Adaptive Fixed-Time Fault-Tolerant Tracking Control and Its Application for Robot Manipulators

This article studies an adaptive fault-tolerant approach with a fixed-time sliding mode for trajectory tracking of uncertain robot manipulators with actuator effectiveness faults. An equivalent system with an adaptive technique is developed to remove the effects of uncertainties on tracking performance, whereas an appropriate system transformation is accomplished to eliminate the effects of the actuator effectiveness faults. A significant feature of this study is that the fixed-time stability is guaranteed theoretically and practically in the presence of uncertainties and actuator effectiveness faults. Moreover, the appearing advantages are that the proposed approach yields an improved tracking performance without utilizing the overestimated control gain and prior knowledge of a robot and, then, overcomes the singularity and algebraic loop problems completely. The effectiveness of the proposed approach for tracking systems is accomplished on simulation and experimental results from a qualitative and quantitative analysis.