Publication

Stratifying the singularity loci of a class of parallel manipulators

Journal Article (2006)

Journal

IEEE Transactions on Robotics

Pages

23-32

Volume

22

Number

1

Doc link

http://dx.doi.org/10.1109/TRO.2005.858861

File

Download the digital copy of the doc pdf document

Abstract

Some in-parallel robots, such as the 3-2-1 and the 3/2 manipulators, have attracted attention because their forward kinematics can be solved by three consecutive trilaterations. In this paper, we identify a class of these robots, which we call flagged manipulators, whose singularity loci admit a well-behaved decomposition, i.e., a stratification, derived from that of the flag manifold. Two remarkable properties must be highlighted. First, the decomposition has the same topology for all members in the class, irrespective of the metric details of each particular robot instance. Thus, we provide explicitly all the singular strata and their connectivity, which apply to all flagged manipulators without any tailoring. Second, the strata can be easily characterized geometrically, because it is possible to assign local coordinates to each stratum (in the configuration space of the manipulator) that correspond to uncoupled rotations and/or translations in the workspace.

Categories

automation.

Author keywords

parallel manipulators, kinematics singularities, manipulator design, stratification, flag manifold

Scientific reference

C. Torras, F. Thomas and M. Alberich-Carramiñana. Stratifying the singularity loci of a class of parallel manipulators. IEEE Transactions on Robotics, 22(1): 23-32, 2006.