Discrete Time Trajectory Tracking Control for Four-Mecanum-Wheeled Mobile Vehicle: An Variable Gain ADRC Method

In this letter, a novel discrete active disturbance rejection control (ADRC) method is proposed to solve the trajectory tracking problem for a four-mecanum-wheeled mobile vehicle (FMWMV). The discrete ADRC method consists of a discrete variable-gain extended state observer (VGESO) and a discrete variable gain disturbance rejection controller. The error-driven gains are respectively incorporated in VGESO and controller to achieve a satisfied transient performance and small steady-state error. The variable gains can alleviate the trade-off between transient performance and steady-state error existing in the linear ADRC method. The specific range of the variable gain function in VGESO is given, which helps the practical implementation. The convergence analyses of the proposed VGESO and the close-loop system are also conducted. Finally, the effectiveness of the proposed method is verified via simulation and experiment results.