Experiment in feature data exchange using PDES

The Product Data Exchange Specification (PDES) is a neutral exchange mechanism designed to completely represent product definition data throughout the life-cycle of a part. PDES consists of a number of interlinked or independent models. Models of interest for mechanical parts are : geometric model, dimension & tolerance model and feature model. PDES is developed in a three layer architecture, with the application layer interfacing with different applications, the logical layer forming the integration, and the physical layer which forms the actual communication medium. This paper presents the results of an investigation into the capabilities of PDES in representing the form feature information of the ASU Testbed Modeler. The design and development of a PDES Preprocessor and a Postprocessor is discussed. The PDES Preprocessor maps the ASU Testbed features into the PDES feature definition, and produces a PDES physical file. The PDES Postprocessor reads the standard PDES physical file and recreates the feature based model in the Testbed Modeler. In addition to the traditional problems of data transfer such as numerical inaccuracies, a number of other factors which increase the complexity of the feature data exchange process have been identified. The loss of semantic information consisting of rules, methods and constraints is a serious limitation of the current PDES feature model. These problems are discussed in more detail and suggestions for improvement of PDES are made.