Global Sliding Mode Fault-Tolerant Control for Nonholonomic Wheeled Robots: Ensuring Prescribed Performance in the Presence of Faults and Slippage

This paper proposes a global integral sliding mode control (GISMC) scheme integrated with an improved disturbance observer (IDO) for robust trajectory tracking of nonholonomic wheeled mobile robots under uncertainties, disturbances, wheel slippage, and actuator faults. The NWMR dynamics are first formulated, followed by the development of the IDO to estimate and compensate for lumped disturbances in real time. The GISMC framework is then designed to ensure finite-time convergence and robustness, while a prescribed performance function (PPF) is incorporated to constrain the tracking errors within predefined bounds and guarantee system stability under dynamic conditions. Experiment results confirm that the proposed GISMC maintains tracking errors within ±0.012 m significantly smaller than those of the backstepping–adaptive sliding mode control (≈0.043 m) and achieves faster convergence with smoother control action than the backstepping–SMC with IDO. The results validate that the proposed controller adapts effectively in real time, providing enhanced robustness and precision in complex and uncertain environments. These findings highlight the potential of the proposed GISMC for practical applications in autonomous mobile systems requiring high accuracy and fault tolerance.