Landing stability evaluation system, landing stability evaluation method, landing stability evaluation processing device, and landing stability evaluation processing method

Abstract

To provide a landing stability evaluation system capable of accurately evaluating stability in landing.SOLUTION: A landing stability evaluation system 1 evaluates stability in landing of an object. The landing stability evaluation system 1 comprises: a planar body which receives a load generated following landing of the object; a plurality of sensors which detects the load at a plurality of different positions on the planar body, at each of a plurality of different time points; and a processing part 20. The processing part 20 acquires an action position where the load acts on the planar body on the basis of the load detected by the plurality of sensors, with respect to each of the plurality of time points, then, acquires a function identification parameter for identifying a function in which the action position approximates a target value following time course, on the basis of the action position acquired for each time point.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a landing stability evaluation system, a landing stability evaluation method, a landing stability evaluation processing device, and a landing stability evaluation processing method. [Background technology]

[0002] There are known center of gravity sway systems used to determine the presence or absence of balance disorders. For example, the center of gravity sway system described in Patent Document 1 includes a flat plate that receives a load generated when a subject steps, acquires time-series data of the center of pressure, which is the position on the flat plate where the load acts, and acquires the total trajectory length and perimeter area of ​​the movement trajectory of the center of pressure based on the acquired time-series data. Furthermore, the center of gravity sway system determines the presence or absence of balance disorders based on the acquired total trajectory length and perimeter area. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-217884 Summary of the Invention [Problem to be solved by the invention]

[0004] Since instability during landing is known to be one of the causes of ankle sprains and falls, if the stability during landing can be evaluated with high accuracy, it will be possible to appropriately evaluate the effectiveness of treatment, rehabilitation training, or the use of exercise aids such as insoles.

[0005] Therefore, it is conceivable to use the center of gravity stabilization system to evaluate the stability of landing after jumping while standing on one leg. However, the total trajectory length and perimeter area of ​​the movement trajectory of the center of pressure vary relatively greatly depending on posture adjustment due to balance function, jump height, and body weight. For this reason, the center of gravity stabilization system has the problem that it may not be possible to evaluate the stability of landing with high accuracy.

[0006] One of the objects of the present invention is to evaluate the stability during landing with high accuracy. [Means for solving the problem]

[0007] In one aspect, the landing stability assessment system assesses the stability of a subject's landing. The landing stability evaluation system comprises a planar body that receives the load generated when a subject lands, a plurality of sensors that detect the load at a plurality of different positions on the planar body at each of a plurality of different times, and a processing unit. The processing unit acquires an action position, which is the position at which the load acts on the planar body, based on the load detected by the multiple sensors for each of the multiple time points, and acquires a function identification parameter that identifies a function by which the action position approaches a target value over time, based on the action position acquired for each of the multiple time points.

[0008] In another aspect, a method for assessing landing stability assesses a subject's stability in landing. The landing stability evaluation method is as follows: Detecting loads at a plurality of different positions on a planar body that receives the loads generated when the subject lands, at each of a plurality of different time points; acquiring an action position, which is a position on the planar body where the load acts, based on the loads detected by the plurality of sensors for each of the plurality of time points; acquiring a function specifying parameter that specifies a function by which the action position approaches a target value over time based on the action position acquired for each of the plurality of time points; This includes:

[0009] In another aspect, the landing stability assessment processing device assesses the stability of the subject's landing. The landing stability evaluation processing device includes a processing unit. The processing unit acquires, for each of a plurality of different time points, an action position, which is the position at which the load acts on the planar body, based on the load detected at a plurality of different positions on the planar body that receives the load generated when the subject lands, and acquires, based on the action position acquired for each of the plurality of time points, a function identification parameter that identifies a function by which the action position approaches a target value over time.

[0010] In another aspect, a landing stability evaluation processing method evaluates the stability of a subject's landing. The landing stability evaluation processing method includes: At each of a plurality of different time points, based on loads detected at a plurality of different positions on the planar body that receives the loads generated when the subject lands, an action position, which is a position on the planar body where the loads act, is acquired; obtaining a function specifying parameter that specifies a function by which the action position approaches the target value over time based on the action position obtained for each of the plurality of time points; This includes: [Effects of the Invention]

[0011] Stability during landing can be evaluated with high accuracy. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating the configuration of a landing stability evaluation system according to a first embodiment. [Figure 2] FIG. 1 is a top view of a floor reaction force meter according to a first embodiment. [Figure 3] FIG. 1 is a side view of a floor reaction force meter according to a first embodiment. [Figure 4] 1 is a block diagram showing the configuration of a landing stability evaluation processing device according to a first embodiment. [Figure 5] FIG. 2 is a block diagram showing the functions of the landing stability evaluation processing device of the first embodiment. [Figure 6] 10 is a graph showing an example of change in action position over time acquired by the landing stability evaluation processing device of the first embodiment. [Figure 7] 4 is a flowchart showing processing executed by the landing stability evaluation processing device of the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of a landing stability evaluation system, a landing stability evaluation method, a landing stability evaluation processing device, and a landing stability evaluation processing method of the present invention will be described with reference to FIGS.

[0014] First Embodiment (overview) The landing stability evaluation system of the first embodiment evaluates the landing stability of a subject. The landing stability evaluation system includes a planar body that receives the load generated when a subject lands, a plurality of sensors that detect the load at a plurality of different positions on the planar body at each of a plurality of different times, and a processing unit. The processing unit acquires an action position, which is the position at which the load acts on the planar body, based on the load detected by the multiple sensors for each of the multiple time points, and acquires a function identification parameter that identifies a function by which the action position approaches a target value over time, based on the action position acquired for each of the multiple time points.

[0015] When the subject lands, the action position approaches the target value over time. Therefore, the function-specific parameters reflect the change in the action position over time with high accuracy. Furthermore, the change in the action position over time has a strong correlation with the stability of the landing. Therefore, according to the landing stability evaluation system, the stability of the landing can be evaluated with high accuracy by using the function-specific parameters. Next, the landing stability evaluation system of the first embodiment will be described in more detail.

[0016] (composition) As shown in Fig. 1, the landing stability evaluation system 1 evaluates the landing stability of an object. In this example, the object is a human. However, the object may be an animal other than a human. The object may also be a robot having at least one leg.

[0017] The landing stability evaluation system 1 includes a floor reaction force meter 10 and a landing stability evaluation processing device 20. In this example, the landing stability evaluation processing device 20 corresponds to the processing unit. The floor reaction force meter 10 may also be referred to as a force plate.

[0018] The floor reaction force meter 10 will be described below using a right-handed Cartesian coordinate system having an x-axis, a y-axis, and a z-axis as shown in FIGS.

[0019] In this example, the x-axis direction, the y-axis direction, and the z-axis direction may be respectively expressed as the left-right direction of the floor reaction force meter 10, the front-to-back direction of the floor reaction force meter 10, and the up-to-down direction of the floor reaction force meter 10. Also, in this example, the positive direction of the x-axis, the negative direction of the x-axis, the positive direction of the y-axis, the negative direction of the y-axis, the positive direction of the z-axis, and the negative direction of the z-axis may be respectively expressed as the right direction of the floor reaction force meter 10, the left direction of the floor reaction force meter 10, the front direction of the floor reaction force meter 10, the rear direction of the floor reaction force meter 10, the up direction of the floor reaction force meter 10, and the down direction of the floor reaction force meter 10. In this example, the positive direction of the z axis and the negative direction of the z axis correspond to the vertically upward direction and the vertically downward direction, respectively.

[0020] Fig. 1 is a perspective view of the floor reaction force meter 10. Fig. 2 is a top view of the floor reaction force meter 10 (in other words, a view of the floor reaction force meter 10 viewed in the negative direction of the z-axis). Fig. 3 is a side view of the floor reaction force meter 10 (in other words, a view of the floor reaction force meter 10 viewed in the positive direction of the y-axis).

[0021] The floor reaction force meter 10 is in the form of a flat plate extending on a horizontal plane. The floor reaction force meter 10 is rectangular (square in this example) when viewed from above. The floor surface GS forms a flat surface (a horizontal surface in this example) and has a recess in which the floor reaction force meter 10 is accommodated. In this example, the floor reaction force meter 10 is placed on the floor surface GS so that the end face of the floor reaction force meter 10 in the positive direction of the z axis (in other words, the top surface of the floor reaction force meter 10) is accommodated in a recess in the floor surface GS and forms the same plane as the part of the floor surface GS other than the recess. Note that the top surface of the floor reaction force meter 10 and the part of the floor surface GS other than the recess may be slightly different in position in the z axis direction. Furthermore, if the floor surface GS does not have a recess, the floor reaction force meter 10 may be placed on the floor surface GS so that it protrudes slightly from the flat floor surface GS.

[0022] The floor reaction force meter 10 includes a support section 11, a plurality of (four in this example) load sensors 12-1 to 12-4, and a force receiving section 13. The number of load sensors included in the floor reaction force meter 10 may be three, or five or more. The support part 11 is a planar body extending in a horizontal plane. In this example, the support part 11 is a flat plate extending in a horizontal plane. The support part 11 is rectangular (in this example, square) in top view. The support part 11 constitutes the end part of the floor reaction force meter 10 in the negative direction of the z axis.

[0023] The force receiving unit 13 is a planar body extending in a horizontal plane. In this example, the force receiving unit 13 is a flat plate extending in a horizontal plane. The force receiving unit 13 is rectangular (square in this example) when viewed from above. The force receiving unit 13 constitutes the end of the force reaction meter 10 in the positive direction of the z axis. Therefore, the force receiving unit 13 receives the load generated when the subject lands.

[0024] Force receiving unit 13 has a marker 131. Marker 131 is located on the end surface of force receiving unit 13 in the positive direction of the z-axis (in other words, on the top surface of force receiving unit 13). Marker 131 indicates a target position for the subject to land on (in other words, the target position). In this example, the target position is the center of force receiving unit 13 in the x-axis direction and the center of force receiving unit 13 in the y-axis direction (in other words, the center of force receiving unit 13 when viewed from above).

[0025] Marker 131 is cross-shaped and has a first linear portion that passes through the center of force receiving portion 13 in the y-axis direction and extends in the x-axis direction, and a second linear portion that passes through the center of force receiving portion 13 in the x-axis direction and extends in the y-axis direction. In this example, the position where the first linear portion and the second linear portion intersect with each other represents the target position of marker 131.

[0026] Force receiving portion 13 is supported by support portion 11 via a plurality of load sensors 12-1 to 12-4 so as to be spaced apart from support portion 11 by a predetermined distance in the z-axis direction.

[0027] The plurality of load sensors 12-1 to 12-4 are sandwiched between the support portion 11 and the force receiving portion 13. In other words, the plurality of load sensors 12-1 to 12-4 are interposed between the support portion 11 and the force receiving portion 13.

[0028] The multiple load sensors 12-1 to 12-4 are located at four corners, respectively, in a top view of the floor reaction force meter 10. In this example, the load sensor 12-1 is located at a corner of the four corners that is on the positive side of the x-axis and the positive side of the y-axis, the load sensor 12-2 is located at a corner of the four corners that is on the negative side of the x-axis and the positive side of the y-axis, the load sensor 12-3 is located at a corner of the four corners that is on the negative side of the x-axis and the negative side of the y-axis, and the load sensor 12-4 is located at a corner of the four corners that is on the positive side of the x-axis and the negative side of the y-axis.

[0029] In this example, the two load sensors 12-1 and 12-4 and the two load sensors 12-2 and 12-3 are positioned symmetrically with respect to a first reference plane that is perpendicular to the x-axis and passes through the center in the x-axis direction of the force receiving portion 13. In other words, the distance between each of the multiple load sensors 12-1 to 12-4 and the first reference plane is a predetermined first distance.

[0030] Furthermore, in this example, the two load sensors 12-1 and 12-2 and the two load sensors 12-4 and 12-3 are positioned symmetrically with respect to a second reference plane that is perpendicular to the y-axis and passes through the center of the force receiving portion 13 in the y-axis direction. In other words, the distance between each of the multiple load sensors 12-1 to 12-4 and the second reference plane is a predetermined second distance. In this example, the second distance is equal to the first distance. Note that the second distance may be different from the first distance.

[0031] Each of the plurality of load sensors 12-1 to 12-4 detects a load in the z-axis direction. Therefore, in this example, the plurality of load sensors 12-1 to 12-4 detects the load received by the end face of force receiving portion 13 in the positive direction of the z-axis (in other words, the upper surface of force receiving portion 13) at a plurality of different positions on force receiving portion 13 (in this example, four corners of force receiving portion 13 when viewed from above). Each of the plurality of load sensors 12-1 to 12-4 may be expressed as a load cell.

[0032] The landing stability evaluation processing device 20 is an information processing device or a computer. For example, the computer may be at least a part of a stationary game console, a portable game console, a television set, a smartphone, or the like. For example, the landing stability evaluation processing device 20 may be a desktop computer, a laptop computer, a tablet computer, a smartphone, or the like. Note that the landing stability evaluation processing device 20 may be composed of multiple devices connected to each other so that they can communicate with each other.

[0033] As shown in FIG. 4, the landing stability evaluation processing device 20 includes a processing device 21, a storage device 22, an input device 23, an output device 24, and a connection device 25, which are connected to one another via a bus BU. The processing device 21 executes a program stored in the storage device 22 to control the storage device 22, the input device 23, the output device 24, and the connection device 25. In this way, the processing device 21 realizes the functions described below.

[0034] In this example, the processing device 21 is a central processing unit (CPU). Note that the processing device 21 may include a micro processing unit (MPU), a graphics processing unit (GPU), or a digital signal processor (DSP) instead of or in addition to the CPU.

[0035] In this example, the storage device 22 includes a volatile memory and a non-volatile memory, such as at least one of a random access memory (RAM), a read only memory (ROM), a semiconductor memory, an organic memory, a hard disk drive (HDD), and a solid state drive (SSD).

[0036] The input device 23 receives information input from outside the landing stability evaluation processing device 20. In this example, the input device 23 includes a keyboard and a mouse. The input device 23 may also include a microphone.

[0037] The output device 24 outputs information to the outside of the landing stability evaluation processing device 20. In this example, the output device 24 includes a display. The output device 24 may also include a speaker. The landing stability evaluation processing device 20 may include a touch panel display that constitutes both the input device 23 and the output device 24 .

[0038] The connection device 25 is communicably connected to devices external to the landing stability evaluation processing device 20. In this example, the connection device 25 is communicably connected to the floor reaction force meter 10. The connection device 25 receives, from the floor reaction force meter 10, detection information indicating the load detected by the multiple load sensors 12-1 to 12-4 provided in the floor reaction force meter 10.

[0039] (function)

[0040] 5, the functions of the landing stability evaluation processing device 20 include an action position acquisition unit 201, an action position storage unit 202, a function specifying parameter acquisition unit 203, and a stability evaluation unit 204. Note that the floor reaction force meter 10 may have at least some of the functions of the landing stability evaluation processing device 20 instead of the landing stability evaluation processing device 20. Furthermore, the landing stability evaluation processing device 20 may be housed inside the floor reaction force meter 10.

[0041] The action position acquisition unit 201 acquires the action position based on the detection information representing the loads detected by the plurality of load sensors 12-1 to 12-4 every time a detection timing arrives. In this example, the detection timing occurs every time a predetermined detection period has elapsed. In this example, the detection period is 2 ms. However, the detection period may be a time between 0.5 ms and 50 ms. In this example, the acting position is the position in the x-axis direction where the load acts on the upper surface of force receiving portion 13.

[0042] In this example, the action position acquisition unit 201 acquires the action position P(t) at each time point t based on the following mathematical formula 1. In this example, the time point t represents the time elapsed since the object landed. In this example, the action position is represented by a coordinate system whose origin is the center of the force receiving unit 13 in the x-axis direction. W1(t) represents the load detected by load sensor 12-1 at each time point t, W2(t) represents the load detected by load sensor 12-2 at each time point t, W3(t) represents the load detected by load sensor 12-3 at each time point t, and W4(t) represents the load detected by load sensor 12-4 at each time point t. D represents the first distance.

number

[0043] In this example, the subject stands on one foot (for example, the right foot or the left foot) at a predetermined waiting position while maintaining the state in which the left-right direction of the subject coincides with the x-axis direction, and then hops while standing on that foot, thereby landing at the target position while standing on that foot. The waiting position is on a line that passes through the target position and extends in the x-axis direction, and is adjacent to the floor reaction force meter 10 in the x-axis direction.

[0044] For example, the standby position is on a line that passes through the target position and extends in the x-axis direction, is adjacent to the floor reaction force meter 10 in the x-axis direction, and is a position in the positive direction of the x-axis relative to the floor reaction force meter 10. Note that the standby position may also be on a line that passes through the target position and extends in the x-axis direction, is adjacent to the floor reaction force meter 10 in the x-axis direction, and is a position in the negative direction of the x-axis relative to the floor reaction force meter 10.

[0045] Therefore, in this example, the subject's landing occurs as the subject moves along a direction of movement, which in this example is a left-right direction of the subject. In this example, the subject's movement is a jump performed while standing on one leg. Therefore, in this example, the action position acquisition unit 201 uses the position in the movement direction of the object (in this example, the x-axis direction) as the action position.

[0046] The movement direction may be the front-to-back direction of the object. The movement direction may also be a direction including both a front-to-back component and a left-to-right component of the object (in other words, a diagonal direction of the object). The movement of the object may also be a jump performed while standing on both feet.

[0047] The solid line in FIG. 6 represents an example of the change over time in the action position acquired by the action position acquisition unit 201.

[0048] The action position storage unit 202 stores, in the storage device 22, action position information in which the action position P(t) acquired by the action position acquisition unit 201 and the time point t are associated with each other.

[0049] The function specifying parameter acquisition unit 203 acquires a function specifying parameter based on the action position P(t) for each of a plurality of different time points represented by the action position information stored in the action position storage unit 202. The function specifying parameter is a parameter that specifies a function by which the action position approaches the target value over time.

[0050] In this example, the function represents the step response of a system having a first-order lag element. Specifically, the function used by the function specifying parameter acquisition unit 203 is expressed by Equation 2. P0 represents the target value. In this example, the target value P0 corresponds to the position in the x-axis direction where the object lands. A represents the initial deviation. In this example, the initial deviation A represents the difference between the action position P(0) and the target value P0 when the time t is 0. τ represents the time constant of the first-order lag element. In this example, the function-specific parameters include the target value P0, the initial deviation A, and the time constant τ.

number

[0051] The dashed lines in FIG. 6 represent an example of a function specified by the function specifying parameters acquired by the function specifying parameter acquisition unit 203. In this example, the function-specific parameters are obtained by using the least squares method. However, the function-specific parameters may be obtained by using a method other than the least squares method (for example, maximum likelihood estimation method, etc.).

[0052] The stability evaluation unit 204 evaluates the stability of the target's landing based on the function specifying parameters acquired by the function specifying parameter acquisition unit 203. In this example, the stability evaluation unit 204 evaluates the target's landing stability so that the smaller the time constant τ, the higher the evaluation value. For example, the stability evaluation unit 204 acquires an evaluation value based on the time constant τ, and outputs evaluation information representing the acquired evaluation value via the output device 24 (in this example, it is displayed on a display). For example, the evaluation value has a value that increases as the stability of the target's landing increases.

[0053] (operation) Next, the operation of the landing stability evaluation system 1 will be described with reference to FIG. The landing stability evaluation processing device 20 executes the processing shown in the flowchart of FIG. First, the landing stability evaluation processing device 20 waits until the detection timing arrives (determination of "No" in step S101 in FIG. 7). In this example, the detection timing arrives every time a detection period elapses.

[0054] When the detection timing arrives, the landing stability evaluation processing device 20 determines "Yes" in step S101 and determines whether the start condition is satisfied (step S102 in FIG. 7). In this example, the start condition is that the total load is greater than a predetermined first threshold. The total load is the sum of the loads detected by the multiple load sensors 12-1 to 12-4.

[0055] Before the object lands, the start condition is not satisfied, so the landing stability evaluation processing device 20 determines "No" in step S102 and returns to step S101.

[0056] Then, while maintaining the left-right direction of the subject aligned with the x-axis direction, the subject stands on one foot (in this example, the right foot) at a predetermined waiting position, jumps on that foot, and lands at the target position on that foot.

[0057] As a result, the start condition is satisfied. Therefore, the landing stability evaluation processing device 20 judges "Yes" in step S102 and waits until the detection timing arrives (judgment of "No" in step S103 in FIG. 7). When the detection timing arrives, the landing stability evaluation processing device 20 judges "Yes" in step S103 and acquires the action position P(t) based on the loads detected by each of the plurality of load sensors 12-1 to 12-4 at time point t (step S104 in FIG. 7). In this example, time point t represents the time that has elapsed since the start condition was satisfied.

[0058] Next, the landing stability evaluation processing device 20 stores, in the storage device 22, action position information in which the acquired action positions P(t) and the time points t are associated with each other (step S105 in FIG. 7).

[0059] Next, the landing stability evaluation processing device 20 determines whether or not a termination condition is satisfied (step S106 in FIG. 7). In this example, the termination condition is that the maximum value of the loads detected by the plurality of load sensors 12-1 to 12-4 is smaller than a predetermined second threshold value. In this example, the second threshold value is smaller than the first threshold value.

[0060] The termination condition is not satisfied until the target posture is stabilized. Therefore, the landing stability evaluation processing device 20 determines "No" in step S106 and returns to step S103. Then, the landing stability evaluation processing device 20 repeatedly executes the processes of steps S103 to S106 until the termination condition is satisfied.

[0061] Thereafter, when the posture of the target becomes stable, the termination condition is satisfied. Therefore, the landing stability evaluation processing device 20 determines "Yes" in step S106, and acquires the function specifying parameters based on the action position information stored in the storage device 22 (step S107 in FIG. 7).

[0062] Next, the landing stability evaluation processing device 20 acquires evaluation information based on the acquired function specifying parameters, and outputs the acquired evaluation information via the output device 24 (step S108 in FIG. 7). Thereby, the landing stability evaluation processing device 20 ends the processing of FIG.

[0063] The start condition may be that the maximum value of the loads detected by the plurality of load sensors 12-1 to 12-4 is greater than a predetermined third threshold value.

[0064] The termination condition may also be that the amount of change in the operating position is smaller than a predetermined fourth threshold. For example, the amount of change in the operating position may be the difference between the maximum and minimum values ​​of the operating position during a predetermined time period in the past. In this case, the fourth threshold may be determined by multiplying the amount of change in the operating position during a predetermined period starting when the start condition is satisfied by a predetermined coefficient.

[0065] The termination condition may also be that the time during which the magnitude of the difference between the action position and the target value (0 in this example) remains smaller than a predetermined fifth threshold value is longer than a predetermined sixth threshold value.

[0066] Alternatively, the termination condition may be that the amount of change in the function identifying parameter is smaller than a predetermined seventh threshold. In this case, the process of step S107 is executed before the process of step S106. For example, the amount of change in the function identifying parameter may be the magnitude of the difference between the time constant included in the function identifying parameter acquired at the previous detection timing and the time constant included in the function identifying parameter acquired at the current detection timing.

[0067] As described above, the landing stability evaluation system 1 of the first embodiment evaluates the stability of landing of a subject. The landing stability evaluation system 1 includes a planar body (in this example, force receiving unit 13) that receives a load generated when the subject lands, a plurality of sensors (in this example, a plurality of load sensors 12-1 to 12-4) that detect the load at a plurality of different positions on the planar body at a plurality of different times, and a processing unit (in this example, landing stability evaluation processing device 20).

[0068] The processing unit acquires an action position, which is the position at which the load acts on the planar body, based on the load detected by the multiple sensors for each of the multiple time points, and acquires a function identification parameter that identifies a function by which the action position approaches a target value over time, based on the action position acquired for each of the multiple time points.

[0069] When the subject lands, the action position approaches the target value over time. Therefore, the function-specific parameters reflect the change in the action position over time with high accuracy. Furthermore, the change in the action position over time has a strong correlation with the stability of the landing. Therefore, according to the landing stability evaluation system 1, the stability of the landing can be evaluated with high accuracy by using the function-specific parameters.

[0070] Furthermore, in the landing stability evaluation system 1 of the first embodiment, the function represents a step response of a system having a first-order lag element, and the function-specific parameters include a time constant of the first-order lag element. The processing unit evaluates the stability of the target's landing so that the smaller the time constant, the higher the evaluation value.

[0071] The step response of a system with a first-order lag element accurately represents the change in the action position over time. Therefore, the time constant of the first-order lag element accurately reflects the time it takes for the action position to reach the target value. Therefore, the landing stability evaluation system 1 can evaluate the stability of landing with high accuracy.

[0072] Furthermore, in the landing stability evaluation system 1 of the first embodiment, the landing of the object is performed in accordance with the movement of the object along the movement direction. The processing unit uses at least one of a position in the movement direction and a position in a direction perpendicular to the movement direction (in this example, a position in the movement direction) as the action position.

[0073] For example, the stability of landing that accompanies the movement of an object is likely to be reflected in the change over time of the action position in the direction of movement or the change over time of the action position in the direction perpendicular to the direction of movement. Therefore, the landing stability evaluation system 1 can evaluate the stability of landing with high accuracy.

[0074] Furthermore, in the landing stability evaluation system 1 of the first embodiment, the movement direction is the left-right direction of the subject, and the movement of the subject is a jump performed while standing on one leg. The processing unit uses a position in the movement direction as the action position.

[0075] The stability of landing after a subject (e.g., a human) jumps left and right while standing on one leg has a strong correlation with the change over time in the load position, which is the position in the left and right direction where the load acts on the planar body. Therefore, the landing stability evaluation system 1 can evaluate the stability of landing with high accuracy.

[0076] The landing stability evaluation processing device 20 of the modified example of the first embodiment may acquire the function identifying parameters based on action position information associated with a time point not included in the exclusion period, among the action position information stored in the storage device 22. For example, the exclusion period may consist of at least one of a first period that starts when a start condition is satisfied and has a length of a predetermined first time, and a second period that ends when a termination condition is satisfied and has a length of a predetermined second time.

[0077] Noise contained in the load detection tends to be large during the first period or the second period. Therefore, according to the landing stability evaluation processing device 20 of the above modified example, the function specifying parameters can be acquired with high accuracy.

[0078] Furthermore, the landing stability evaluation processing device 20 of the modified first embodiment may use a position in a direction perpendicular to the moving direction of the object (in this example, the y-axis direction) as the action position. In this case, the landing stability evaluation processing device 20 obtains the action position P(t) at each time point t based on the following formula 3. In this example, D represents the second distance.

number

[0079] Furthermore, the landing stability evaluation processing device 20 of the modified example of the first embodiment may acquire a first function specifying parameter by using a position in the movement direction of the object (in this example, the x-axis direction) as the position of action, and may acquire a second function specifying parameter by using a position in a direction perpendicular to the movement direction of the object (in this example, the y-axis direction) as the position of action. In this case, the landing stability evaluation processing device 20 may evaluate the stability of the landing of the object based on both the time constant included in the first function specifying parameter and the time constant included in the second function specifying parameter.

[0080] The floor reaction force meter 10 of the first embodiment is placed on a floor surface GS. Note that the floor reaction force meter 10 of the modified first embodiment may constitute at least a part of a prosthetic leg or a leg of a robot. The upper surface of the force receiving section 13 of the floor reaction force meter 10 of the first embodiment is flat. However, the force receiving section 13 of the floor reaction force meter 10 of the modified example of the first embodiment may be curved. In this case, the floor reaction force meter 10 may constitute at least a part of the insole or sole.

[0081] The present invention is not limited to the above-described embodiment. For example, various modifications that can be understood by those skilled in the art may be made to the above-described embodiment without departing from the spirit of the present invention.

[0082] For example, in the landing stability evaluation system 1 according to a modification of the first embodiment, the floor reaction force meter 10 may generate action position information in which the action position P(t) and the time t are associated with each other for each of a plurality of different points in time. In this case, the landing stability evaluation processing device 20 may receive the action position information from the floor reaction force meter 10. In this case, the landing stability evaluation processing device 20 may also receive the action position information generated by the floor reaction force meter 10 using an information-readable storage medium. [Explanation of symbols]

[0083] 1. Landing stability evaluation system 10 Floor reaction force meter 11 Support part 12-1~12-4 Load sensors 13 Force receiving part 131 Marker 20 Landing stability evaluation processing device 21 Processing equipment 22 Storage device 23 Input Devices 24 Output Devices 25 Connection Device 201 Action position acquisition unit 202 Action position memory section 203 Function specific parameter acquisition unit 204 Stability Evaluation Section BU Bus GS floor

Claims

1. A landing stability evaluation system for evaluating stability in landing of a subject, a planar body that receives a load generated by the landing; a plurality of sensors that detect the load at a plurality of different positions on the planar body at a plurality of different times; a processing unit that acquires an action position, which is a position on the planar body where the load acts, based on the loads detected by the plurality of sensors for each of the plurality of time points, and acquires, based on the action position acquired for each of the plurality of time points, a function specifying parameter that represents a change in the action position over time and specifies a function by which the action position approaches a target value over time; A landing stability evaluation system comprising:

2. The landing stability evaluation system according to claim 1, The function represents the step response of a system with a first-order lag element, the function-specific parameters include a time constant of the first-order lag element; The processing unit evaluates the stability so that the stability increases as the time constant decreases.

3. The landing stability evaluation system according to claim 1 or 2, the landing is performed in association with the movement of the object along a movement direction; A landing stability evaluation system, wherein the processing unit uses at least one of a position in the movement direction and a position in a direction perpendicular to the movement direction as the action position.

4. The landing stability evaluation system according to claim 3, the movement direction is a left-right direction of the object, The movement of the subject is a jump performed while standing on one leg, The processing unit uses a position in the movement direction as the action position.

5. A landing stability evaluation method for evaluating the stability of a subject's landing, comprising: At each of a plurality of different time points, the load is detected at a plurality of different positions on a planar body that receives the load generated by the landing, acquiring an action position, which is a position on the planar body where the load acts, based on the loads detected at the plurality of positions for each of the plurality of time points; acquiring a function specifying parameter that specifies a function that represents a change in the action position with respect to time and that causes the action position to approach a target value over time, based on the action position obtained for each of the plurality of time points; A landing stability evaluation method comprising:

6. A landing stability evaluation processing device that evaluates the stability of a target's landing, A landing stability evaluation processing device comprising: a processing unit that acquires, for each of a plurality of different time points, an action position, which is the position on the planar body where the load acts, based on the load detected at a plurality of different positions on the planar body that receives the load generated by the landing, and acquires, based on the action position acquired for each of the plurality of time points, a function identification parameter that represents the change in the action position over time and identifies a function by which the action position approaches a target value over time.

7. A landing stability evaluation processing method for evaluating stability in landing of a target, At each of a plurality of different time points, based on the load detected at a plurality of different positions on the planar body that receives the load generated by the landing, an action position is acquired, which is a position on the planar body where the load acts, for each of the plurality of time points; acquiring a function specifying parameter that specifies a function that represents a change in the action position with respect to time and that causes the action position to approach a target value over time, based on the action position obtained for each of the plurality of time points; A landing stability evaluation processing method, comprising:

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