Fuzzy logic for small microcontrollers

Because of its association with neural networks and artificial intelligence, many people expect fuzzy logic to require complex algorithms and lots of processing horsepower. Surprisingly, even a small 8-bit microcontroller can be programmed to perform fuzzy logic inference. A freeware fuzzy inference kernel is available on Motorola´s freeware BBS at (512) 891-3733. This M68HC11 assembly language program is only about 250 bytes and can execute a pendulum balancing problem in well under a millisecond. This speed is appropriate for many common control applications, and the small program size can easily fit within the budget of a small MCU system. This paper discusses the requirements of fuzzy logic and describes the structure of a general purpose fuzzy inference program that is suitable for use in small 8-bit microcontroller systems