A practical design of fuzzy PD controller and its application to magnetic levitation system

This paper presents a new approach to the design of a fuzzy logic control scheme for a general class of nonlinear systems. For practical consideration, we firstly define two generalized errors as inputs to form a novel two-input single-output fuzzy PD controller. Then, a supervisor is incorporated into the control scheme to help achieve its closed-loop stability. The supervisor is derived based on variable structure control theory and the closed-loop stability is justified using Lyapunov theory. The validity of the proposed fuzzy PD control scheme with variable structure-based supervisor is verified through practical testing on the experimental setup called magnetic levitation system. These results strongly suggest that the newly proposed control scheme is simple yet effective for use in a variety of feedback control systems.