Optimal Observer-Based Fault Detection and Estimation Approaches for T–S Fuzzy Systems

In this article, optimal observer-based fault detection (FD) and estimation schemes for Takagi–Sugeno fuzzy systems with process faults are investigated. In particular, an optimal FD scheme for fuzzy systems is proposed first aiming at enhancing the sensitivity to the faults and simultaneously increasing robustness against unknown inputs, which gives the extension of the socalled unified solution to fuzzy systems. To further provide the fault information, a least squares fault estimation scheme is developed. It is noteworthy that, the observers for the proposed FD and estimation schemes are updated online recursively. A case study on the laboratory three-tank system is then given to demonstrate the proposed FD and estimation approaches.