Robust Nonlinear Predictive Control Of Omnidirectional Rehabilitative Training Walker

With the increasing number of the aging population and the patients with lower limb walking disorder caused by accidental injuries,the disadvantages of traditional rehabilitation medical methods gradually emerge.Under the demand of rehabilitation market,rehabilitation training walker has been widely used in medical field.In order to solve the problem of optimal trajectory tracking of rehabilitation training walker,many domestic and abroad scholars have studied it from different ways in different methods.However,among the many achievements,the main is to solve the trajectory tracking problem of rehabilitation training walker,and the influence of speed and acceleration on the safety and comfort of the human-machine system and the interference brought by the trainer are ignored.Combined with the predictive control theory,the optimal trajectory tracking problem was studied under constrained conditions.The main contents are as follows:Aiming at the nonlinear characteristics of the dynamic model which omnidirectional rehabilitation training walker,the discrete state space model was obtained by Taylor expansion,and the optimal trajectory tracking with multi-variable simultaneous constraints was realized by combining the model predictive control method.Under the constraint condition of trajectory error,velocity error and control increment,the control input of the rehabilitative training walker system was constrained.In order to solve the problem of trajectory tracking in the infinite horizon,the model predictive control method in the infinite horizon was adopted.The feasibility of the optimal solution was analyzed,and the stability of the rehabilitative training walker closed-loop system was proved.Simulation results show that the infinite horizon predictive control method with control input constraints can achieve optimal trajectory tracking.In order to solve the interference problem of the rehabilitative training walker system,an observation method with the trainer interference is proposed.The observation error system was established and its stability was proved.In order to realize the safety trajectory tracking of the rehabilitation training walker,a nonlinear robust predictive control method was proposed.At the same time,the position,speed and acceleration were constrained in the process of motion.The results of simulation and experiment show the effectiveness and superiority of the robust predictive control method considering trainer interference.