On the supervisory control of marked graphs

This paper presents a control synthesis approach for discrete event systems modeled by marked graphs with uncontrollable and / or unobservable transitions. It solves forbidden state problems characterized by a set of General Mutual Exclusion Constraints. We show that there exist a unique marking from which all other possible current markings can be reached uncontrollably by firing sequences of uncontrollable transitions. This feature allows us to design efficient control policies based on proper separation of observation and control. Taking into account time information allows generating more permissive controllers by knowing which is at a certain time the number of token in a place.