REPRESENTATION OF MANUFACTURING SYSTEMS IN TERMS OF ENTITIES AND RELATIONSHIPS

Implementation of computer integrated manufacturing (CIM) has become a major objective of many companies. Complex technologies with stringen t control requirements are an integral part of today's manufacturing e nvironment. With movement towards reduced life cycles and just-in-time operation to reduce costs, the inherent rigidity of cell control syst ems is a major roadblock in their implementation. To achieve configura bility economically, a consistent software representation of manufactu ring entities is required. It is necessary to insulate generic control functions from the wide variations found in low-level devices. System information must be organized in a standard format allowing other ent ities to understand and use the information effectively. Virtual manuf acturing entities (VME) are intended to address problems faced in manu facturing integration. A VME is defined as an abstraction of a specifi c set of resources and functions possessed by a physical device. VMEs are a standardized representation masking the proprietary nature of re al manufacturing entities from other software modules in a control env ironment. They can be used as a loose coupling mechanism in constructi ng integrated control systems. Their design and implementation is guid ed by the physical structure of real manufacturing entities, simplifyi ng these tasks for software developers and bridging the gap between de velopers and users.