REPRESENTATION OF GEOMETRIC FEATURES, TOLERANCES, AND ATTRIBUTES IN SOLID MODELERS BASED ON CONSTRUCTIVE GEOMETRY.

Tolerancing and surface finish data are essential for automatically planning the manufacture, inspection, and robotic assembly of mechanical components. A scheme for representing surface features in a solid modeler, based on constructive solid geometry (CSG), is presented for associating tolerances and other attributes with the tolerancing and surface data. The basic structure proposed for representing features and attributes is a graph called a variational graph (VGraph). The VGraph's integration in a CSG-based solid modeler that operates in a multiple-object environment and supports flexible editing facilities is examined. These issues axre studied in the specific context of the experimental VGraph subsystem of the PADL-2 modeler, but the discussion is broadly applicable to all CSG-based systems.