ABSTRACT
This chapter presents the applications of Petri nets (PNs) to complex system scheduling. It proposes the introduction to basic concepts and extensions of PNs, a hierarchical coloured timed Petri nets (HCTPN). The chapter discusses the complete scheduling solution for semiconductor wafer fabrication, which is composed of an appropriate model and embedded scheduling algorithm. The model is based on PNs. The embedded algorithm is extended from a conventional genetic algorithms (GA). The combined modelling and scheduling solution is validated by simulation based on real-factory scenarios. Being one of the most complicated manufacturing systems, semiconductor wafer fabrication is characterized by its high complexity and high uncertainty. Fabrication layer HCTPN describes the logical process flow of a wafer fabrication system. The work adopts an HCTPN model as a modelling tool to describe complicated production processes in a semiconductor manufacturing system. Based on the model, the studies about such issues as scheduling and real-time control can be conducted.
