Robust fault detection of T-S fuzzy systems with time-delay using fuzzy functional observer

This paper presents a new fuzzy functional observer based fault detection technique for fuzzy systems with time-delay subject to exogenous disturbance. The estimation error of the fuzzy functional observer is used to obtain a residual to detect the fault. The proposed fault detection scheme does not require any threshold to compare with the residual. The exogenous disturbance is decoupled from the error dynamics using the concept of unknown input observers to ensure the robustness of the residual generator. The time-delay is considered to be time-varying and bounded. Sufficient conditions are presented to ensure the asymptotic stability of the observer by linear matrix inequality approach. The proposed design technique is illustrated and verified using examples to demonstrate its effectiveness for fault diagnosis. (C) 2019 Elsevier B.V. All rights reserved.