Adaptive Abrupt Disturbance Rejection Tracking Control for Wheeled Mobile Robots

Uncertain disturbances increase the difficulty of robust tracking control for wheeled mobile robots (WMRs) in industrial scenarios, especially when exhibiting abrupt changes. This letter proposes an adaptive abrupt disturbance-rejection sliding mode controller (SMC). To address the increased variability in the disturbance boundaries caused by abrupt transitions, a new adaptive disturbance observer (ADOB) is designed to improve the tracking robustness and weaken the chattering of SMC by generating auxiliary system variables without depending on any prior boundary information about disturbance and its change rate. Then, a novel barrier function-based switching law is constructed to suppress the residual-disturbance estimation error of the ADOB at the transient state, which achieves the tradeoffs between the necessary sufficient gain and chattering by avoiding gain overestimation. The finite-time Lyapunov stability of the sliding variables and the estimated errors have been proved theoretically. The practical effectiveness is illustrated in experiments with the custom-developed WMRs.