Multiple-valued Logic Approach to Fuzzy Controllers Implementation

This paper offers a new technique for designing fuzzy controllers as analog hardware devices on bases of CMOS implementation of multi-valued logical functions. This approach is based on using a summing amplifier with saturation as a building block that can be considered as a multi-threshold logical element. The functional completeness in an arbitrary-valued logic of a summing amplifier with saturation is proven. This fact gives a theoretical background for an analog implementation of fuzzy devices. In contrast with the traditional software approach to fuzzy controller implementations based on explicit fuzzification, fuzzy inference, and defuzzification procedures, hardware implementations of fuzzy controllers as analog devices have advantages of higher speed, lower power consumption, smaller die area and more. Universal and proper design methods for such type of hardware are offered. The paper illustrates design examples for real industrial fuzzy controllers and provides SPICE simulation results of their functioning. Key-Words: Fuzzy Logic, Fuzzy Controller, Fuzzy rules, Fuzzy inference, Fuzzification and Defuzzification, Multi-Valued Logic, Multi-threshold Element, Functional Completeness, Summing Amplifier.