Timed Petri Nets in Modeling and Analysis of Manufacturing Systems

Petri nets are formal models of systems which exhibit concurrent activities. As formal models, Petri nets are bipartite directed graphs, in which the two types of vertices represent, in a very general sense, conditions and events. In order to study performance aspects of systems modeled by Petri nets, the durations of modeled activities must also be taken into account. This can be done in different ways, resulting in different types of nets “with time”. In timed Petri nets, occurrence times are associated with events. For timed nets with constant occurrence times, if the net is covered by a family of simple cyclic subnets, basic performance characteristics can be obtained by structural analysis, without the exhaustive generation of the state space. The paper briefly recalls basic concepts of Petri nets and timed Petri nets, and then derives hierarchical Petri net models of manufacturing systems. Key-Words: timed Petri nets, performance analysis, manufacturing systems, hierarchical modeling.