Robust fault tolerant controller design using indirect adaptive sliding mode control strategy

In this paper, indirect adaptive sliding mode control schemes are developed to solve the robust fault tolerant control (FTC) design problem of actuator fault and perturbation compensations for linear time-invariant systems. While both eventual faults on actuators and perturbations are unknown, the adaptive schemes are addressed to estimate the upper bounds of perturbations online, as well as to estimate control effectiveness on actuators. Thus, on the basis of the information from adaptive schemes, an adaptive sliding mode controller is designed to compensate the effects of faults and perturbations automatically. According to Lyapunov stability theory, it is shown that both the reachability of sliding surfaces and the stability of sliding mode dynamics can be ensured even in the presence of actuator faults and disturbances. Moreover, the adaptive sliding mode control can reduce the phenomenon of chattering. An example is provided to further illustrate the fault compensation effectiveness.