FDI Design for Uncertain Nonlinear Systems with Both Actuator and Sensor Faults

This paper considers the problems of simultaneous actuator and sensor fault detection and isolation ( FDI ) for a class of uncertain Lipschitz nonlinear systems when the observer matching condition is not satisfied. An augmented vector is proposed to construct an augmented system that contains a fault vector consisting of both the actuator and sensor faults of the original system. An auxiliary output vector is constructed to satisfy the observer matching condition, and a high‐gain sliding mode observer is designed to approximately estimate the auxiliary output vector. An adaptive robust sliding mode observer is developed as a fault detector to detect the actuator and sensor faults simultaneously. Then, multi‐observers are designed to attain the actuator and sensor fault isolation purpose. Finally, a numerical simulation is given to show the effectiveness of the proposed methods.