Volume decomposition and feature recognition .1. Objects

A method has been developed that decomposes a polyhedron into maximal cells by intersecting it with half spaces of its faces having concave edges. Every set of such half spaces that would result in maximal convex cells is found very efficiently without actual intersection operations by examining the relationships among the half spaces and the neighbourhoods of concave edges. One application of this decomposition method is recognition of intersecting features for process planning. Recognition of intersecting features has been a major difficulty in automating process planning. With this decomposition method, a delta volume is decomposed into maximal convex cells. By subtracting maximal convex cells from each other in different orders, multiple interpretations of features are generated. Since the number of interpretations, which may reach N! for N maximal convex cells, can be very large and thus selecting one of them for machining may be difficult, we tried to generate a machining sequence directly from maximal convex cells of a delta volume using a small number of heuristics on machining. The result was the same machining sequence as the one suggested by a machinist.