The Study Of Modeling, Simulation And Scheduling Of Manufacturing System Based On Petri Nets

With the development of China's manufacture, the productive efficiency became the focus of attention. Recent years, researchers in China focus on the production control and management technology for manufacturing with modern science especially the computer technology. One of the precondition of production control is modeling for the manufacturing processes.As the modeling and analysis tool of distributed system, Petri nets are convenient to describe the relations to the process in the system just like sequence, concurrency, conflict, synchronization and so on. Manufacturing system, as the discrete event dynamic system(DEDS),mainly consist of the relations above, so that modeling with Petri nets can assure the correctness and the effectiveness of models. In the case of productive units of two job shops from one factory in HaiNan, this paper introduced the method of modeling with Petri nets, then discussed the scheduling problem with the models we built.The main contributions in this paper are summed up as follows:1) By analyzing the manufacturing system, the basic models of manufacturing unit based on Petri nets are presented. Then we finish modeling the productive process of two job shops from one factory in HaiNan. And the reachability graph generation algorithm is designed.2) In the process of modeling the assembly shop, we introduce the timed place Petri nets(TPPN).Additionally we deal with the scheduling problem with A* algorithm creatively, and get the best solution to the minimize the processing time. 3) Based on the modeling, we simulate the production process with ExSpect to verify the results calculated by the A* algorithm. The analysis and evaluation to the results are given with Gantt chart in the end.