FDI Based on High-gain Robust Sliding Mode Observers

This paper considers the problems of actuator and sensor fault detection and isolation for a class of uncertain linear systems. By introducing an augmented vector, an augmented system which contains a fault vector consisting of both the actuator and sensor faults of original system is constructed. An auxiliary output vector is proposed so that the observer matching condition for the new augmented system is satisfied. A high-order sliding mode observer is considered to obtain the exact estimates of the auxiliary outputs. Then, a robust sliding mode observer is developed as fault detection observer to detect actuator and sensor faults. Furthermore, multi-observers are used for the actuator and sensor fault isolation purpose. Finally, a numerical simulation example is given to show the effectiveness of the proposed methods.