Active Adaptive Observer-Based Fault-Tolerant Control Strategy for a Class of T–S Fuzzy Systems With Unmeasurable Premise Variables

This article addresses the problem of fault-tolerant output tracking control for a class of Takagi–Sugeno (T–S) fuzzy systems with unmeasurable premise variables subject to additive and multiplicative actuator faults and external disturbances. In nominal conditions, utilizing a quadratic Lyapunov function and nonparallel distributed compensation technique, the suggested strategy delivers linear-matrix-inequality-based constraints. Simultaneously design of the proportional-integral (PI)-like state feedback controller and fuzzy antiwindup compensator is achieved with the aim of output tracking. In the faulty case, by considering the nominal system as a reference model, a direct adaptive projection-based approach is developed using the T–S fuzzy modeling and control techniques to supply the adaptive fault-tolerant controller components. An enhanced PI state/fault observer with unmeasurable premise variables is introduced only to provide the estimation of states to be used in the proposed controller. The overall closed-loop system ensures the uniformly ultimately bounded solutions for error dynamics. Two examples, subsuming an inverted pendulum and a chaotic power system, have been used to present the merits and efficiency of the suggested approach persuasively.