MODELING AND SIMULATION OF PETRI NETS FOR COMPLEX SCHEDULING RULES OF AUTOMATED MANUFACTURING SYSTEMS

Discrete event systems such as automated manufacturing systems and engineering systems can be modeled and simulated by Petri nets. Precedence relations between activities or events, concurrent processes, synchronization, resource sharing, mutual exclusion, etc can be well modeled by Petri nets. However, discrete event systems, especially discrete event manufacturing systems, tend to have diverse complex scheduling rules to optimally utilize the resources, meet scheduling requirements and constraints, and optimize the performance measures such as makespan or cycle time. In this paper, we propose ways of modeling such complex scheduling rules by controlling the firing sequences and timing of the associated transitions in the Petri net model. We also present a Petri net model for scheduling a robotized indexer cell for flat panel display manufacturing.