Computed-torque plus robust adaptive compensation control for robot manipulator with structured and unstructured uncertainties

A computed-torque plus robust adaptive compensation control scheme (CTRACC) is proposed for trajectory tracking control of a robot manipulator with uncertain dynamics. To eliminate structured and unstructured uncertainties, an adaptive fuzzy control algorithm and a robust H∞ control mode are incorporated in the conventional computed-torque controller. The adaptive fuzzy control algorithm is employed to compensate for structured uncertainties, and the robust H∞ control model is designed to eliminate the effects of unstructured uncertainties and approximation errors. The convergence and the stability of the CTRACC approach are proved by using Lyapunov's direct method. Performance comparisons between the CTRACC approach and the conventional computed-torque controller are carried out. The validity of the CTRACC approach is investigated by numerical simulations of a two-link rotary robot manipulator and experiments conducted on a real six degrees of freedom robot manipulator.