Most studies of the so-called CACSD (Computer-Aided Control System Design) have aimed at the development of computer systems which will assist control engineers to design effectively, making better use of sophisticated machine interfaces and the graphic environment, and do not aim at automated control design beyond assisting the user in designing control systems. The present study has developed a system, which is aimed at the automation of classical control system design, by describing the dialogue between man and computer as a computer program through techniques of knowledge engineering. In particular, hypothetical reasoning systems supported by TMS (Truth Maintenance System) are used in order to automate trial and error procedures which are problems in classical design methods. In other words, a hierarchical system has been constructed where a control system-designing expert system based on hypothetical reasoning is placed at the meta-rule layer above the procedure and tool layers. This paper illustrates the basic structure of this expert system and the utilization forms of hypothetical reasoning in control system design, and shows the actual operation of the system as seen through a design example.
