation unit 120, the angle calculation unit 190, the load determination unit 160a, and the load information calculation unit 170a in FIG. The computer may store (install) the program recorded in the recording medium in the RAM 102 or the HDD 103, read the program from the storage device, and execute the program.

DESCRIPTION OF SYMBOLS 1 load detection apparatus 1a 1st calculation part 1b 2nd calculation part 1c determination part 1d calculation part 2 subject 2a site|part 3 acceleration sensor 4 imaging device 5 motion capture system

Claims (8)

Computer
Calculating a first angle indicating the inclination of the part of the human body, based on the first measurement result by the acceleration sensor attached to the human body,
A second angle indicating the inclination of the part in the same coordinate system as the first angle is calculated based on the second measurement result of the human body by the imaging device ,
Based on the difference between the first angle and the second angle, the presence or absence of a load applied to the part is determined.
Load detection method. The load detection method according to claim 1, wherein the second measurement result is a measurement result by a motion capture system including the imaging device .   When it is determined that the load is applied to the part, the direction of the load applied to the part and the magnitude of the load are determined based on the acceleration vector of the part based on the first measurement result and the second angle. The load detection method according to claim 2, wherein the index to be calculated is calculated.   In the calculation of the orientation and the index, a third measurement result obtained by converting the first measurement result into a value of a coordinate system in which the second measurement result is defined is calculated based on the second angle, The load detection method according to claim 3, wherein the direction and the index are calculated based on a motion acceleration component obtained by removing a gravity acceleration component from the third measurement result.   The load detection method according to claim 1, wherein the second measurement result indicates a position of the part.   The load detection method according to claim 1, wherein the first angle is calculated by performing an interpolation operation on the first measurement result by the acceleration sensor mounted around the portion. . A first calculator that calculates a first angle indicating the inclination of the part of the human body based on a first measurement result by the acceleration sensor attached to the human body;
A second calculator that calculates a second angle indicating the inclination of the part in the same coordinate system as the first angle based on the second measurement result of the human body by the imaging device ;
A determination unit that determines the presence or absence of a load applied to the region based on the difference between the first angle and the second angle;
Load detection device having a. On the computer,
Calculating a first angle indicating the inclination of the part of the human body, based on the first measurement result by the acceleration sensor attached to the human body,
A second angle indicating the inclination of the part in the same coordinate system as the first angle is calculated based on the second measurement result of the human body by the imaging device ,
Based on the difference between the first angle and the second angle, the presence or absence of a load applied to the part is determined.
A load detection program that executes processing.

Images