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

A strategy is proposed for fault-tolerant control system (FTCS) design using multiple controllers. The design of such multiple controllers is shown to be unique in the sense that the resulting control system does neither have the problem of conservativeness of conventional passive fault-tolerant control (FTC) nor the risk of instability associated with active FTCS in case of an incorrect fault detection and isolation (FDI) decision. In other words, the stability of the closed-loop system is always ensured regardless the FDI decisions. The correct FDI decision will further lead to optimal performance of the system. The paper presents an interesting way to deal with the conflicting requirements among stability, redundancy, and graceful degradation in performance for fault-tolerant control systems. Detailed design procedure has been presented with consideration of possible parameter uncertainties