Membership function generator circuit for a fuzzy logic controller

Abstract

A CMOS integrated circuit implementation of a membership function for a fuzzy controller is presented in this paper. The design is based on analog circuits. This circuit accepts analog inputs in real time, invokes a triangular membership function and produces an analog output appropriate to the degree of membership of the input. The analog design results in a circuit which is very efficient in terms of transistor count and chip area. Each rule for error or change of error can be programmed individually in the rule generator. The slope of the membership function and the value of the peak voltage can be altered. The membership function circuit can utilize fuzzy linguistic information in the form of NL (negative large), NM (negative medium), NS (negative small), ZR (zero), PS (positive small), PM (positive medium), PL (positive large).<>