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Title: Quantizing euclidean motions via double-coset decomposition
Authors: Wülker, C.
Ruan, S.
Chirikjian, G.S. 
Issue Date: 2019
Publisher: American Association for the Advancement of Science
Citation: Wülker, C., Ruan, S., Chirikjian, G.S. (2019). Quantizing euclidean motions via double-coset decomposition. Research 2019 : 1608396. ScholarBank@NUS Repository.
Rights: Attribution 4.0 International
Abstract: Concepts from mathematical crystallography and group theory are used here to quantize the group of rigid-body motions, resulting in a "motion alphabet" with which robot motion primitives are expressed. From these primitives it is possible to develop a dictionary of physical actions. Equipped with an alphabet of the sort developed here, intelligent actions of robots in the world can be approximated with finite sequences of characters, thereby forming the foundation of a language in which robot motion is articulated. In particular, we use the discrete handedness-preserving symmetries of macromolecular crystals (known in mathematical crystallography as Sohncke space groups) to form a coarse discretization of the space SE(3) of rigid-body motions. This discretization ismade finer by subdividing using the concept of double-coset decomposition.More specifically, a very efficient, equivolumetric quantization of spatial motion can be defined using the group-theoretic concept of a double-coset decomposition of the form ?\SE(3)/?, where ? is a Sohncke space group and ? is a finite group of rotational symmetries such as those of the icosahedron.Theresulting discrete alphabet is based on a very uniformsampling of SE(3) and is a tool for describing the continuous trajectories of robots and humans. An efficient coarse-to-fine search algorithm is presented to round off any motion sampled from the continuous group of motions to the nearest element of our alphabet. It is shown that our alphabet and this efficient rounding algorithm can be used as a geometric data structure to accelerate the performance of other sampling schemes designed for desirable dispersion or discrepancy properties. Moreover, the general "signals to symbols" problem in artificial intelligence is cast in this framework for robots moving continuously in the world. Copyright © 2019 Christian Wülker et al.
Source Title: Research
ISSN: 2639-5274
DOI: 10.34133/2019/1608396
Rights: Attribution 4.0 International
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