An End-Effector for Pinch and Slide Unfolding Using a Protruding Passive Rotation Mechanism

In this study, we focus on pinch and slide unfolding, an effective method for unfolding clothes. However, pinch and slide unfolding exhibits its drawbacks. For instance, when a cloth is unfolded, gravity pulls it downward, causing the cloth to fall through the gap between the fingers. Hence, this paper proposes a novel end-effector used for cloth manipulation to improve the success rate of unfolding. Our approach demonstrates two main characteristics: (1) By devising an appropriate finger shape and gripping motion, the hem of clothes can be prevented from being pinched in a bent state; (2) A protrusion is attached to the finger pad that can be passively rotated by a bearing, enabling continuous capturing of minute irregularities on the hem of clothes during pinch and slide unfolding. The proposed end-effector was constructed and attached to a robot arm. The end-effector’s effectiveness was confirmed through experiments of unfolding squared cloth sheets.