| Computer Aided Process Planning (CAPP) systems receive two major criticisms: First, they are viewed as isolated from production control systems due to the lack of proper integration hooks and a generic vision for process plans, that is, a deterministic description of what process plans are, and how they should be represented is yet to evolve. Second, most CAPP systems are static systems that do not adapt readily to changes in a dynamic manufacturing environment. One of the primary reasons for this is that many of the existing CAPP systems are designed in an ad-hoc manner, without an underlying formal model that can be used for problem solving. In this research, a comprehensive view of process plans and CAPP systems design as they relate to CIM has been addressed. Topics addressed in this dissertation include: a generic vision of process planning in a CIM environment, an information architecture for interfacing process plans and a Shop Floor Control System (SFCS), and a formal model of process planning which describes reasoning procedures associated with process planning. A clear functional link between process planning and shop floor control has been identified. Based on the functional link, a process plan representation model has been developed to provide required "hooks" for interfacing process plans and SFCSs. The design of the interface architecture focuses on the compliance of process plans with the information requirements of a real-time SFCS. The formal model of process planning covers formal descriptions of a part representation, process planning structures, and decision tree models as an implementation tool for knowledge representation. The formal model of process planning is intended to define the requirements for a generic software environment that provides a fundamental framework for development and maintenance of CAPP systems. |
