AN ALGEBRAIC APPROACH TO FEATURE INTERACTIONS

Various approaches have been proposed to provide communication between CAD systems and process planning systems, including automated feature extraction, design by features, and human-supervised feature extraction. Regardless of which approach is used, a major problem is that due to geometric interactions among features, there may be several equally valid sets of manufacturable features describing the same part, and different sets of features may differ in their manufacturability. Thus, to produce a good process plan-or, in some cases, even to produce a process plan at all-it may be necessary to interpret the part as a different set of features than the one initially obtained from the CAD model. This paper proposes a way to address this problem, based on an algebra of features. Given a set of features describing a machinable part, other equally valid interpretations of the part can be produced by performing operations in the algebra. This will enable automated process planning systems (such as [39]) to examine these interpretations in order to see which one is most appropriate for use in manufacturing. The feature algebra has been implemented for a restricted domain and integrated with the Protosolid [42] solid modeling system and the EFHA process planning system [39].