A Novel Approach To Improve The Performance Of Fuzzy￾Logic Based Controllers For Systems With Wide Range disturbances And Uncertain Parameters

Applications offuzzy logic controllers have proved that a tuning algorithm must be added to
improve its perfomance against the system disturbances. The tuning methodr represent an
additional costs and complexiry for implementation. This paper, presents a novel method which
implies a self-tuned controh capable of damping the system oscillations whatever the
disturbance changes. Moreover, this controller is robust to a degree that permits more than
2500% parameters uncertainties to be considered. The idea of this approach is to combine two
control signals, one from a conventional stabilizer, e.g. lead lag compensator, and the other
from a fuzzy logic controller. The stabilizer is designed based on modal techniques for the
worst case of oscillations and is independent on the system disturbance. On the other side, the
ranges of membership firnetions requiredfor the design of fuzzy logic controller are selected
based on the worst experience of the input/output behavior. Thefinal controller is testedfor
diflerent disturbances and system parameters and the results show a satisfactoory perfomance
and robustness.