JP2016221008A - Load detection method, load detection device, and load detection program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the presence or absence of a load in any region of a human body.SOLUTION: A load detection device 1 comprises a first calculation unit 1a, a second calculation unit 1b, and a determination unit 1c. The first calculation unit 1a calculates a first angle indicating the inclination of a region 2a of a subject 2 on the basis of a first measurement result obtained by an acceleration sensor 3 fitted to the subject 2. The second calculation unit 1b calculates a second angle indicating the inclination of the region 2a on the basis of a second measurement result of the subject 2 obtained by another sensor of a kind different from the acceleration sensor 3. The determination unit 1c determines the presence or absence of a load on the region 2a on the basis of the difference between the first angle and the second angle.SELECTED DRAWING: Figure 1

Description

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

Low back pain is known as one of occupational diseases. For example, low back pain is said to develop when a heavy load is lifted and a sudden force is applied to the intervertebral disc or muscles to damage it.
In addition, a technique for measuring a load applied to a specific part of a human body has been proposed. For example, a low back pain prevention device has been proposed that calculates a load applied to the lower back based on information detected by an angle sensor attached to the trunk of the worker and a load sensor attached to the sole of the worker. Yes. Also proposed is a technique in which a three-axis accelerometer is attached to the knee and the buttocks, and the load applied to the knee and hips is measured from the impulse calculated based on the acceleration measured from the three-axis accelerometer. Has been.

JP 2012-183291 A JP 2012-183294 A

In the above technique, there is a problem that it is only possible to measure a load applied to a specific part of the human body such as the waist, knee, and buttocks.
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 at any part of a 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 the part of the human body based on the first measurement result by the acceleration sensor attached to the human body, and other types different from the acceleration sensor. Based on the second measurement result of the human body by the sensor, a second angle indicating the inclination of the part is calculated, and the presence / absence of a load applied to the part is determined based on the difference between the first angle and the second angle. To do.

  In one aspect, a load detection device is provided. The load detection device includes 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 a first measurement result by the acceleration sensor attached to the human body. The second calculation unit calculates a second angle indicating the inclination of the part based on the second measurement result of the human body by another sensor different from the acceleration sensor. The determination unit determines the presence or absence of a load applied to the part based on the difference between the first angle and the second angle.

  In one aspect, a load detection program is provided. The load detection program 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 on the computer, and other types different from the acceleration sensor. Based on the second measurement result of the human body by the sensor, a second angle indicating the inclination of the part is calculated, and the presence / absence of a load applied to the part is determined based on the difference between the first angle and the second angle. To 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 made the test subject wear the acceleration sensor and the reflective marker. It is a figure which shows the function example of a load detection apparatus. It is a figure shown about calculation of a sensor angle. It is a figure which shows the outline | summary of a load determination process. It is a figure shown about the process which pinpoints the generation | occurrence | production location of load. It is a flowchart which shows the example of a load determination process. It is a figure shown about calculation of the direction and magnitude | size of load. It is a figure for demonstrating the 1st method converted into a two-dimensional coordinate. It is a figure for demonstrating the 2nd method converted into a two-dimensional coordinate. It is a figure which shows the function example 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 illustrating 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 are 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 include a set of multiple processors (multiprocessor).

  The load detection device 1 is a device that detects the presence or absence of a load on the body part 2 a 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, for example.

  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 the acceleration value 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 a measurement result by the acceleration sensor 3.

  Moreover, the load detection apparatus 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 computing unit 1 d outputs a measurement result related to 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 part 2a of the subject 2 and the periphery thereof, and the imaging device 4 images these markers. In addition, each marker may be imaged from different positions by a plurality of imaging devices 4. The computing unit 1d measures the position of each marker in the three-dimensional space based on the imaging result by the imaging device 4.

  Note that the function of the calculation unit 1d may be implemented in a device different from the load detection device 1. Further, as the imaging device 4, for example, a device that captures an image in the visible region, a device that captures an image in the infrared region, or a composite device that combines these devices may be used. Furthermore, the motion capture system 5 is not limited to an optical system, and a system using another system such as a magnetic system using a magnetic sensor can also be used.

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

  The first calculation unit 1a calculates a first angle indicating the inclination of the part 2a based on the measurement result by the acceleration sensor 3. For example, the first calculator 1a calculates the first angle based on the direction of gravity based on the measured values in the x, y, and z directions measured by the acceleration sensor 3. The second calculation unit 1b calculates a second angle indicating the inclination of the part 2a based on the measurement result by the motion capture system 5. Note that the first angle and the second angle may be angles on a three-dimensional space or 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 hardly occurs in the first angle based on the measurement result of the acceleration sensor 3. However, when the part 2a is moving with acceleration, the measurement result of the acceleration sensor 3 includes a motion acceleration component in addition to the gravitational acceleration component. In such a state, an error due to the motion acceleration component occurs 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. For this reason, when the difference between the first angle and the second angle is not 0, the part 2a is moving, and it is estimated that an error due to the motion acceleration component occurs in the first angle.

  The determination unit 1c determines whether or not a load is applied to the part 2a by using such an error that may occur in the first angle. That is, the determination unit 1c determines the presence / absence of a load applied to the part 2a based on the difference between the first angle and the second angle. If there is a difference between the first angle and the second angle, the cause is due to the motion acceleration component. Since motion acceleration is added to the part 2a having a difference between the first angle and the second angle, the second law of motion (F = ma: F is force, m is mass, and a is motion acceleration) Therefore, it can be said that the load is applied to the part 2a. Thus, the determination part 1c determines with the load being applied to the site | part 2a, when there exists a difference in a 1st angle and a 2nd angle. Note that the part 2a that is determined to be loaded may be limited to a specific region of the body, or may represent a wide region.

  According to the first embodiment described above, the load detection device 1 can accurately determine the presence or absence of a load on the part 2a by using an angle calculation error based on the acceleration sensor 3. In addition, the inclination based on the measurement value of the acceleration sensor 3 and the inclination based on the measurement value obtained by motion capture can be detected at any part of the body of the subject 2. Therefore, the load detection device 1 can determine whether or not there is a load at any part of the body of the subject 2 as long as the part can detect the inclination in this way.

  In the above example, the second angle based on the measurement result by the motion capture system 5 is calculated. However, 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 illustrating 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 an example of the acceleration sensor 3 of FIG. 2 is an example of a device 4;

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

  The acceleration sensors 200a, 200b,... Are so-called “wearable sensors” that are worn by the subject. The acceleration sensors 200a, 200b,... Are triaxial acceleration sensors that detect acceleration in three axial directions with respect to the direction of gravity. 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 an optical motion capture system, a subject is equipped with a reflective marker (hereinafter sometimes referred to as a marker). The cameras 300a to 300d capture the light reflected on the reflective marker and reflected from the reflective marker. The load detection apparatus 100 calculates the position (three-dimensional coordinate) of the reflective marker in a three-dimensional space using the principle of triangulation based on 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 apparatus 100. The processor 101 may be a multiprocessor including a plurality of processing elements. The processor 101 is, for example, a CPU, DSP, ASIC, or FPGA. The processor 101 may be a combination of two or more elements among 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 part of an OS program and application programs to be executed by the processor 101. The RAM 102 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 to and from the built-in magnetic disk. The HDD 103 stores an OS program, application programs, and various data. The load detection device 100 may include other types of auxiliary storage devices such as flash memory and 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 in accordance with 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), and an organic EL (Electro-Luminescence) display can be used. The load detection device 100 may include the display 11 as an integral unit.

  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 apparatus 100 may include the input device 12 integrally.

  The reading device 106 is a device that reads a program and data recorded on the portable recording medium 13. As the recording medium 13, for example, a magnetic disk such as a flexible disk (FD) or an HDD, an optical disk such as a CD (Compact Disc) or a DVD (Digital Versatile Disc), or a magneto-optical disk (MO) is used. 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. For example, the reading device 106 stores the program and data read from the recording medium 13 in the RAM 102 or the HDD 103 in accordance with an instruction from the processor 101.

  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 a network. The communication interfaces 107 and 107a may be wired communication interfaces or wireless communication interfaces.

  FIG. 4 is a diagram illustrating a state in which the subject is wearing an acceleration sensor and a reflective marker. On the back of the subject 900, an acceleration sensor and a reflective 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 attached to 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 region obtained by dividing the spine into five regions such as the lumbar spine. The acceleration sensor is mounted at an intermediate position between the reflection markers on both sides. Note that, as will be described later, in the present embodiment, the position of the reflective marker is a target site where the presence or absence of a load is detected.

  The subject 900 performs some operation while wearing the acceleration sensor and the reflective marker. The load detection apparatus 100 acquires a measurement value measured by each acceleration sensor mounted on the back of the subject 900 in operation via the network.

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

  FIG. 5 is a diagram illustrating a function example of the load detection device. The load detection apparatus 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. Implemented. The history storage unit 180 is mounted as a storage area secured in the RAM 102 or the HDD 103, for example.

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

  The acquisition unit 110 may not 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 respective measurement values of the acceleration sensor 200 and the camera 300 measured at the same time from the HDD 103. To do.

  The measurement values acquired by the acquisition unit 110 from the acceleration sensor 200 are accelerations in the x, y, and z directions for each acceleration sensor. 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 the tilt angles in the left-right direction and the front-rear direction, as viewed from the subject, at the location where each acceleration sensor is mounted, based on the measurement values measured by each acceleration sensor. Hereinafter, the inclination angle of the place where the acceleration sensor is mounted may be referred to as “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. When the sensor angle is stationary, this is equivalent to the inclination angle of the acceleration sensor itself.

  Note that when the acceleration sensor is attached to the subject in a tilted state, the sensor angle calculation unit 120 calculates a sensor angle obtained 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 uses the calculated tilt angle as it is as the sensor angle.

  The motion capture processing unit 130 calculates the position (three-dimensional coordinate) of each reflective marker using the principle of triangulation based on the information acquired from the camera 300. Hereinafter, the position of the reflective 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 converter 140 converts the three-dimensional coordinates of the marker position into two-dimensional coordinates on a vertical plane along the subject's front-rear direction and two-dimensional coordinates on a horizontal plane along the subject's left-right direction. Convert to coordinates.

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

  The marker angle calculation unit 150 performs an interpolation operation on the sensor angle and calculates an angle of the marker position (marker angle). Specifically, since a reflective marker exists between two acceleration sensors, the marker angle calculation unit 150 regards, for example, the average of sensor angles at the respective positions of the two acceleration sensors as the angle of the marker position.

  In addition, the marker angle calculation unit 150 calculates the marker position angle (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 thereto.

  In some cases, the motion capture processing unit 130 can directly calculate the inclination of each marker position. 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-rear direction. The marker angle calculation unit 150 outputs the separated components in place of the inclination in the left-right direction and the front-rear direction based on the two-dimensional coordinates.

  The load determination unit 160 determines, for each marker position, whether 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. When there is a difference in angle, the cause is due to an error in the former marker angle caused by the motion acceleration component. Since the motion acceleration is added 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). It can be said that. Therefore, the load determination unit 160 determines a marker position having a difference in angle as a place where a load is applied. The load determination unit 160 stores information (marker number or the like) of the portion where the load is applied in the history storage unit 180. When there is no difference in angle, the load determination unit 160 determines that no load is applied to the corresponding marker position.

  In this embodiment, the load measurement point is the marker position, but 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, and calculates the angle at the sensor position. Then, for each sensor position, it may be determined whether 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 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 attached 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.

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

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

  Note that the load at each sensor position is measured by the load detection device 100 at every measurement time set at a constant interval. The history storage unit 180 accumulates information on load measurement results at each measurement time. The accumulated information is used when the load information calculation unit 170 calculates the load magnitude as a relative value.

FIG. 6 is a diagram illustrating 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 in the upper left side of FIG. 6, the acceleration sensor 200a measures accelerations in the x direction, the y direction, and the z direction. The x direction, the y direction, and the z direction are detected as directions relative to the direction of gravity g.

  The x direction indicates a direction orthogonal to the front-rear 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 rear direction of the subject 900 is the positive direction for the x direction, and the right direction of the subject 900 is the positive direction for the y direction. The z direction indicates a 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 measurement value as described above 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 the 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-rear direction is calculated as an angle with respect to the vertical upward direction on a vertical plane including the front-rear 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 vertical upward direction on a vertical plane including the left-right direction of the subject 900. In addition, when the mounting location of the acceleration sensor is not inclined with respect to the left-right direction, the angle deviation with respect to the left-right direction is 0 °.

  FIG. 7 is a diagram showing an outline of the load determination process. FIG. 7 (i) shows examples of sensor positions and marker positions. As shown in FIG. 7 (i), the subject 900 is alternately mounted with an acceleration sensor and a reflective marker. In the present embodiment, an acceleration sensor and a reflective marker are attached along the spine.

  The sensor angle calculation unit 120 calculates an inclination angle (sensor angle) at each sensor position based on the measurement result acquired from the acceleration sensor corresponding to each sensor position. FIG. 7 (ii) shows that the sensor angle is calculated based on the measurement values 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 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 interpolation calculation of the sensor angle. The marker angle is, for example, an angle obtained by averaging the sensor angles at the positions of the two acceleration sensors existing above and below the corresponding reflective 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, 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 reflective marker attached to the subject 900. FIG. 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 it is calculated.

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

FIG. 8 is a diagram illustrating processing for specifying a load occurrence location. FIG. 8 shows only the marker angle with respect to the front-rear direction as an example.
Reflective markers 400a, 400b, 400c, and 400d are attached to the subject's back 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-rear direction at the position of the first reflective marker 400a from the top is represented 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-rear direction at the position of the first reflective marker 400a from the top is represented 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 movement. This error occurs because the (virtual) measured value by the acceleration sensor at the i-th marker position includes not only the gravitational 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 does not cause an error due to whether or not 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. When 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 specifies the position of the reflective marker 400a as a place where a load is applied.

  In this way, the load determination unit 160 identifies a marker position where the marker angle difference is not 0 as a place where a load is applied. If there is no difference in the marker angle, the load determination unit 160 determines that no load is applied to the corresponding marker position.

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

  (S11) The acquisition unit 110 acquires measurement values in the x direction, the y direction, and the z direction measured by each acceleration sensor at time t. Moreover, the acquisition part 110 acquires the information which each camera imaged the reflective marker at the time t.

(S12) The sensor angle calculation unit 120 calculates the tilt angles in the left-right direction and the front-rear direction for the sensor position where each acceleration sensor is mounted, based on the measurement value of each acceleration sensor acquired in step S11. The calculated tilt angle is expressed as an angle with respect to the direction of gravity. 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). X _iS , Y _iS , and Z _iS indicate acceleration measured values in the x, y, and z directions 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 y direction of the acceleration sensor is tilted, that is, when the acceleration sensor is mounted in a tilted state when viewed from the rear side of the subject, the tilt angle φ _{iS1 in the} left and right direction is assumed. Correct.

When the inclination angle in the left-right direction of the acceleration sensor is expressed as φ _{i01 in the} reference posture (that is, when the acceleration sensor is not inclined to the subject), the sensor angles θ _iS01 , θ _iS02 in the left-right direction and the front-rear direction are 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 plane in the left-right direction are parallel, the sensor angle θ _iS02 and the tilt 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 horizontal direction and the front-rear direction at each marker position. Marker angle 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 manner, the marker angle at the marker position is calculated based on the sensor angles at the two sensor positions. For example, in the case of i = 1, the marker angle calculation unit 150 includes the acceleration sensor 2
The marker angle at the position of the reflective marker 400a is calculated using the sensor angle at the positions 00a and 200b. Since the marker angle is calculated from the two sensor angles, the number of reflective markers is one less than the number of acceleration sensors.

As another method, for example, the marker angle calculation unit 150 may approximate each sensor angle change 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 with a quadratic function in each of the left-right direction and the front-rear direction, and calculates the marker angles θ _iS1 and θ _iS2 using the quadratic function. .

  (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 imaging the reflective 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 respectively corresponding to the left-right direction and the front-rear direction of the subject.
The processes of steps S15 and S16 are performed as follows, for example. When imaged by the camera, the subject is arranged to face a specific direction in a three-dimensional coordinate system (marker coordinate system) defined in 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. And a test subject is arrange | positioned so that it may face the direction of an 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 ).

In steps S15 and S16, the method described later with reference to FIG. 11 or FIG. 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-rear direction at the i-th marker position is calculated according to the following equations (4-1) and (4-2). Formula (4-1) is a calculation formula when i is 2 or more, and Formula (4-2) is a calculation formula 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.
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), and (5-3). Formula (5-1) is a calculation formula when i = number of markers, Formula (5-2) is a calculation formula when 2 ≦ i <number of markers, and Formula (5-3) is a calculation formula when i = 1.

Note that the marker angle θ _iM1 in the left-right direction at the i-th marker position is _expressed by the equations (4-1), (4-2), (5-1), (5-2), and (5-3). , Θ _iM1 can be substituted for θ _iM2 , and (X _iC1 , Y _iC1 ) can be substituted for (X _iC2 , Y _iC2 ).

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

Note that the value compared with the predetermined threshold value in step S19 may be a value that takes into account the acceleration vector at the marker position. For example, the load determining unit 160, and the gravity acceleration vector G _e at the marker position, by using the acceleration vector A _r at the position of the marker calculated from sensor, _{"G e · A r / (||} G e || · | The value H is calculated according to the equation | A _r ||) ”. Acceleration vector A _r at the marker position, for example, an acceleration vector based on the measurement value of the acceleration at the sensor position of both sides of the marker position is calculated by averaging. || G _e || and || A _r || indicate the magnitude (norm) of the gravitational acceleration vector G _e and the acceleration vector A _r , respectively. In step S19, for example, the load determination unit 160 compares the value obtained by multiplying the value H by a predetermined weighting factor with the absolute value of the difference, and the threshold value, thereby comparing the marker position. It is determined whether a 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.
If past information in the history storage unit 180 is referred to in step S20 to calculate the relative magnitude of the load, the following processing is further performed in step S20. The load information calculation unit 170 registers the value of 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 in the history storage unit 180 for all marker positions. For the marker position determined to be unloaded in step S19, motion acceleration = 0 is registered.

  In FIG. 9, the processing is executed using both the left and right and front and rear marker angles. However, for example, even when the processing is executed using the left and right and front and rear marker angles. Good. In this case, it is possible to detect the presence or absence of a load on one of the left and right directions and the front and rear direction.

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

For example, it is assumed that the i-th reflective marker 400 — i from the top is specified as a place where a load is applied. Here, actually, no acceleration sensor is mounted at the position of the reflective marker 400 — i. Therefore, the load information calculation unit 170 uses the virtual measurement values (b _x , b _y , b _z ) of the acceleration by the acceleration sensor at the position of the reflective marker 400 — i to measure the plurality of acceleration sensors around the marker position. Calculate by interpolation from the value. For example, the measurement values (b _x , b _y , b _z ) are the measurement values (X _iS , Y _iS , Z _iS ) of the i th acceleration sensor and the measurement values (X _(i (i + 1)) of the (i + 1) th acceleration sensor. _{+1) S} , Y _{(i + 1) S} , Z _{(i + 1) S} ) are obtained by calculating each of the x component, the y component, and the z component.

In FIG. 10A, the x-axis, y-axis, and 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. Further, the x-axis, y-axis, and z-axis of the coordinate system (marker coordinate system) for the three-dimensional coordinates of the reflective marker are represented by X _M , Y _M , and Z _M , respectively. As described above, the marker coordinate system is a three-dimensional coordinate system defined in motion capture. As an example, here, the direction of X _M axis of the marker coordinate system is a forward direction of the subject, the direction of Y _M axis is the right direction of the subject, the direction of the Z _M axis is assumed to be vertical upwards.

Further, 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 reflective marker 400 — _i . Since the total acceleration vector b includes a component of the gravitational acceleration vector g and a 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 formula 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 obtains the measured values (b _x , b _y , b _z ) as values of the sensor coordinate system. Converted to measurement values (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 around 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-right direction of the subject. The measurement values (b _xM , b _yM , b _zM ) in the marker coordinate system are expressed by the following equations (6-1), (6-2), and (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 , b _yM , b _zM ). The gravitational acceleration vector g is expressed as (0, 0, G).

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

  Further, the magnitude of the load is calculated as a product of the motion acceleration and the mass. The mass of the detection target location is a constant determined in advance, and assuming that the mass at each marker position is the same, the load information calculation unit 170 uses the motion acceleration calculated from Equation (7) as an index indicating the magnitude of the load. The magnitude 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 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 of motion acceleration at the time t of the load detection object || a (t) ||, 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 calculates the relative load magnitude || F (t) || / || F ( t-1) || is calculated.

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

FIG. 11 is a diagram for explaining a first method of converting into two-dimensional coordinates. In FIG. 11, it is assumed that the coordinates of each reflective 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.

Coordinate conversion unit 140, using principal component analysis, X _p of the reflective markers, variance of the values of Y _p (coordinates) to calculate the eigenvector with the maximum. In FIG. 11, the eigenvector is represented by q ₁ . For example, in FIG. 11, since the subject is bent 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 reflection marker exists in the q ₁ -Z _p plane.

However, it is not known whether the subject's movement is in the front-rear direction. Therefore, for example, when the coordinate conversion unit 140 determines 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 exists in the q ₁ -Z _p plane. As another method, the subject may be instructed to move only in the front-rear direction.

The coordinate conversion unit 140 calculates the inner product of the X _p and Y _p values of the reflective marker and the direction q ₁ for each reflective marker. Thereby, the values (coordinates) of X _p and Y _p are projected onto the vector q ₁ . The coordinate conversion unit 140 converts the calculated inner product value to X _iC2 and the value of Z _p to Y _iC2 (X _iC2 , Y _iC2 ) for the three-dimensional coordinates representing each reflective marker.
In the above description, the case where the subject moves in the front-rear direction has been described, but even when the subject moves in the left-right direction, it can be converted into two-dimensional coordinates by the same processing. However, in the first method, conversion can be made only to two-dimensional coordinates corresponding to one of the left-right direction and the front-rear direction.

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

  In FIG. 12, the reflective markers 401a and 401b are attached to both shoulders of the subject in addition to the back. Moreover, the reflective markers 401a and 401b may be attached to places other than both shoulders. For example, reflection markers 401a and 401b are attached to both arms of the subject. The reflective markers 401a and 401b are attached at positions shifted 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 points R ₁ and R ₂ , respectively. The coordinate conversion unit 140 calculates a vector q ₂ orthogonal to the straight line including the points R ₁ and R ₂ from the origin Q. Coordinate conversion unit 140, for each reflective markers, and calculates an inner product between the value and the vector q ₂ of each component of X _r, Y _r of the reflective markers. Thereby, the values (coordinates) of X _r and Y _r are projected onto the vector q ₂ . The coordinate conversion unit 140 sets two-dimensional coordinates (X _iC2 , Y _iC2 ) in the front-rear direction, with the calculated inner product value set to X _iC2 and the value of Z _r set to Y _iC2 for the three-dimensional coordinates representing each reflective marker. ).

In addition, the coordinate conversion unit 140 calculates a vector q ₃ that is orthogonal to the vector q ₂ in the X _r -Y _r plane. The coordinate conversion unit 140 calculates the inner product of the values of the reflection markers X _r and Y _r and the vector q ₃ for each reflection marker. Thereby, the values (coordinates) of X _r and Y _r are projected onto the vector q ₃ . The coordinate conversion unit 140 sets two-dimensional coordinates (X _iC1 , Y _iC1 ) in the left-right direction with the calculated inner product value set to X _iC1 and the value of Z _r set to Y _iC1 for the three-dimensional coordinates representing each reflective marker. ).

In this way, it is possible to convert three-dimensional coordinates indicating each marker position into two-dimensional coordinates using two methods.
According to 2nd Embodiment, the location of the load added to a test subject can be specified using an acceleration sensor and a 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 at any location on the subject's body as long as the slope can be calculated.

[Third Embodiment]
Next, a third embodiment will be described. Differences from the second embodiment will be mainly described, and descriptions of common matters will be omitted.

  In 2nd Embodiment, the location of the load added to a test subject was specified using the acceleration sensor and the motion capture. In 3rd Embodiment, the function which pinpoints the location of the load added to a test subject is provided using an acceleration sensor and an inclinometer.

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

  FIG. 13 is a diagram illustrating an example of functions of the load detection device according to the third embodiment. The load detection apparatus 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 a hardware configuration similar to that of the load detection device 100 in FIG. Further, the communication interface 107a of the load detection device 100a communicates with an inclinometer via a network. For example, 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 as modules of programs executed by the processor 101 included in the load detection device 100a.

  The acquisition unit 110a acquires measurement values measured at the same time from the acceleration sensor 200 and the inclinometer 500. The inclinometer 500 collectively shows 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 biaxial inclinometer, the acquisition unit 110a acquires, for each inclinometer, a measurement value that indicates the inclination in the left-right direction or the front-rear direction with respect to the installation location of each inclinometer. When the inclinometer 500 is a triaxial inclinometer, the acquisition unit 110 acquires measurement values in the x direction, the y direction, and the z direction for each inclinometer.

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

  The angle calculation unit 190 calculates an angle at the position of the inclinometer 500 (hereinafter sometimes referred to as “inclinometer position”) based on the sensor angle and the measured value of the inclinometer 500. Specifically, the angle calculation unit 190 interpolates the respective angles in the left-right direction and the front-rear direction at the inclinometer position and the respective sensor angles by the same procedure as the marker angle calculation unit 150 of the second embodiment. To calculate. In addition, when the inclinometer 500 is a triaxial inclinometer, the angle calculation unit 190 calculates respective angles in the left-right direction and the front-rear direction at each inclinometer position based on the measurement values acquired for each inclinometer. When the inclinometer directly outputs the respective angles in the left-right direction and the front-rear 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 measured value of the inclinometer does not cause an error due to the movement of the mounting position of the inclinometer. Therefore, for each inclinometer position, the load determination unit 160a determines whether 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 measured value of the inclinometer. When there is a difference in angle, the cause is due to the error in the former angle caused by the motion acceleration component. Since motion acceleration is added to the inclinometer position with a difference in angle, the 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 inclinometer position having a difference in angle is a place where a load is applied. The load determination unit 160a stores information (inclinometer number and the like) on the location 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. As described above, the angle of the inclinometer position based on the measured value of the inclinometer does not include an error due to motion acceleration, so this angle indicates an accurate angle based on the vertical direction of the ground coordinate system. It can be said. That is, the angle based on the measured 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 the angle based on the measured value of the inclinometer in the same procedure as the conversion of the sensor coordinate system to the marker coordinate system by the load information calculation unit 170 of the second embodiment, Convert the sensor coordinate system to the ground coordinate system. As a result, the load information calculation unit 170a performs 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 in the same procedure as in the second embodiment. Can be calculated. The load information calculation unit 170a indicates the direction of the load at the inclinometer position and the magnitude of the load 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 indicator.

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

  Thus, according to 3rd Embodiment, the location of the load added to a test subject can be specified using an acceleration sensor and an 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 at any location on the subject's body as long as the slope can be calculated.

  Note that 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 on a computer-readable recording medium.

  For example, the program can be distributed by distributing a recording medium on which the program is recorded. In addition, separate programs for realizing 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 are provided. Each program may be distributed separately. 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. For example, the computer may store (install) the program recorded in the recording medium in the RAM 102 or the HDD 103 and read and execute the program from the storage device.

DESCRIPTION OF SYMBOLS 1 Load detection apparatus 1a 1st calculation part 1b 2nd calculation part 1c Judgment part 1d Operation part 2 Test subject 2a Part 3 Acceleration sensor 4 Imaging device 5 Motion capture system

Claims (8)

Computer
Based on the first measurement result by the acceleration sensor attached to the human body, a first angle indicating the inclination of the part of the human body is calculated,
Based on a second measurement result of the human body by another sensor different from the acceleration sensor, a second angle indicating the inclination of the part is calculated,
Based on the difference between the first angle and the second angle, the presence / absence of a load on 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 other sensor.   When it is determined that a load is applied to the part, the direction and the magnitude of the load applied to the part are determined based on the acceleration vector and the second angle in the part based on the first measurement result. The load detection method according to claim 2, wherein an index to be indicated is calculated.   In the calculation of the orientation and the index, a third measurement result obtained by converting the first measurement result into a coordinate system value in which the second measurement result is defined based on the second angle is calculated. 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 gravitational 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.   6. The load detection method according to claim 1, wherein the first angle is calculated by interpolating the first measurement result obtained by the acceleration sensor mounted around the part. 7. . A first calculation unit that calculates a first angle indicating an inclination of a portion of the human body based on a first measurement result by an acceleration sensor attached to the human body;
A second calculation unit for calculating a second angle indicating the inclination of the part based on a second measurement result of the human body by another sensor different from the acceleration sensor;
A determination unit that determines the presence or absence of a load applied to the part based on a difference between the first angle and the second angle;
A load detecting device. On the computer,
Based on the first measurement result by the acceleration sensor attached to the human body, a first angle indicating the inclination of the part of the human body is calculated,
Based on a second measurement result of the human body by another sensor different from the acceleration sensor, a second angle indicating the inclination of the part is calculated,
Based on the difference between the first angle and the second angle, the presence / absence of a load on the part is determined.
A load detection program that executes processing.

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