Knowledge Rich Machines as a Mechanism for the Integration of Process Planning and Production Planning

Abstract

This paper introduces a new conceptual framework for organising manufacturing systems incorporating Knowledge Rich Machine Controllers (KRMC). The functions of a Knowledge Rich Machine Controller are: to store and manipulate data relevant to a single machine tool; to aid distributed process planning; and to allow a ‘collaborative strategy’ of production planning. Modern machine tool controllers often contain a reasonably low-cost, yet powerful, computer, which can be part of a factory-wide (or larger) network. The potential of this situation is the subject of ongoing research, to determine the tasks which should be delegated to the machine tool controller. The machine level is the ideal place to store machine-specific information which contributes to a larger knowledge-base at the cell and factory levels; this hierarchical decomposition of the shop floor provides a template for the decomposition of the planning tasks the factory is to perform. A new model of the factory incorporating KRMs is presented; the structure of a KRM is documented; each functional module, and its role in the factory, is described; the new mechanism for factory level process and production planning using KRMs is also introduced. Shop floor capability is described in terms of machine-independent units, which are used as a grammar for describing process plans and for enhancing scheduling functions to utilise the inherent flexibility of a general purpose job-shop floor. The common notation for process planning and production planning removes a significant barrier from the integration of two of the most complex functions in manufacturing.