Modified tuning of a fuzzy logic controller

In this paper, a modified tuning method of the simplest form of fuzzy PI controller is proposed and incorporated in a tuning formula based on the gain and phase margins, so as to achieve an appreciable improvement in the performance of the auto-tuner. In the modification, the scaling factors of the fuzzy PI controller are made to vary with respect to the plant's normalized dead-time and system state error, such that the system converges faster with smaller settling time. Phase-plane-based analyses are carried out to show that the modified toning actually makes the FLC able to adapt the control environment. Numerical simulations and experiments are presented to show the validity of the proposed tuning methods.