Actuator fault detection and estimation for a class of nonlinear systems

The problem of actuator gain fault detection and estimation (FDE) for a class of nonlinear Lipschitz systems subject to unstructured uncertainty is addressed. The proposed diagnostic scheme is based on the adaptive observer which is used to present the estimation of states and faults. For the fault estimation purpose, adaptive algorithm is designed in the sense of Lyapunov theory. In addition, robustness of the proposed scheme is treated. Also design procedure of the proposed scheme is reformulated as a linear matrix inequality (LMI) problem, this reformulation provides an effective approach to compute the design parameters. Finally the presented fault detection and estimation scheme is applied to a single-link flexible joint robot system. Simulation results verify the efficiency of the proposed FDE scheme.