Generalized fault estimator-based prescribed performance control for a class of strict-feedback nonlinear systems

This paper addresses fault estimation and prescribed performance control for strict-feedback nonlinear systems subject to unknown time-varying faults. By introducing a novel intermediate variable for fault estimation, an adaptive fault estimator and a fault-tolerant controller are proposed. Utilizing a proof by contradiction, the designed prescribed performance control scheme resolves the complex coupling between fault estimation and adaptive control. Furthermore, all closed-loop signals are proven bounded, with both tracking and state errors converging to predesigned compact sets. Finally, numerical simulation on a single-link robot system validates the effectiveness of the proposed algorithm.