Unified controller for position stabilization and tracking of wheeled mobile robots

Under the assumption that for the desired point, only the position states are known, a continuous state feedback unified control law is derived based on Lyapunov technique, sliding-mode approach and a lemma about non-vanishing disturbances, guaranteeing that the position errors globally exponentially converge to a small neighborhood of the origin, and are globally uniformly ultimately bounded despite the uncertain parameters, furthermore this neighborhood and the ultimate bound can be made arbitrary small via tuning the controller parameters. The simulation results show that using the proposed control law the robot can track the dynamic target with any movement form.