FUZZY CONTROL OF ETHANOL CONCENTRATION FOR EMULSAN PRODUCTION IN A FED-BATCH CULTIVATION OF ACINETOBACTER-CALCOACETICUS RAG-1

A fuzzy control system was organized and applied to the control of eth anol concentration in a fed-batch cultivation process for emulsan prod uction by Acinetobacter calcoaceticus RAG-I. The membership functions and fuzzy rules were determined by sets of data and experiences obtain ed from the preliminary culture experiments. The input variables, erro r (the difference between the set point value and the process variable ) and the change of the error, were fuzzified by using the membership functions and the output variable, change of the ethanol feed rate, wa s inferred based on the membership functions and the given fuzzy rules . To obtain the numerical value for the output variable, the center-of -gravity method was used in the defuzzification procedure. The results showed that the ethanol concentration was well regulated around optim al level and the emulsan yield was increased compared with that of the cultivation controlled by the conventional feedback control loop.