A Pair of End-Effectors for Unfold-to-Fold a Fabric by Dual-Arm Manipulation*

This paper describes a pair of end-effectors for doing a unified fabric manipulation task termed unfold-to-fold. For the unfolding action, a pinch-and-slide motion have been employed, and the mechanical structure and motion method of the robot end-effectors have been studied to increase the success rate of this motion. However, there are several factors that can cause the work to fail. One of them is the gravity applied to the fabric itself. During the unfolding, the fabric may be pulled downward and falls through the gap between the fingers. If cloth manipulation can be performed in a way that avoids this accident as much as possible, the usefulness of pinch-and-slide unfolding will increase. In this study, we propose a novel end-effector that can improve the success rate of the unfolding. We also make it possible to fold the fabric in two while lifting it up with the other novel end-effector, thereby streamlining the folding manipulation. We confirmed the effectiveness of the proposed end-effectors by conducting an experiment with several fabrics of different thicknesses and weights.