Estimation of time-varying and state-dependent fault using adaptive observer for a class of discrete- time systems

In this paper, the estimation problem of actuator faults in uncertain discrete-time systems is investigated. Under some assumptions, the uncertain system is separated to two subsystems, such that the states of the subsystem which is affected by the fault are measurable. Then, the states of the subsystem which is unaffected by the actuator fault are estimated by an adaptive observer. Finally, the actuator fault is estimated using the estimations of states obtained from the adaptive observer. The simulation results are presented to demonstrate the effectiveness of the proposed method and the efficiency of the observer in estimating the time-varying and state-dependent faults.