PID-type fuzzy logic controller for active magnetic bearing system

This paper describes the design of a PID-type Fuzzy Logic Controller (PID-FLC) and its application on the stabilization of an Active Magnetic Bearing System (AMB). The proposed PID-FLC is obtained by combining a PD-type Fuzzy Logic Controller (PD-FLC) and a Pi-type Fuzzy Logic Controller (PI-FLC). A multi-objective Genetic Algorithm (MOGA) is used to determine the scaling factors of the inputs and outputs of the PID-FLC. The designed controller is then coded in C and implemented in real-time on a Digital Signal Processor (DSP) card. The results from the PID-FLC are compared with those of a conventional lead-lag type controller and the system´s on-board analogue controller. Designing controllers based on classical methods could become tedious, especially for systems with high order model. In contrast, PID-FLC controller design requires only the tuning of some scaling factors in the control loop and hence is much simpler than classical design methods. The experimental results have also verified the enhanced performance and robustness of the system under the proposed PID-FLC control in the presence of disturbance.