A virtual factory based approach to on-line simulation and scheduling for an FMS and a case study

The recent years have witnessed a revolution in computing capabilities. At the same time, modern manufacturing systems are becoming increasingly complex and capital-intensive. Here, we propose a virtual factory wherein an efficient prototyping testbed will be provided. It will be possible to develop detailed models to support system design and operation, to test different system configurations. Besides, It will be possible to manipulate all system features which impact performance, and to see the results of these manipulations, all without disrupting the actual system. This paper is one among very few that tries to represent the virtual factory in an analytic form so that many existing mathematical analyses can be applied. New pseudo resources can be added to form a new virtual environment, and control policy designed by engineers will be evaluated before being issued. Since a state-transition sequence of the virtual factory from the initial state to the final state can be seen as a schedule of the modeled system. An effective schedule of the processing can be obtained by using an A\ast based search algorithm, namely, Limited-Expansion A algorithm.