AN ONLINE ADVISORY CONTROL-SYSTEM FOR THE LACTIC-ACID FERMENTATION PROCESS

A fuzzy expert system was developed for online diagnosing and controll ing of bioprocesses. The system was constructed in object-oriented Sma lltalk/V for diagnosing and controlling of bioprocesses. Lactic acid f ermentation with an industrial strain of Lactobacillus casei was chose n as the model system. The performance of the fuzzy expert system and the knowledge base utilizing experts' knowledge and several facts obta ined from the experiments were successfully validated with on-line fer mentations. The fuzzy expert system could diagnose a fault on-line and give reasonable advice to the process operator. In order to achieve t he diagnosing faculty, a database, a knowledge base, and both backward and forward chaining procedures were implemented employing the object -oriented programming environment. A defuzzifier was implemented in th e system to achieve on-line control. In order to realize a decision-ma king system with a human operator and a fuzzy expert system, a new con trol strategy named Advice was also introduced. Several cultivations w ere carried out in order to collect knowledge on the effects concerned with inoculum properties to the process and to construct a database i ncluding standard time-course profiles. The performance of the fuzzy e xpert control system was successfully tested with on-line experiments.