Design And Kinematic Modeling Of Soft Actuator For Wrist Movement Rehabilitation

Chinese society is entering the stage of aging population,the number of middle-aged and elderly patients suffering from stroke is increasing;traffic accidents and work acci-dents also bring a large number of patients with impaired limb motor function;daily sports injuries and long-time keyboard operation at desk also cause a great number of pa-tients with hand / wrist joint strain.Wrist rehabilitation training is an indispensable link in the rehabilitation treatment of many patients with impaired limb motor function.In order to meet this practical demand,combined with the characteristics of human wrist move-ment,this paper proposes a software actuator design and kinematics modeling method for human wrist rehabilitation training,which integrates drive and perception.Aiming at the double-chamber soft actuator with spatial multi-directional bending ability proposed in this paper,combined with the finite element simulation,the influence of the structural parameters of the actuator on the bending performance is analyzed.a multiple regression model between the comprehensive curvature of the actuator and the air pressure in two chambers is established.An implantable PMMA flexible optical fiber sensor is designed,and the mapping model of pressure difference in two chambers,opti-cal loss parameter and compound bending angle is established,so the decoupling meas-urement of the compound bending state formed by flexion/extension and prona-tion/supination is realized with only one optical fiber.A wearable flexible exoskeleton de-vice for wrist rehabilitation training is designed,and the effectiveness of the device was tested from two aspects of bending angle and output force.The main research contents are as follows(1)The skeletal structure and motion mode of human wrist are analyzed,the rehabil-itation needs of patients with wrist dysfunction are clarified,and the motion mode and range of wrist rehabilitation exoskeleton are determined.The design principle of pneu-matic network double-chamber soft actuator with multi-directional bending ability is proposed,and the structure parameters of the soft actuator with optimal bending ability are obtained by finite element simulation optimization method.(2)According to the results of the finite element simulation of the actuator under various working conditions,the coordinate change data of the characteristic points in the process of bending motion of the actuator are collected,and the functional relationship between the motion state of the actuator and the input air pressure is established by least square fitting.(3)An implantable PMMA flexible optical fiber sensor is designed,and the arrange-ment scheme of the sensor is determined according to the structure of the actuator.The sensor calibration method based on inertial measurement system is designed,and the decoupling model of flexion/extension and pronation/supination angles of actuator in compound bending state is established by using the pressure difference of double cavity of actuator and the output signal of optical fiber sensor.(4)A wearable wrist rehabilitation device for hand rehabilitation training is designed,and wearing experiments are carried out on the wrist of human body and prosthetic hand,The effective output force and bending angle of the soft actuator are tested and the ap-plication potential of the device in wrist rehabilitation training is verified.