Sliding Mode Observer-Based Fault Reconstruction for Uncertain Linear Systems

Problem statement: Fault reconstruction scheme is different from the majority of Fault Detection and Isolation (FDI) methods described in the literature in the sense that it not only detects and isolates the fault, but provides an estimate of the fault. This approach is very useful for incipient faults and slow drifts, which are very difficult to detect. Also, this approach is very useful for Fault Tolerant Control (FTC) systems in the sense that instead of reconfiguration of the control system, the faulty sensors or actuators can be corrected and the simple control method can still be effectively used. Motivated by these useful features of fault, we are interested in performing observer-based fault reconstruction scheme for uncertain linear systems. Approach: In this study we present a scheme to design robust sliding mode observer for linear systems where both faults and uncertainties are considered. The objective is to derive a sufficient condition using Linear Matrix Inequalities (LMIs) for the stability of the observer. The so-called equivalent output error injection is discussed for fault reconstruction. Results: we get a simple sliding mode observer design for detection and reconstruction of faults for uncertain linear systems. Conclusion: With the real model of the seventh-order aircraft we show that the methods provided by present paper have good performances.