Caging polygonal objects using equilateral three-finger hands

Hallel A. Bunis, Elon D. Rimon, Yoav Golan, Amir Shapiro

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Multifinger caging offers a robust object grasping approach. While efficient computation of two-finger caging grasps is well developed, the computation of three-finger caging grasps has remained a challenging open problem. This letter considers the caging of polygonal objects with three-finger hands which maintain an equilateral triangle formation during the grasping process. While the c-space of such hands is four-dimensional (4-D), their contact space which represents all two and three finger contacts along the grasped object's boundary forms a 2-D stratified manifold. The letter describes a caging graph that can be constructed in the hand's relatively simple contact space. Starting from a desired immobilizing grasp of the object, the caging graph is searched for the largest finger opening that maintains a three-finger cage about the object. This finger opening determines the caging regions, and any equilateral finger placement within the caging regions guarantees a robust object grasping. The technique is illustrated with a detailed example and a video showing caging experiments with an equilateral robot hand.

Original languageEnglish
Article number7812670
Pages (from-to)1672-1679
Number of pages8
JournalIEEE Robotics and Automation Letters
Issue number3
StatePublished - 1 Jul 2017


  • Caging
  • grasp planning
  • grasping
  • multifingered hands

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Biomedical Engineering
  • Human-Computer Interaction
  • Mechanical Engineering
  • Computer Vision and Pattern Recognition
  • Computer Science Applications
  • Control and Optimization
  • Artificial Intelligence


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