Influence of the membership functions number of fuzzy logic controller on the performances of dynamic systems

Abstract

The aim of this work is to study the influence of the number of membership functions (MF) of fuzzy logic controller (FLC) on the temporal performances of dynamical systems. A second contribution to this idea is the introduction of the disturbance signal as an additional input to the FLC and this makes it possible to deliver a command taking into account the values of this undesirable signal. In order to illustrate the influence of the number of membership functions of an FLC, the angular position in a linear model of an Autonomous Underwater Vehicle (AUV) will be controlled around a given reference. The simulation results show that it is sufficient to limit the number of membership functions to a maximum of 5 MF and this is interpreted by the boundary fuzzy decision surface of the fuzzy control because there is no influence, in the case of adding other supplementary MFs, on the performances of the system.

Keywords

• fuzzy logic controller
• membership functions
• fuzzy rules
• autonomous underwater vehicles
• temporal performances