On user-defined features

Feature-based design is becoming one of the fundamental design paradigms of CAD systems. In this paradigm, the basic unit is a feature and parts are constructed by a sequence of feature attachment operations. The type and number of possible features involved depend upon product type, the application reasoning process and the level of abstraction. Therefore to provide CAD systems with a basic mechanism to define features that fit the end-user needs seems more appropriate than trying to provide a large repertoire of features covering every possible application. A procedural mechanism is proposed for generating and deploying user-defined features in a feature-based design paradigm. The usefulness of the mechanism relies on two functional capabilities. First the shape and size of the user-defined features are instantiated according to parameter values given by the end-user. Second the end-user positions and orients the feature in the part being designed by means of geometric gestures on geometric references. (C) 1998 Elsevier Science Ltd. All rights reserved.