Institute for Systems Research
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Item Non-blocking Supervisory Control of Nondeterministic Systems via Prioritized, Synchronization(1993) Kumar, Ratnesh; Shayman, M.A.; ISRIn a previous paper [15], we showed that supervisory control of nondeterministic discrete event systems, in the presence of driven events, can be achieved using prioritized synchronous composition as a mechanism of control, and trajectory models as a modeling formalism. The specifications considered in [15] were given by prefix-closed languages. In this paper, we extend the theory of trajectory models and prioritized synchronous composition to include markings so that non-closed specifications and issues such as blocking can be addressed. It is shown that the usual notion of non-blocking, called language model non- blocking, is inadequate in the setting of nondeterministic systems, and a stronger notion, called trajectory model non- blocking, is introduced. Necessary and sufficient conditions for the existence of non-marking and language model non-blocking as well as trajectory model non-blocking supervisors is obtained for nondeterministic systems in the presence of driven events. We also show that our approach is also suitable for modular supervisory control.Item Supervisory Control of Nondeterministic Systems with Driven Events via Prioritized Synchronization and Trajectory Models(1992) Shayman, M.A.; Kumar, Ratnesh; ISRWe study the supervisory control of nondeterministic discrete event dynamical systems (DEDS's) with driven events in the setting of prioritized synchronization and trajectory models introduced by Heymann. Prioritized synchronization captures the notions of controllable, uncontrollable, and driven events in a natural way, and we use it for constructing supervisory controllers. The trajectory model is used for characterizing the behavior of nondeterministic DEDS's since it is a sufficiently detailed model (in contrast to the less detailed language or failures models), and serves as a language congruence with respect to the operation of prioritized synchronization. We obtain results concerning controllability and observability in this general setting.