Knot tying

From RobotLab

Researchers: Bell and Balkcom

Research description

Knot tying poses a challenge to robotic and human manipulation due to the need to regrasp a flexible string. Without sensing, it becomes nearly impossible to guess where the string is. However, by using a fixture, the string can be continually grasped during the entire tying process. We have developed fixtures for a simple overhand knot and a square knot. We can tie knots in different types of wire and fishing line using these fixtures. In addition, we used a Cobra i600 SCARA arm to autonomously tie multiple knots in sequence without sensing, using solder as the string-like material (see video below).

Recent work has focused on adapting our fixtures to work with string, and on making more robust fixtures for wire.

Publications

• M. Bell, D. Balkcom.  "Knot Tying with Single Piece Fixtures". IEEE International Conference on Robotics and Automation (ICRA 2008), May 2008.

Videos

AVI of the lab's 4DOF arm tying a knot using Matt Bell's overhand knot fixture. (40 MB)