Trajectory tracking of a wheeled mobile robot based on the predefined-time sliding mode control scheme

In this paper, a double-loop control method is proposed to improve the trajectory tracking performance of a wheeled mobile robot (WMR) with slippage properties and external disturbances. Considering the strong robustness and the ability to enable the system to converge in a short time, the predefined-time sliding mode control (PTSMC) strategy is applied to the design of a double-loop controller. Furthermore, a nonlinear disturbance observer (NDO) is adopted to comply with the feedforward compensation of the external disturbances. In turn, the controller only needs to deal with the internal disturbance of the system under the premise of using the NDO, thereby reducing the burden of the sliding mode controller. Based on Lyapunov methods, the stability of the double-loop controller and the NDO is analyzed. Finally, the feasibility of the double-loop control strategy is proven by simulations of the WMR operating along circular, sin-shaped, and eight-shaped roads.