Contact Force Estimation And Compliance Control For Multi-joint Prosthetic Arms

The multi-joint prosthetic arm needs to contact with the changing environment in the operation process,and good flexibility is the premise of the safe and stable operation of the prosthetic arm.Therefore,the compliance control of the prosthetic arm is very necessary,especially in the case of the inability to measure the sensor,how to conduct the compliance control of the prosthetic arm is a great challenge.In this paper,the contact force estimation and compliant control of multi-articular prosthetic arm are studied.Firstly,according to the structural characteristics of the prosthetic arm,the forward and inverse kinematics models of the multi-joint prosthetic arm were established by using DH coordinate method,and the dynamics model of the prosthetic arm was established by using Lagrange dynamics equation,and the simulation analysis was carried out to verify the kinematics and dynamics model of the prosthetic arm.Then,for the prosthesis without contact force measurement,kalman filter is used to estimate the contact force,the advantages and disadvantages of strong tracking Kalman filter are analyzed,and a fuzzy adaptive strong tracking Kalman filter contact force estimation algorithm is proposed,and the real-time performance and estimation accuracy of the proposed contact force estimation algorithm are verified by simulation.Then,according to the requirements of position tracking and expected force tracking of multi-joint prosthetic arm,a sliding mode impedance control strategy based on model reference adaptive was proposed,and the stability of the closed-loop control system was analyzed.By introducing model reference adaptive control algorithm makes it possible to fast track the prosthetic arm expectations,join the sliding mode control to improve the robustness of control system,combined with the contact force estimation algorithm,the estimation of contact force feedback controller,the adaptive impedance realized under the condition of no contact force measuring impedance control of the prosthetic arm,the rationality of the proposed control algorithm is verified by the simulation analysis.Finally,the contact force estimation and compliance control experiments were carried out on the multi-joint prosthetic arm experimental platform.The results show that the proposed contact force estimation method has the ability of fast and high precision contact force estimation.The proposed sliding mode impedance control strategy has better force tracking and trajectory tracking capability,which can meet the requirements of the compliant operation of the prosthetic arm.