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Identification and analysis of robot manipulator singularities

Journal Article · · International Journal of Robotics Research; (United States)
 [1];  [2]
  1. Univ. of Rochester, NY (United States)
  2. National Univ. of Singapore, (Singapore)

The existence of singular positions inside the robot workspace is an inherent problem for task planning and robot control. At manipulator configurations near singular positions, very large joint motions are required to produce relatively small end-effector displacements. In the limit, when a singularity is encountered, the required joint motions become unbounded and the manipulator loses at least one degree of freedom. Identifying the singularities in the robot workspace is not always an analytically tractable problem, except for manipulators with opportune placement of the joint axes. Typically, it is easier and more informative to evaluate the robot arm and wrist singularities, which reflect the limitation of the lower-order robot subsystems responsible for positioning and orienting, respectively, the end effector in space. The objective of this article is to define analytically the interplay between the individual arm and wrist singularities. Specifically, a general formula that defines manipulator singularities in terms of the subsystem singularities is developed. The analysis leads to a novel, efficient method for identifying the singularities of six-axis manipulator. This is then illustrated through an example.

OSTI ID:
6956356
Journal Information:
International Journal of Robotics Research; (United States), Journal Name: International Journal of Robotics Research; (United States) Vol. 11:3; ISSN IJRREL; ISSN 0278-3649
Country of Publication:
United States
Language:
English

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