Exoskeleton series elastic actuator with joint torque compensation

Abstract

The application provides a series elastic actuator for exoskeleton with joint torque compensation, which comprises a fixed seat module, an elastic element module, a driving element, an encoder module and an exoskeleton joint module. A plurality of disc spring groups are symmetrically arranged at two ends of a fixed shaft, a plurality of elastic element fixing shafts are symmetrically arranged at two ends of a first fixed shaft and a second fixed shaft, the two ends of the first fixed shaft are respectively fixedly connected with a first nut and a second nut through first mounting holes of the elastic element fixing shafts, the two ends of the second fixed shaft are respectively fixedly connected with a third nut and a fourth nut through second mounting holes of the elastic element fixing shafts, and the middle portions of the first fixed shaft and the second fixed shaft are respectively fixedly connected with a second mounting end and a third mounting end of an elastic element fixing seat. The elastic coefficient of the elastic element module is obtained by changing the number of disc-shaped elastic elements in the disc spring groups. The elastic element module of the application not only realizes the size and mass reduction of the overall series elastic actuator, but also realizes the mutual cooperation of multiple joints.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of exoskeleton joints, in particular to an exoskeleton series elastic actuator with compensation for joint torque. BACKGROUND

[0002] In recent years, exoskeletons are a hot research direction in the field of medical rehabilitation. Under the background of the continuous development of intelligent robot technology, domestic and foreign institutions have begun to use rehabilitation exoskeleton robots to gradually replace rehabilitation physicians. Not only can they provide more reliable and convenient recovery training programs for patients, but also can effectively reduce treatment costs. Exoskeleton robots can enable wearers to achieve rehabilitation training by providing certain assistance externally. The driver connected by the exoskeleton joint is the power source mechanism of the exoskeleton, which needs to meet the requirements of good stability, high safety, accurate control of output force and speed, and prevention of secondary injury to the wearer.

[0003] However, most of the series elastic drivers developed for exoskeleton joints currently use rotary elastic elements or telescopic rod structures. The series elastic drivers are generally large in size and mass, which increases the power consumption of the exoskeleton robot and is inconvenient to wear.

[0004] In addition, most of the series elastic drivers developed for exoskeleton joints currently are difficult to accurately calculate the output speed and force, and the recovery degree of the patient is difficult to quantitatively calculate. Therefore, the present application provides an exoskeleton series elastic actuator for measuring and compensating joint torque, thereby achieving accurate control of the rehabilitation treatment of patients at different stages and different degrees. SUMMARY

[0005] In view of the problems existing in the prior art, the present application provides an exoskeleton series elastic actuator with compensation for joint torque. By connecting an elastic element module between the driving member and the exoskeleton joint module, the elastic coefficient of the elastic element module can be obtained by sequentially changing the number of disc springs in the first, second, third and fourth disc spring groups, which is controllable. By measuring the displacement difference between the encoder of the driving member and the hollow encoder and the elastic coefficient of the elastic element module, the compensation torque is obtained. Then, the output torque is subtracted from the ideal output torque to obtain an error value. Then, the adaptive PID control algorithm is used for adaptive adjustment, and finally the joint torque is accurately measured and compensated, thereby solving the problems of heavy, difficult to wear and accurate calculation of compensation speed and force of exoskeleton robots on the market at present.

[0006] The application provides a series elastic drive device of an exoskeleton with joint torque compensation, which comprises a fixed seat module, an elastic element module, a driving element, an encoder module and an exoskeleton joint module. The fixed seat module comprises a driving element fixing seat, an elastic element fixing seat and an exoskeleton joint fixing seat, the fixed end of the driving element is fixedly connected with the driving element fixing seat, the output end of the driving element is fixedly connected with the first mounting end of the elastic element fixing seat, the exoskeleton joint module is fixedly connected with the first mounting end of the exoskeleton joint fixing seat, and the encoder module is located in the interior of the exoskeleton joint module, and the fixed end of the encoder module is fixedly connected with the second mounting end of the exoskeleton joint fixing seat. The elastic element module comprises an elastic element fixing shaft, a first fixing shaft, a second fixing shaft, a first nut, a second nut, a third nut, a fourth nut, a first disc spring group, a second disc spring group, a third disc spring group and a fourth disc spring group, the first disc spring group and the second disc spring group are symmetrically distributed at the two ends of the first fixing shaft, the third disc spring group and the fourth disc spring group are symmetrically distributed at the two ends of the second fixing shaft, the elastic element fixing shaft is symmetrically distributed at the two ends of the first fixing shaft and the second fixing shaft, the two ends of the first fixing shaft are fixedly connected with the first nut and the second nut through the first mounting holes of the elastic element fixing shaft respectively, the two ends of the second fixing shaft are fixedly connected with the third nut and the fourth nut through the second mounting holes of the elastic element fixing shaft respectively, the middle mounting ends of the first fixing shaft and the second fixing shaft are fixedly connected with the second mounting end and the third mounting end of the elastic element fixing seat respectively, and the third mounting end of the exoskeleton joint fixing seat is fixedly connected with the mounting end of the elastic element fixing shaft. The elastic coefficient of the elastic element module is obtained by sequentially changing the number of disc-shaped elastic elements in the first disc spring group, the second disc spring group, the third disc spring group and the fourth disc spring group.

[0007] Preferably, the encoder module comprises a hollow encoder, and the hollow encoder accurately calculates the compensation force or speed according to the feedback value thereof.

[0008] Preferably, the output shaft of the driving element, the elastic element fixing seat, the mounting shaft of the encoder module and the shaft of the exoskeleton joint fixing seat are on the same straight line.

[0009] Preferably, the first disc spring group, the second disc spring group, the third disc spring group and the fourth disc spring group each comprise a plurality of disc-shaped elastic elements with the same structure.

[0010] Preferably, the first nut and the second nut are symmetrically distributed at two ends of the first fixed shaft, and the compression amount of the first disc spring group and the second disc spring group is improved by adjusting the first nut and the second nut at the mounting position of the first fixed shaft respectively, the third nut and the fourth nut are symmetrically distributed at two ends of the second fixed shaft, and the compression amount of the third disc spring group and the fourth disc spring group is improved by adjusting the third nut and the fourth nut at the mounting position of the second fixed shaft respectively.

[0011] Compared with the prior art, the present application has the following advantages:

[0012] 1. The present application can realize the size and mass reduction of the overall series elastic driver through the disc-shaped elastic element in the elastic element module, and solve the problem of the heavy and difficult-to-wear exoskeleton robot on the market at present. When used in multiple exoskeleton robot joints, the elastic element module of the present application not only can realize lightweight and greatly improve the overall sensitivity, but also can realize the mutual cooperation of multiple joints and complete precise and subtle movements.

[0013] 2. Through the displacement difference between the encoder on the motor and the encoder module and the elastic coefficient of the elastic element module, the present application adopts a force closed-loop control system and an adaptive PID algorithm to accurately measure and compensate the output force, realize the feedback of accurate speed and force value, and thus realize the monitoring of the exoskeleton joint and the dynamic adjustment of the input and output, so as to realize the effect that the user can accurately control.

[0014] 3. The present application is suitable for different joints of different types of exoskeleton robots, has strong universality and universality, and is convenient to replace the damaged series elastic driver at any time when a fault or damage occurs. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a left view of the overall mechanical structure of the exoskeleton series elastic driving device with joint torque compensation of the present application.

[0016] Figure 2 It is a front view of part of the mechanical structure of the exoskeleton series elastic driving device with joint torque compensation of the present application.

[0017] Figure 3 It is a bottom view of part of the mechanical structure of the exoskeleton series elastic driving device with joint torque compensation of the present application.

[0018] Figure 4 It is a top view of part of the mechanical structure of the exoskeleton series elastic driving device with joint torque compensation of the present application.

[0019] Figure 5 It is a bottom view of part of the mechanical structure of the exoskeleton series elastic driving device with joint torque compensation of the present application without a driving member.

[0020] Figure 6 Figure 1 is a schematic diagram of the elastic element module of the exoskeleton series elastic actuator with joint torque compensation of the present application;

[0021] Figure 7 Figure 2 is a left view of the mounting overall fixed seat mechanical structure of the exoskeleton series elastic actuator with joint torque compensation of the present application.

[0022] Main reference signs:

[0023] Fixed seat module 1, drive member fixed seat 2, drive member 3, elastic element fixed seat 4, elastic element fixed shaft 5, elastic element module 6, encoder module 7, exoskeleton joint fixed seat 8, exoskeleton joint module 9, first fixed shaft 10, second fixed shaft 11, first nut 12, second nut 13, third nut 14, fourth nut 15, first disc spring set 17, second disc spring set 18, third disc spring set 19, fourth disc spring set 20. DETAILED DESCRIPTION

[0024] In order to fully understand the technical content, structural features, purposes achieved and effects of the present application, the following will be described in detail in combination with the drawings of the specification.

[0025] The exoskeleton series elastic actuator with joint torque compensation, as shown in Figure 1 Figure 1, comprises a fixed seat module 1, an elastic element module 6, a drive member 3, an encoder module 7 and an exoskeleton joint module 9. The drive member 3 is composed of a servo motor. The drive member 3 drives the elastic element module 6 to drive the exoskeleton joint module 9 to perform forward and reverse rotation. The present application adopts a disc-shaped elastic element, which has the characteristics of compact structure and strong shock absorption and vibration absorption capacity. Through the displacement difference between the encoder on the drive member 3 and the encoder module 7 and the elastic coefficient of the elastic element module 6, a force closed-loop control system is adopted to realize the characteristics of accurate measurement and compensation of output force, which is convenient for flexible control of joint twisting. Therefore, it has strong interchangeability and is suitable for each joint of the exoskeleton. The exoskeleton joint module 9 can be adjusted according to user needs.

[0026] The fixed seat module 1 comprises a drive member fixed seat 2, an elastic element fixed seat 4 and an exoskeleton joint fixed seat 8, as shown in Figure 2 and Figure 7 The fixed end of the drive member 3 is fixedly connected with the drive member fixed seat 2. The output end of the drive member 3 is fixedly connected with the first mounting end of the elastic element fixed seat 4. The exoskeleton joint module 9 is fixedly connected with the first mounting end of the exoskeleton joint fixed seat 8. The encoder module 7 is located inside the exoskeleton joint module 9. The fixed end of the encoder module 7 is fixedly connected with the second mounting end of the exoskeleton joint fixed seat 8. In a preferred embodiment of the present application, the encoder module is composed of a hollow encoder. The hollow encoder accurately calculates the compensation force or speed according to its feedback value.

[0027] The elastic element module 6, as shown in Figure 5 and Figure 6 , comprises an elastic element fixing shaft 5, a first fixing shaft 10, a second fixing shaft 11, a first nut 12, a second nut 13, a third nut 14, a fourth nut 15, a first disc spring group 17, a second disc spring group 18, a third disc spring group 19 and a fourth disc spring group 20. The first disc spring group 17 and the second disc spring group 18 are symmetrically distributed at both ends of the first fixing shaft 10, the third disc spring group 19 and the fourth disc spring group 20 are symmetrically distributed at both ends of the second fixing shaft 11, the elastic element fixing shaft 5 is symmetrically distributed at both ends of the first fixing shaft 10 and the second fixing shaft 11, the both ends of the first fixing shaft 10 are fixedly connected with the first nut 12 and the second nut 13 through the first mounting hole of the elastic element fixing shaft 5, the both ends of the second fixing shaft 11 are fixedly connected with the third nut 14 and the fourth nut 15 through the second mounting hole of the elastic element fixing shaft 5, the middle installation end of the first fixing shaft 10 and the second fixing shaft 11 are fixedly connected with the second installation end and the third installation end of the elastic element fixing seat 4, and the third installation end of the exoskeleton joint fixing seat 8 is fixedly connected with the installation end of the elastic element fixing shaft 5.

[0028] Specifically, the elastic coefficient of the elastic element module 6 is obtained by changing the number of disc-shaped elastic elements in the first disc spring group 17, the second disc spring group 18, the third disc spring group 19 and the fourth disc spring group 20 in turn. The first disc spring group 17, the second disc spring group 18, the third disc spring group 19 and the fourth disc spring group 20 are respectively composed of a plurality of disc-shaped elastic elements with the same structure.

[0029] As shown in Figure 3 and Figure 4 , the first nut 12 and the second nut 13 are symmetrically distributed at both ends of the first fixing shaft 10, the compression amount of the first disc spring group 17 and the second disc spring group 18 is improved by adjusting the installation position of the first nut 12 and the second nut 13 on the first fixing shaft 10, the third nut 14 and the fourth nut 15 are symmetrically distributed at both ends of the second fixing shaft 11, and the compression amount of the third disc spring group 19 and the fourth disc spring group 20 is improved by adjusting the installation position of the third nut 14 and the fourth nut 15 on the second fixing shaft 11.

[0030] Further, in order to ensure the measurement accuracy of the series elastic drive device, the output shaft of the driving member 3, the elastic element fixing seat 4, the installation shaft of the encoder module 7 and the axis of the exoskeleton joint fixing seat 8 are on the same straight line.

[0031] The above described embodiments are only to illustrate the preferred embodiments of the present application, and are not intended to limit the scope of the present application. Any modification and improvement of the technical solutions of the present application made by those skilled in the art without departing from the design spirit of the present application shall fall within the protection scope of the present application.

Claims

1. An exoskeleton series elastic actuator with joint torque compensation, comprising a fixed seat module, an elastic element module, a driving element, an encoder module and an exoskeleton joint module, characterized in that, the fixed seat module comprises a driving element fixed seat, an elastic element fixed seat and an exoskeleton joint fixed seat, the fixed end of the driving element is fixedly connected with the driving element fixed seat, the output end of the driving element is fixedly connected with the first mounting end of the elastic element fixed seat, the exoskeleton joint module is fixedly connected with the first mounting end of the exoskeleton joint fixed seat, the encoder module is located inside the exoskeleton joint module, and the fixed end of the encoder module is fixedly connected with the second mounting end of the exoskeleton joint fixed seat; the elastic element module comprises an elastic element fixed shaft, a first fixed shaft, a second fixed shaft, a first nut, a second nut, a third nut, a fourth nut, a first disc spring group, a second disc spring group, a third disc spring group and a fourth disc spring group, the first disc spring group and the second disc spring group are symmetrically distributed at two ends of the first fixed shaft, the third disc spring group and the fourth disc spring group are symmetrically distributed at two ends of the second fixed shaft, the elastic element fixed shaft is symmetrically distributed at two ends of the first fixed shaft and the second fixed shaft, the two ends of the first fixed shaft are respectively fixedly connected with the first nut and the second nut through first mounting holes of the elastic element fixed shaft, the two ends of the second fixed shaft are respectively fixedly connected with the third nut and the fourth nut through second mounting holes of the elastic element fixed shaft, the middle mounting ends of the first fixed shaft and the second fixed shaft are respectively fixedly connected with the second mounting end and the third mounting end of the elastic element fixed seat, and the third mounting end of the exoskeleton joint fixed seat is fixedly connected with the mounting end of the elastic element fixed shaft; elastic coefficients of the elastic element module are obtained by sequentially changing the number of disc-shaped elastic elements in the first disc spring group, the second disc spring group, the third disc spring group and the fourth disc spring group.

2. The series elastic actuation device for an exoskeleton with joint torque compensation according to claim 1, characterized in that, the encoder module is composed of a hollow encoder, and the hollow encoder accurately calculates compensation force or speed according to feedback values thereof.

3. The series elastic actuation device for an exoskeleton with joint torque compensation according to claim 1, characterized in that, the output shaft of the driving element, the elastic element fixed seat, the mounting shaft of the encoder module and the axis of the exoskeleton joint fixed seat are on the same straight line.

4. The series elastic actuation device for an exoskeleton with joint torque compensation according to claim 1, characterized in that, the first disc spring group, the second disc spring group, the third disc spring group and the fourth disc spring group are respectively composed of a plurality of disc-shaped elastic elements with the same structure.

5. The series elastic actuation device for an exoskeleton with joint torque compensation according to claim 1 or 4, characterized in that, the first nut and the second nut are symmetrically distributed at two ends of the first fixed shaft, the compression amount of the first disc spring group and the second disc spring group is improved by adjusting the mounting positions of the first nut and the second nut on the first fixed shaft, the third nut and the fourth nut are symmetrically distributed at two ends of the second fixed shaft, and the compression amount of the third disc spring group and the fourth disc spring group is improved by adjusting the mounting positions of the third nut and the fourth nut on the second fixed shaft.

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