A new global accessibility algorithm for a polyhedral model with convex polygonal facets

Global accessibility information of a CAD model has been utilized widely in various manufacturing applications. This information needs fast-computing to improve the efficiency of manufacturability analysis. It needs compact representation to increase the effective utilization in its process-planning task We propose a new geometric algorithm to explicitly find the global accessibility cones (GAC) of a polyhedral model. The proposed algorithm has three main steps. The first is concave region extraction, collecting facets that are not on the convex hull of the entire model. Second, inaccessibility of convex polygonal facets in these concave regions is analyzed in order to find their inaccessibility cones (IAC). The method is done in 2D instead of 3D. Finally, to compute GACs of those facets, the complement of the IACs union is determined for an exact solution, while the slicing-method is proposed to find a near-exact solution. In this paper, geometric examples are demonstrated and a comparison of the computational complexity with existing algorithms is provided. (C) 2009 Elsevier Ltd. All rights reserved.