Design Of Active And Passive Hybrid Hydraulic Ankle Power Prosthetics And Research On Its Control

Due to diseases,traffic accidents and other reasons,the number of tibial amputation patients in China has increased year by year.At present,wearing prosthetics is a common treatment for amputee patients,while passive prostheses do not have active assist function,so that the wearer consumes more energy during walking.With the continuous development of high-power motors,miniature sensors,control technology and computer technology,people begin in-depth research on smart prosthetics.But at present,most of the excellent ankle prostheses are products of foreign companies.In order to improve the walking ability of tibial amputee patients and improve amputees quality of life,this project designs an active and passive hybrid hydraulic ankle joint power prosthesis based on electro-hydraulic drive technology and improved control algorithm based on the analysis of the movement characteristics of healthy human ankle joints,which aims to help lower limb amputee patients recover their walking ability.The specific work content is as follows:Firstly,the kinematic and mechanical characteristics of healthy human ankle joints are analyzed,the motor characteristics are summarized,and the gait phase is divided.According to the human movement characteristics,the design goal is proposed,and then the ankle prosthesis drive mode is determined,and the electro-hydraulic drive system design is completed,in which the single-acting hydraulic cylinder is used as the actuator to simplify the hydraulic system in order to achieve the requirements of prosthetic integration and lightweight.After that,the mechanical structure model of the prosthesis is established,and the relevant components are selected.Secondly,the mathematical model of power ankle kinematics,motor speed regulation model and hydraulic system model are established,the simulation model of electro-hydraulic direct drive system is established,the reliability of the system is analyzed and the influence of the main parameters is determined,and the simulation analysis of the electro-hydraulic system of the prosthesis is carried out,and the analysis results show that the prosthetic motion meets the needs of angle following and torque output,which proves the feasibility and effectiveness of the drive system.Then,the control strategy of the power ankle prosthetic system is designed,and the upper control uses the gait finite state control machine to identify the ankle movement state in the gait cycle and control the switching between active and passive modes.The lower control uses a PID controller optimized based on genetic algorithm and BP neural network to improve controller performance,and verify the effectiveness of the controller through simulation analysis.Finally,the experimental results show that the maximum damping force of the highspeed switch valve is about 770 N,the prosthesis angle following effect is better,and the torque output of the motor is about 32% of the human body,which verifies the damping adjustment ability of the hydraulic system and the function and feasibility of walking through the human body.