Caging polygonal objects using formationally similar three-finger hands

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

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Caging offers a robust strategy for grasping objects with robot hands. This letter describes an efficient caging-to-grasping algorithm for polygonal objects using minimalistic three-finger robot hands. This letter describes how to cage and then grasp polygonal objects, using single actuator triangular three-finger formations, whose shape is determined by any desired immobilizing grasp of the polygonal object. While the hand's configuration space is four-dimensional, the algorithm uses the hand's two-dimensional contact space, which represents all two- and three-finger contacts along the grasped object boundary. This letter describes how the problem of computing the critical cage formation that allows the object to escape the hand is reduced to a search along a caging graph constructed in the hand's contact space. Starting from a desired immobilizing grasp, the graph is searched for the critical cage formation, which is used to determine the caging regions surrounding the immobilizing grasp. Any three-finger placement within these regions guarantees robust object grasping. The technique is demonstrated with a detailed computational example and a video clip, which shows caging experiments with a single actuator three-finger robot hand.

Original languageEnglish
Pages (from-to)3271-3278
Number of pages8
JournalIEEE Robotics and Automation Letters
Issue number4
StatePublished - 1 Oct 2018


  • Caging
  • robot grasp planning
  • robot grasping

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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