Robust fault-tolerant compensation tracking control for omni-directional rehabilitative training walker

This paper is concerned with the problem of robust fault-tolerance tracking control on the omni-directional rehabilitative training walker. The nonlinear robust fault-tolerance compensation method is proposed when a fault occurs on one wheel actuator. The aim of the study is to design an asymptotically stable controller that can guarantee the safety of user and ensure tracking on a training path planned by a physical therapist. The controller that can satisfy asymptotic stability is obtained by constructing the energy storage function and the dissipation inequality. An evaluation signal is designed to verify the nonlinear gain performance index. Finally, the simulation results confirm the feasibility and effectiveness of the designed scheme and indicate the walker can ensure safety motion when one wheel is at fault by compensation input forces for another three wheels.