Fault diagnosis and fault-tolerant control for sampled-data attitude control systems: an indirect approach

This article proposes an indirect approach for fault diagnosis and fault-tolerant control in the satellite attitude control system with sampled-data measurements. The proposed method is based on a discrete-time approximation model of the continuous attitude dynamics. By considering the fault term as an auxiliary state vector, an augmented plant is constructed. Then an observer is designed to simultaneously estimate the system state vector and the fault term. Specifically, the observer design problem is reformulated as a set of linear matrix inequalities and can be conveniently solved by standard linear matrix inequality tools. The fault-tolerant controller is easily derived using the fault diagnosis result and the H-infinity index is adopted to analyze the fault-tolerant control performance. Finally, numerical simulation results are given to demonstrate the effectiveness of the proposed method.