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

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.