Robust motion control of a four wheel drive skid-steered mobile robot

In this paper robust motion control of a four wheel drive skid-steered mobile robot (4WD SSMR) is presented. We have developed a motion control system where a kinematic trajectory tracking controller based on the vector field orientation (VFO) strategy and a robust dynamic velocity controller based on the sliding mode control (SMC) technique and the computed torque method (CTM) are combined. Asymptotic stability for a class of reference trajectories is guaranteed by the VFO method while the stability of the velocity controller is based on the Lyapunov theory. In addition to the original VFO method a multi parameter orienting control is used. A 4WD SSMR is designed in a three dimensional (3D) realistic simulation environment to test the performance of the motion control system developed. Simulation results have shown the stability and robustness of the motion control system even under heavy perturbed conditions and the proposed multi parameter orienting control strategy has the advantage of smoother path tracking.