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 stringent control requirements are an integral part of today's manufacturing environment. With movement towards reduced life cycles and just-in-time operation to reduce costs, the inherent rigidity of cell control systems is a major roadblock in their implementation. To achieve configurability economically, a consistent software representation of manufacturing 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 entities to understand and use the information effectively. Virtual manufacturing entities (VME) are intended to address problems faced in manufacturing integration. A VME is defined as an abstraction of a specific set of resources and functions possessed by a physical device. VMEs are a standardized representation masking the proprietary nature of real manufacturing entities from other software modules in a control environment. They can be used as a loose coupling mechanism in constructing integrated control systems. Their design and implementation is guided by the physical structure of real manufacturing entities, simplifying these tasks for software developers and bridging the gap between developers and users.