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

A flexible manufacturing system (FMS) is designed to combine high productiv ity and production flexibility. But the design of a FMS requires high inves tment. Furthermore, this preliminary phase is strategic and the decisions a t this stage have to be made very carefully in order to ensure that the man ufacturing system will successfully satisfy the demands of an ever-changing market. Discrete-event simulation has been widely used to design productio n systems such as FMSs. More particularly, it has been used to design and s ize the hardware part of a FMS. On the other hand, simulation is more and m ore used to design and evaluate decision strategies. In this paper, we prop ose to integrate in a single simulation model a physical model which corres ponds to the hardware elements of the FMS with their physical characteristi cs 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 methodol ogy 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...) with in a discrete-event simulation language. On a FMS, for example described in this paper, the results obtained show that with a high level shop congesti on, the control layer does not increase the job flowtime. (C) 2000 Elsevier Science B.V. All rights reserved.