Modeling and Robust Computed Torque Control for Lower Limb Exoskeleton Contacting with Ground

Abstract

Rehabilitation devices perform nowadays suitable and excellent treatment for stroke patients. A Lower limb exoskeleton as a type of Rehabilitation devices has become the most known solution for lower limb rehabilitation of stroke patients. The essential part on lower limb exoskeleton work is to model and control it using a suitable modeling method and an efficient controller. For controlling a three degrees of freedom lower limb exoskeleton in case of contacting with ground ‘ a comparative study between a conventional computed torque controller (CCTC) and robust computed torque controller (RCTC) has been established. Simulation results has performed by comparing both controllers in the same conditions. Stability analysis of the control system has been performed by using a Lyapunov stability theorem. The results of simulation indicate that robust computed torque controller has a good tracking performance and an excellent robustness against system uncertainties and external disturbances as compared with conventional computed torque controller.