Intermediate observer based simultaneous estimation of system states and multiple faults

In this paper, an intermediate observer is proposed for simultaneously estimating the system state, actuator fault and sensor fault. The necessary and sufficient condition is given with respect to the existence of the designed observer. The observer gain matrix is guaranteed through solving Riccati inequalities. The estimation errors of the system state, actuator fault and sensor fault are proved to be globally uniformly stable with the prescribed performance index. Finally, a simulation study is given to verify the effectiveness of the proposed method.