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 extracti on. 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 d ifferent sets of features may differ in their manufacturability. Thus, to produce a good process plan-or, in some cases, even to produce a p rocess plan at all-it may be necessary to interpret the part as a diff erent set of features than the one initially obtained from the CAD mod el. This paper proposes a way to address this problem, based on an alg ebra of features. Given a set of features describing a machinable part , other equally valid interpretations of the part can be produced by p erforming operations in the algebra. This will enable automated proces s planning systems (such as [39]) to examine these interpretations in order to see which one is most appropriate for use in manufacturing. T he feature algebra has been implemented for a restricted domain and in tegrated with the Protosolid [42] solid modeling system and the EFHA p rocess planning system [39].