JP6264400B2 - Multiple link mechanism and exercise assistance method - Google Patents

Description

  The technology disclosed in this specification is used by being attached to a human body such as an elderly person who mainly needs assistance or care, and is used in an exercise assistance device and an exercise assistance method for physically and psychologically assisting the movement of the human body. In particular, the present invention relates to an exercise assisting device and an exercise assisting method for assisting a variety of motions of a human body in general, including walking motion.

  Japan's aging rate (the proportion of the population aged 65 and over in the total population) is expected to reach 23.1% in 2010 and 30% in 2025. As the proportion of the population of the elderly grows rapidly, the elderly can stay healthy and lively as much as possible without being in need of long-term care. There is an urgent need to realize a society that can prevent people from living and live independently.

  With the advent of an aging society, there is an increasing demand for mechatronic equipment for the purpose of assisting the mind and body of the elderly in nursing homes for the elderly and families with the elderly. There is also a need for mental assistance that effectively incorporates robots into occupational therapy, as well as physical assistance such as autonomous walking aids and power assist suits.

  One of the important points in the development of mechatronic devices for assistance and nursing care is to maintain and promote as much as possible without disturbing the activities of the elderly. Even if the physical fitness of the elderly declines, if the machine takes over the activities of the elderly, the physical fitness of the elderly declines and the situation worsens (disuse syndrome). A power assist suit is a device that adds artificial force in addition to the force generated by a person's muscles. It can be said that it is desirable equipment in that it can be maintained.

  However, the penetration rate of power assist suits is not high at present. The reason is considered as follows.

(1) It takes time to install.
(2) It is expensive.
(3) The equipment is heavy.
(4) Only awkward support is provided.
(5) The appearance when worn is not good.
(6) The operation time is short.

  For example, recently, a force control type power assist method that gives a driving force to a joint based on an output from a myoelectric sensor and a result of motion phase estimation has recently attracted attention (see, for example, Non-Patent Document 1). ) However, the myoelectric sensor has to be attached at nine places on one leg, which takes time and effort. In addition, the myoelectric sensor may peel off from the skin due to aging and sweat. If the adhesion between the myoelectric sensor and the skin is lost, the output value of the myoelectric sensor may become unstable, and the power assist suit may run away or improper force may be applied to the worn human body.

  In addition, a proposal has been made for a walking assist device in which a design torque pattern corresponding to the phase of walking is applied to the human body during walking of the human body (for example, see Non-Patent Document 2). On the other hand, the user's walking patterns are diverse, and there are many cases that cannot be covered by the designed torque pattern. For this reason, it is easy to fall into the result of feeling uncomfortable at the time of walking, and being able to perform only unnatural and low-speed walking.

  On the other hand, a human body assist device that does not use a myoelectric sensor has also been proposed (see, for example, Non-Patent Document 3). The device is configured to sense the movement of a user's joint and apply a force to the joint to support it. However, this apparatus has a problem that it is difficult to reflect the intention of the user's movement with high sensitivity if there is an apparatus that inhibits the movement of the user's joint. For example, the viscous resistance of the gear part included in the joint part of the existing power assist suit can be a factor that hinders the movement of the user's joint. In the future, it will be necessary to eliminate such obstruction factors.

  Many power assist suits that do not use myoelectric sensors generate force based on empirical rules or control laws that lack evidence. Ideally, a myoelectric sensor can directly reflect the user's intention to exercise (however, in reality, there is a problem that the myoelectric sensor is difficult to stably sense). On the other hand, it is difficult to extract the user's intention from sensing joint motion. Under such conditions, the applicant believes that a rational control law is necessary to provide the user with force support without stress or unnatural feeling.

  For example, a walking assist system that assists in swinging out a leg while supporting a user's balance and weight has been proposed (see, for example, Patent Document 1). This walking assist system consists of an inverted pendulum type moving body gripped by the user and a walking assist device that assists the user's leg movement, and the target moving speed between the inverted pendulum type moving body and the walking assist device is a predetermined speed. The inverted pendulum type moving body controls the movement based on the movement of the base body and the target moving speed when the user grips, and the walking assist device uses the movement of the leg of the user and the target moving speed. To transmit the force to the user. That is, it can be said that the system performs a rhythm assist that supports the hip joint according to the layer of walking. However, the object to which the assist of the walking assist system is applied is a walking motion and does not have versatility applicable to other human motions. In other words, weight assist having a saddle at the crotch has been proposed, but it has a problem of being an obstacle to sitting and poor appearance.

  Further, a conventional power assist suit generally has a configuration in which one actuator is provided for driving each joint. Therefore, if an attempt is made to assist more joint parts, the increase in the number of actuators causes an increase in the weight and cost of the device, resulting in poor practicality. In addition, since the ratio of actuators in the equipment is high, design design is restricted, and the appearance of the equipment tends to be ugly, and the drive power is also increased, resulting in shortening of the operation time.

  The purpose of the technology disclosed in the present specification is used by being worn on a human body that mainly needs assistance or nursing care, such as an elderly person, and can favorably assist human body movement from the physical and psychological aspects. Another object of the present invention is to provide an exercise assistance device and an exercise assistance method.

  A further object of the technology disclosed in the present specification is to provide an excellent exercise assisting device and an exercise assisting method that provide natural force support using fewer actuators with respect to the number of joints, and realize weight reduction and price reduction. It is to provide.

The present application has been made in consideration of the above problems, and the technology according to claim 1
A jth link attached to the jth part of the user;
An i-th joint portion rotatably connected at one end of the i-th link;
A (j + 1) th link attached to the (j + 1) th part of the user;
An (i + 1) th joint part integral with one end of the (j + 1) th link and connected to the other end of the jth link;
A single actuator installed on either the j-th link or a link adjacent to the j-th link;
A transmission section for transmitting the driving force of the actuator to the i-th joint section and the (i + 1) -th joint section;
Is an exercise assisting device.

  According to the technology described in claim 2 of the present application, the transmission unit of the exercise assisting device according to claim 1 is configured so that the generated torque of the i-th joint unit and the generated torque of the (i + 1) -th joint unit are between The actuator is configured to transmit the driving force of the actuator so that a proportional relationship is established.

  According to the technique described in claim 3 of the present application, in the transmission unit of the exercise assisting device according to claim 1, the driving direction is reversed between the i-th joint unit and the (i + 1) -th joint unit. In this way, the driving force of the actuator is transmitted.

  According to the technique of claim 4 of the present application, the transmission unit of the exercise assisting device of claim 1 applies a driving force of the actuator to the i-th joint unit and the (i + 1) -th joint unit by a wire. Configured to communicate.

  According to the technique described in claim 5 of the present application, the transmission section of the exercise assisting apparatus according to claim 4 crosses the wire between the i-th joint section and the (i + 1) -th joint section. .

  According to the technique described in claim 6 of the present application, the j-th link of the exercise assistance device according to claim 1 is a thigh link attached to a thigh of the leg of the user, and the i-th link. The joint is a hip joint pitch axis that is rotatably connected at the upper end of the thigh link, the (j + 1) th link is a shin link attached to the shin of the leg, and the (i + 1) th The joint is a knee joint pitch axis that is integral with the upper end of the shin link and is connected to the lower end of the thigh link, and the actuator is installed on the thigh link.

  According to the technique described in claim 7 of the present application, the transmission unit of the exercise assisting device according to claim 6 is wound around the output shaft of the actuator and then The wire is wound in the same direction as the rotation direction and then wound in the direction opposite to the rotation direction of the actuator with respect to the knee joint pitch axis.

  According to the technique described in claim 8 of the present application, the j-th link of the exercise assisting device according to claim 1 is a thigh link attached to a thigh of the leg of the user, and the i-th link. The joint is a knee joint pitch axis that is rotatably connected at the lower end of the thigh link, and the (j + 1) th link is a pelvic link attached to the thigh of the leg, i + 1) The joint is a hip joint pitch axis that is integral with the pelvic link and connected to the upper end of the thigh link, and the actuator is installed on the shin link adjacent to the thigh link.

  According to the ninth aspect of the present application, the transmission unit of the exercise assisting apparatus according to the eighth aspect is wound around the output shaft of the actuator and then the actuator with respect to the knee joint pitch axis. The wire is wound in the same direction as the rotation direction, and then wound in the direction opposite to the rotation direction of the actuator with respect to the hip joint pitch axis.

  According to the technique of claim 10 of the present application, the exercise assisting device of claim 1 is configured to torque a target torque determining unit that determines a torque target value of the actuator and the actuator based on the torque target value. An actuator control unit that is controlled by the control is further provided.

  According to the technique described in claim 11 of the present application, the exercise assisting device according to claim 10 includes a joint angle measuring unit that measures a joint angle of the joint part, and a torque that measures an external torque acting on the actuator. A measurement unit is further provided. The actuator control unit torque-controls the actuator so that a desired relationship is established between the joint angle measured by the joint angle measurement unit and the external torque measured by the torque measurement unit. It is configured as follows.

According to the technique of claim 12 of the present application, the actuator control unit of the exercise assisting device of claim 11 calculates a disturbance torque τ _d when the actuator is driven with the target torque τ _{A. A} target value of joint angular acceleration achieved by the response of the actuator based on the target torque τ _A , the external torque τ _e, and the joint angular velocity obtained by time differentiation of the joint angle is provided. A target torque τ ^ref obtained by multiplying a target joint angular acceleration target value obtained from the theoretical response model of the actuator to be obtained and output by a nominal value J _n of the inertia in the actuator was obtained by the disturbance observer in the previous control cycle. with modification disturbance torque tau _d, determines the command torque tau to said actuator in the current control cycle Is constructed sea urchin.

  According to the technique described in claim 13 of the present application, the exercise assisting device according to claim 6 includes a state detection unit that detects whether the leg is a standing leg or a free leg, and the hip joint pitch axis. And a joint angle measuring unit for measuring a joint angle of the knee joint pitch axis, and a joint angle of the hip joint pitch axis or the knee joint pitch axis depending on whether the leg is a standing leg or a free leg state. The apparatus further includes a target torque determining unit that determines the torque target value based on the target torque. The actuator control unit is configured to control the actuator by torque control based on the torque target value.

  According to the technique described in claim 14 of the present application, the target torque determining unit of the exercise assisting device according to claim 13 is configured such that, when the leg is a standing leg, the torque is based on a joint angle of the knee joint pitch axis. A target value is determined, and when the leg is a free leg, the torque target value based on the joint angle of the hip joint pitch axis is determined.

  According to the technique of Claim 15 of this application, the said state detection part of the exercise assistance apparatus of Claim 13 consists of a contact switch which performs installation determination of the leg | foot part of the said leg.

A technique according to claim 16 of the present application is an exercise assistance method for assisting a user's exercise using the exercise assistance device according to claim 6,
A state detection step of detecting whether the leg is a standing leg or a free leg; and
A joint angle measuring step of measuring a joint angle of the hip joint pitch axis and the knee joint pitch axis;
A target torque determination step for determining the torque target value based on a joint angle of the hip joint pitch axis or the knee joint pitch axis, depending on whether the leg is a standing leg or a free leg; and
An actuator control step of controlling the actuator by torque control based on the torque target value;
Is an exercise assisting method.

  According to the technology disclosed in this specification, an excellent exercise assisting device and an exercise assisting method are provided that are configured to apply force to a plurality of joints with a single actuator, thereby realizing weight reduction and price reduction. can do.

  In addition, according to the technique disclosed in this specification, by performing wire interference driving so that a certain relationship is formed between the hip joint and the knee joint, both the hip joint and the knee joint can be performed with one actuator. An excellent exercise assistance device that realizes driving, enables weight support of the stance leg and lifting effect of the free leg, and realizes weight reduction and price reduction without damaging natural force support And a method of assisting exercise can be provided.

  The power assist suit to which the technology disclosed in this specification is applied reduces the proportion of the actuator in the device, so it is easy to design a beautiful design, and the drive power of the actuator can be reduced. , Can increase the operating time.

  Other objects, features, and advantages of the technology disclosed in the present specification will become apparent from a more detailed description based on the embodiments to be described later and the accompanying drawings.

FIG. 1 is a diagram schematically showing a configuration of a leg assist suit 100 to which the technology disclosed in this specification is applied. 2 is an enlarged view of the periphery of the hip joint and knee joint of the leg assist suit shown in FIG. 1 (configuration example in which the actuator 201 is installed on the thigh link 207). FIG. 3 is a diagram showing a configuration example of the actuator (A) applied to the joint drive of the leg assist suit shown in FIG. FIG. 4 is a diagram showing a configuration example of the leg assist / suit control system 100 constructed around the host computer 203. FIG. 5 is a diagram showing a state in which the leg assist suit 100 shown in FIG. 1 generates support force on the leg portions on the standing leg side and the free leg side. FIG. 6 is a diagram illustrating a state in which the leg assist suit 100 illustrated in FIG. 1 generates support force on the leg portions on the standing leg side and the free leg side. FIG. 7 is a diagram showing a bending angle θ _knee of the knee joint on the standing leg side and a refraction angle θ _hip of the _hip joint on the free leg side. FIG. 8 is an enlarged view of the periphery of the hip joint and knee joint in the leg assist suit shown in FIG. 1 (configuration example in which the actuator 201 is installed on the shin link 206). FIG. 9 is a flowchart showing a processing procedure for providing force support to the user wearing the leg assist suit 100. FIG. 10 is a control block diagram for realizing an ideal response of the actuator 201.

  Hereinafter, embodiments of the technology disclosed in this specification will be described in detail with reference to the drawings.

  FIG. 1 schematically shows a configuration of a leg assist suit 100 to which the technology disclosed in this specification is applied.

  The illustrated leg assist suit 100 has 8 degrees of freedom in total, with 3 degrees of freedom of roll, pitch and yaw at the hip joint and 1 degree of freedom of the pitch at the knee joint for each of the left and right legs of the human body. In FIG. 1, the right joint and link on the front side of the paper are drawn with solid lines, and the left joint and link behind the right leg behind the paper are drawn with dotted lines.

  Each joint is connected by a rigid link. Specifically, the left and right hip joints are connected by a pelvic link (Pelvis Link: PL) 208, and the left and right hip joints and knee joints are connected by a thigh link (High Link: TL) 207. The knee joint and the ankle joint are connected by a shin link (SL) 206. It is assumed that the pelvic link (PL) 208, the thigh link 207, and the shin link 206 are fixed to the human body by bands (not shown).

  The illustrated leg assist suit 100 has a hip yaw axis (HYJ) 209, a hip roll axis (HRJ) 210, and a hip joint pitch axis (HPJ) for each of the left and right legs. 204, having four joint degrees of freedom of knee joint pitch (KPJ) 205. Of these joints, the only drive joints (Active Joints) that generate drive force are the hip joint pitch axis 204 and the knee joint pitch axis 205, and the other hip joint yaw axis 209 and hip joint roll axis 210 generate force. Do not use free joints. Also, the ankle is only fixed with a band, and there is no degree of freedom for the ankle joint.

  A host computer 203 that controls the leg assist suit 100 is mounted on the pelvis. In addition, a contact sensor (footSW) 211 for detecting the ground contact state between the sole and the road surface is mounted on the left and right soles, and the left and right legs are standing on the basis of the output of the contact sensor 211. It is possible to determine which state is the free leg.

FIG. 2 is an enlarged view of the periphery of the hip joint and knee joint in the leg assist suit 100 shown in FIG. As shown, the left and right hip joint pitch axes 204 and knee joint pitch axes 205 are drive joints, which are driven by one actuator 201. This actuator 201 is installed on the thigh link 207, and its output is transmitted to the hip joint pitch axis 204 and the knee joint pitch axis 205 via the wire 202. The left and right knee joint pitch shafts 205 are not provided with actuators, but are separately attached with encoders (not shown in FIG. 2) for measuring the joint angle θ _knee of the knee joint pitch shafts 205. .

  In the example shown in FIG. 2, after the wire 202 is wound around the output shaft of the actuator 201, the wire 202 is wound around the hip joint pitch shaft 204 in the same direction as the rotation direction of the actuator 201, that is, regular. The knee joint pitch axis 205 is wound in a direction opposite to the rotation direction of the actuator 201, that is, an opposite law. The wire 202 is crossed between the hip joint pitch axis 204 and the knee joint pitch axis 205.

  The knee joint pitch axis 205 is fixed with respect to the shin link 206. Specifically, the pulley of the knee joint pitch shaft 205 is formed integrally with the shin link 206. Therefore, when the rotation of the output shaft of the actuator 201 is transmitted to the knee joint pitch shaft 205 via the wire 202, the shin link 206 operates integrally with the knee joint pitch shaft 205.

On the other hand, the hip joint pitch shaft 204 is freely attached to the thigh link 207. Specifically, the pulley of the hip joint pitch shaft 204 is not integral with the thigh link 207 but is rotatable via a bearing (not shown). Therefore, the thigh link 207 does not operate via the pulley of the hip joint pitch shaft 204 simply by rotating the output shaft of the actuator 201, and the torque τ _hip is not generated in the _hip joint pitch shaft 204.

Here, when an external force is applied to the ankle and a torque τ _knee is generated in the knee joint pitch shaft 205 integral with the shin link 206, an interference torque τ is applied to the hip joint pitch shaft 204 by the interference drive via the wire 202. _Hip occurs (see Non-Patent Document 4). As will be described later, a proportional relationship is established between the torque τ _hip generated on the hip joint pitch axis 204 and the torque τ _knee generated on the knee joint pitch axis 205.

  As described above, since the hip joint pitch axis 204 and the knee joint pitch axis 205 have a restraint relationship by wire interference driving, the leg assist suit 100 uses only a single actuator 201 for the knee and thigh. The parts can be operated simultaneously.

  FIG. 3 shows a configuration example of an actuator 201 applied to simultaneous driving of the hip joint pitch axis 204 and the knee joint pitch axis 205 of the leg assist suit 100 shown in FIG. The illustrated actuator 201 includes a motor 300 main body including a rotor 301 and a stator 302, and a speed reduction unit 303 including a gear such as a wave gear device, and is mounted on an interface board 304. An encoder 305 that detects the rotational position, that is, the angle of the joint axis, is attached to the rotor of the motor. In addition, a downstream link (not shown) is connected to the output shaft of the speed reduction portion via a bearing portion 306, and a torque sensor 307 for detecting output torque is attached.

The hip joint pitch axis 204 is wound around the wire 202 so as to be in the same direction as the rotation direction of the actuator 201. Therefore, the joint angle θ _hip of the hip joint pitch axis 204 can be measured by the output of the encoder 305 in the actuator 201. The joint angle θ _knee of the knee joint pitch axis 205 can be measured by an encoder (described above) separately attached to the knee joint pitch axis 205.

  FIG. 4 shows a configuration example of a control system for the leg assist suit 100 constructed around the host computer 203 mounted on the pelvic part of the leg assist suit 100. The actuators 201L / R disposed on the left and right sides are provided with microcomputers 401L / R for performing torque control and communication with the host computer 203, respectively. The host computer 203 can give a torque control target value to the motor 300 in the actuator 201 via the microcomputer 401L / R. Further, the host computer 203 can read out the detection values of the encoder 305L / R and the torque sensor 307L / R included in the actuator 201L / R through the microcomputer 401L / R. Further, a microcomputer 402L / R is provided together with the encoders 403L / R for the left and right knee joints, and a microcomputer 404L / R is also provided for the contact sensor 211L / R mounted on the left and right soles. The host computer 203 can read out the outputs of the encoder 403L / R and the left and right foot contact sensors 211L / R via the microcomputers 402L / R and 404L / R through similar communication.

The host computer 203 can obtain the joint angle θ _hip of the _hip joint pitch axis from the output value of the encoder 305L / R in the actuator 201L / R, and can determine the knee joint pitch axis from the output value of the encoder 403L / R of the knee joint. The joint angle θ _knee can be obtained.

In the present embodiment, the host computer 203 employs a force control method instead of position control for the actuator 201, but does not use a myoelectric sensor, and the joint angle of the hip joint pitch axis 204 corresponding to the movement of the user's joint. Force control is performed based on θ _hip and the joint angle θ _knee of the knee joint pitch axis 205. Therefore, the user is relieved from the trouble of wearing the myoelectric sensor on the human body, and is freed from the risk of malfunction due to the instability of the output value of the myoelectric sensor.

  These joints have factors that cause large errors that are difficult to model and identify, such as friction and inertia. Therefore, in order to realize an ideal joint (IJU), the actuator 201 is driven by dealing with disturbance factors that are difficult to model and identify such as friction and inertia existing in the joint, and by applying a mathematical model (ideal An actuator control device that can indicate an output torque based on a response model is used. Specifically, the actuator 201 is controlled using the value of the torque sensor 307 and the output of the encoder 305 to realize a precise response based on a mathematical model (see, for example, Patent Document 2). The actuator 201 shows a precise secondary system response governed by the specified inertia and viscous resistance with respect to the command torque and the external torque. As a result, the movement of the joint is not hindered by friction in the gear of the speed reducer, and even if a slight force acts on the joint, it can be accurately expressed as an angular acceleration change of the actuator 201. it can. Therefore, by performing control using the output torque obtained by the torque sensor 307 and the detection angle by the encoder 305, a precise response based on the mathematical model can be realized. As a result, it is possible to generate a force that supports exercise without giving resistance to the joint of the user wearing the leg assist suit 100.

  When the leg assist suit 100 shown in FIG. 1 and the mass property of the person wearing the leg assist suit are known and a system combining the person and the leg assist suit is modeled as a two-legged robot, the actuator is used in the dynamics calculation. 201 is modeled by a mathematical formula as shown in the following formula (1).

In the above equation (1), I _a is a joint virtual inertia, q _A is a joint angle (corresponding to θ _hip and θ _knee obtained as an encoder output), and τ _A is a torque that is a command value of the generated torque of the joint. The target value, τ _e is an external torque acting on the joint, and ν _a is _a virtual viscosity coefficient (unknown and difficult to model) inside the joint. _A method for calculating the torque target value τ _A will be described later.

From the above equation (1), it can be seen that the theoretical model includes an external torque term τ _e acting on the joint. Therefore, it is necessary to detect this external torque τ _e in order to correct the response of the actuator 201 so that it matches the theoretical model. In the present embodiment, as described above, the actuator 201 is provided with the torque sensor 307 for measuring the external torque τ _e on the output shaft of the speed reducing unit 303 (see FIG. 3). The torque measurement results are collected by the host computer 203.

  The actuator 201 responding according to the theoretical model expressed by the above equation (1) is nothing but the achievement of the joint angular acceleration on the left side when the right side of the above equation (1) is given. . In order to configure such a joint angular acceleration control system, by applying a disturbance observer for estimating a disturbance torque, the joint torque τ can be determined with high accuracy based on a theoretical response model.

FIG. 10 shows a control block diagram for realizing the ideal response of the actuator 201. In the figure, a portion surrounded by a dotted line corresponds to a disturbance observer, and a robust acceleration control system is constructed by estimating the disturbance torque τ _d and removing the influence on the control system. Where J _n is the nominal value of the inertia in the joint, J is the (unknown) actual value of the inertia in the joint, and q _A is the joint angle. Further, it is assumed that _a virtual constant is given to the joint virtual inertia Ia as _a design item in the dynamics calculation.

On the host computer 203, a target torque τ _A that is a command value for the actuator 201 is determined by a force control method at each control cycle, and a torque sensor 307 attached to the output shaft of the deceleration unit 303 of the actuator 201 is used. The measured external torque measured value τ _e and the measured angular velocity value obtained from the joint angle q _A measured by the encoder 305 or the like are sent from the microcomputer 401 provided in the actuator 201. Then, these target torque tau _A, external torque actual measurement value tau _e, and the angular velocity actual measurement value of the joint angle q _A is substituted into the theoretical response model expressed by the above formula (1), the equation left side of the joint angle q _A Acceleration target value is obtained, and this angular acceleration target value is input to the disturbance observer.

In the disturbance observer, the input acceleration target value of the joint angle q _A is multiplied by the joint virtual inertia nominal value J _n to convert it into a torque target value τ ^ref in the current control cycle. When the disturbance torque τ _d obtained in the previous control cycle by the disturbance observer is corrected to the torque target value τ ^ref , the torque command value τ for the joint in the current control cycle is obtained.

When force control consisting of the torque command value τ is applied to the joint consisting of the transfer function 1 / J _n , the joint is rotated while being influenced by disturbances such as friction and inertia existing in the joint. Specifically, the torque command value τ is converted into a current command value, which becomes an instruction input to the drive circuit of the motor 300. While being measured is generated torque tau _e and the joint angle q _A at that time, etc. Each torque sensor 307 and encoder 305, joint angular velocity is obtained by differentiating the joint angle output q _A time.

The disturbance observer can estimate the torque acting on the joint by applying the transfer function J _n s consisting of the joint nominal inertia value J _n to the measured angular velocity of the joint angle q _A. The disturbance torque τ _d can be estimated by subtracting the torque from the torque command value τ to the joint. The disturbance torque τ _d obtained in the current control cycle is fed back and used to correct the torque command value τ in the next control cycle. A low-pass filter (LPF) represented by g / (s + g) inserted in the middle is for preventing the divergence of the system.

In this way, the acceleration response of the actuator can be made to follow the acceleration target value even if there are disturbance components such as friction and inertia that cannot be modeled in the joint. That is, since the joint angular acceleration on the left side is achieved when the right side of the above equation (1) is given, the actuator can realize a response according to the theoretical model despite being affected by the disturbance. However, the low-pass filter g / (s + g) is inserted in the middle of feeding back the disturbance torque τ _d (described above), and is not suitable for removing disturbances in the high frequency range.

  The disturbance observer estimates the disturbance component in the plant and feeds it back to the control input, thereby having the effect of reaching the target state even if the plant has unknown parameter fluctuation or disturbance. However, in order to correctly estimate the disturbance, it is necessary to repeat the feedback calculation over a plurality of cycles.

In the control block configuration shown in FIG. 10, the disturbance observer obtains the angular acceleration of the joint angle q _A by the above equation (1), and sets this as the joint angular acceleration target value for the actuator of the joint portion. The angular acceleration of the joint angle q is determined based on the external torque τ _e obtained from the torque sensor 307, the target torque τ _{A of the} joint, and the time derivative of the joint angle q _A output from the encoder 305 or the like. . By adopting such a configuration, the joint portion, it is possible to perform the response according to the inertia I _a and viscosity coefficient [nu _a, are idealized.

  As described above, after the wire 202 is wound around the output shaft of the actuator 201, the wire 202 is wound around the hip joint pitch shaft 204 in the same direction as the rotation direction of the actuator 201, and then the knee joint pitch. The shaft 205 is wound around in a direction opposite to the rotation direction of the actuator 201 (see FIG. 2). Due to the interference driving of the wire 202, torque as shown in the following expression (2) is generated on each axis of the leg assist suit 100 (see, for example, Non-Patent Document 4).

In the above equation (2), τ _i is a torque generated in the i-th joint, and f _j is a tension generated in the j-th wire. However, it is assumed that the j-th wire is wound around the i-th joint with a pulley having a radius r _ij . Further, s _ij represents the direction in which the j-th wire is wound around the pulley of the i-th joint with a positive / negative sign. If the tension f _j is rotated in the forward direction of the joint angle acting s _ij +1, if counter-rotating s _ij has a value of -1.

It is assumed that an actuator that generates a torque τ _j expressed by the following equation (3) is connected to the tip of the j-th wire via a pulley having a radius R _j .

From the above equation (2) and the above equation (3), the torque τ _i generated in the i-th joint is expressed as the following equation (4).

Here, when all the pulleys have the same diameter, and the above equation (4) is applied to the example shown in FIG. 1, the hip and knee joints are respectively represented by the following equations (5) and (6). It can be seen that torques τ _hip and τ _knee are generated.

However, in the above formulas (5) and (6), τ _A is the torque generated by the actuator 201 disposed on the thigh. From the above equations (5) and (6), it can be seen that the wire joint drive generates torques of the same magnitude and in opposite directions on the hip joint pitch shaft 204 and the knee joint pitch shaft 205. If the diameters of the pulleys of the hip joint pitch axis 204 and the knee joint pitch axis 205 are not the same, the magnitudes of the torques τ _hip and τ _knee are not the same, but they are opposite to each other at a constant ratio according to the ratio of the pulley diameters. It can be said that torque is generated.

  In the leg assist suit 100, in the leg on the stance side, the knee joint pitch axis 205 operates to extend the thigh link 207 and the shin link 206 (see reference numeral 501 in FIG. 5). It has a role to increase the user's weight, which is important when climbing stairs, for example. At the same time, the hip joint pitch axis 204 operates to extend the thigh link 207 relative to the user's torso (see reference numeral 502 in FIG. 5) to maintain the upper body posture. It is preferable to make it. At that time, the knee joint pitch axis 205 moves clockwise in FIG. 5 and the hip joint pitch axis 204 moves counterclockwise. Therefore, it can be said that the hip joint pitch axis 204 is in a cooperative relationship with the knee joint pitch axis 205 when standing.

  On the other hand, in the leg on the free leg side, the hip joint pitch axis 204 operates to bend the thigh link 207 with respect to the user's torso (reference number 503 in FIG. 5) to raise the user's free leg. There is a role. At the same time, the knee joint pitch axis 205 operates so that the thigh link 207 and the shin link 206 bend (reference number 504 in FIG. 5) so that the toe of the free leg does not hit the ground. It is preferable to do. At that time, the hip joint pitch axis 204 operates clockwise in FIG. 5 and the knee joint pitch axis 205 operates counterclockwise. Therefore, it can be said that the knee joint 205 is in a cooperative relationship with the hip joint pitch axis 204 during the swing leg.

  Further, even if the hip joint pitch axis 204 and the knee joint pitch axis 205 are in a cooperative relationship, the free leg (and the standing leg) can take any posture according to the user's intention (for example, as shown in FIG. 6). Thus, only the hip joint pitch axis is operated, or only the knee joint pitch axis is operated), and the hip joint pitch axis 204 and the knee joint pitch axis 205 need to be configured such that the angles can be changed independently.

  The leg assist suit 100 has a configuration as shown in FIG. 1, so that even if the drive source is only one actuator 201, the torque control and the interference drive by the wire 202 can be used for the hip joint and the knee joint 2. The joint angles can be coordinated simultaneously and the joint angles can be changed independently. That is, as shown in FIG. 5, the leg assist suit 100 generates a support force that pushes up the weight at the leg portion on the standing leg side, and a support force that lifts the leg at the leg portion on the free leg side. Can be generated. However, the direction of torque generation in FIG. 5 indicates the direction of torque that acts on the link on the lower limb tip (plantar) side from the link on the lower limb root (pelvis) side.

In the leg on the standing leg side, the knee joint pitch axis 205 plays a more important role from the viewpoint of pushing up the weight of the user. In the leg on the free leg side, the hip joint pitch axis 204 plays a more important role from the viewpoint of raising the leg. Therefore, as a force support law, on the stance side, the torque τ _{A of the} actuator 201 is generated according to the flexion / extension angle θ _knee of the knee joint (see the following equation (7)), and on the free leg side, the hip joint The torque τ _{A of the} actuator 201 is generated in accordance with the refraction angle θ _hip (see the following equation (8)). The bending / extension angle θ _knee of the knee joint on the stance leg side and the refraction angle θ _hip of the _hip joint on the swing leg side are as shown in FIG.

  FIG. 2 shows a configuration example in which a single actuator 201 is installed on the thigh link 207 and the two joints of the hip joint pitch axis 204 and the knee joint pitch axis 205 are driven by wire interference. In this configuration example, the wire 202 is wound so that the hip joint pitch axis 204 is in the same direction and the knee joint pitch axis 205 is opposite to the rotation direction of the output shaft of the actuator 201, and the pulley of the knee joint pitch axis 205 is wound. Is integrated with the shin part link 206, while the pulley of the hip joint pitch shaft 204 is rotatable with respect to the thigh link 207.

  On the other hand, the leg assist suit 100 can be configured such that a single actuator 201 is installed not on the thigh link 207 but on the shin link 206. In the example shown in FIG. 8, the wire 202 is wound around the output shaft of the actuator 201 installed on the shin link 206 and then the same direction as the rotation direction of the actuator 201 with respect to the knee joint pitch shaft 205, that is, regular. Then, it is wound around the hip joint pitch axis 204 in a direction opposite to the rotation direction of the actuator 201, that is, an opposite law. The wire 202 is crossed between the knee joint pitch axis 205 and the hip joint pitch axis 204.

  The hip joint pitch axis 204 is fixed with respect to the pelvis link 208. Specifically, the pulley of the hip joint pitch shaft 204 is formed integrally with the pelvic link 208. Therefore, when the rotation of the output shaft of the actuator 201 is transmitted to the hip joint pitch shaft 204 via the wire 202, the thigh link 207 operates with respect to the pelvic link 208.

On the other hand, the knee joint pitch axis 205 is not integrated with any of the free shin part link 206 and the thigh link 207 with respect to both the shin part link 206 and the thigh link 207, and has a bearing (not shown). It is free to rotate through. Therefore, if the output shaft of the actuator 201 simply rotates, the shin link 206 does not operate via the pulley of the knee joint pitch shaft 205, and the torque τ _knee does not occur in the knee joint pitch shaft 205.

Here, when a torque τ _hip is generated in the _hip joint pitch shaft 204 integral with the pelvis link 208 due to an external force applied to the pelvis link 208, the interference torque is applied to the knee joint pitch shaft 205 by the interference drive via the wire 202. τ _knee occurs (same as above). As described above, a proportional relationship is established between the torque τ _hip generated on the hip joint pitch axis 204 and the torque τ _knee generated on the knee joint pitch axis 205.

  As described above, also in the configuration example shown in FIG. 8, since there is a restraint relationship between the hip joint pitch axis 204 and the knee joint pitch axis 205 by the wire interference drive, the leg assist suit 100 is a single unit. The knee and thigh can be simultaneously operated using only the actuator 201 of the above.

2 or 8, the torque τ _{A of the} actuator 201 is generated according to the flexion / extension angle θ _knee of the knee joint on the standing leg side (see the above equation (7)). On the free leg side, it is understood that the force support law described above is effective, in which the torque τ _{A of the} actuator 201 is generated according to the refraction angle θ _hip of the _hip joint (see the above equation (8)). I want.

  FIG. 9 shows a processing procedure for providing force support to a user wearing the leg assist suit 100 in the form of a flowchart. This processing procedure is realized by the host computer 203 executing a predetermined program code, for example.

  First, the host computer 203 reads the outputs of the contact sensors 211L / R mounted on the left and right soles through the microcomputer 404L / R, and determines the ground contact state of the left and right feet (step S901).

Next, the host computer 203 reads the output of the encoder 305L / R included in the actuator 201L / R through the microcomputer 401L / R, and reads the output of the encoders 403L / R of the left and right knee joints through the microcomputer 402L / R. The joint angle θ _hip of the left and right _hip joints and the joint angle θ _knee of the knee joints are acquired (step S902).

  Next, the host computer 203 calculates the torque target value of the actuator 201L / R for the left and right legs based on the above equations (7) and (8) (step S903).

  Then, the host computer 203 gives the torque target value obtained in step S903 to the motor 300 in the actuator 201 via the microcomputer 401L / R (step S904).

  By executing the above processing procedure every control cycle of, for example, 10 milliseconds, the leg assist suit 100 can perform natural force support for exercises such as walking of the user wearing the leg assist suit.

  Since the leg assist suit 100 according to the present embodiment is configured to apply force to a plurality of joints with a single actuator 201, it is possible to achieve weight reduction and cost reduction. In particular, the leg assist suit 100 performs the wire interference drive so that a certain relationship is formed between the hip joint pitch axis 204 and the knee joint pitch axis 205, thereby supporting the weight of the stance leg, The lifting effect of the free leg can be achieved, and the weight can be reduced without impairing the natural force support.

Note that the technology disclosed in the present specification can also be configured as follows.
(1) a j-th link attached to the j-th part of the user;
An i-th joint portion rotatably connected at one end of the i-th link;
A (j + 1) th link attached to the (j + 1) th part of the user;
An (i + 1) th joint part integral with one end of the (j + 1) th link and connected to the other end of the jth link;
A single actuator installed on either the j-th link or a link adjacent to the j-th link;
A transmission section for transmitting the driving force of the actuator to the i-th joint section and the (i + 1) -th joint section;
An exercise assistance device comprising:
(2) The transmission unit transmits the driving force of the actuator so that a proportional relationship is established between the generated torque of the i-th joint portion and the generated torque of the (i + 1) -th joint portion.
The exercise assisting device according to (1) above.
(3) The transmission unit transmits the driving force of the actuator so that the driving direction is reversed between the i-th joint unit and the (i + 1) -th joint unit.
The exercise assisting device according to (1) above.
(4) The transmission unit transmits the driving force of the actuator to the i-th joint unit and the (i + 1) -th joint unit using a wire.
The exercise assisting device according to (1) above.
(5) The transmission unit crosses the wire between the i-th joint unit and the (i + 1) -th joint unit,
The exercise assisting device according to (4) above.
(6) a thigh link attached to the thigh of the user's leg;
A hip joint pitch axis rotatably connected at the upper end of the thigh link;
A shin link attached to the shin of the leg;
A knee joint pitch axis that is integral with the upper end of the shin link and connected to the lower end of the thigh link;
An actuator installed on the thigh link;
A transmission unit for transmitting the driving force of the actuator to the hip joint pitch axis and the knee joint pitch axis;
An exercise assistance device comprising:
(7) The transmission unit transmits the driving force in the same direction as the driving direction of the actuator to the hip joint pitch axis, and the driving force in a direction opposite to the driving direction of the actuator with respect to the knee joint pitch axis. Communicate,
The exercise assisting device according to (6) above.
(8) The transmission unit is wound around the output shaft of the actuator, then wound in the same direction as the rotation direction of the actuator with respect to the hip joint pitch axis, and then with respect to the knee joint pitch axis. Consists of a wire wound in the direction opposite to the rotation direction of the actuator,
The exercise assisting device according to (6) above.
(9) The transmission unit crosses the wire between the hip joint pitch axis and the knee joint pitch axis.
The exercise assisting device according to (8) above.
(10) a thigh link attached to the thigh of the user's leg;
A knee joint pitch axis rotatably connected at the lower end of the thigh link;
A pelvic link attached to the thigh of the leg;
A hip pitch axis that is integral with the pelvic link and connected to the upper end of the thigh link;
An actuator installed in the shin link adjacent to the thigh link;
A transmission unit for transmitting the driving force of the actuator to the hip joint pitch axis and the knee joint pitch axis;
An exercise assistance device comprising:
(11) The transmitting unit transmits the driving force in the same direction as the driving direction of the actuator to the knee joint pitch axis, and the driving force in a direction opposite to the driving direction of the actuator with respect to the hip joint pitch axis. Communicate,
The exercise assisting device according to (10) above.
(12) The transmission unit is wound around the output shaft of the actuator, then wound around the knee joint pitch axis in the same direction as the rotation direction of the actuator, and then the hip joint pitch axis Consists of a wire wound in the direction opposite to the rotation direction of the actuator,
The exercise assisting device according to (10) above.
(13) The transmission unit crosses the wire between the knee joint pitch axis and the hip joint pitch axis.
The exercise assisting device according to (12) above.
(14) a target torque determining unit that determines a torque target value of the actuator;
An actuator controller for controlling the actuator by torque control based on the torque target value;
The exercise assisting device according to any one of (1), (6), and (10), further comprising:
(15) a joint angle measurement unit that measures a joint angle of the joint part;
A torque measuring unit for measuring an external torque acting on the actuator;
The actuator control unit torque-controls the actuator so that a desired relationship is established between the joint angle measured by the joint angle measurement unit and the external torque measured by the torque measurement unit;
The exercise assisting device according to (14) above.
(16) The actuator control unit
_A disturbance observer for calculating a disturbance torque τ _d when the actuator is driven with the target torque τ _A ,
An actuator that obtains and outputs a target value of joint angular acceleration achieved by the actuator responding based on the target torque τ _A , the external torque τ _e, and the joint angular velocity obtained by time differentiation of the joint angle The torque target value τ ^ref obtained by multiplying the joint angular acceleration target value obtained from the theoretical response model by the nominal value J _n of the inertia in the actuator is the disturbance torque τ _d obtained by the disturbance observer in the previous control cycle. Modify to determine the command torque τ for the actuator in the current control period;
The exercise assisting device according to (15) above.
(17) a state detection unit that detects whether the leg is a standing leg or a free leg;
A joint angle measuring unit for measuring joint angles of the hip joint pitch axis and the knee joint pitch axis;
A target torque determining unit that determines the torque target value based on a joint angle of the hip joint pitch axis or the knee joint pitch axis according to whether the leg is a standing leg or a free leg;
The actuator control unit controls the actuator by torque control based on the torque target value.
The exercise assisting device according to any one of (6) and (10) above.
(18) The target torque determination unit determines the torque target value based on a joint angle of the knee joint pitch axis when the leg is a standing leg, and the joint of the hip joint pitch axis when the leg is a free leg. Determining the torque target value based on an angle;
The exercise assisting device according to (17) above.
(19) The state detection unit includes a contact switch that performs installation determination of the foot portion of the leg.
The exercise assisting device according to (17) above.
(20) An exercise assistance method for assisting a user's exercise using the exercise assistance device according to any one of (1), (6), and (10),
A target torque determining step for determining a torque target value of the actuator;
An actuator control step of controlling the actuator by torque control based on the torque target value;
A method for assisting exercise.
(21) An exercise assistance method for assisting a user's exercise using the exercise assistance device according to any one of (6) and (10) above,
A state detection step of detecting whether the leg is a standing leg or a free leg; and
A joint angle measuring step of measuring a joint angle of the hip joint pitch axis and the knee joint pitch axis;
A target torque determination step for determining the torque target value based on a joint angle of the hip joint pitch axis or the knee joint pitch axis, depending on whether the leg is a standing leg or a free leg; and
An actuator control step of controlling the actuator by torque control based on the torque target value;
A method for assisting exercise.
(22) In the target torque determining step, when the leg is a standing leg, the torque target value is determined based on a joint angle of the knee joint pitch axis, and when the leg is a free leg, the hip pitch axis joint is determined. Determining the torque target value based on an angle;
The exercise assisting method according to (21) above.

JP 2011-62463 A Japanese Patent No. 4715863

Kawamoto H. et al. Lee S. , Kanbe S. Sankai Y .; : “Power Assist Method for HAL-3 using EMG-based Feedback Controller”, Proc. of Int'l Conf. on Systems, Man and Cybernetics (SMC 2003), pp. 1648-1653, 2003 Kenta Suzuki, Gouji Mito, Hiroaki Kawamoto, Yasuhiha Hasegawa, Yoshiyuki RippoSports for Paraport. 21, no. 12, pp. 1441-1469, 2007 J. et al. Ghan, R.A. Steger, Kazeroni, H, “Control and System Identification for the Berkeley Lower Extreme Exoskeleton”, Advanced Robotics, Volume 9, Numb. 989-1014, Number 9, 2006 K. Yokoi et al. “Design and Control of a Seven-Degrees-of-Freedom Manipulator Actuated by a Coupled Tendon-Driving System”, In Proc. Annual Conf. of Robotics Society of Japan, 1991, pp. 461-464.

  As described above, the technology disclosed in this specification has been described in detail with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications and substitutions of the embodiments without departing from the scope of the technology disclosed in this specification.

  In the present specification, the embodiment applied to the leg assist suit has been mainly described, but the gist of the technology disclosed in the present specification is not limited to this. It is also possible to apply the technique disclosed in this specification to various types of assist suits to be worn on a person's site other than the legs to assist various exercises of people other than walking.

  In short, the technology disclosed in the present specification has been described in the form of exemplification, and the description content of the present specification should not be interpreted in a limited manner. In order to determine the gist of the technology disclosed in this specification, the claims should be taken into consideration.

DESCRIPTION OF SYMBOLS 100 ... Leg part assist suit 201 ... Actuator, 202 ... Wire 203 ... Host computer 204 ... Hip joint pitch axis, 205 ... Knee joint pitch axis 206 ... Tibial link, 207 ... Thigh link 208 ... Pelvic link, 209 ... Hip joint yaw axis 210 ... Hip roll axis 211 ... Contact sensor 300 ... Motor 301 ... Rotor 302 ... Stator 303 ... Deceleration part 304 ... Interface board 305 ... Encoder (inside actuator), 306 ... Bearing part 307 ... Torque Sensor 401, 402, 404 ... Microcomputer 403 ... Encoder (knee joint), 405 ... Contact sensor

Claims (13)

The first link,
A first joint that rotatably supports one end of the first link;
A second link,
A second joint fixed to the second link and rotatably connecting one end of the second link to the other end of the first link;
An actuator installed in the first link;
A transmission unit that transmits the driving force of the actuator to each of the first joint unit and the second joint unit via a wire;
Comprising
The transmission unit includes the first joint unit such that the first joint unit rotates in the same direction as the rotation direction of the actuator and the second joint unit rotates in a direction opposite to the rotation direction of the actuator. And crossing the wire between the second joint part,
Multiple link mechanism. The second joint is integral with the second link, but the first joint is rotatable with respect to the first link;
When an external force is applied to the second link or a torque is generated in the second joint, the transmission unit and the generated torque of the first joint are coupled with the generated torque by the interference drive via the wire. Transmitting the driving force of the actuator so that a proportional relationship is established between the torques generated by the two joints;
The multiple link mechanism according to claim 1. The first link is a thigh link attached to a thigh of a user's leg,
The first joint part is a hip joint pitch axis that rotatably supports the upper end of the thigh link,
The second link is a shin link attached to the shin of the leg,
The second joint is a knee joint pitch axis that is integral with the upper end of the shin link and connected to the other end of the thigh link,
The actuator is installed on the thigh link,
The multiple link mechanism according to claim 1. The wire is wound around the output shaft of the actuator and then wound in the same direction as the rotation direction of the actuator with respect to the hip joint pitch axis, and then the rotation direction of the actuator with respect to the knee joint pitch axis. And wound in the opposite direction,
The multiple link mechanism according to claim 3. The first link is a shin link attached to the shin of the user's leg,
The second link is a thigh link attached to the thigh of the leg,
The first joint portion is a knee joint pitch axis that connects an upper end of the shin link and a lower end of the thigh link,
The second joint part is a hip joint pitch axis that is integral with a pelvic link adjacent to the thigh link and supports the upper end of the thigh link rotatably.
The actuator is installed on the shin link;
The multiple link mechanism according to claim 1. The wire is wound around the output shaft of the actuator, and then wound in the same direction as the rotation direction of the actuator with respect to the knee joint pitch axis, and then the rotation direction of the actuator with respect to the hip pitch axis And wound in the opposite direction,
The multiple link mechanism according to claim 5. A target torque determining unit for determining a torque target value of the actuator;
An actuator controller for controlling the actuator by torque control based on the torque target value;
The multiple link mechanism according to claim 1, further comprising: A joint angle measuring unit for measuring a joint angle of the joint part;
A torque measuring unit for measuring an external torque acting on the actuator;
The actuator control unit torque-controls the actuator so that a desired relationship is established between the joint angle measured by the joint angle measurement unit and the external torque measured by the torque measurement unit;
The multiple link mechanism according to claim 7. The actuator controller is
_A disturbance observer for calculating a disturbance torque τ _d when the actuator is driven with the target torque τ _A ,
An actuator that obtains and outputs a target value of joint angular acceleration achieved by the actuator responding based on the target torque τ _A , the external torque τ _e, and the joint angular velocity obtained by time differentiation of the joint angle The torque target value τ ^ref obtained by multiplying the joint angular acceleration target value obtained from the theoretical response model by the nominal value J _n of the inertia in the actuator is the disturbance torque τ _d obtained by the disturbance observer in the previous control cycle. Modify to determine the command torque τ for the actuator in the current control period;
The multiple link mechanism according to claim 8. A state detection unit that detects whether the user's leg is standing or swinging; and
A joint angle measuring unit for measuring joint angles of the first joint part and the second joint part;
A target torque determining unit configured to determine the torque target value based on a joint angle of the first joint unit or the second joint unit depending on whether the leg is a standing leg or a free leg; ,
The actuator control unit controls the actuator by torque control based on the torque target value.
The multiple link mechanism according to claim 3. The target torque determining unit determines the target torque value based on the joint angle of the second joint when the leg is a standing leg, and the joint of the first joint when the leg is a free leg. Determining the torque target value based on an angle;
The multiple link mechanism according to claim 10. The state detection unit is composed of a contact switch that performs installation determination of the foot part of the leg,
The multiple link mechanism according to claim 10. An exercise assistance method for assisting a user's exercise using the multiple link mechanism according to claim 10,
A state detection step of detecting whether the leg is a standing leg or a free leg; and
A joint angle measuring step of measuring joint angles of the first joint part and the second joint part;
A target torque determination step for determining the torque target value based on a joint angle of the first joint part or the second joint part depending on whether the leg is in a standing leg or a free leg state;
An actuator control step of controlling the actuator by torque control based on the torque target value;
A method for assisting exercise.