Efficiency improvement in generation of a contact state graph by eliminating unnecessary elements

In this paper, we propose a method to improve efficiency of generating a contact state graph by eliminating unnecessary elements. The method is based on our previously proposed framework for automatic generation of contact states using triangulation of faces, where contact states are formally represented with topologies of polyhedral objects' elements which are vertex, edge, and triangle. The adjacency of elements is defined to determine priority of elements to be used for developing a contact state graph. Starting from elements adjacent to the initial contact state, the priority of each element is determined by computing its adjacency to the target contact state. The unnecessary elements are eliminated by generating contact states from high priority elements until a generated contact state reaches to the target contact state. If a contact state graph is completed with elements of high priority, the number of contact states is significantly reduced because the other elements are not used. Finally, we can obtain at least a realizable contact sequence from the contact state graph.