Robust Sliding Mode Tracking Control of an Omnidirectional Mobile Robot with Structural Uncertainty

ABSTRACT In this paper, a nonlinear controller is designed for a wheeled mobile robot with three omnidirectional wheels. The omnidirectional wheel has an advantage of universal moving directions on a flat surface without changing its pose. The dynamics of the omnidirectional wheel includes rolling and slipping. Three configurations of mobile robots and an input-additive perturbation are considered. Furthermore, the maneuverability of the omnidirectional mobile robot is analyzed with the vehicle’s controllability that provides a measure on the omnidirectional mobile robots ability to track a trajectory. In controller design, a computed torque control law is applied to counterbalance the nonlinear terms of the system. Then a sliding mode controller is developed for trajectory tracking control. The effectiveness of the proposed control strategy is demonstrated by computer simulations.