A HIERARCHICAL KNOWLEDGE MODEL FOR THE ENGINEERING OF PRODUCTION SYSTEMS

The modelling of industrial knowledge is a fundamental step in the analysis or the design of a production system. In this paper, we put forward a knowledge model based on a unifying concept of industrial object which allows us to modulate the visibility of a manufacturing process, as circumstances require, with particular reference to the case of assembly processes. The industrial object is defined as being the temporary assembly of components from the manufacturing universe (i.e. product and machinery components). Each object is identified by a set of variables that depicts its composition and position in the workshop. The industrial object concept leads on to the concept of the manufacturing task; a task is defined by the changes in state that it brings about on the objects upon which it acts. This approach allows us to formalize the material transformations of the product throughout the manufacturing process, including the phase of batch processing, the initial distribution of components and the final packaging. The knowledge model is hierarchical; from a purely technological description in which the sphere of visibility comprises all the objects within its scope, one can isolate the involvement of the equipment in the completion of tasks so as to retain only its effect on the manufacturing process (production followup). Conversely, from a purely functional description of the manufacturing process and by refining some of the tasks, we reach a description that incorporates the machinery.