Information processing device, electronic appliance, information processing system, information processing method, and program

Abstract

An information processing device according to the present invention is provided with a control unit. The control unit acquires first data concerning motion of the thigh of a user from a first sensor instrument. At least on the basis of the first data, the control unit estimates the timings of landing of the feet of the user and acquires estimated values of the loads that will be applied to the knee joints of the user.

Description

Information processing device, electronic device, information processing system, information processing method, and program Cross-reference to related applications

[0001] This application claims priority to Japanese Patent Application No. 2021-090694, filed on May 28, 2021, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to an information processing device, an electronic device, an information processing system, an information processing method, and a program.

[0003] Conventionally, techniques for evaluating the load applied to a user's joints are known.

[0004] For example, the joint load visualization system described in Patent Document 1 includes a range camera that measures a person's three-dimensional posture, a force sensor, and a computing means. The force sensor detects the magnitude and direction of the force and moment applied to a tool that the person's hand comes into contact with. The computing means calculates the load on the joints of a multi-joint link model that mimics a human, based on the information on the person's posture acquired by the range camera and the information on the force and moment acquired by the force sensor.

[0005] For example, the system described in Patent Document 2 includes a first sensing assembly that senses a characteristic related to the physiological function of the joint, a second sensing assembly that senses a characteristic related to the structure of the joint, and a health status assessment unit that interprets the characteristics from the first and second sensing assemblies to assess the health status of the joint.

[0006] Japanese Patent Application Laid-Open No. 2016-179048 Japanese Patent Application Laid-Open No. 2018-521722

[0007] An information processing device according to one embodiment of the present disclosure includes a control unit that acquires first data regarding the movement of a user's thigh from a first sensor device, estimates the timing of the user's foot landing based on at least the first data, and acquires an estimated value of the load applied to the user's knee joint.

[0008] An information processing device according to one embodiment of the present disclosure includes a control unit that acquires third data related to the movement of a user's ankle from a third sensor device, acquires a reference angular velocity of the user based on at least the third data, the reference angular velocity being the angular velocity of the ankle during a contact phase in which at least a part of the foot is in contact with the ground, and acquires an estimated value of the load applied to the user's knee joint calculated based on the correlation between the reference angular velocity and the load applied to the knee joint and the user's reference angular velocity.

[0009] The electronic device according to an embodiment of the present disclosure includes a notification unit that notifies information about the estimated value acquired by the information processing device.

[0010] An information processing system according to one embodiment of the present disclosure includes: a first sensor device; and an information processing device that acquires first data related to the movement of a user's thigh from the first sensor device, wherein the information processing device estimates the timing at which the user's foot lands based on at least the first data, and acquires an estimated value of the load applied to the user's knee joint.

[0011] An information processing method according to one embodiment of the present disclosure includes: acquiring first data relating to the movement of a user's thigh from a first sensor device; and estimating the timing of the user's foot landing based on at least the first data, and acquiring an estimate of the load applied to the user's knee joint.

[0012] A program according to one embodiment of the present disclosure causes a computer to: acquire first data relating to the movement of a user's thigh from a first sensor device; and, based on at least the first data, estimate the timing of the user's foot landing and acquire an estimated value of the load applied to the user's knee joint.

[0013] 14 is a diagram showing a schematic configuration of an information processing system according to an embodiment of the present disclosure. FIG. 14 is a functional block diagram showing the configuration of the information processing system shown in FIG. 1. FIG. 14 is a diagram showing a schematic configuration of a foot. FIG. 14 is a diagram for explaining a walking cycle. FIG. 14 is a graph showing the angle of the knee joint of a subject with a large load applied to the knee joint. FIG. 14 is a graph showing the angle of the knee joint of a subject with a small load applied to the knee joint. FIG. 14 is a graph showing the angular velocity of the thigh of a subject with a large load applied to the knee joint. FIG. 14 is a graph showing the angular velocity of the thigh of a subject with a small load applied to the knee joint. FIG. 14 is a diagram showing the distribution of the load applied to the knee joint relative to the angular velocity of the thigh. FIG. 14 is a graph showing the angular velocity of the knee joint of a subject with a large load applied to the knee joint. FIG. 14 is a graph showing the angular velocity of the knee joint of a subject with a small load applied to the knee joint. FIG. 14 is a diagram showing the distribution of the load applied to the knee joint relative to the angular velocity of the ankle. FIG. 14 is a flowchart showing the operation of an evaluation process executed by the electronic device shown in FIG. 1. FIG. 14 is a functional block diagram showing the configuration of an information processing system according to another embodiment of the present disclosure. FIG. 14 is a sequence diagram showing the operation of the evaluation process executed by the information processing system shown in FIG. 14. FIG. 15 is a sequence diagram showing the operation of an evaluation process executed by the information processing system shown in FIG. 14 .

[0014] There is a need for a technique for easily evaluating the load applied to a user's joints. According to the present disclosure, it is possible to provide a technique for easily evaluating the load applied to a user's joints.

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same components are denoted by the same reference numerals.

[0016] In this disclosure, a "local coordinate system" is a coordinate system based on the position of a sensor device. The local coordinate system is composed of, for example, three mutually orthogonal axes. Hereinafter, the three axes constituting the local coordinate system are assumed to be parallel to the front-to-back direction, the left-to-right direction, and the up-to-down direction, respectively, as viewed from the sensor device.

[0017] In the present disclosure, a "global coordinate system" refers to a coordinate system based on a position in the space in which the user walks. The global coordinate system is composed of, for example, three mutually orthogonal axes. Hereinafter, the three axes constituting the global coordinate system are assumed to be parallel to the front-to-back direction, the left-to-right direction, and the up-to-down direction, respectively, as seen from the user.

[0018] (System Configuration) The information processing system 1 shown in Fig. 1 can evaluate the load applied to the knee joint of a user while walking. The information processing system 1 includes a first sensor device 10A, a second sensor device 10B, and an electronic device 20. However, the information processing system 1 does not need to include the second sensor device 10B. The information processing system 1 may include a third sensor device 10C in place of either the first sensor device A or the second sensor device 10B, or in addition to the first sensor device A and the second sensor device 10B.

[0019] Hereinafter, when the first sensor device 10A, the second sensor device 10B, and the third sensor device 10C are not particularly distinguished from each other, they are also collectively referred to as "sensor devices 10."

[0020] The sensor device 10 and the electronic device 20 can communicate with each other via a communication line. The communication line may be wired or wireless.

[0021] The first sensor device 10A is located at a position where it can detect data indicating the movement of the user's thighs. In this embodiment, the first sensor device 10A is located at a position where it can detect data indicating the movement of the left thigh of the user's two thighs. However, the first sensor device 10A may be located at a position where it can detect data indicating the movement of the right thigh of the user's two thighs, or may be located at a position where it can detect data indicating the movement of both thighs.

[0022] The first sensor device 10A is worn on, for example, the user's thigh. In this embodiment, the first sensor device 10A is worn on the left thigh of the user's two thighs. However, the first sensor device 10A may be worn on the right thigh or both thighs of the user's two thighs. The first sensor device 10A may be a wearable device. The first sensor device 10A may be worn on the user's thigh by any method. The first sensor device 10A may be worn on the user's thigh by a belt. The first sensor device 10A may be worn on the thigh by being placed in a pocket near the thigh of pants worn by the user. The first sensor device 10A may be worn on the user's thigh by being attached to pants, underwear, shorts, a support, a prosthetic limb, an implant, or the like.

[0023] The first sensor device 10A detects first data related to the movement of the user's thigh. The first data may be data indicating the movement of the user's thigh. The first data includes, for example, data indicating at least one of the velocity, acceleration, angle, and angular velocity of the user's thigh. The first data is, for example, data in a local coordinate system based on the position of the first sensor device 10A.

[0024] The local coordinate system based on the position of the first sensor device 10A is composed of axes A1, A2, and A3, for example, as shown in FIG. 3 (described later). In FIG. 3, the position of the first sensor device 10A is indicated by a dashed line. Axis A1, A2, and A3 are perpendicular to one another. Axis A1 and A2 are included in, for example, a sagittal plane. The sagittal plane is, for example, a plane that divides the user's body symmetrically or a plane parallel to the plane that divides the user's body symmetrically. Axis A3, for example, intersects perpendicularly with the sagittal plane.

[0025] The second sensor device 10B is located at a position where data indicating the movement of the user's feet can be detected. In this embodiment, the foot refers to the part of the user's foot from the ankle to the toes. In this embodiment, the second sensor device 10B is located at a position where data indicating the movement of the left foot of the user's two feet can be detected. However, the second sensor device 10B may be located at a position where data indicating the movement of the right foot of the user's two feet can be detected, or may be located at a position where data indicating the movement of both feet can be detected.

[0026] The second sensor device 10B is attached to, for example, the user's foot. In this embodiment, the second sensor device 10B is attached to the left foot of the user's two feet. However, the second sensor device 10B may be attached to the right foot or both feet of the user's two feet. The second sensor device 10B may be a shoe-type wearable device. The second sensor device 10B may be attached to the user's foot by any method. The second sensor device 10B may be provided on a shoe. The second sensor device 10B may be attached to the user's foot by being attached to an anklet, a band, a friendship bracelet, a false nail, a tattoo sticker, a support, a cast, a sock, an insole, a prosthetic limb, a ring, an implant, or the like.

[0027] The second sensor device 10B detects second data related to the movement of the user's foot. The second data may be data indicating the movement of the user's foot. The second data includes, for example, data indicating at least one of the velocity, acceleration, angle, and angular velocity of the user's foot. The second data is, for example, data in a local coordinate system based on the position of the second sensor device 10B.

[0028] The local coordinate system based on the position of the second sensor device 10B is composed of axes B1, B2, and B3, as shown in FIG. 3 (described later), for example. In FIG. 3, the position of the second sensor device 10B is indicated by a dashed line. Axis B1, B2, and B3 are perpendicular to one another. Axis B1 and Axis B2 are included in the sagittal plane, for example. Axis B3 intersects the sagittal plane perpendicularly, for example.

[0029] The third sensor device 10C is located at a position where it can detect data indicating the movement of the user's ankles. In this embodiment, the third sensor device 10C is located at a position where it can detect data indicating the movement of the left ankle of the user's two ankles. However, the third sensor device 10C may be located at a position where it can detect data indicating the movement of the right ankle of the user's two ankles, or may be located at a position where it can detect data indicating the movement of both ankles.

[0030] The third sensor device 10C is worn, for example, on the user's ankle. In this embodiment, the third sensor device 10C is worn on the left ankle of the user's two ankles. However, the third sensor device 10C may be worn on the right ankle or both ankles of the user's two ankles. The third sensor device 10C may be a wearable device. The third sensor device 10C may be worn on the user's ankle by a belt. The third sensor device 10C may be worn on the user's ankle by any method. The third sensor device 10C may be worn on the user's ankle by being attached to an anklet, a band, a friendship bracelet, a tattoo sticker, a supporter, a cast, a sock, a prosthetic limb, an implant, or the like.

[0031] The third sensor device 10C detects third data related to the movement of the user's ankle. The third data may be data indicating the movement of the user's ankle. The third data includes, for example, data indicating at least one of the velocity, acceleration, angle, and angular velocity of the user's ankle. The third data is, for example, data in a local coordinate system based on the position of the third sensor device 10C.

[0032] The local coordinate system based on the position of the third sensor device 10C is composed of axes C1, C2, and C3, as shown in FIG. 3 (described later), for example. In FIG. 3, the position of the third sensor device 10C is indicated by a dashed line. The axes C1, C2, and C3 are perpendicular to one another. The axes C1 and C2 are included in the sagittal plane, for example. The axis C3 intersects the sagittal plane perpendicularly, for example.

[0033] Hereinafter, when there is no particular distinction between the first data detected by the first sensor device 10A, the second data detected by the second sensor device 10B, and the third data detected by the third sensor device 10C, these will be collectively referred to as "data."

[0034] The electronic device 20 is carried by a user while walking. In this embodiment, the electronic device 20 functions as an information processing device and acquires an estimated value of the load applied to the user's knee joint based on data detected by the sensor device 10. The electronic device 20 is, for example, a mobile device such as a mobile phone, a smartphone, or a tablet.

[0035] As shown in FIG. 2, the sensor device 10 includes a communication unit 11, a sensor unit 12, a storage unit 13, and a control unit 14.

[0036] The communication unit 11 includes at least one communication module capable of communicating with the electronic device 20 via a communication line. The communication module is a communication module that complies with the standard of the communication line. The standard of the communication line is, for example, a short-range wireless communication standard including Bluetooth (registered trademark), Wi-Fi (registered trademark), infrared, and NFC (Near Field Communication).

[0037] The sensor unit 12 is configured to include any sensor depending on the data to be detected by the sensor device 10. The sensor unit 12 is configured to include, for example, at least one of a three-axis motion sensor, a three-axis acceleration sensor, a three-axis speed sensor, a three-axis gyro sensor, a three-axis geomagnetic sensor, and a camera. When the sensor unit 12 is configured to include a camera, the camera can capture an image of a part of the user's body and analyze the generated image to detect data indicating the movement of the part.

[0038] The storage unit 13 includes at least one semiconductor memory, at least one magnetic memory, at least one optical memory, or a combination of at least two of these. The semiconductor memory may be, for example, a random access memory (RAM) or a read-only memory (ROM). The RAM may be, for example, a static random access memory (SRAM) or a dynamic random access memory (DRAM). The ROM may be, for example, an electrically erasable programmable read-only memory (EEPROM). The storage unit 13 may function as a main storage device, an auxiliary storage device, or a cache memory. The storage unit 13 stores data used in the operation of the sensor device 10 and data obtained by the operation of the sensor device 10. For example, the storage unit 13 stores system programs, application programs, embedded software, and the like.

[0039] The control unit 14 is configured to include at least one processor, at least one dedicated circuit, or a combination of these. The processor is a general-purpose processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), or a dedicated processor specialized for specific processing. The dedicated circuit is, for example, an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The control unit 14 controls each part of the sensor device 10 and executes processing related to the operation of the sensor device 10.

[0040] The control unit 14 receives a signal instructing the start of data detection from the electronic device 20 via the communication unit 11. Upon receiving this signal, the control unit 14 starts data detection. For example, the control unit 14 acquires data detected by the sensor unit 12 from the sensor unit 12. The control unit 14 transmits the acquired data to the electronic device 20 via the communication unit 11.

[0041] The control unit 14 acquires data from the sensor unit 12 at a predetermined time interval and transmits the acquired data via the communication unit 11. This time interval may be set based on, for example, the walking speed of a typical user. When the information processing system 1 includes a first sensor device 10A and a second sensor device 10B, this time interval may be the same for the first sensor device 10A and the second sensor device 10B. By making this time interval the same for the first sensor device 10A and the second sensor device 10B, the timing at which the first sensor device 10A and the second sensor device 10B detect data can be synchronized. When the information processing system 1 includes a third sensor device 10C in addition to the first sensor device 10A, etc., this time interval may be the same for the first sensor device 10A, etc. and the third sensor device 10C. In other words, this time interval may be the same for all sensor devices 10 included in the information processing system 1.

[0042] 2 , the electronic device 20 includes a communication unit 21, an input unit 22, a notification unit that notifies information, a storage unit 24, and a control unit 25. In this embodiment, the notification unit is the output unit 23. However, the notification unit is not limited to the output unit 23.

[0043] The communication unit 21 includes at least one communication module capable of communicating with the sensor device 10 via a communication line. The communication module is a communication module that complies with the standard of the communication line. The standard of the communication line is, for example, a short-range wireless communication standard including Bluetooth (registered trademark), Wi-Fi (registered trademark), infrared, and NFC.

[0044] The communication unit 21 may further include at least one communication module connectable to a network 2 as shown in Fig. 14 described below. The communication module is a communication module compatible with mobile communication standards such as LTE (Long Term Evolution), 4G (4th Generation), or 5G (5th Generation).

[0045] The input unit 22 can receive input from a user. The input unit 22 includes at least one input interface that can receive input from a user. The input interface is, for example, a physical key, a capacitance key, a pointing device, a touch screen that is integrated with a display, a microphone, or the like.

[0046] The output unit 23 is capable of outputting data. The output unit 23 includes at least one output interface capable of outputting data. The output interface is, for example, a display or a speaker. The display is, for example, an LCD or an organic EL display.

[0047] The storage unit 24 is configured to include at least one semiconductor memory, at least one magnetic memory, at least one optical memory, or a combination of at least two of these. The semiconductor memory is, for example, a RAM or a ROM. The RAM is, for example, an SRAM or a DRAM. The ROM is, for example, an EEPROM. The storage unit 24 may function as a main storage device, an auxiliary storage device, or a cache memory. The storage unit 24 stores data used in the operation of the electronic device 20 and data obtained by the operation of the electronic device 20. For example, the storage unit 24 stores system programs, application programs, embedded software, etc.

[0048] The control unit 25 is configured to include at least one processor, at least one dedicated circuit, or a combination of these. The processor is a general-purpose processor such as a CPU or GPU, or a dedicated processor specialized for a specific process. The dedicated circuit is, for example, an FPGA or an ASIC. The control unit 25 controls each part of the electronic device 20 and executes processes related to the operation of the electronic device 20.

[0049] The control unit 25 receives an input instructing the execution of an evaluation process via the input unit 22. This input causes the electronic device 20 to execute a process for evaluating the load applied to the knee joint. For example, this input is input via the input unit 22 by a user wearing the sensor device 10. For example, the user inputs this input via the input unit 22 before starting to walk. When the control unit 25 receives this input via the input unit 22, it transmits a signal instructing the sensor device 10 to start data detection via the communication unit 21.

[0050] When the information processing system 1 includes the first sensor device 10A and the second sensor device 10B, the control unit 25 may transmit a signal instructing the start of data detection to the first sensor device 10A and the second sensor device 10B as a broadcast signal via the communication unit 21. By transmitting the signal instructing the start of data detection to the first sensor device 10A and the second sensor device 10B as a broadcast signal, the multiple sensor devices 10 can start data detection simultaneously. When the information processing system 1 includes the third sensor device 10C in addition to the first sensor device 10A, etc., the control unit 14 may transmit a signal instructing the start of data detection to the third sensor device 10C in addition to the first sensor device 10A, etc. as a broadcast signal via the communication unit 21. In other words, the control unit 14 may transmit a signal instructing the start of data detection to all sensor devices 10 included in the information processing system 1 as a broadcast signal via the communication unit 21.

[0051] The control unit 25 receives data detected by the sensor device 10 from the sensor device 10 via the communication unit 21. The control unit 25 acquires data from the sensor device 10 by receiving the data from the sensor device 10. The control unit 25 estimates a landing timing (described later) of the user's foot based on at least the first data, and acquires an estimated value of the load applied to the user's knee joint. Before describing the details of the process of acquiring the estimated value, the principle of acquiring the estimated value of the load applied to the knee joint will be described with reference to Figures 3 to 9.

[0052] A method for calculating the load applied to the knee joint will be described with reference to Fig. 3. Fig. 3 shows a schematic diagram of the structure of the foot.

[0053] The foot 30 is the left leg of the user's two legs. The foot 30 includes a foot portion 31, a shin portion 32, a knee joint 33, and a thigh portion 34. The knee joint 33 is located between the shin portion 32 and the thigh portion 34. In the schematic configuration shown in Fig. 3, the shin portion 32 and the thigh portion 34 are each considered to be an axis.

[0054] The load applied to the knee joint 33 is calculated by multiplying the reaction force Fy of the knee joint 33 by the angular velocity ωz of the knee joint 33 .

[0055] The reaction force Fy of the knee joint 33 is, for example, a force along the axial direction of the shin 32. The positive direction of the reaction force Fy of the knee joint 33 is, for example, the direction from the foot 31 toward the knee joint 33 in the axial direction of the shin 32. The reaction force Fy of the knee joint 33 is the sum of the force with which the knee joint 33 presses the shin 32 due to the weight of the thigh 34 and the upper body above the waist, the reaction force with which the shin 32 presses against the thigh 34 due to the floor reaction force received from the ground via the foot 31, and the tension of the muscles that move the knee joint 33. These forces act in the negative direction of the reaction force Fy, so the direction of these forces is the negative direction of the reaction force Fy. The muscles that move the knee joint 33 include, for example, the vastus lateralis and vastus intermedius.

[0056] The angle of the knee joint 33 is expressed as a relative angle of the shin 32 with respect to the thigh 34, with zero degrees being the angle when the knee joint 33 is extended. The positive direction of the angle of the knee joint 33 is, for example, the rotation direction from the thigh 34 toward the rear of the user among the rotation directions around the knee joint 33 in the sagittal plane. The angular velocity ωz of the knee joint 33 is the angular velocity of the knee joint 33 in the sagittal plane. Like the angle of the knee joint 33, the positive direction of the angular velocity ωz of the knee joint 33 is, for example, the rotation direction from the thigh 34 toward the rear of the user among the rotation directions around the knee joint 33 in the sagittal plane.

[0057] The user's walking cycle will be described with reference to Fig. 4. The upper part of Fig. 4 shows the user's walking state. In Fig. 4, the user's left foot is marked with the letter L, and the right foot is marked with the letter R. Fig. 4 shows the user's walking state from when the left foot lands on the ground until the left foot lands on the ground again.

[0058] A gait cycle is the period from when one of the user's two feet lands on the ground until it lands on the ground again. The start and end points of a gait cycle are the landing timings of one of the user's two feet. The landing timing is the timing at which a foot lands on the ground. For example, in FIG. 4 , the gait cycle is the period from when the left foot of the user's two feet lands on the ground until it lands on the ground again. The gait cycle includes a stance phase and a swing phase.

[0059] The stance phase is the period from when one of the user's two feet lands on the ground until it lifts off. The stance phase starts when one of the user's two feet lands on the ground. In FIG. 4 , the stance phase is the period from when the user's left foot lands on the ground until it lifts off.

[0060] The contact phase is a period during which at least a part of one of the user's two feet is in contact with the ground. The contact phase may be a period during which any part of one of the user's two feet is in contact with the ground. The contact phase is part of the stance phase. In this embodiment, the contact phase is a period from the timing when one of the user's two feet lands to the time when the heel of that foot leaves the ground. The contact phase may include a heel contact phase. The heel contact phase is a period during which the heel of one of the user's two feet is in contact with the ground. In FIG. 4 , the contact phase is a period from the timing when the left foot lands to the time when the heel of the left foot leaves the ground.

[0061] The swing phase is the period from when one of the user's two feet leaves the ground until it lands on the ground. The start of the swing phase is the end of the stance phase. In Figure 4, the swing phase is the period from when the user's left foot leaves the ground until it lands on the ground.

[0062] 5 and 6, it will be explained that there is a correlation between the angular velocity of the knee joint and the load applied to the knee joint.

[0063] Figure 5 shows graphs of the knee joint angle [deg], knee joint angular velocity [deg / s], vastus lateralis tension [N], knee joint reaction force [N], and knee joint load [N·deg / s] for subjects with a large load on the knee joint.

[0064] Figure 6 shows graphs of the knee joint angle [deg], knee joint angular velocity [deg / s], vastus lateralis tension [N], knee joint reaction force [N], and knee joint load [N·deg / s] for subjects with a small load on the knee joint.

[0065] The horizontal axes in Figures 5 and 6 correspond to the gait cycle. The horizontal axes in Figures 5 and 6 represent the gait cycle as normalized values ​​ranging from 0 to 1. The stance phase corresponds to the period from 0 to 0.75 on the horizontal axis. The contact phase corresponds to the period from 0 to 0.4 on the horizontal axis. The swing phase corresponds to the period from 0.75 to 1 on the horizontal axis.

[0066] The data on the knee joint angular velocity, vastus lateralis tension, and knee joint load shown in Figures 5 and 6 were obtained by inverse dynamics calculation. The knee joint angle and knee joint reaction force shown in Figures 5 and 6 were used in the inverse dynamics calculation. Inverse dynamics calculation is a method for calculating the joint angular velocity and muscle force required to realize the subject's movement obtained through measurement. The data on the subject's knee joint angle and other data used in the inverse dynamics calculation were obtained from data provided by "Yoshiyuki Kobayashi, Naoto Hida, Kanako Nakajima, Masahiro Fujimoto, and Masaaki Mochimaru, "2019: AIST Gait Database 2019," [Online], [Retrieved May 24, 2021], Internet: https: / / unit.aist.go.jp / harc / ExPART / GDB2019_e.html." This gait database contains the gait data of multiple subjects. The subjects' gait data was detected using a motion capture system and a floor reaction force sensor. The inverse dynamics calculation methods used were the method described in "Scott L. Delp et al., "OpenSim: Open-Source Software to Create and Analyze Dynamic Simulations of Movement", IEEE Transactions on Biomedical Engineering, 2007, Volume: 54, Issue: 11, pp. 1940-1950", the method described in "[Online], [Retrieved May 24, 2021], Internet <https: / / simtk-confluence.stanford.edu / display / OpenSim / Getting+Started+with+CMC>", and the method described in "Thelen DG et al., "Generating dynamic simulations of movement using computed muscle control", Journal of Biomechanics, 2003, Volume: 36, pp. 321-328".

[0067] As shown in Figure 5, in subjects with a large load on the knee joint, the knee joint angle is greater than 0 degrees during the contact phase, which is between 0 and 0.4 on the horizontal axis. In other words, in subjects with a large load on the knee joint, the knee joint is bent during the contact phase. Furthermore, the knee joint angle reaches a positive peak value around 0.1 on the horizontal axis during the contact phase.

[0068] As shown in Figure 6, in subjects with a small load on the knee joint, the knee joint angle is maintained at approximately 0 [deg], i.e., a constant value, during the contact phase, from 0 to 0.4 on the horizontal axis. In other words, in subjects with a small load on the knee joint, the knee joint is maintained in a nearly extended state during the contact phase.

[0069] As shown in Figure 5, for subjects with a large load applied to the knee joint, the angular velocity of the knee joint fluctuates during the contact phase from 0 to 0.4 on the horizontal axis. The angular velocity of the knee joint reaches a positive peak value near 0.04 on the horizontal axis. This positive peak value is the first positive peak value in the angular velocity of the knee joint after the landing timing. The angular velocity of the knee joint decreases from near 0.04 to near 0.2 on the horizontal axis. The angular velocity of the knee joint reaches a negative peak value near 0.2 on the horizontal axis. This negative peak value is the first negative peak value in the angular velocity of the knee joint after the landing timing.

[0070] As shown in Figure 6, for subjects with a small load on the knee joint, the angular velocity of the knee joint is maintained at a constant value of approximately 0 [deg / s] during the contact phase, from 0 to 0.4 on the horizontal axis. For subjects with a small load on the knee joint, the knee joint is in a nearly extended state during the contact phase, so the angular velocity of the knee joint is maintained at approximately 0 [deg / s].

[0071] As shown in Figure 5, in subjects with a large load on the knee joint, the tension of the vastus lateralis exceeds 0 [N] during the contact phase, which is between 0 and 0.4 on the horizontal axis. In subjects with a large load on the knee joint, the knee joint is bent during the contact phase, so the tension of the vastus lateralis, which moves the knee joint, exceeds 0 [N]. In addition, the tension of the vastus lateralis reaches a positive peak value near 0.1 on the horizontal axis.

[0072] As shown in Figure 6, in subjects with a small load on the knee joint, the tension in the vastus lateralis is maintained at approximately 0 [N] during the ground contact phase, which is between 0 and 0.4 on the horizontal axis. In subjects with a small load on the knee joint, the knee joint is maintained in an almost extended state during the ground contact phase, so the tension in the vastus lateralis, which moves the knee joint, is maintained at approximately 0 [N].

[0073] As shown in Figure 5, in subjects with a heavy load on the knee joint, the knee joint reaction force fluctuates more during the ground contact period from 0 to 0.4 on the horizontal axis than in subjects with a light load on the knee joint as shown in Figure 6. As described above with reference to Figure 3, the knee joint reaction force is the floor reaction force that the knee joint receives from the ground via the foot, etc., minus the tension of muscles that move the knee joint, such as the vastus lateralis and vastus intermedius. In subjects with a heavy load on the knee joint, the knee joint reaction force reaches a negative peak value near 0.1 on the horizontal axis, where the tension of the vastus lateralis reaches a positive peak value.

[0074] As shown in Figure 6, in subjects with a small load on the knee joint, the knee joint reaction force fluctuates less during the ground contact phase from 0 to 0.4 on the horizontal axis than in subjects with a large load on the knee joint as shown in Figure 5. As described above with reference to Figure 3, the knee joint reaction force is calculated by subtracting the tension of muscles that move the knee joint, such as the vastus lateralis and vastus intermedius, from the floor reaction force that the knee joint receives from the ground via the foot, etc. As described above, in subjects with a small load on the knee joint, the tension of the vastus lateralis is maintained at approximately 0 [N] during the ground contact phase. By maintaining the tension of muscles that move the knee joint, such as the vastus lateralis, at approximately 0 [N], in subjects with a small load on the knee joint, the knee joint reaction force is mainly influenced by the floor reaction force that the knee joint receives from the ground.

[0075] As shown in Figure 5, subjects with a high load on the knee joint exhibit greater fluctuations in the load on the knee joint during the contact phase, ranging from 0 to 0.4 on the horizontal axis, than subjects with a low load on the knee joint, as shown in Figure 6. As described above with reference to Figure 3, the load on the knee joint is calculated as the product of the knee joint's reaction force and the angular velocity of the knee joint. The load on the knee joint reaches a negative peak value near 0.04 on the horizontal axis during the contact phase, when the angular velocity of the knee joint reaches a positive peak value.

[0076] As shown in Figure 6, for subjects with a small load on their knee joint, the load on the knee joint is maintained at approximately 0 [N deg / s] during the contact phase, from 0 to 0.4 on the horizontal axis. As described above with reference to Figure 3, the load on the knee joint is calculated by multiplying the reaction force of the knee joint by the angular velocity of the knee joint. For subjects with a small load on their knee joint, the angular velocity of the knee joint is maintained at approximately 0 [deg / s] during the contact phase, and therefore the load on the joint is also maintained at approximately 0 [N deg / s].

[0077] Thus, there is a correlation between the angular velocity of the knee joint during the contact phase and the load on the knee joint. For example, as shown in Figure 5, for subjects with a large load on the knee joint, the load on the knee joint reaches a negative peak value near 0.04 on the horizontal axis, where the angular velocity of the knee joint reaches a positive peak value. Also, as shown in Figure 6, for subjects with a small load on the knee joint, the load on the knee joint is maintained at approximately 0 [N·deg / s] because the angular velocity of the knee joint is maintained at approximately 0 [deg / s].

[0078] Therefore, if the angular velocity of the user's knee joint during the ground contact phase can be obtained, the load applied to the user's knee joint can be obtained based on the correlation between the angular velocity of the knee joint during the ground contact phase and the load applied to the knee joint.

[0079] 7 and 8, it will be explained that there is a correlation between the angular velocity of the thigh and the load applied to the knee joint.

[0080] Figure 7 shows a graph of the angular velocity [deg / s] of the thigh of a subject with a large load on the knee joint. Figure 7 also shows graphs of the angular velocity [deg / s] of the subject's thigh in both the local coordinate system and the global coordinate system. Figure 7 also shows graphs of the knee joint angle [deg] and knee joint angular velocity [deg / s] shown in Figure 5.

[0081] Figure 8 shows a graph of the angular velocity [deg / s] of the thigh of a subject with a small load on the knee joint. Figure 8 also shows graphs of the angular velocity [deg / s] of the thigh of the subject in each of the local coordinate system and the global coordinate system. Figure 8 also shows graphs of the knee joint angle [deg] and knee joint angular velocity [deg / s] shown in Figure 6.

[0082] The horizontal axes in FIGS. 7 and 8 correspond to the walking period, as do the horizontal axes in FIGS. 5 and 6 .

[0083] The data of the angular velocity of the thigh shown in FIGS. 7 and 8 was obtained by inverse dynamics calculation in the same manner as or similar to the data of the angular velocity of the knee joint shown in FIGS. 5 and 6 .

[0084] 7 and 8, the angular velocity of the thigh in the global coordinate system is substantially the same as the angular velocity of the thigh in the local coordinate system. In other words, the angular velocity of the thigh in the local coordinate system detected by the first sensor device 10A may be used as the angular velocity of the thigh in the global coordinate system. Hereinafter, unless there is any particular distinction between the angular velocity of the thigh in the global coordinate system and the angular velocity of the thigh in the local coordinate system, they will also be collectively referred to as the "angular velocity of the thigh."

[0085] As shown in Figure 7, in subjects with a large load applied to the knee joint, the angular velocity of the thigh exhibits fluctuations similar to those of the knee joint. For example, as described above, the angular velocity of the knee joint decreases from approximately 0.04 on the horizontal axis toward approximately 0.2. Similar to the angular velocity of the knee joint, the angular velocity of the thigh decreases from 0 on the horizontal axis, i.e., the landing timing, toward approximately 0.2 on the horizontal axis. Furthermore, similar to the angular velocity of the knee joint, the angular velocity of the thigh reaches a negative peak value near 0.2 on the horizontal axis.

[0086] As shown in Figure 8, in subjects with a small load applied to the knee joint, the angular velocity of the thigh exhibits fluctuations similar to that of the knee joint. For example, as described above, the angular velocity of the knee joint is maintained at approximately 0 [deg / s], i.e., a constant value, during the contact phase from 0 to 4 on the horizontal axis. Similar to the angular velocity of the knee joint, the angular velocity of the thigh is maintained at a constant negative value during the contact phase from 0 to 4 on the horizontal axis.

[0087] Thus, during the contact phase, the angular velocity of the thigh exhibits fluctuations similar to those of the knee joint. One reason for this is that the thigh and knee joint move in coordination. As described above, there is a correlation between the angular velocity of the knee joint during the contact phase and the load applied to the knee joint. Because the angular velocity of the thigh exhibits fluctuations similar to those of the knee joint during the contact phase, there is a correlation between the angular velocity of the thigh during the contact phase and the load applied to the knee joint, similar to the angular velocity of the knee joint.

[0088] FIG. 9 shows the distribution of the load applied to the knee joint relative to the angular velocity of the thigh. The horizontal axis of FIG. 9 represents the negative peak value of the angular velocity of the thigh during the contact phase. The vertical axis of FIG. 9 represents the negative peak value of the load applied to the knee joint during the contact phase. By performing a regression analysis on the distribution shown in FIG. 9, a regression equation (y = -64.72x - 4267.2) was obtained. The correlation coefficient was 0.8. It can be seen that there is a strong correlation between the angular velocity of the thigh during the contact phase and the load applied to the knee joint.

[0089] As described above, there is a correlation between the angular velocity of the thigh during the contact phase and the load on the knee joint. Therefore, if the angular velocity of the thigh during the contact phase of the user can be obtained, the load on the knee joint of the user can be obtained based on the correlation between the angular velocity of the thigh during the contact phase and the load on the knee joint.

[0090] 10 and 11, it will be explained that there is a correlation between the angular velocity of the ankle and the load applied to the knee joint.

[0091] Figure 10 shows graphs of the knee joint angle [deg], ankle angular velocity [deg / s], vastus lateralis tension [N], knee joint reaction force [N], and knee joint load [N·deg / s] for a subject with a large knee joint load. All of these graphs, except for the ankle angular velocity [deg / s] graph, are the same as the graph shown in Figure 5.

[0092] Figure 11 shows graphs of the knee joint angle [deg], ankle angular velocity [deg / s], vastus lateralis tension [N], knee joint reaction force [N], and knee joint load [N·deg / s] for a subject with a small knee joint load. All of these graphs, except for the ankle angular velocity [deg / s] graph, are the same as the graph shown in Figure 6.

[0093] The horizontal axes in FIGS. 10 and 11 correspond to the walking cycle, as do the horizontal axes in FIGS.

[0094] The data of the ankle angular velocity shown in FIGS. 10 and 11 was obtained by inverse dynamics calculation in the same manner as or similar to the data of the knee joint angular velocity etc. shown in FIGS. 5 and 6.

[0095] In Figures 10 and 11, the angular velocity of the ankle is the angular velocity of the ankle in the sagittal plane.

[0096] As shown in Figure 10, for a subject with a large load applied to the knee joint, the ankle angular velocity fluctuates during the contact phase from 0 to 0.4 on the horizontal axis. The ankle angular velocity reaches a negative peak value near 0.04 on the horizontal axis. This negative peak value is the first negative peak value in the ankle angular velocity after the landing timing. The ankle angular velocity increases from near 0.04 to near 0.2 on the horizontal axis. The ankle angular velocity reaches a positive peak value near 0.2 on the horizontal axis. This positive peak value is the first positive peak value in the ankle angular velocity after the landing timing. This fluctuation in the ankle angular velocity is similar to the fluctuation in the knee joint angular velocity shown in Figure 5.

[0097] As shown in Figure 11, for subjects with a small load on the knee joint, the ankle angular velocity is maintained at approximately 0 [deg / s], i.e., a constant value, during the contact phase from 0 to 0.4 on the horizontal axis. For subjects with a small load on the knee joint, the knee joint is in a nearly extended state during the contact phase. Therefore, the ankle angular velocity is maintained at approximately 0 [deg / s]. This variation in the ankle angular velocity is similar to the variation in the knee joint angular velocity shown in Figure 6.

[0098] As described above, the angular velocity of the ankle during the contact phase exhibits fluctuations similar to those of the knee joint shown in Figures 5 and 6. One reason for this is that the ankle and knee joint move in coordination. As described above, there is a correlation between the angular velocity of the knee joint during the contact phase and the load applied to the knee joint. Because the angular velocity of the ankle exhibits fluctuations similar to those of the knee joint during the contact phase, there is a correlation between the angular velocity of the ankle during the contact phase and the load applied to the knee joint, similar to the angular velocity of the knee joint.

[0099] FIG. 12 shows the distribution of the load applied to the knee joint relative to the angular velocity of the ankle. The horizontal axis of FIG. 12 represents the negative peak value of the angular velocity of the ankle during the contact phase. The vertical axis of FIG. 12 represents the negative peak value of the load applied to the knee joint during the contact phase. By performing a regression analysis on the distribution shown in FIG. 12, a regression equation (y = -0.0008x + 0.0686) was obtained. The correlation coefficient was 0.6456. It can be seen that there is a strong correlation between the angular velocity of the ankle during the contact phase and the load applied to the knee joint.

[0100] [Process for Obtaining Estimated Values] The control unit 25 estimates the landing timing of the user's foot based on at least the first data, and obtains the user's reference angular velocity. The reference angular velocity is the angular velocity of the thigh or the angular velocity of the knee joint during the contact phase. As described above, the angular velocity of the thigh or the angular velocity of the knee joint during the contact phase has a correlation with the load applied to the knee joint. Therefore, the reference angular velocity has a correlation with the load applied to the knee joint.

[0101] The control unit 25 acquires an estimated value of the load applied to the user's knee joint, calculated based on the correlation between the reference angular velocity and the load applied to the knee joint and the user's reference angular velocity. The control unit 25 may use, as the correlation, a regression equation acquired from a distribution such as that shown in FIG. 9 , or may use a learning model that has learned the correlation between the reference angular velocity and the load applied to the knee joint. When the control unit 25 uses the regression equation as the correlation, the control unit 25 acquires the estimated value of the load applied to the knee joint by calculating the estimated value of the load using the acquired user's reference angular velocity and the regression equation. The learning model is, for example, a neural network learning model. When information about the reference angular velocity is input, the learning model may calculate and output a score indicating the estimated value of the load applied to the knee joint. When the control unit 25 uses the learning model as the correlation, the control unit 25 inputs information about the acquired user's reference angular velocity into the learning model and acquires a score indicating the estimated value of the load applied to the knee joint calculated by the learning model. The regression equation or learning model is, for example, acquired in advance and stored in the storage unit 24 .

[0102] Below, an example in which the reference angular velocity is the angular velocity of the thigh and an example in which the reference angular velocity is the angular velocity of the knee joint will be described.

[0103] Example 1: The reference angular velocity may be the angular velocity of the thigh during the contact phase. That is, the control unit 25 may obtain an estimate of the load applied to the user's knee joint based on the correlation between the angular velocity of the thigh during the contact phase and the load applied to the knee joint, and the angular velocity of the thigh during the contact phase of the user. In this case, the control unit 25 may estimate the user's landing timing and obtain the angular velocity of the thigh during the contact phase of the user, based on at least the first data. The control unit 25 may obtain the angular velocity of the user's thigh according to the correlation.

[0104] As an example, the control unit 25 may use the correlation between the negative peak value of the angular velocity of the thigh during the contact phase and the load applied to the knee joint. In this case, the control unit 25 acquires the negative peak value of the angular velocity of the user's thigh during the contact phase as the angular velocity of the user's thigh according to the correlation. For example, as described below, the control unit 25 estimates the landing timing based on the first data or the second data. After estimating the landing timing, the control unit 25 acquires the first negative peak value of the angular velocity of the user's thigh from the landing timing using only the first data. As can be seen from FIG. 7 , the first negative peak value of the angular velocity of the thigh from the landing timing is the negative peak value of the angular velocity of the thigh during the contact phase. Here, as shown in FIG. 8 , for a user with a small load applied to the knee joint, the negative peak value of the angular velocity of the thigh may not appear during the contact phase. In this case, it is expected that the negative peak value of the angular velocity of the thigh during the contact phase cannot be acquired. Therefore, if the control unit 25 cannot obtain a negative peak value of the angular velocity of the thigh within a first time T1a from the landing timing as shown in Figure 8, the control unit 25 may obtain the angular velocity of the user's thigh at a second time T2 from the landing timing using the first data. The first time T1a may be set based on, for example, an average value of the length of the ground contact period. The second time T2 may be set based on, for example, an average value of the time from the landing timing to the appearance of a negative peak value in the angular velocity of the thigh.

[0105] As another example, the control unit 25 may use the correlation between the angular velocity of the thigh at the time of landing and the load applied to the knee joint. In this case, the control unit 25 acquires the angular velocity of the user's thigh at the time of landing as the angular velocity of the user's thigh according to the correlation. For example, as described below, the control unit 25 estimates the landing timing based on the first data or the second data. After estimating the landing timing, the control unit 25 acquires the angular velocity of the user's thigh at the time of landing using only the first data.

[0106] Here, the control unit 25 may estimate the landing timing based only on the first data. The control unit 25 may estimate the landing timing by estimating the floor reaction force based on at least one of the thigh acceleration and the thigh angular velocity included in the first data. The user's thigh receives the floor reaction force from the ground via the foot, etc. As the user's thigh receives the floor reaction force, the thigh acceleration and the thigh angular velocity fluctuate in accordance with fluctuations in the floor reaction force. In other words, fluctuations in the floor reaction force can be estimated from fluctuations in at least one of the thigh acceleration and the thigh angular velocity. Furthermore, the floor reaction force fluctuates as the user's foot lands on the ground. In other words, the landing timing can be estimated by estimating fluctuations in the floor reaction force based on at least one of the thigh acceleration and the thigh angular velocity.

[0107] The control unit 25 may estimate the landing timing based on the second data. Since the second data is data indicating the movement of the foot, the control unit 25 can estimate the landing timing, which is the timing when the foot lands on the ground, using the second data. By using the second data indicating the movement of the foot, the landing timing can be estimated with high accuracy.

[0108] When the control unit 25 acquires the angular velocity of the user's thigh, it acquires an estimated value of the load applied to the user's knee joint based on the correlation and the acquired angular velocity of the user's thigh. As an example, the control unit 25 may use, as the correlation, a regression equation acquired from the distribution of the load applied to the knee joint with respect to the angular velocity of the thigh, as shown in FIG. 9 . In this case, the control unit 25 acquires the estimated value of the load applied to the knee joint by calculating the estimated value using the acquired angular velocity of the user's thigh and the regression equation. As another example, the control unit 25 may use, as the correlation, a learning model that has learned the correlation between the angular velocity of the thigh and the load applied to the knee joint. The learning model may calculate and output a score indicating an estimated value of the load applied to the knee joint when information on the angular velocity of the thigh is input. In this case, the control unit 25 inputs the acquired information on the angular velocity of the user's thigh into the learning model and acquires a score indicating the estimated value of the load applied to the knee joint calculated by the learning model.

[0109] Example 2: The reference angular velocity may be the angular velocity of the knee joint during the contact phase. That is, the control unit 25 may obtain an estimate of the load applied to the user's knee joint based on the correlation between the angular velocity of the knee joint during the contact phase and the load applied to the knee joint, and the angular velocity of the user's knee joint during the contact phase. In this case, the control unit 25 may estimate the user's landing timing based on at least the first data, and obtain the angular velocity of the user's knee joint during the contact phase. The control unit 25 may obtain the angular velocity of the user's knee joint according to the correlation.

[0110] As an example, the control unit 25 may use the correlation between the positive or negative peak value of the angular velocity of the knee joint during the contact phase and the load applied to the knee joint. In this case, the control unit 25 acquires the positive or negative peak value of the angular velocity of the user's knee joint during the contact phase as the angular velocity of the user's knee joint according to the correlation. For example, as described above, the control unit 25 estimates the landing timing based on the first data or the second data. After estimating the landing timing, the control unit 25 acquires the first positive or negative peak value of the angular velocity of the user's knee joint from the landing timing based on the data detected by the sensor device 10. As can be seen from FIG. 5 , the first positive or negative peak value of the angular velocity of the knee joint from the landing timing is the positive or negative peak value of the angular velocity of the knee joint during the contact phase. As will be described later, the control unit 25 may acquire the angular velocity of the user's knee joint using the first data and the second data. As shown in FIG. 6 , for a user with a small load on the knee joint, positive and negative peak values ​​of the angular velocity of the knee joint may not appear during the contact phase. In this case, it is expected that positive and negative peak values ​​of the angular velocity of the knee joint cannot be obtained during the contact phase. Therefore, when the positive peak value of the angular velocity of the knee joint is used, if the positive peak value of the angular velocity of the knee joint cannot be obtained within the first time T1b from the landing timing as shown in FIG. 6 , the control unit 25 may obtain the angular velocity of the user's knee joint at a time when a third time T3 has elapsed from the landing timing using the first data or the second data. The first time T1b may be set based on, for example, the average length of the contact phase. The first time T1b may be the same as the first time T1a as shown in FIG. 8 or may be different from the first time T1a as shown in FIG. 8 . The third time T3 may be set based on, for example, the average time from the landing timing to the appearance of a positive peak value in the angular velocity of the knee joint. Furthermore, when the negative peak value of the angular velocity of the knee joint is used, if the negative peak value of the angular velocity of the knee joint cannot be obtained within a first time T1b from the landing timing as shown in Fig. 6, the control unit 25 may obtain the angular velocity of the user's knee joint at a point when a fourth time T4 has elapsed from the landing timing, using the first data or the second data. The fourth time T4 may be set based on, for example, an average value of the time from the landing timing to the appearance of the negative peak value in the angular velocity of the knee joint.

[0111] As another example, the control unit 25 may use the correlation between the angular velocity of the knee joint at the time of landing and the load applied to the knee joint. In this case, the control unit 25 acquires the angular velocity of the user's knee joint at the time of landing as the angular velocity of the user's knee joint according to the correlation. For example, as described above, the control unit 25 estimates the landing timing based on the first data or the second data. After estimating the landing timing, the control unit 25 acquires the angular velocity of the user's knee joint at the time of landing based on the data detected by the sensor device 10. The control unit 25 may acquire the angular velocity of the user's knee joint using the first data and the second data, as described below.

[0112] Here, the control unit 25 may estimate and acquire the angular velocity of the user's knee joint based on the first data and the second data. As shown in Fig. 3, the knee joint is located between the thigh and the foot. Because the knee joint is located between the thigh and the foot, the angular velocity of the knee joint can be estimated based on the first data indicating the movement of the thigh and the second data indicating the movement of the foot.

[0113] When the control unit 25 acquires the angular velocity of the knee joint, it acquires an estimated value of the load applied to the user's knee joint based on the correlation and the acquired angular velocity of the user's knee joint. As an example, the control unit 25 may use, as the correlation, a regression equation acquired from the distribution of the load applied to the knee joint relative to the angular velocity of the knee joint. In this case, the control unit 25 acquires the estimated value of the load applied to the knee joint by calculating the estimated value of the load applied to the knee joint using the acquired angular velocity of the user's knee joint and the regression equation. As another example, the control unit 25 may use, as the correlation, a learning model that has learned the correlation between the angular velocity of the knee joint and the load applied to the knee joint. The learning model may calculate and output a score indicating an estimated value of the load applied to the knee joint when information on the angular velocity of the knee joint is input. In this case, the control unit 25 inputs the acquired information on the angular velocity of the user's knee joint into the learning model and acquires a score indicating the estimated value of the load applied to the knee joint calculated by the learning model.

[0114] [Another Example of Estimated Value Acquisition Process] The reference angular velocity may be the angular velocity of the ankle during the contact phase. Hereinafter, as another example of the estimated value acquisition process, a case where the reference angular velocity is the angular velocity of the ankle during the contact phase will be described.

[0115] The control unit 25 estimates the landing timing of the user's foot based on at least the third data and acquires the angular velocity of the user's ankle. The control unit 25 acquires an estimated value of the load applied to the user's knee joint based on the correlation between the angular velocity of the ankle during the contact phase and the load applied to the knee joint, and the angular velocity of the ankle during the contact phase. The control unit 25 may acquire the angular velocity of the user's ankle based on the correlation.

[0116] As an example, the control unit 25 may use the correlation between the positive or negative peak value of the angular velocity of the ankle during the contact phase and the load applied to the knee joint. In this case, the control unit 25 acquires the positive or negative peak value of the angular velocity of the user's ankle during the contact phase as the angular velocity of the user's ankle according to the correlation. For example, as described above, the control unit 25 estimates the landing timing based on the first data or the second data. After estimating the landing timing, the control unit 25 acquires the first positive or negative peak value of the angular velocity of the user's knee joint from the landing timing based on the third data detected by the third sensor device 10C. As can be seen from FIG. 10 , the first positive or negative peak value of the angular velocity of the ankle from the landing timing corresponds to the positive or negative peak value of the angular velocity of the ankle during the contact phase. Here, as shown in FIG. 11 , in a user with a small load applied to the knee joint, the positive and negative peak values ​​of the angular velocity of the ankle may not appear during the contact phase. In this case, it is expected that positive and negative peak values ​​of the ankle angular velocity cannot be obtained during the contact phase. Therefore, when the negative peak value of the ankle angular velocity is used, if the positive peak value of the knee joint angular velocity cannot be obtained within the first time T1c from the landing timing as shown in FIG. 11 , the control unit 25 may acquire the user's ankle angular velocity at a point in time when a fifth time T5 has elapsed from the landing timing using the third data. The first time T1c may be set based on, for example, the average length of the contact phase. The first time T1c may be the same as the first time T1a as shown in FIG. 8 or may be different from the first time T1a as shown in FIG. 8. The fifth time T5 may be set based on, for example, the average time from the landing timing to the appearance of a negative peak value in the ankle angular velocity. Furthermore, when the positive peak value of the ankle angular velocity is used, if the positive peak value of the ankle angular velocity cannot be obtained within a first time T1c from the landing timing as shown in Fig. 11, the control unit 25 may obtain the angular velocity of the user's ankle at a sixth time T6 from the landing timing, using the third data. The sixth time T6 may be set based on, for example, the average value of the time from the landing timing to the appearance of a positive peak value in the ankle angular velocity.

[0117] As another example, the control unit 25 may use the correlation between the angular velocity of the ankle at the time of landing and the load applied to the knee joint. In this case, the control unit 25 acquires the angular velocity of the user's ankle at the time of landing as the angular velocity of the user's ankle according to the correlation. For example, as described above, the control unit 25 estimates the landing timing based on the first data or the second data. After estimating the landing timing, the control unit 25 acquires the angular velocity of the user's ankle at the time of landing based on the third data detected by the third sensor device 10C.

[0118] Here, the control unit 25 may estimate the landing timing based on the third data. Since the third data is data indicating the movement of the ankle, the control unit 25 can estimate the landing timing, which is the timing when the foot lands on the ground, using the third data. By using the third data indicating the movement of the ankle, the landing timing can be estimated with high accuracy.

[0119] When the control unit 25 acquires the ankle angular velocity, it acquires an estimated value of the load applied to the user's knee joint based on the correlation and the acquired angular velocity of the user's ankle. As an example, the control unit 25 may use, as the correlation, a regression equation acquired from the distribution of the load applied to the knee joint relative to the ankle angular velocity. In this case, the control unit 25 acquires the estimated value of the load applied to the knee joint by calculating the estimated value of the load applied to the knee joint using the acquired angular velocity of the user's ankle and the regression equation. As another example, the control unit 25 may use, as the correlation, a learning model that has learned the correlation between the ankle angular velocity and the load applied to the knee joint. The learning model may calculate and output a score indicating an estimated value of the load applied to the knee joint when information on the ankle angular velocity is input. In this case, the control unit 25 inputs the acquired information on the user's ankle angular velocity into the learning model and acquires a score indicating the estimated value of the load applied to the knee joint calculated by the learning model.

[0120] [Notification Processing] The control unit 25 may cause the output unit 23, which functions as a notification unit, to notify information indicating an estimated value of the load applied to the knee joint of the user. When the control unit 25 acquires the estimated value as a score output from the learning model, the control unit 25 may cause the output unit 23, which functions as a notification unit, to notify information indicating the score. As an example of notification, the control unit 25 may cause the output unit 23 to output information indicating the estimated value or score of the load applied to the knee joint. By outputting the information indicating the estimated value or score of the load applied to the knee joint from the output unit 23, the user can know whether the load applied to his or her knee joint is large or not.

[0121] As another example of the notification, the control unit 25 may output information indicating an estimated value or a score of the load applied to the knee joint of the user as sound from the speaker of the output unit 23. Outputting the information indicating the estimated value or the score of the load applied to the knee joint as sound reduces the possibility of interfering with the user's walking.

[0122] The control unit 25 may transmit a signal indicating an estimated value or score of the load applied to the user's knee joint to an external device via the communication unit 21. For example, if the user is wearing earphones, the control unit 25 transmits a signal indicating the estimated value or score of the load applied to the knee joint to the earphones as an external device via the communication unit 21. With this configuration, information indicating the estimated value or score of the load applied to the knee joint is output as audio from the earphones worn by the user. By outputting information indicating the estimated value or score of the load applied to the joint as audio from the earphones, the possibility of interfering with the user's walking is reduced.

[0123] The control unit 25 may accumulate the estimated value of the load applied to the user's knee joint in, for example, the memory unit 24 for a predetermined set period. The set period may be set based on, for example, the frequency with which the user walks. The control unit 25 may determine whether the accumulated estimated value exceeds a threshold. When the control unit 25 determines that the accumulated estimated value exceeds the threshold, the control unit 25 may cause the output unit 23, which functions as a notification unit, to issue information indicating a warning. As an example of the notification, the control unit 25 may cause the output unit 23 to output information indicating a warning. The threshold may be set based on the amount of load that may accumulate in the knee joint and cause a knee joint disease. When the output unit 23, which functions as a notification unit, issues the information indicating the warning, the user can understand that the load accumulated in his or her knee joint is relatively large.

[0124] When the control unit 25 determines that the accumulated estimated value exceeds the threshold, the control unit 25 may transmit a signal indicating a warning to an external device via the communication unit 21. For example, when the user is wearing earphones, the control unit 25 transmits a signal indicating a warning to the earphones serving as an external device via the communication unit 21. With this configuration, information indicating a warning is output as sound from the earphones worn by the user. Outputting the information indicating a warning as sound from the earphones reduces the possibility of the warning interfering with the user's walking.

[0125] (System Operation) FIG. 13 is a flowchart showing the operation of the evaluation process executed by the electronic device 20 shown in FIG. 1 . This operation corresponds to an example of an information processing method according to this embodiment. For example, when the control unit 25 receives an input instructing execution of the evaluation process via the input unit 22, the control unit 25 starts the evaluation process from the processing of step S10. Hereinafter, the reference angular velocity is assumed to be the angular velocity of the thigh during the ground contact phase. Furthermore, the control unit 25 acquires an estimated value of the load applied to the user's knee joint using a learning model that has learned the correlation between the angular velocity of the thigh during the ground contact phase and the load applied to the knee joint.

[0126] The control unit 25 receives an input instructing execution of the evaluation process via the input unit 22 (step S10). This input is input from the input unit 22 by the user wearing the sensor device 10.

[0127] The control unit 25 transmits a signal instructing the start of data detection to the first sensor device 10A via the communication unit 21 (step S11). When the information processing system 1 includes the first sensor device 10A and the second sensor device 10B, the control unit 25 may transmit the signal instructing the start of data detection as a broadcast signal to the first sensor device 10A and the second sensor device 10B via the communication unit 21. After the processing of step S11 is executed, the data detected by the sensor device 10 is transmitted from the sensor device 10 to the electronic device 20.

[0128] The control unit 25 receives data detected by the sensor device 10 from the sensor device 10 via the communication unit 21 (step S12).

[0129] The control unit 25 estimates the landing timing of the user based on the data received in the process of step S12 (step S13). The control unit 25 acquires the angular velocity of the user's thigh during the ground contact period (step S14).

[0130] The control unit 25 inputs the angular velocity of the user's thigh acquired in step S14 into the learning model to acquire a score indicating an estimated value of the load applied to the user's knee joint (step S15). In the processing of step S15, the control unit 25 stores the estimated value indicated by the score in the storage unit 24.

[0131] The control unit 25 causes the output unit 23, which functions as a notification unit, to notify the information indicating the score acquired in the process of step S15 (step S16).

[0132] The control unit 25 determines whether the accumulated estimated value exceeds the threshold value (step S17). If the control unit 25 determines that the accumulated estimated value exceeds the threshold value (step S17: YES), the control unit 25 proceeds to the process of step S18. On the other hand, if the control unit 25 does not determine that the accumulated estimated value exceeds the threshold value (step S17: NO), the control unit 25 ends the evaluation process.

[0133] In the process of step S18, the control unit 25 causes the output unit 23, which serves as a notification unit, to notify information indicating a warning. After executing the process of step S18, the control unit 25 ends the evaluation process.

[0134] After completing the evaluation process, the control unit 25 may execute the evaluation process again at any time interval. This time interval may be set based on the walking speed of a typical user, etc. When the evaluation process is executed again, the control unit 25 may start the process from step S11. The control unit 25 may repeatedly execute the evaluation process until an input instructing the end of the evaluation process is received from the input unit 22. This input is, for example, input from the input unit 22 by the user. For example, the user inputs this input from the input unit 22 when he or she finishes walking.

[0135] In this way, in the electronic device 20 serving as an information processing device, the control unit 25 estimates the user's landing timing and obtains an estimated value of the load applied to the user's knee joint based on at least the first data. In other words, in this embodiment, as long as there is a sensor device 10 capable of detecting data for estimating the user's landing timing, etc., it is possible to obtain an estimated value of the load applied to the user's knee joint even without, for example, a load sensor that detects floor reaction force, etc. Therefore, according to this embodiment, it is possible to provide a technology for easily evaluating the load applied to the user's joint.

[0136] Furthermore, the reference angular velocity may be the angular velocity of the thigh during the contact period. That is, the control unit 25 may obtain an estimated value of the load applied to the user's knee joint based on the correlation between the angular velocity of the thigh during the contact period and the load applied to the knee joint, and the angular velocity of the user's thigh during the contact period. In this case, the control unit 25 may estimate the landing timing based only on the first data detected by the first sensor device 10A. The control unit 25 may obtain the angular velocity of the user's thigh based only on the first data detected by the first sensor device 10A. With this configuration, an estimated value of the load applied to the user's knee joint can be obtained based only on the first data detected by the first sensor device 10A. That is, the user only needs to wear one first sensor device 10A. This improves user convenience.

[0137] Furthermore, the reference angular velocity may be the angular velocity of the knee joint during the contact phase. That is, the control unit 25 may obtain an estimated value of the load applied to the user's knee joint based on the correlation between the angular velocity of the knee joint during the contact phase and the load applied to the knee joint, and the angular velocity of the user's knee joint during the contact phase. As described above with reference to FIG. 3 , the load applied to the knee joint is calculated by multiplying the reaction force of the knee joint by the angular velocity of the knee joint. There is a stronger correlation between the angular velocity of the knee joint and the load applied to the knee joint than, for example, between the angular velocity of the thigh and the load applied to the knee joint. Therefore, by using the correlation between the angular velocity of the knee joint during the contact phase and the load applied to the knee joint, it is possible to obtain a more accurate estimated value of the load applied to the user's knee joint.

[0138] In recent years, walking has been attracting attention as a convenient form of exercise. However, a user is required to pay attention to obstacles ahead or nearby while walking. Because a user is required to pay attention to obstacles ahead or nearby while walking, the user may not be able to pay attention to their own posture. If a user is unable to pay attention to their posture while walking, the user may unknowingly walk with an incorrect posture. If a user walks with an incorrect posture, excessive load may be placed on the user's knee joint. If a user continues walking while excessive load is placed on the knee joint, the user's knee joint may develop a disease such as osteoarthritis.

[0139] In the electronic device 20 according to this embodiment, the control unit 25 can cause the output unit 23 or the like to output information indicating an estimated value or score of the load on the user's knee joint. This configuration allows the user to determine whether the load on their knee joint is large or not. Because the user can determine whether the load on their knee joint is large or not, the possibility that the user will continue walking with excessive load on the knee joint is reduced. Reducing the possibility that the user will continue walking with excessive load on the knee joint reduces the possibility of developing a disease, such as osteoarthritis, in the user's knee joint.

[0140] (Configuration of Another System) FIG. 14 is a functional block diagram showing the configuration of an information processing system 101 according to another embodiment of the present disclosure.

[0141] The information processing system 101 includes a sensor device 10, an electronic device 20, and a server 40. In the information processing system 101, the server 40 functions as an information processing device and evaluates the load applied to the knee joint of the user.

[0142] The electronic device 20 and the server 40 can communicate with each other via a network 2. The network 2 may be any network including a mobile communication network, the Internet, and the like.

[0143] The control unit 25 of the electronic device 20 receives data detected by the sensor device 10 from the sensor device 10 via the communication unit 21 in the same manner as or similar to the information processing system 1. In the information processing system 101, the control unit 25 transmits the data detected by the sensor device 10 to the server 40 via the network 2 via the communication unit 21.

[0144] The server 40 is, for example, a server that belongs to a cloud computing system or another computing system. The server 40 includes a communication unit 41, a storage unit 42, and a control unit 43.

[0145] The communication unit 41 includes at least one communication module that can be connected to the network 2. The communication module is, for example, a communication module that complies with standards such as a wired LAN (Local Area Network) or a wireless LAN. The communication unit 41 is connected to the network 2 via the wired LAN or wireless LAN by the communication module.

[0146] The storage unit 42 is configured to include at least one semiconductor memory, at least one magnetic memory, at least one optical memory, or a combination of at least two of these. The semiconductor memory is, for example, a RAM or a ROM. The RAM is, for example, an SRAM or a DRAM. The ROM is, for example, an EEPROM. The storage unit 42 may function as a main storage device, an auxiliary storage device, or a cache memory. The storage unit 42 stores data used in the operation of the server 40 and data obtained by the operation of the server 40. For example, the storage unit 42 stores system programs, application programs, embedded software, etc.

[0147] The control unit 43 is configured to include at least one processor, at least one dedicated circuit, or a combination of these. The processor is a general-purpose processor such as a CPU or GPU, or a dedicated processor specialized for a specific process. The dedicated circuit is, for example, an FPGA or ASIC. The control unit 43 controls each part of the server 40 and executes processes related to the operation of the server 40.

[0148] The control unit 43 receives data detected by the sensor device 10 from the electronic device 20 via the network 2 using the communication unit 41. The control unit 43 acquires the data detected by the sensor device 10 by receiving the data detected by the sensor device 10 via the electronic device 20. The control unit 43 acquires an estimated value of the load applied to the knee joint of the user by performing processing that is the same as or similar to the processing performed by the control unit 25 of the electronic device 20 described above. For example, the control unit 43 estimates the timing of the user's landing and acquires an estimated value of the load applied to the knee joint of the user based on at least the first data.

[0149] The control unit 43 transmits a signal indicating an estimated value of the load applied to the user's knee joint to the electronic device 20 via the network 2 using the communication unit 41. When the control unit 43 acquires the estimated value as a score output from the learning model, the control unit 43 may transmit a signal indicating the score to the electronic device 20 via the network 2 using the communication unit 41. In the electronic device 20, the control unit 25 receives a signal indicating the estimated value or a signal indicating the score from the server 40 via the network 2 using the communication unit 21. The control unit 25 causes the output unit 23, which serves as a notification unit, to notify the output unit 23 of information indicating the estimated value or information indicating the score. As an example of notification, the control unit 25 causes the output unit 23 to output the information indicating the estimated value or the score.

[0150] The control unit 43 may accumulate the estimated value of the load applied to the user's knee joint in, for example, the storage unit 42 for the set period. When the control unit 43 determines that the accumulated estimated value exceeds the threshold, the control unit 43 may transmit a signal indicating a warning to the electronic device 20 via the network 2 by the communication unit 41. In the electronic device 20, the control unit 25 receives the signal indicating the warning from the server 40 via the network 2 by the communication unit 21. The control unit 25 causes the output unit 23, which serves as an alarm unit, to issue information indicating the warning. As an example of the alarm, the control unit 25 causes the output unit 23 to output information indicating the warning.

[0151] (Operation of Other Systems) FIGS. 15 and 16 are sequence diagrams showing the operation of the evaluation process executed by the information processing system 101 shown in FIG. 14 . This operation corresponds to an example of an information processing method according to this embodiment. When the electronic device 20 receives an input instructing execution of gait evaluation, the information processing system 101 starts the evaluation process from step S20 as shown in FIG. 15 . Hereinafter, the reference angular velocity is assumed to be the angular velocity of the thigh during the contact phase. Furthermore, the control unit 43 acquires an estimated value of the load applied to the user's knee joint using a learning model that has learned the correlation between the angular velocity of the thigh during the contact phase and the load applied to the knee joint.

[0152] In the electronic device 20, the control unit 25 receives an input instructing execution of an evaluation process via the input unit 22 (step S20). The control unit 25 transmits a signal instructing the sensor device 10 to start data detection via the communication unit 21 (step S21). When the information processing system 101 includes the first sensor device 10A and the second sensor device 10B, the control unit 25 may transmit the signal instructing the sensor device 10 to start data detection as a broadcast signal via the communication unit 21 to the first sensor device 10A and the second sensor device 10B.

[0153] In the sensor device 10, the control unit 14 receives a signal from the electronic device 20 via the communication unit 11 instructing the start of data detection (step S22). Upon receiving this signal, the control unit 14 starts data detection. The control unit 14 acquires data detected by the sensor unit 12 from the sensor unit 12 and transmits the acquired data to the electronic device 20 via the communication unit 11 (step S23).

[0154] In the electronic device 20, the control unit 25 receives the data from the sensor device 10 via the communication unit 21 (step S24). The control unit 25 transmits the data detected by the sensor device 10 to the server 40 via the network 2 via the communication unit 21 (step S25).

[0155] In the server 40, the control unit 43 receives data detected by the sensor device 10 from the electronic device 20 via the network 2 through the communication unit 41 (step S26). The control unit 43 estimates the user's landing timing based on the data received in the process of step S26 (step S27). The control unit 43 acquires the angular velocity of the user's thigh during the ground contact period based on the data received in the process of step S26 (step S28). The control unit 43 inputs the angular velocity of the user's thigh acquired in the process of step S28 into a learning model to acquire a score indicating an estimated value of the load applied to the user's knee joint (step S29). In the process of step S29, the control unit 43 stores the estimated value indicated by the score in the memory unit 42. The control unit 43 transmits a signal indicating the score to the electronic device 20 via the network 2 through the communication unit 41 (step S30).

[0156] After executing the process of step S30, the information processing system 101 proceeds to the process of step S31 as shown in FIG.

[0157] In the electronic device 20, the control unit 25 receives a signal indicating the score from the server 40 via the network 2 through the communication unit 21 (step S31). The control unit 25 then causes the output unit 23, which serves as a notification unit, to notify the information indicating the score (step S32).

[0158] In the server 40, the control unit 43 determines whether the accumulated estimated value exceeds the threshold value (step S33). If the control unit 43 determines that the accumulated estimated value exceeds the threshold value (step S33: YES), the control unit 43 transmits a signal indicating a warning to the electronic device 20 via the network 2 by the communication unit 41 (step S34). After executing the process of step S34, the information processing system 101 proceeds to the process of step S35. On the other hand, if the control unit 43 does not determine that the accumulated estimated value exceeds the threshold value (step S33: NO), the information processing system 101 ends the evaluation process.

[0159] In the process of step S35, the control unit 25 of the electronic device 20 receives a signal indicating a warning from the server 40 via the network 2 through the communication unit 21 (step S35). The control unit 25 then causes the output unit 23, which serves as a notification unit, to notify the information indicating the warning (step S36). After executing the process of step S36, the information processing system 101 ends the evaluation process.

[0160] After completing the evaluation process, the information processing system 101 may execute the evaluation process again at any time interval as described above. When executing the evaluation process again, the information processing system 101 may start from the process of step S23. The information processing system 101 may repeatedly execute the evaluation process until the electronic device 20 receives an input from the input unit 22 instructing the end of the evaluation process.

[0161] The information processing system 101 can achieve the same or similar effects as the information processing system 1 .

[0162] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art could make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications or alterations are included in the scope of the present disclosure. For example, the functions included in each component can be rearranged so as not to cause logical inconsistencies, and multiple components can be combined or divided into one.

[0163] For example, the communication unit 11 of the sensor device 10 may further include at least one communication module connectable to a network 2 as shown in Fig. 14. The communication module is, for example, a communication module compatible with a mobile communication standard such as LTE, 4G, or 5G. In this case, in the information processing system 101 as shown in Fig. 14, the control unit 15 of the sensor device 10 may transmit data detected by the sensor device 10 to a server 40 via the network 2 using the communication unit 11.

[0164] For example, an embodiment is also possible in which a general-purpose computer functions as the electronic device 20 according to the present embodiment. Specifically, a program describing the processing content for realizing each function of the electronic device 20 according to the present embodiment is stored in the memory of the general-purpose computer, and the program is read and executed by a processor. Therefore, the configuration according to the present embodiment can also be realized as a program executable by a processor or a non-transitory computer-readable medium storing the program.

[0165] In this disclosure, descriptions such as "first" and "second" are identifiers for distinguishing the configuration. Configurations distinguished by descriptions such as "first" and "second" in this disclosure can exchange numbers in the configuration. For example, a first sensor device can exchange identifiers "first" and "second" with a second sensor device. The exchange of identifiers is performed simultaneously. The configurations remain distinguished even after the identifier exchange. Identifiers may be deleted. A configuration from which an identifier has been deleted is distinguished by a symbol. The descriptions of identifiers such as "first" and "second" in this disclosure should not be used solely to interpret the order of the configurations or to justify the existence of identifiers with smaller numbers.

[0166] 1, 101 Information processing system 2 Network 10 Sensor device 10A First sensor device 10B Second sensor device 10C Third sensor device 11 Communication unit 12 Sensor unit 13 Memory unit 14 Control unit 20 Electronic device 21 Communication unit 22 Input unit 23 Output unit 24 Memory unit 25 Control unit 30 Foot 31 Foot 32 Shin 33 Knee joint 34 Thigh 40 Server 41 Communication unit 42 Memory unit 43 Control unit

Claims

1. acquiring first data relating to a movement of the user's thigh from a first sensor device; An information processing device comprising: a control unit that estimates a landing timing of the user's foot based on at least the first data, and obtains an estimated value of a load applied to the user's knee joint.

2. The control unit is acquiring a reference angular velocity of the user based on at least the first data, the reference angular velocity being an angular velocity of a thigh or an angular velocity of a knee joint during a ground contact phase in which at least a part of a foot is in contact with the ground; The information processing device according to claim 1 , further comprising: acquiring the estimated value calculated based on a correlation between the reference angular velocity and the load applied to a knee joint and the reference angular velocity of the user.

3. The information processing device according to claim 2 , wherein the control unit estimates a landing timing of the user based only on the first data.

4. The control unit is acquiring second data relating to a movement of the user's foot from a second sensor device; The information processing device according to claim 2 , further comprising: a landing timing of the user being estimated based on the second data.

5. the reference angular velocity is the angular velocity of the thigh during the ground contact phase, the correlation being a correlation between the angular velocity of the thigh during the ground contact phase and a load applied to the knee joint; The control unit is The information processing device according to claim 3 , wherein the angular velocity of the thigh of the user during the ground contact period is obtained only from the first data.

6. the reference angular velocity is an angular velocity of the knee joint during the contact phase, the correlation is a correlation between an angular velocity of the knee joint during the contact phase and a load applied to the knee joint, The control unit is The information processing device according to claim 3 , further comprising: an angular velocity of the knee joint of the user during the ground contact phase estimated and acquired based on the first data and second data indicating a movement of the user's foot detected by a second sensor device.

7. acquiring third data relating to a movement of the user's ankle from a third sensor device; obtaining a reference angular velocity of the user based on at least the third data, the reference angular velocity being an angular velocity of an ankle during a ground contact phase in which at least a part of a foot is in contact with the ground; an information processing device comprising: a control unit that acquires an estimated value of a load applied to the knee joint of the user calculated based on a correlation between the reference angular velocity and a load applied to a knee joint and the reference angular velocity of the user.

8. The information processing device according to claim 2 , wherein the control unit uses, as the correlation, a learning model that has learned the correlation.

9. Further comprising a notification unit, The information processing apparatus according to claim 1 , wherein the control unit causes the notification unit to notify information indicating the estimated value.

10. Further comprising a notification unit, The information processing apparatus according to claim 1 , wherein the control unit is configured to cause the notification unit to notify information indicating a warning when the accumulated estimated value exceeds a threshold value.

11. Further comprising a communication unit, The information processing apparatus according to claim 1 , wherein the control unit transmits a signal indicating the estimated value to an external device via the communication unit.

12. Further comprising a communication unit, The information processing apparatus according to claim 1 , wherein the control unit transmits a signal indicating a warning to an external device via the communication unit when the accumulated estimated value exceeds a threshold value.

13. An electronic device comprising: a notification unit that notifies information about the estimated value acquired by the information processing device according to claim 1 .

14. A first sensor device; an information processing device that acquires first data related to a movement of the user's thigh from the first sensor device; The information processing system includes an information processing device that estimates a landing timing of the user's foot based on at least the first data, and obtains an estimated value of a load applied to the user's knee joint.

15. Obtaining first data relating to a movement of a thigh of a user from a first sensor device; estimating a landing timing of the user's foot based on at least the first data, and obtaining an estimate of a load applied to the user's knee joint.

16. On the computer, Obtaining first data relating to a movement of a thigh of a user from a first sensor device; estimating a landing timing of the user's foot based on at least the first data, and obtaining an estimated value of a load applied to the user's knee joint.