STEP implementation of imperfect EXPRESS model in fuzzy object-oriented databases

Information that has imprecision and uncertainty is inherently present in engineering design and manufacturing. The product data model, being a core model of the intelligent manufacturing system, consists of all concerned data in the product life cycle. It is possible that crisp data as well as imperfect data are involved in the product data model. EXPRESS is a powerful tool with which to develop a product data model and should be extended for this purpose. In this paper, we focus on extending the parts of EXPRESS related to the aspects of database modeling with fuzzy sets and possibility distributions, and implementing such fuzzy EXPRESS models with databases. Formal methods for mapping the fuzzy EXPRESS models to the fuzzy object-oriented databases are proposed. The requirements of standard data access interface (SDAI) functions are investigated to manipulate the EXPRESS-defined data in the databases. Depending on the fuzzy object-oriented database platform, various implementation algorithms of these SDAI functions are developed.