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 non-fixed 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