Modelling Manufacturing Systems with Place/Transition Nets and Timed Petri Nets

This chapter discusses the Place Nets (PN) in manufacturing systems modelling. It presents the basics of place/transition nets (P/T), which is the simplest logic framework among the various PN modelling methodologies. In the literature, two main classes of PNs with time have been defined: timed Petri nets (TdPNs) and time Petri nets (TPNs). The chapter summarizes the basics of the timed extension of P/T nets, showing how an enhanced framework may effectively be employed in manufacturing. Since the P/T net model of a manufacturing system typically suffers from the state explosion problem, two approaches have been proposed to cope the problem: Reduction techniques, allowing to simplify the computational effort of analysing large and complex P/T nets, and Synthesis methods, which construct nets systematically such that the desired properties are guaranteed without analysis in the final nets. Reduction methods classified into: place transformations, fusion of transitions and addition of nets.