Study On The Control Strategy Of Upper Extremity Soft Exoskeleton

According to the survey,China’s aging rate has been the highest in the world.In 2016,the number of elderly people over 60 years old in China was about 212 million,accounting for 15.6% of the total population.In the sixth national census data of 2010,The elderly population over the age of 60 is only 10.33%.With the aging problem,the problems of physiological function decline and motor dysfunction have come one after another,which has led to a sharp decline in the quality of life of the elderly,resulting in a heavier burden on families and society,and with the development of the times,the economic level and living standards,people are paying more and more attention to their own health problems,and their requirements for quality of life are getting higher and higher.Manual instruments such as crutches and canes have not been able to meet the needs of the elderly.The development of wearable exoskeletons has made this problem a solution,moreover the wearable exoskeleton has broad application prospects in the civil and military fields.Based on the above research background,this paper designs a soft-exoskeleton robot for upper limb based on tendon-sheath system,and proposes power-assisted control strategies based on human motion intention.The main contents of the thesis are presented as follows:Based on the theory of human upper limb anatomy,the corresponding structural design requirements are proposed for the comfort,safety and portability of the upper extremity soft exoskeleton system.The structure of the upper extremity soft exoskeleton is described in detail,including the upper extremity soft exoskeleton drive module and the tendon-sheath system.Then introduced the upper extremity soft exoskeleton system,including the sensing detection system,data acquisition system and motion control system based on Matlab/RTW real-time development environment.Based on the softness of the upper extremity soft exoskeleton,a soft exoskeleton sensor detection system with no rigid structure is designed,which mainly consists of micro tension sensor,surface myoelectric sensor and inertial measurement unit.Based on the analysis of surface EMG signal characteristics,a joint torque estimation strategy based on myoelectric sensor is proposed.The real-time joint estimation torque is obtained by the nonlinear relationship between EMG signal and joint torque and Kalman filter.The inertial measurement unit is used to capture the motion information during the movement of the upper limbs,and the nine-axis output data is fused by the Mahony complementary filtering algorithm to solve the quaternion character representing the current motion posture.Based on the quaternion theory,a joint angle estimation algorithm based on inertial measurement unit is proposed.The real-time joint estimation angle is calculated by the mutual conversion relationship between quaternions.Based on the upper extremity soft exoskeleton sensing system,three power-assisted control strategies for soft exoskeleton are proposed,including PID force control strategy based on joint estimation torque,PID force/position hybrid control strategy based on joint estimation torque,PID force/position hybrid control strategy based on Neural network and minimized estimated torque.Based on the geometric model of the upper extremity soft exoskeleton,the mathematical expressions and control block diagrams of the three assist control strategies are derived.Finally,the experimental platform based on Matlab/RTW system is built,and the experimental methods and steps are designed to verify the effectiveness and reliability of the three boost control strategies.The maximum boosting effect can reach 50.23%.