FPGA as a tool for implementing non-fixed structure fuzzy logic controllers

This paper presents an open architecture design to implement Fuzzy Logic Controllers (FLC) on a Field Programmable Gate Array (FPGA) integrated circuit. This nonfixed structures design is capable of Fuzzy Inference Engine (FIE) parameters on-line user specification, achieves a design space that includes Mamdani FIE, max-min rule evaluation, and weighted average defuzzification method, with user defined Membership Function(MF)type and number, MF parameters, antecedent and consequent rule construction, and output variable MFs; achieving it within a single chip, high speed, low cost, small footprint FPGA. VHDL language is use for hardware design description of a tested 8-bit resolution FLC; portability and scalability is possible with minor modifications. Algorithms, timing diagrams and hardware resources required are presented; truncation related errors and processing speed achieved is reported.