MIXED ANALOG-DIGITAL FUZZY-LOGIC CONTROLLER WITH CONTINUOUS-AMPLITUDEFUZZY INFERENCES AND DEFUZZIFICATION

A fuzzy logic controller has been realized using mixed analog-digital CMOS very large scale integration (VLSI) circuits for application in c ases where the input and output variables are in analog form. It emplo ys a new architecture where time sweeping of variables allows continuo us-amplitude evaluation of fuzzy inferences and defuzzification during each evaluation cycle without having to discretize input and output v ariables. Direct processing of the analog input signal is used to obta in the corresponding crisp value; the digital portion is used only for programmability. No A/D and D/A converters are needed. The controller can handle three inputs, one output, and 25 programmable fuzzy rules. The test IC chips were fabricated using 0.7-mu m CMOS technology. A c ontrol problem of stabilizing a ping-pong bah in a tube with a control lable air flow has been successfully demonstrated.