The supervised control of discrete event dynamic systems: a new approach

The objective of the supervisory control theory of discrete event dynamic systems (DEDS), first introduced by Ramadge and Wonham (1989), is to design supervisors in such a way that a process coupled with the supervisors behaves according to logical constraints. In this framework, a supervisor can prevent some events from occurring but cannot force any event to appear. Nevertheless, most processes require the addition of an external control agent that forces some events to occur. This has led us to define the supervised control concept. In this new approach, control and supervision are clearly separated. This provides a hierarchical frame that permits us to formalize and systematize the transition from the synthesis to the implementation of the control. Grafcet is a powerful description tool that offers a great conciseness for modelling. In this paper, this tool is intensively used for the supervised control design.