A Qualitative Discretization for Two-Body Contacts

Abstract

In this work we use contact alignments as qualitative landmarks to discretize the relative motion between two 3D objects. We use assembly planning as a sample domain, and address the question of obtaining the assembly blocking graphs from the geometry and the motion constraints. Starting from a geometrical description of the objects we characterize contacts involving topologically distinct feature sets, called contact formations (CF) and obtain a qualitative decomposition of the configuration space based on CFs. We show how standard algorithms for finding the configuration-space routinely discard CF information, and how these can be extracted at no additional computational cost. Finally we show how CFs can be used to generate assembly solutions and for correcting jamming and other assembly.