Output Feedback Robust Fault-Tolerant Control of Interval Type-2 Fuzzy Fractional Order Systems With Actuator Faults

This paper is concerned with the stabilization problem for a class of uncertain nonlinear fractional order systems described by an interval type-2 fuzzy model, under actuator faults. To solve the problem, a robust fault-tolerant control (FTC) scheme composed mainly of an augmented non-fragile observer and a new-type H-infinity controller is developed. The resulting control system is with the following advantages. On the one hand, the system stability domain is extended significantly, attributed to introducing the concept of D-stability to the control design and stability analysis, instead of the conventional indirect Lyapunov theory. Theoretically, the stability domain can be expanded from the original half-plane to nearly the overall plane. On the other hand, the control system is robust against the measurement noise and external disturbances which however are not taken into account in the related works. This is achieved by adopting the H-infinity control method in a novel way, in which a new technical lemma is presented to solve real linear matrix inequalities (LMIs). In this way, the robust FTC design is also simplified, wherein the number of the required decision variables is reduced from four to two. Besides, the control design is less restrictive: three common requirements for the system matrix or the control gain selection are eliminated. Finally, the simulation results on an electrical circuit system and a numeral example both illustrate the above theoretical findings.