A 12b general-purpose fuzzy logic controller chip

The digital CMOS 12b fuzzy coprocessor chip SAE 81C991 is presented. Designed as a fuzzy logic controller, the chip exhibits a silicon area of 17.9 mm/sup 2/ and computation speed in the submillisecond region. Real-time fuzzy control or classification tasks in industry electronics, image processing, and automotive are its main fields of applications. Up to 131072 rules, 4096 inputs, and 1024 outputs with arbitrary membership functions can be processed. The definition or fuzzy algorithms is facilitated with ten operation modes, eight inference operators, and four defuzzification methods. Fuzzification of four 12b inputs, inference of 80 rules, and center of gravity defuzzification for a 16b output takes only 16 s. This knowledge base covers only half a kbyte as the memory has to store only the knowledge base data but almost no operation code for the coprocessor. Moreover, the membership functions as part of the knowledge base data are stored with their characteristic values reducing the memory demand significantly in comparison with a look-up table. Minimized memory demand and fuzzy algorithms tailored for digital CMOS logic are the key elements for a small chip area microcontrollers. Interfaces with 8b or 16b microcontrollers are supported.