Adaptive Control of Systems with Actuator Failures Using an Adaptive Reference Model

This paper considers model reference adaptive control of uncertain plants under actuator failures when the plant model matching conditions are violated due to abnormal changes in the plant or incorrect knowledge of the plant's mathematical structure. The approach consists of direct adaptation of state feedback gains for state tracking to compensate for model errors and actuator failures and simultaneous estimation of the plant model mismatch. Because of mismatch resulting from large changes in the plant, the original reference model may no longer be appropriate, and it may be desirable to track the state of a modified reference model that still provides satisfactory performance. The reference model is redesigned if the estimated plant model mismatch exceeds a bound that is determined via robust stability and/or performance criteria. The proposed controller is a hybrid direct indirect adaptive controller that offers asymptotic state tracking in the presence of plant model mismatch, parameter deviations, and actuator failures.