Adaptive Fault-Tolerant Control of Wheeled Mobile Robots With Multiple Actuator Faults and Saturation

The actuator fault problems under saturation bring significant challenges to the stable and accurate tracking of wheeled mobile robots (WMRs) in industrial applications. This letter proposes a novel adaptive fault-tolerant control (FTC) method for WMR systems simultaneously considering uncertain multiple actuator faults, namely lock-in-place (LIP) and partial loss-of-effectiveness (LOE) faults, and saturation. First, a novel barrier function-based nonsingular terminal sliding mode controller is explored to address the actuator LIP failures and unknown dead zones. Then, a two-auxiliary-variable-based adaptive law is designed by estimating the boundary of the actuation effectiveness and saturation coefficient, and uniformly handles the actuator LOE fault and saturation. The adaptive fault-tolerant controller is constructed based on these adaptive laws, achieving the error/sliding variables finite-time convergence and being confined within a predetermined neighborhood of the origin. Finally, practical experiments demonstrate the effectiveness and advantages of the designed FTC scheme.