A Petri Net Based Approach for FMS Performance Evaluation

In this paper a Petri Net based approach to evaluate the performance of manufacturing systems is proposed. Starting from the Petri Net model of the plant, it is possible to make a set of assessments of its performance in various operating conditions. These conditions include the change in the topology of the plant, for example concerning the effect of moving some machines from one cell to another in order to assess the impact on overall performance. The advantage of the performance evaluation approach we propose is evident: the designer can assess the effect of any modification in the topology of the plant before it is actually made, and thus decide in advance whether to introduce it or not. The proposed approach is applied to a real semiconductor plant. Here the transport system, which must deliver the products to the relevant machines, plays an essential role in the performance of the plant. The evaluation of the impact on the overall performance of the topology of the machines the transport system must connect appears very interesting. After a brief description of this plant, the Petri Net model and the results obtained through simulation, are carefully described. They highlight an increase in performance through suitable changes in the topology of the plant.