Research On Timed Colored Petri Net Based Modeling And Simulation Technology Of Controlling System Of Discrete Manufacturing

The production and assembly process of auto parts are the typical flexible manufacturing process. And the four parts of a car are processed in the respective manufacturing areas according to processing craft. Processing of these four parts belong to mixed-flow processing which is prone to have conflict and deadlock in manufacturing. This thesis respectively makes static and dynamic simulation model to the whole processing by means of Petri net and Flexsim software to find out the choke point, conflict and deadlock in the system as well as optimizing and marshalling the established model, which prove the feasibility and versatility of Petri net and Flexsim software modeling.As automation production capacity increasingly gets improvement, there appear more and more enterprises which regard flexible manufacturing as the main mode of production. FMS, the typical classification of DEDS, is composed of the unified information control management system, material handling and storage system and a series of numerical control processing equipments, which can adapt to automation machinery manufacturing system of processing object conversion. However, the operation of flexible manufacturing system will have all kinds of sudden situations in system apart from handling the reserved processing craft. In the case of limited resources, how to effectively allocate the resources is the key to improve the efficiency of the whole system. And it is extremely unrealistic to remould the whole production system in order to improve efficiency, so we should make use of computer simulation technology to model the whole system and change model corresponding variables according to the actual production so as to draw the relevant conclusion.The common research method of system marshalling and controlling are heuristic algorithm dispatching rules, Markov chain method, queuing network method, mathematical method, artificial intelligence, etc. but these methods have premises of steady state and independence while the system may not completely meet these requirements, therefore, the accuracy of conclusion cannot be guaranteed. Petri net is intuitive, easy to understand and use, which has both the intuitive graphical representation and rigorous mathematical expression formula. It can not only be used for static structural analysis, but also be used for dynamic behavior analysis, thus the flexible manufacturing system is analyzed by means of combining Petri net modeling and Flexsim simulation.First, Petri net is applied to model the objects involved in the whole system. It is to model the static logical structure of the whole system, focusing on the logical relationship between various objects, such as, product processing craft, material feeding plan and assembly list, etc. The basic Petri net can well express some simple logical relationships, but the number of nodes in Petri net will increase exponentially when the number of objects described by Petri increase. If the basic Petri net is still used to modeling, the readability of the whole net becomes extremely bad, which is inconvenient for system analysis. In order to reduce the node number of the whole net system, the Petri net with color factors is brought in, namely the colored Petri net. And the Petri net is layered by coloring the flow resource-Tulken, namely, giving them same or different eigenvalue so as to reduce the size of the whole net system. All the actions of the basic Petri net are instantaneously finished; the expression of the real system processing time and the logistics consuming time in Petri net need to bring in time factor. The assign Petri net can effectively solve this problem and it can correspond with the real system factor by giving different time delay to nodes of net system. And then Flexsim simulation software is adopted to dynamically simulate production system. Flexsim is a type of three-D visual simulation software, which not only has the modeling technology to objects but also can analyze the modeling system data. In accordance with the Petri net, the relevant parameter is set, operating and getting data by the transition between Petri net and FlexsimThrough the establishment of production system simulation model, this thesis analyzes such situations as conflict and deadlock in model and the proposed scheme provides basis for the production improvement, which reasonably solve the problem of resource flow and utilization in production process, greatly improve the production efficiency. It is a good exploration to the controlling marshalling and the optimization and modification of production system, which has a great significance.