Fluid models and hybrid automata in manufacturing

In this paper we discuss a hybrid formulation for the modeling and control of automated manufacturing systems within a framework that distinguishes two levels of aggregation. At the lower level the discrete flows of parts are approximated by first-order fluid models. At the higher level a finite automaton represents the transitions of the system through a sequence of admissible macro-states at the occurrence of the macro-events. We describe both levels with a single formalism by a hybrid automaton and we approach the safety verifcation of the system requirements by addressing the reachability problem in terms of the timing information associated with the verification problem