A Practical Two-Input Single-Output Fuzzy Logic Controller with an Alpha-Beta Prefilter

Abstract

This paper deals with the design of a practical two-input single-output (TISO) fuzzy logic controller for a nonlinear system. We firstly define two generalized errors for a nonlinear system and develop a stable feedback control scheme. Then a novel fuzzy logic controller is designed and incorporated into this scheme to achieve a better tracking response. The key feature of the proposed control scheme is that a discrete prefilter, called alpha-beta filter is placed in front of the fuzzy logic controller. The significance of using the Kalman-like fixed-gain filter is its capability of suppressing noise and feeding the fuzzy logic controller with smooth signals. From an implementation point of view, the discrete TISO fuzzy logic controller with the alpha-beta prefilter is believed to be quite simple, general and useful for practical applications. The validity of the proposed control scheme is verified through practical testing on the experimental setup called magnetic levitation system. The test results strongly suggest that the newly proposed control scheme is simple yet effective for use in a variety of feedback control systems.