Simulation and test study of PAM-MRB flexible knee joints based on MFAC-ILC
[Objective]Aiming at the nonlinear influence of the composite structure of the pneumatic artificial muscle(PAM)and magnetorheological damper(MRB)on the tracking accuracy of the PAM-MRB knee joint motion trajectory,a model-free adaptive control(MFAC)combined with iterative learning control(ILC)algorithm was proposed.[Methods]Firstly,com-bined with the mechanical model of pneumatic muscle and magnetorheological damper,the dynamic model of the PAM-MRB flexible knee joint was derived.Secondly,a model-free adaptive iterative controller(MFAC-ILC)was designed by using the model-free adaptive control combined with the iterative algorithm,and the effectiveness of the proposed control method was simulated and verified by Matlab software.Finally,a prototype platform was built to verify the proposed control method.[Re-sults]The results show that MFAC-ILC has better control effect than the PID control,and the control error is reduced by about 5°.The MFAC-ILC has faster trajectory tracking convergence speed for the PAM-MRB flexible knee joint than the PID control,which could reduce the tracking error by 2°,and avoid the trajectory tracking error caused by the accurate knee joint modeling.
Pneumatic artificial muscleMagnetorheological damperModel-free adaptive controlIterative control
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