Adaptive logic-based switching fault-tolerant controller design for nonlinear uncertain systems

This paper deals with the problem of fault-tolerant control (FTC) for a class of nonlinear uncertain systems against actuator faults using adaptive logic-based switching control method. The uncertainties under consideration are assumed to be dominated by a bounding system which is linear in growth in the unmeasurable states but can be a continuous function of the system output, with unknown growth rates. Several types of common actuator faults, e.g., bias, loss-of-effectiveness, stuck and hard-over faults are integrated by a unified fault model. By utilizing a novel adaptive logic-based switching control scheme, the actuator faults can be detected and automatically accommodated by switching from the stuck actuator to the healthy or even partly losing-effectiveness one with bias, in the presence of large parametric uncertainty. In particular, two switching logics for updating the gain in the output feedback controllers are designed to ensure the global stability of the nominal (fault-free) system and the boundedness of all closed-loop signals of the faulty system, respectively. Two simulation examples of an aircraft wing model and a single-link flexible-joint robot are given to show the effectiveness of the proposed FTC controller. Copyright (C) 2010 John Wiley & Sons, Ltd.