On-line synthesis of supervisors for discrete events in automated manufacturing systems

Mutual exclusion and synchronization are two important control problems of discrete events in automated manufacturing systems. Mutual exclusion concerns itself with allowing only one process at a time to use a certain resource. Synchronization concerns itself with the coordination of events in the interacting processes. These two control problems can be specified by the legal constraint languages with forbidden states and forbidden event strings. Ramadge and Wonham proposed (1987) a formal framework for studying discrete logic systems and algorithms for the automatic synthesis of supervisory controllers from their specifications. However, an explicit implementation of these algorithms is often not practical because the size of the discrete state-space renders traditional computational methods infeasible. In this paper, we developed an online synthesis scheme of supervisors for discrete events of automated manufacturing systems under the legal constraint languages. Some theoretic issues about this online synthesis scheme, such as, monotonicity and convergence, were also discussed.