Research On Ground Reaction Force Control Of Knee Prosthesis Test Platform

Knee prosthesis,as the most widely used type of lower limb prosthesis,is an important auxiliary device for knee amputees to return to normal life.In the context of the rapid development of science and technology,the current advanced knee prosthesis can meet the wearer’s basic walking needs and achieve more complex human-computer interaction functions,so as to cope with the challenges of maintaining normal gait in different scenarios.In the process of prosthesis development,practical wear testing is needed to verify whether it meets the design requirements.However,due to the complex function of knee prosthesis and the diversity of amputee patients,the testing process has many difficulties.At present,prosthetic testing is mainly based on qualitative feedback from amputees and professional prosthetic testers while wearing the prosthesis.There are many limitations and lack of safety.In this case,it is of great significance for the development and testing of artificial knee prosthesis to overcome the shortcomings in the process of artificial knee prosthesis testing by constructing a testing platform.This paper based on the research background of the national key research and development project "Research on Key technologies and Applications of knee and Ankle Integrated bionic intelligent lower limb prosthesis",and on the basis of the established knee prosthesis testing platform,this paper studies the ground reaction force and control problems generated by the prosthesis during the testing process.The purpose is to reproduce the human walking gait law in both kinematics and dynamics during the testing of the tested prosthesis,so that the prosthesis testing platform can simulate the actual state of the tested subjects wearing the prosthesis as much as possible,and provide effective data closer to the human body for the development of the prosthesis.This paper analyzes the movement law of the lower limbs in the process of human gait,converts the movement law into a mathematical expression through function fitting,and conducts a detailed analysis of the ground reaction force(GRF)mechanism in the prosthetic test platform,including its principle and specific implementation methods,etc.,for the motion control and trajectory tracking of the subsequent control system provide a theoretical basis.The electromechanical system simulation model of the knee joint prosthesis test platform was established through Simulink’s Simscape Multibody module,and the input force trajectory was set for simulation tracking simulation,which preliminarily verified the feasibility of the GRF control implementation scheme of the test platform.On the basis of simulation modeling,the AC servo motor control method is improved,and the deadbeat predictive current control(DPCC)is applied to the current loop of the servo motor.Compared with PI control,the force control performance of the system is improved.Finally,relying on the Lab VIEW host computer,ADLINK PCI9221 multi-function data acquisition card and sensor components,a closed-loop control system of the GRF of the prosthesis test platform was constructed,and the permanent magnet synchronous motor was used as the driving source.On this basis,the GRF control experiment of the knee joint prosthesis was implemented.The experimental data results verify the correctness of the simulation model and the feasibility of the designed GRF control system for the knee joint prosthesis.The research on the control of GRF in the prosthetic test platform in the paper expands the bionic ability of the prosthesis testing platform,which makes the testing platform no longer limited to single control of the motion trajectory of the prosthesis,but also simulates more complex testing conditions of the prosthesis through the state of force and motion trajectory at the same time,such as stairs and climbing hills,etc.,so as to enrich the application scenarios of the knee prosthesis testing platform.It is of great significance for the development and continuous innovation of intelligent lower limb prosthesis.