Petri Net-based workflow management systems for in-process control in a plastic processing plant

To manage a complex system, an operation model is proposed for evaluating the effectiveness and efficiency of each possible plan. During the planning process, an easy-to-use modeling system for operation modeling could be very useful for assisting the shop floor manager to understand and predict the performance of operation plans. In this paper, the Petri Net is used as a tool to realize the proposed modeling concept. Derived from the basic Colored Petri Net (CPN) language, a Modular Colored Petri Net (MCPN), composed of a number of CPN Modules (CPNMs), is proposed for this adaptive modeling approach. The CPN in each CPNM represents the discrete event logic of the corresponding operation. Despatching rules of the material and activities are modeled by the components and functions of the CPNs in these CPNMs, and the dynamics of the system can be modeled by the transition firing and connections amongst them. In this way, the time and cost for the development and maintenance of the shop floor operation model can be reduced. The application of the system in in-process control in a plastic processing plant is illustrated in the paper.