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Volume 20 Issue 06 - Publications Date: 1 June 2001
 
Planning Motions Compliant to Complex Contact States
 
X. Ji University of North Carolina at Charlotte and J. Xiao
 
Many robotic tasks require compliant motions, but planning such motions poses special challenges not present in collision-free motion planning. One challenge is how to achieve exactness, that is, how to make sure that a planned path is exactly compliant to a desired contact state, especially when the configuration manifold of such a contact state is hard to describe analytically due to high geometrical complexity and/or high dimensionality. The authors tackle the problem with a hybrid approach of direct exploitation of contact constraints and randomized planning. They particularly focus on planning motion that maintains certain contact state or contact formation (CF), called a CF-compliant motion, because a general compliant motion is a sequence of such CF-compliant motions with respect to different CFs. This paper describes a randomized planner for planning CF-compliant motion between two arbitrary polyhedral solids, extending the probabilistic roadmap paradigm for planning collision-free motion to the space of contact configurations. Key to this approach is a novel sampling strategy to generate random CF-compliant configurations. The authors also present and discuss examples of sampling and planning results.
 
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