| Summary: | 碩士 === 逢甲大學 === 工業工程學系 === 87 === In flexible manufacturing systems, CNC machine tools and robots are controlled by their corresponding computers. These computers are communicated with each other through passing messages. They can be arranged by different management structures. In most conventional computer controlled manufacturing systems, the centralized computer system is the most implemented structure. Since the center computer under this structure has to control a lot of resources, it is unable to concurrently control these resources in real time. Recently, the hierarchical distributed computer system has become a popular structure to be implemented in computer controlled manufacturing systems. Under this structure, the computers and resources are distributed to several levels. Thus making concurrent control of resources in real time can be achieved.
When we design the control architecture of a flexible manufacturing system, if the dynamic behavior of the manufacturing system can be manipulated by this control architecture, the deadlocks and conflicts should be able to be resolved in the design phase. Therefore, selecting an appropriate tool capable of manipulating systems’ dynamic behavior is important for the design phase. In this research, we will employ Object-oriented Petri Net (OPN) 、Timed Petri Net (TPN) and Colored Petri Net (CPN) to model control architecture of a flexible manufacturing system. The computer management structure of our control architecture will be the hierarchical distributed computer system. With the characteristics of Petri Net, the control activities of the manufacturing system can be shown distinctly, the conflicts can be resolved in advance, and the deadlocks can be avoided before actually operating the manufacturing system. In addition, with the characteristics of Object-oriented Petri Net, when we need to add new resources or machined workpieces to our system in the future, it is as simple and easy as adding same class of objects to the original designed Petri Net. At last, we use reachability tree to analyze whether any deadlock exists between objects.
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