Extended state observer‐based trajectory tracking control of a wheeled mobile robot with one unpowered trailer

Abstract In this paper, trajectory tracking control is investigated for a wheeled mobile robot with one unpowered trailer using an extended state observer (ESO). The unpowered trailer is added to improve load capacity, which results in a large impact on trajectory tracking as a slow‐varying and large disturbance. A backstepping controller is proposed to generate desired velocities in an outer loop of a double closed‐loop structure. The ESO is employed in an inner loop to estimate the slow‐varying and large disturbance from the unpowered trailer. An integral sliding mode controller is also designed in the inner loop to track the desired velocities from the outer loop. Stability analysis for the ESO, the backstepping controller and the integral sliding mode controller is conducted via Lyapunov methods. Simulation results are provided to show the effectiveness of the trajectory tracking control for a wheeled mobile robot with one unpowered trailer.