TWO FUZZY ADAPTIVE CONTROLLERS FOR LINEAR SYSTEMS WITH LINEAR DISTURBANCES

Abstract

In this paper two adaptive fuzzy control algorithms are developed. The first fuzzy logic controller, which we call a fuzzy adaptive-proportional-o-integral (FAPαI) controller, has the same form as an adaptive-proportional-α-integral (APαI) except that the controller parameters a, β, and γ are time-varying parameters generated directly by a fuzzy logic controller. The second fuzzy controller, which we call a fuzzy adaptive variable structure (FAVS) controller, combines the performance of an adaptive-proportional-α-integral (APαI) and an adaptive-proportional-integral-integral (API 2 ). The FAPαI tunes the controller parameters α, β, and γ and the FAVS controller schedules the final control signals under different antecedents such that it inherits the merits of the two conventional controllers. For both controllers the objective is to design an adaptive feedback law that gives good output regulation and disturbance rejection in any controllable linear time-invariant system. In addition, the problem of linear disturbance in linear time-invariant lumped single-input/single-output unstable minimum phase plants with relative degree one is studied. All simulation results prove that the performance of each of the FAPαI and FAVS controllers is better than the performance of the other controllers. On the other hand, the performance of FAVS is better than that of the FAPaI. Also, we show that, for our problem, the performance of the conventional PI controller (CPI) is completely unacceptable.