Motion measurement device and motion measurement method

Abstract

To provide an operation measurement device and an operation measurement method which can accurately and surely measure an operation of a dynamic body.SOLUTION: An operation measurement device comprises: module information processing parts 231-235 which decide a position and a direction of a prescribed portion of an operation measurement object at a prescribed time interval on the basis of first estimation information being information about the absolute position and direction estimated about the prescribed portion of the operation measurement object and second estimation information being information about the position and direction of the prescribed portion estimated by measuring inertial force at the prescribed portion; and an operation measurement part 236 which measures the operation of the operation measurement object on the basis of the decided information transition. The module information processing parts 231-235, when a change amount of the corresponding estimation information becomes equal to or greater than a prescribed value in a case where the position and direction of the prescribed portion of the operation measurement object are decided on the basis of one of the first estimation information and the second estimation information, performs switching so as to decide the position and direction of the prescribed portion of the operation measurement object on the basis of the other estimation information.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This disclosure relates to a motion measurement device and a motion measurement method. [Background technology]

[0002] Some skills, achieved through specific human movements, require a long time to master. To efficiently acquire the movements for such skills, it is conceivable to quantitatively measure the movements of experts in those skills and use this measured information when beginners are learning those movements.

[0003] Technologies for quantitatively measuring human movement include optical motion capture and inertial measurement devices. Optical motion capture is a technology that measures human movement by placing markers on characteristic parts of the human body, such as joints, and recording the position and movement of these markers with a camera device. Inertial measurement devices, on the other hand, measure human movement using measurement information from gyro sensors and accelerometers placed on the person being measured. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2000-321044 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] One of the skills that requires a long time to master, as described above, is the skill required for welding. In welding, for example, a worker holds a welding holder and moves their upper arm and upper body in a predetermined position.

[0006] In welding operations, extremely strong welding light is generated during the process, which posed a problem when attempting to measure the worker's movements using optical motion capture. This was because the camera system could not acquire the marker position, making measurement impossible. Furthermore, welding operations also generate heat and electromagnetic waves, making it difficult to measure the worker's movements using inertial measurement devices.

[0007] This disclosure is made in view of the above circumstances and aims to provide a motion measurement device and a motion measurement method that can accurately and reliably measure the movement of a moving object. [Means for solving the problem]

[0008] The motion measurement device according to this disclosure comprises: an absolute position information processing unit that acquires first estimated information, which is information on the absolute position and direction of a predetermined part of an object to be measured, at predetermined time intervals; an inertia information processing unit that acquires second estimated information, which is information on the position and direction of a predetermined part estimated by measuring the inertial force at the predetermined part, at predetermined time intervals; a determination unit that determines the position and direction of a predetermined part of the object to be measured at predetermined time intervals based on the first estimated information or the second estimated information; and a motion measurement unit that measures the motion of the object to be measured based on the transition of information determined by the determination unit, wherein when the determination unit is determining the position and direction of a predetermined part of the object to be measured based on either the first estimated information or the second estimated information, if the amount of change in the corresponding estimated information exceeds a predetermined value, it switches to determining the position and direction of the predetermined part of the object to be measured based on the other estimated information.

[0009] Furthermore, after the determination unit switches to determining the position and direction of a predetermined part of the object to be measured based on the other estimated information, if the amount of change in the estimated information that was being processed before the switch falls below a predetermined value, it may switch back to determining the position and direction of a predetermined part of the object to be measured based on the estimated information that was being processed before the switch.

[0010] Furthermore, the predetermined part may be multiple parts, the determination unit may determine the position and direction of each of the multiple parts, and the motion measurement unit may measure the motion of the motion measurement target based on the transition of information for each part determined by the determination unit.

[0011] The motion measurement device may further include a video information generation unit that generates video information showing the motion of the object being measured, as measured by the motion measurement unit.

[0012] Furthermore, the motion measurement method relating to this disclosure acquires first estimated information, which is information on the absolute position and direction of a predetermined part of the object to be measured, at predetermined time intervals; acquires second estimated information, which is information on the position and direction of the predetermined part estimated by measuring the inertial force at the predetermined part, at predetermined time intervals; determines the position and direction of the predetermined part of the object to be measured at predetermined time intervals based on the first estimated information or the second estimated information; when the change in the amount of the corresponding estimated information is greater than or equal to a predetermined value while the position and direction of the predetermined part of the object to be measured is being determined based on either the first estimated information or the second estimated information, switches to determining the position and direction of the predetermined part of the object to be measured based on the other estimated information; and measures the motion of the object to be measured based on the transition of the determined information. [Effects of the Invention]

[0013] According to the motion measurement device and motion measurement method disclosed herein, the motion of a moving object can be measured accurately and reliably. [Brief explanation of the drawing]

[0014] [Figure 1] This is an overall diagram showing the configuration of a motion measurement system using a motion measurement device according to one embodiment. [Figure 2] This is a block diagram showing the configuration of the first to fifth sensor modules connected to a motion measurement device according to one embodiment. [Figure 3] This block diagram shows the configuration of a motion measurement device according to one embodiment. [Figure 4] It is a block diagram showing the configuration of the first to fifth module information processing units in the operation measurement device according to an embodiment. [Figure 5] It is a flowchart showing the operations of the first to fifth module information processing units in the operation measurement device according to an embodiment.

Mode for Carrying Out the Invention

[0015] In the following embodiments, the case where the operation measurement device according to the present disclosure measures the operations of worker X who performs welding work and torch T held by worker X will be described.

[0016] 〈Configuration of an Operation Measurement System Using an Operation Measurement Device According to an Embodiment〉 The configuration of an operation measurement system using an operation measurement device according to an embodiment will be described with reference to FIG. 1. The operation measurement system 1 according to this embodiment includes five sensor modules, namely, a first sensor module 10-1, a second sensor module 10-2, a third sensor module 10-3, a fourth sensor module 10-4, and a fifth sensor module 10-5 (hereinafter referred to as "the first sensor module 10-1 to the fifth sensor module 10-5"), and an operation measurement device 20 that is connected to these first sensor module 10-1 to fifth sensor module 10-5 so as to enable wired communication and wireless communication.

[0017] The first sensor module 10-1 is installed, for example, on the back of worker X who is the operation measurement target. The second sensor module 10-2 is installed on the upper arm of worker X. The third sensor module 10-3 is installed on the forearm of worker X. The fourth sensor module 10-4 is installed on the wrist of worker X. The fifth sensor module 10-5 is installed on torch T held by worker X.

[0018] Figure 2 is a block diagram showing the configuration of the first sensor module 10-1 to the fifth sensor module 10-5. The first sensor module 10-1 includes a camera device 11-1, a module wired communication unit 12-1, an IMU (Inertial Measurement Unit) sensor 13-1, and a module wireless communication unit 14-1.

[0019] The configuration of the first sensor module 10-1 will now be described. The camera device 11-1 is composed of, for example, a webcam and takes pictures of the area around worker X during motion measurement processing. The module wired communication unit 12-1 performs wired communication with the motion measurement device 20. The IMU sensor 13-1 has a gyro sensor 131-1 that measures angular velocity, which indicates inertial force, at predetermined time intervals, and an acceleration sensor 132-1 that measures acceleration, which indicates inertial force, at predetermined time intervals. The module wireless communication unit 14-1 performs wireless communication with the motion measurement device 20.

[0020] Since the second sensor module 10-2 to the fifth sensor module 10-5 have the same configuration as the first sensor module 10-1, a detailed explanation will be omitted.

[0021] Figure 3 is a block diagram showing the configuration of the motion measurement device 20. The motion measurement device 20 includes a wired measurement device communication unit 21, a wireless measurement device communication unit 22, a CPU 23, a GUI (Graphical User Interface) information storage unit 24, and a display unit 25.

[0022] The wired communication unit 21 of the measuring device performs wired communication with the first sensor module 10-1 to the fifth sensor module 10-5. The wireless communication unit 22 of the measuring device performs wireless communication with the first sensor module 10-1 to the fifth sensor module 10-5.

[0023] The CPU 23 includes a first module information processing unit 231, a second module information processing unit 232, a third module information processing unit 233, a fourth module information processing unit 234, a fifth module information processing unit 235, an operation measurement unit 236, and a GUI information generation unit 237 which serves as a video information generation unit.

[0024] The first module information processing unit 231, the second module information processing unit 232, the third module information processing unit 233, the fourth module information processing unit 234, and the fifth module information processing unit 235 (hereinafter referred to as "the first module information processing unit 231 to the fifth module information processing unit 235") have the same configuration. Figure 4 is a block diagram showing the configuration of the first module information processing unit 231 to the fifth module information processing unit 235.

[0025] The first module information processing unit 231 includes an imaging information acquisition unit 231a, an absolute position estimation unit 231b as an absolute position information processing unit, an inertial information acquisition unit 231c, an inertial information processing unit 231d, and a determination unit 231e. The first module information processing unit 231 processes the information acquired by the first sensor module 10-1.

[0026] The imaging information acquisition unit 231a acquires imaging information captured by the camera device 11-1 of the first sensor module 10-1 via the measurement device wired communication unit 21. The absolute position estimation unit 231b analyzes the imaging information acquired by the imaging information acquisition unit 231a and estimates the absolute position and direction of the first sensor module 10-1 at predetermined time intervals using VisualSLAM (Simultaneous Localization and Mapping) technology. The absolute position estimation unit 231b acquires the estimated absolute position and direction information of the first sensor module 10-1 as first estimated information.

[0027] The inertial information acquisition unit 231c acquires angular velocity information measured by the gyro sensor 131-1 and acceleration information measured by the acceleration sensor 132-1 of the first sensor module 10-1 as inertial information via the measurement device wireless communication unit 22.

[0028] The inertial information processing unit 231d estimates the position and orientation of the first sensor module 10-1 at predetermined time intervals based on the inertial information acquired by the inertial information acquisition unit 231c. The inertial information processing unit 231d acquires the estimated position and orientation information of the first sensor module 10-1 as second estimated information. The inertial information processing unit 231d also corrects the coordinate system information recognized by the inertial information processing unit 231d at predetermined time intervals based on the coordinate system information recognized by the absolute position estimation unit 231b for estimating the position and orientation of the first sensor module 10-1.

[0029] The determination unit 231e determines the position or direction of the first sensor module 10-1 at predetermined time intervals using an extended Kalman filter, based on the first estimated information estimated by the absolute position estimation unit 231b or the second estimated information estimated by the inertial information processing unit 231d.

[0030] In this case, when the determination unit 231e is determining the position and orientation of the first sensor module 10-1 based on either the first estimated information or the second estimated information, it monitors whether the amount of change in the relevant estimated information exceeds a predetermined value. When the amount of change in the relevant estimated information exceeds a predetermined value, the determination unit 231e switches to determining the position and orientation of the first sensor module 10-1 based on the other estimated information. In this embodiment, when the determination unit 231e is determining the position and orientation of the first sensor module 10-1 based on the first estimated information, if the amount of change in the first estimated information exceeds a predetermined value, it switches to determining the position and orientation based on the second estimated information.

[0031] The second module information processing unit 232 has the same configuration as the first module information processing unit 231 and processes information acquired by the second sensor module 10-2. The third module information processing unit 233 has the same configuration as the first module information processing unit 231 and processes information acquired by the third sensor module 10-3. The fourth module information processing unit 234 has the same configuration as the first module information processing unit 231 and processes information acquired by the fourth sensor module 10-4. The fifth module information processing unit 235 has the same configuration as the first module information processing unit 231 and processes information acquired by the fifth sensor module 10-5.

[0032] The motion measurement unit 236 measures the movements of worker X based on the information transitions determined by the first module information processing unit 231 to the fifth module information processing unit 235. The GUI information generation unit 237 generates GUI information that shows the movements of worker X measured by the motion measurement unit 236 as video information.

[0033] The GUI information storage unit 24 stores the GUI information generated by the GUI information generation unit 237. The display unit 25 displays the GUI information stored in the GUI information storage unit 24.

[0034] <Operation of a motion measurement system according to one embodiment> Next, the operation of the motion measurement system 1 according to this embodiment will be described. First, the first sensor module 10-1 is installed on the back of worker X, the second sensor module 10-2 is installed on the upper arm of worker X, the third sensor module 10-3 is installed on the forearm of worker X, the fourth sensor module 10-4 is installed on the wrist of worker X, and the fifth sensor module 10-5 is installed on the torch T held by worker X. When the motion measurement device 20 is operated to start measurement processing, the motion measurement system 1 starts processing the motion of the welding work performed by worker X.

[0035] When the motion measurement process begins, the camera devices 11-1 to 11-5 in the first sensor module 10-1 to the fifth sensor module 10-5 begin taking pictures of the area around worker X. The image information captured by the camera devices 11-1 to 11-5 is sequentially transmitted to the motion measurement device 20 via the module wired communication units 12-1 to 12-5.

[0036] Furthermore, the gyro sensors 131-1 to 131-5 of the IMU sensors 13-1 to 13-5 of the first sensor module 10-1 to the fifth sensor module 10-5 measure angular velocity at predetermined time intervals. In addition, the acceleration sensors 132-1 to 132-5 of the IMU sensors 13-1 to 13-5 measure acceleration at predetermined time intervals. The angular velocity information measured by the gyro sensors 131-1 to 131-5 and the acceleration information measured by the IMU sensors 13-1 to 13-5 are sequentially transmitted to the motion measurement device 20 via the module wireless communication units 14-1 to 14-5.

[0037] In the motion measurement device 20, imaging information transmitted from the first sensor module 10-1 to the fifth sensor module 10-5 is acquired by the CPU 23 via the measurement device wired communication unit 21. In addition, angular velocity information and acceleration information transmitted from the first sensor module 10-1 to the fifth sensor module 10-5 are acquired by the CPU 23 via the measurement device wireless communication unit 22.

[0038] In the CPU 23, the imaging information transmitted from the first sensor module 10-1 is acquired by the imaging information acquisition unit 231a of the first module information processing unit 231, and the angular velocity information and acceleration information are acquired as inertial information by the inertial information acquisition unit 231c.

[0039] Furthermore, the imaging information transmitted from the second sensor module 10-2 is acquired by the imaging information acquisition unit 232a of the second module information processing unit 232, and the angular velocity information and acceleration information are acquired as inertial information by the inertial information acquisition unit 232c.

[0040] Furthermore, the imaging information transmitted from the third sensor module 10-3 is acquired by the imaging information acquisition unit 233a of the third module information processing unit 233, and the angular velocity information and acceleration information are acquired as inertial information by the inertial information acquisition unit 233c.

[0041] Furthermore, the imaging information transmitted from the fourth sensor module 10-4 is acquired by the imaging information acquisition unit 234a of the fourth module information processing unit 234, and the angular velocity information and acceleration information are acquired as inertial information by the inertial information acquisition unit 234c.

[0042] Furthermore, the imaging information transmitted from the fifth sensor module 10-5 is acquired by the imaging information acquisition unit 235a of the fifth module information processing unit 235, and the angular velocity information and acceleration information are acquired as inertial information by the inertial information acquisition unit 235c.

[0043] The following describes the processing performed by the first module information processing unit 231, which has acquired information transmitted from the first sensor module 10-1. First, the absolute position estimation unit 231b analyzes the imaging information acquired by the imaging information acquisition unit 231a and uses VisualSLAM technology to estimate the absolute position and direction of the first sensor module 10-1 at predetermined time intervals. The absolute position estimation unit 231b acquires the estimated absolute position and direction information of the first sensor module 10-1 as first estimated information.

[0044] Furthermore, the inertial information processing unit 231d obtains the absolute position and direction at the start of the motion measurement process from the absolute position estimation unit 231b. Then, based on the inertial information obtained by the inertial information acquisition unit 231c, the inertial information processing unit 231d detects the relative amount of movement from the absolute position and direction at the start of the motion measurement process, thereby estimating the position and orientation of the first sensor module 10-1 at predetermined time intervals. The inertial information processing unit 231d obtains the estimated position and orientation information of the first sensor module 10-1 as second estimated information.

[0045] Furthermore, at predetermined time intervals, the inertial information processing unit 231d corrects the coordinate system information it recognizes based on the coordinate system information recognized by the absolute position estimation unit 231b in order to estimate the position and orientation of the first sensor module 10-1.

[0046] Next, the determination unit 231e uses an extended Kalman filter to determine the position and orientation of the first sensor module 10-1 at predetermined time intervals from the information estimated by the absolute position estimation unit 231b and the information estimated by the inertial information processing unit 231d.

[0047] The determination process for determining the position and orientation of the first sensor module 10-1, which is performed by the determination unit 231e at predetermined time intervals, will now be described. The determination unit 231e sets the following equations (1) and (2) in advance as information to be used in the determination process.

[0048]

number

[0049] The decision unit 231e synthesizes the state values x1...x4 of the position or direction of the first sensor module 10-1 calculated by the above formula (1) and the observed values z1...z4 or the observed values z5...z8 calculated by the above formula (2), and calculates a decision value for the position or direction of the first sensor module 10-1. The decision unit 231e presets a Kalman gain indicating which of the two values of the state values x1...x4 and the observed values z1...z4 or the observed values z5...z8 and how much to reflect. Then, the decision unit 231e calculates a decision value for the position or direction of the first sensor module 10-1 based on the set Kalman gain.

[0050] When calculating the decision value for the position or direction of the first sensor module 10-1, the decision unit 231e estimates the uncertainty of the observed value. The decision unit 231e predicts the uncertainty of the decision value in the next decision process from the estimated uncertainty of the observed value and the decision value of the position or direction of the first sensor module 10-1, and updates the Kalman gain based on this. Specifically, if the uncertainty of the observed value is small, the Kalman gain is updated so that the degree of reflection of the observed values z1...z4 or the observed values z5...z8 calculated by the above formula (2) becomes large. Also, if the uncertainty of the observed value is large, the Kalman gain is updated so that the degree of reflection of the state values x1...x4 calculated by the above formula (1) becomes large.

[0051] When performing the decision process at a predetermined time interval in this way, the update process of the Kalman gain executed by the decision unit 231e will be described with reference to the flowchart of FIG. 5.

[0052] At the start of the decision process, the decision unit 231e sets the Kalman gain so that the highly accurate first estimation information estimated by the absolute position estimation unit 231b becomes the object of the decision process (S1). Specifically, the decision unit 231e sets the H k matrix in the above formula (2) to multiply the state values x1...x4 by 1, and sets the value of v k to an appropriate measurement error level. Also, for the observed values z1...z4 with respect to the first estimation information, v kThe value of v relative to the observed values ​​z5...z8 from the second estimation information k The value is lowered. By setting it in this way, the uncertainty of the observed values ​​z5...z8 is reduced, and the Kalman gain is set so that the first estimated information takes precedence over the second estimated information. The decision unit 231e starts the decision process based on the set Kalman gain.

[0053] If strong welding light or sparks are generated during the determination process, the absolute position estimation unit 231b will be unable to obtain proper first estimation information, and the determination unit 231e will determine that the change in the determined value from the previous process is greater than or equal to a predetermined value (YES in S2).

[0054] When the determination unit 231e determines that the amount of change in the determined value from the previous processing is greater than or equal to a predetermined value, it updates the Kalman gain setting so that the second estimated information estimated by the inertia information processing unit 231d becomes the target of the determination processing (S3). Specifically, the determination unit 231e determines the H of equation (2) above. k In the matrix, set the state values ​​x1...x4 to be multiplied by 0, v k The value of is set to an extremely large value. By setting it in this way, the uncertainty of the observed values ​​z1...z4 and z5...z8 increases, and the Kalman gain setting is updated so that the value estimated by the inertial information processing unit 231d becomes dominant.

[0055] Subsequently, the determination unit 231e monitors whether the amount of change in the first estimated information that was being processed before the switch has fallen below a predetermined value (S4). When the welding work that generates welding light and sparks is finished and the change in imaging information acquired by the imaging information acquisition unit 231a becomes small, the determination unit 231e determines that the amount of change in the first estimated information since the previous processing has fallen below a predetermined value (YES in S4).

[0056] When the determination unit 231e determines that the amount of change in the first estimated information since the previous processing has fallen below a predetermined value, it resets the Kalman gain setting so that the first estimated information takes precedence (S5). This concludes the explanation of the Kalman gain update process performed by the determination unit 231e.

[0057] Similarly, the position and orientation of the second sensor module 10-2 is determined in the second module information processing unit 232, the position and orientation of the third sensor module 10-3 is determined in the third module information processing unit 233, the position and orientation of the fourth sensor module 10-4 is determined in the fourth module information processing unit 234, and the position and orientation of the fifth sensor module 10-5 is determined in the fifth module information processing unit 235.

[0058] Next, the motion measurement unit 236 measures the movements of worker X based on the information transitions determined by the first module information processing unit 231 to the fifth module information processing unit 235. Specifically, it measures the transitions of position and direction information determined by each module information processing unit as movements of worker X's back, upper arm, forearm, wrist, and torch T, respectively. Next, the GUI information generation unit 237 generates GUI information that shows the movements of worker X measured by the motion measurement unit 236 as video information. The generated GUI information is stored in the GUI information storage unit. Then, the display unit 25 displays the GUI information stored in the GUI information storage unit 24.

[0059] According to the above embodiment, the motion measurement device acquires, with respect to a predetermined part of the worker X being measured, first estimated information, which is highly accurate position and direction information estimated from imaging information, and second estimated information, which is position and direction information estimated from inertial information. The motion measurement device then switches to using the second estimated information when strong welding light or sparks are generated during welding work and the first estimated information can no longer be properly estimated. As a result, the motion measurement device can measure the movements of worker X accurately and stably.

[0060] Furthermore, after switching the estimated information to be processed, the motion measurement device resets its settings to process the previously processed estimated information when the change in the previously processed estimated information falls below a predetermined value. This allows the motion measurement device to return the processed estimated information to its initial state at an appropriate time after switching the processed estimated information, enabling accurate motion measurement processing.

[0061] Furthermore, the motion measurement device uses multiple sensor modules to acquire first and second estimated information for each of the multiple body parts of the worker X being measured, and uses this information to measure the movements of worker X. In this way, the motion measurement device can measure the movements of multiple body parts of worker X and accurately measure even complex movements.

[0062] Furthermore, the motion measurement device can visualize the worker X's movements by generating and displaying video information showing the measured movements of worker X. This allows for the generation of video information showing the movements of both skilled and novice workers, and by comparing these, it can be used as a tool for novice workers to acquire the same movements as skilled workers.

[0063] Furthermore, although the above-described embodiment described a case in which the actions of worker X performing welding work were measured, the method is not limited to this, and the actions of a person playing sports, a person dancing, or a person playing a musical instrument may also be measured.

[0064] When measuring the movements of athletes, the high speed of the movements can make it difficult to continuously perform motion measurement processing based on the analysis of image data, which requires a long processing time. In such cases, the determination unit of the motion measurement device described above normally determines the position and direction of a predetermined part of the object to be measured based on second estimation information estimated from inertial information. The determination unit may then switch to determining the position and direction of a predetermined part of the object to be measured based on first estimation information estimated from image data when the amount of change in the second estimation information exceeds a predetermined value and proper estimation processing becomes impossible.

[0065] Furthermore, while the above-described embodiment described a case in which the absolute position estimation unit estimates the position and orientation of the sensor module to be measured by analyzing imaging information captured by the camera device, the embodiment is not limited to this. For example, a distance measuring sensor may be installed on the sensor module, and the position and orientation of the sensor module may be estimated based on distance information to multiple points of objects around the worker X measured by this distance measuring sensor.

[0066] Although several embodiments have been described, it is possible to modify or transform the embodiments based on the above disclosure. All components of the above embodiments, and all features described in the claims, may be taken individually and combined, provided that they do not conflict with each other. [Explanation of Symbols]

[0067] 1. Motion Measurement System 10-1~10-5 Sensor Modules 11-1~11-5 Camera equipment 12-1~12-5 Module Wired Communication Section 13-1~13-5 IMU Sensor 14-1~14-5 Module Wireless Communication Section 20. Motion measurement device 21 Measuring device wired communication section 22 Measuring device wireless communication unit 23 CPU 24 GUI information storage section 25 Display section 131-1~131-5 Gyro Sensor 132-1~132-5 Accelerometer 231-235 Module Information Processing Unit 231a~235a Imaging information acquisition unit 231b~235b Absolute position estimation unit 231c~235c Inertial information acquisition section 231d~235d Inertial Information Processing Unit 231e~235e Decision section 232 236 Motion Measurement Unit 237 GUI information generation section

Claims

1. An absolute position information processing unit acquires first estimated information, which is information about the absolute position and direction estimated for a predetermined part of an object whose movement is measured, at predetermined time intervals. An inertial information processing unit acquires second estimated information, which is information about the position and direction of the predetermined part estimated by measuring the inertial force at the predetermined part, at predetermined time intervals. A determination unit that determines the position and direction of a predetermined part of the object to be measured at predetermined time intervals based on the first or second estimation information, The system includes an action measurement unit that measures the motion of the object to be measured based on the information transitions determined by the determination unit, The motion measurement device, when the determination unit is determining the position and direction of a predetermined part of the motion measurement object based on either the first estimation information or the second estimation information, switches to determining the position and direction of the predetermined part of the motion measurement object based on the other estimation information when the amount of change in the relevant estimation information exceeds a predetermined value and proper estimation becomes impossible.

2. The motion measurement device according to claim 1, wherein the determination unit switches to determining the position and direction of a predetermined part of the motion measurement object based on the other estimated information, and then, when the amount of change in the estimated information that was being processed before the switch falls below a predetermined value, it returns to determining the position and direction of a predetermined part of the motion measurement object based on the estimated information that was being processed before the switch.

3. The aforementioned predetermined parts consist of multiple parts, The determination unit determines the position and direction of each of the multiple parts, The motion measurement device according to claim 1 or 2, wherein the motion measurement unit measures the motion of the object to be measured based on the transition of information for each part determined by the determination unit.

4. The motion measurement device according to claim 1 or 2, further comprising a video information generation unit that generates video information showing the motion of the object to be measured, as measured by the motion measurement unit.

5. First estimated information, which is information about the absolute position and direction estimated for a predetermined part of the object being measured, is acquired at predetermined time intervals. Second estimated information, which is information about the position and direction of the predetermined part estimated by measuring the inertial force at the predetermined part, is acquired at predetermined time intervals. Based on the first estimated information or the second estimated information, the position and direction of a predetermined part of the object to be measured are determined at predetermined time intervals. When determining the position and direction of a predetermined part of the object to be measured based on either the first or second estimation information, if the amount of change in the relevant estimation information exceeds a predetermined value and proper estimation becomes impossible, the system switches to determining the position and direction of the predetermined part of the object to be measured based on the other estimation information. A motion measurement method for measuring the motion of an object to be measured based on the transition of determined information.

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