Adaptive fault-tolerant backstepping control against actuator gain faults and its applications to an aircraft longitudinal motion dynamics

The problem of fault-tolerant control (FTC) for a class of uncertain nonlinear systems with actuator faults is discussed, and an observer-based FTC scheme is proposed. Adaptive fuzzy observers are designed to provide a bank of residuals for fault detection and isolation. Using a backstepping approach, we proposed a novel fault diagnosis algorithm, which removes the classical assumption that the time derivative of the output error should be known. Further, an accommodation scheme is proposed to compensate for the effect of the fault, where it is not needed to know the bounds of the time derivative of the fault. The proposed controller guarantees that all signals of the closed-loop system are semi-globally uniformly ultimately bounded and converge to a small neighborhood of the origin by appropriately choosing designed parameters. In addition, a sufficient condition for the existence of an fault detection and isolation observer is derived using Lyapunov stability theory. Finally, a numerical example and a practical aircraft longitudinal motion dynamics are used to demonstrate the effectiveness of the proposed FTC approach. Copyright (c) 2013 John Wiley & Sons, Ltd.