Ring on the hook: placing a ring on a moving and pendulating hook based on visual input

Anders Kjær-Nielsen, Anders Glent Buch, Andreas Kryger Jensen, Bent Møller, Dirk Kraft, Norbert Krüger, Henrik Gordon Petersen, Lars-Peter Ellekilde

Research output: Contribution to journalJournal articleResearchpeer-review


Purpose – The purpose of this paper is to describe a robot vision system which put rings on hooks that are moving freely on a conveyor belt. The hook can show a significant swinging which can be well approximated by a pendulum movement. The problem is of large relevance for many industrial applications and the challenge is to compute a 3D pose that is sufficiently precise to allow for successful placements of the rings.

Design/methodology/approach – This requires a fast and precise tracking and a compensation for latencies connected to the processing of visual information as well as the actual robot action.

Findings – The authors achieve this through a precise pose estimation in a high-resolution stereo setup, as well as a modeling of the hook movement as a combination of a translational and a pendulum movement.

Originality/value – The paper shows that under normal conditions close to 100 percent success can be achieved such that this technology now can be transferred into industrial systems.
Original languageEnglish
JournalIndustrial Robot: the international journal of robotics research and application
Issue number3
Pages (from-to)301-314
Publication statusPublished - 2011


  • Robotics
  • Conveyors
  • Tracking
  • Assembly


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