INTERACTIVE GRAPHICS AND SYMBOLIC MANIPULATION OF BLOCK DIAGRAMS IN UNDERGRADUATE CONTROL COURSES.

This paper describes an expert system assistant which can be used for reducing complicated block-diagrams to canonical form with updated graphics display of the diagram and transfer-function at each stage in the reduction. The system contains all block-diagram rules and includes an explanation for each rule as it is instantiated. In addition to the automatic mode where the rules are repeatedly applied until the overall transfer-function is determined, a drill mode may be entered where one reduction rule is applied. If a user suggested reduction step is not valid, the appropriate explanation message is displayed. Results showing the application of the program to a servo-drive in a robot system are presented. Future work, particularly in the area of synthesis, is outlined.