Adaptive fuzzy fault-tolerant control for robot manipulators with user-defined performance

This paper proposes a user-defined performance fault-tolerant control strategy for robot manipulators utilizing FLSs and a prescribed performance function. A user-defined performance function is developed for the robot manipulator, which can not only drive the tracking error to arrive at the prescribed boundary but also allow the arrival time to be adjusted according to users’ demands. This crucial feature overcomes the difficulty of the time and a compact set of unknown problems. Subsequently, an error transformation is performed to constrain the tracking errors within a specific range. Furthermore, in order to enhance the tracking performance of the system and account for the nonlinear dynamics, a fuzzy fault-tolerant performance control (FTPC) strategy is introduced. The model uncertainties, disturbances, and fault components are approximated by FLSs, which relaxes the assumption of bounded lumped uncertainties. The whole system achieves global practical fixed-time stability under the proposed FTPC, and the initial states have no bearing on the convergence time. Moreover, the tracking errors remain within a preset region even when there are actuator malfunctions. Finally, a two-link robot manipulator system is used to run simulations. The results demonstrate that the proposed method is both superior and feasible.