Ordered firing-an expert system feature for CAD of control systems

The use of expert system techniques has enabled human design expertise to be coded in terms of rules. Several such rules are used to achieve a particular design goal. Some of them are fired and some are not. If the firing and unfiring of these rules can be made to follow some preset sequences, an automatic design mode can be set up. This is achieved by the use of ordered firing, a feature added to an expert system that makes use of a firing order unit to select the next appropriate rule for firing. The firing order unit mimics the ability (expertise) of a human designer to thread several design rules in sequence in order to achieve some design goals.<>