Research On The Scheduling Of Flexible Manufacturing System Based On Petri Nets

Flexible manufacturing system (FMS) is a kind of highly automated manufacturing system with high efficiency, high quality, and high flexibility. However, the design and implementation of FMS are very complicated, thereby technology-intensive and costly. Therefore the modeling and simulation of FMS are necessary and virtal. The scheduling is a key problem in FMS, and attracks extensive inverest from the engineering field and the academic field. The purpose of scheduling is to efficiently utilize existing resources to shorten the cycle-time as well as improve competitive power of enterprises. As a formal description and analysis tool, Petri Nets has become a popular method for modeling and scheduling of FMS.This paper concentrates on the scheduling of FMS based on Petri Nets, and proposes effective and practical heuristic algorithms to solve some classical FMS scheduling problems. The main work and innovation in this paper are as follows:1. The modeling and scheduling of FMS are first analyzed, and then a software platform for FMS scheduling simulation is developed. With the designed software, we can test various models and algorithms conveniently by storing Petri Nets model in the database.2. To speed up the search process, we proposed an improved algorithm by introducing the search window based on combined heuristic A* algorithm with controlled backtracking algorithm. And the improved algorithm is called dynamic heuristic search algorithm. Further, Sevral heuristic functions and the corresponding results are given when the presented algorithm is utilized to search the object in the Petri Nets model. The results show that the improved algorithm improves the efficiency of searching.3. We study dynamic scheduling of FMS and the optimal path search problem of Automated Guided Vehicle in the flexible manufacturing system.