Static Stability of Robotic Fabric Strip Folding

Planning accurate manipulation of deformable objects requires the ability to predict their state. Prediction is often complicated by a loss of stability that can result in the collapse of a deformable object. This article studies the stability of fabric strip folding performed by a robot. We show that a static instability exists in the folding process. This instability is detected in a physics-based simulation, and the position of the instability is experimentally verified for various fabric materials during robotic manipulation. Three state-of-the-art methods for folding are assessed in the presence of static instability. It is shown that one of the existing folding paths is suitable for the folding of materials with internal friction, such as fabrics. A folding path that utilizes dynamic motion exists for ideal elastic materials without internal friction. Our results show that instability needs to be considered during the planning phase in order to ensure accurate manipulation of deformable objects.