Conservatism-Relaxed Disturbance Observer-based Composite Control for Wheeled Mobile Robots Subject to Abrupt Disturbance

This paper investigates the robust and accurate control problem of wheeled mobile robot (WMR) systems with uncertain disturbance, especially exhibits abrupt changes. To end this, a conservatism-relaxed disturbance observer (CRDOB)-based sliding-mode controller is proposed under a composite control structure. To address the uncertainties of the abrupt disturbance, a CRDOB is designed without requiring any assumptions about disturbance boundary information. With aiding from a continuous gain-switching mechanism with reducing chattering of the SMC, a composite controller is developed to compensate for the residual-disturbance estimation error of the CRDOB, and then avoid large errors when disturbances instantaneous change. Simulations and experiments demonstrate the improvement of the tracking control performance and system robustness.