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 o n the gain and phase margins, so as to achieve an appreciable improvem ent in the performance of the auto-tuner. In the modification, the sca ling 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-ba sed analyses are carried out to show that the modified toning actually makes the FLC able to adapt the control environment. Numerical simula tions and experiments are presented to show the validity of the propos ed tuning methods.