New formalisms for modeling discrete event systems and their interactions

The control of Discrete Event Systems (DESs) requires inherent knowledge of what the model of the system is and of the system's desired acceptable behavior. A vast body of tools exist for synthesizing appropriate control measures, notable amongst them is the Ramadge and Wonham (RW) supervisory control theory (SCT) framework in which both the system's operations and its control specifications are modeled by interactions of finite automata. Any correct control strategy within this framework then, would rely on the correctness of the automata models of both plant and specification. In this dissertation we develop new, and simple yet powerful ways for modeling certain classes of DESs, as well as the interaction between them.; A new modeling formalism for DESs has been proposed which enables construction and developing automata models of DESs used in automated manufacturing and process control is an enormously difficult task, owing to the need for tracking down every eventuality in the automata model. The modeling formalism we propose simplifies the task of modeling to that of manageable proportions by developing rules under which events occur in the system. It relies on first order predicate logic for generating the rules based model of the system, which can then be transformed into automata models and then analyzed in a formal way. Modeling the conditions causing change of signal values using rules forms the basis of this methodology. This has the added advantage of being intuitive, besides providing a canonicity of notation, and most importantly being polynomial in the number of signals.; In order to transform the rules based modeling formalism into an automata model, first extended automata for all signals in the system are developed, having the enabling conditions of these rules as guard conditions. These are then composed synchronously to directly yield the complete automaton model of the system. We present practical applications of the modeling formalism.; A new formalism for modeling the interaction mechanism between automata based DESs has been proposed which generalizes existing composition methodologies. This allows for complete modes of interaction operations for combining DESs. This extends the traditional way of composition including synchronous, asynchronous, inter-leaved and prioritized composition, by subsuming them into one extended composition mechanism we call prioritized composition with exclusion. We also develop the most general composition mechanism for automata based system interaction, called the generalized composition, which permits systems to perform interactions beyond prioritized composition with exclusion.