Modeling and simulation of the control framework on a flexible manufacturing system

A flexible manufacturing system (FMS) is designed to combine high productivity and production flexibility. But the design of an FMS requires high investment. Furthermore, this preliminary phase is strategic and the decisions at this stage have to be made very carefully in order to ensure that the manufacturing system will successfully satisfy the demands of an ever-changing market. Discrete-event simulation has been widely used to design production systems such as FMSs. More particularly, it has been used to design and size the hardware part of an FMS. On the other hand, simulation is more and more used to design and evaluate decision strategies. In this paper, we propose to integrate in a single simulation model a physical model which corresponds to the hardware elements of the FMS with their physical characteristics and interactions, and a logic model which corresponds to the modeling of the computer control system and its interaction with the material part (i.e., the control framework and the network). For this, we present a methodology which allows the integration in a single simulation model of a logical layer representing the control framework and a physical layer representing the FMS elements (i.e., machines, vehicles, transportation network ...) within a discrete-event simulation language. On an FMS, for example described in this paper, the results obtained show that with a high level shop congestion, the control layer does not increase the job flowtime.