An expert system approach to chemical process control is presented. As a case study, an expert system was developed for aiding control engineers in choosing the direction of controller's action. Programmed in OPS5, the expert system can perform heuristic inference reasoning and make an intelligent decision. A design criterion is developed, which complements the knowledge of controller design technique. The Adaptive Feedback Testing System (AFTS) is developed to provide high reliability of the design results. This expert system has some additional important features: its knowledge base can be modified and new production rules can be created in the running process to solve special problems; and the hierarchy of meta-level control strategy provides the means to manage the knowledge base efficiently.
