A stability guaranteed active fault-tolerant control system against actuator failures

In this paper, a new strategy for fault-tolerant control system design has been proposed using multiple controllers. The design of such controllers is shown to be unique in the sense that the resulting control system neither suffers from the problem of conservativeness of conventional passive fault-tolerant control nor from the risk of instability associated with active fault-tolerant control in case that an incorrect fault detection and isolation decision is made. In other words, the stability of the closed-loop system is always ensured regardless of the decision made by the fault detection and isolation scheme. A correct decision will further lead to optimal performance of the closed-loop system. This paper deals with the conflicting requirements among stability, redundancy, and graceful degradation in performance for fault-tolerant control systems by using robust control techniques. A detailed design procedure has been presented with consideration of parameter uncertainties. Both total and partial actuator failures have been considered. This new control strategy has been demonstrated by controlling a McDonnell F-4C airplane in the lateral-direction through simulation. Copyright (C) 2004 John Wiley Sons, Ltd.