Adaptive wrapping with active elastic band-based gripper for stable in-hand manipulation

Achieving both compliant grasping and robust in-hand manipulation for a robotic hand is a challenging task, especially for fragile or irregularly shaped objects. Active surface grippers usually rely on non-stretchable belts and compliant finger mechanisms for adaptive manipulation and grasping, requiring complex tensioning mechanisms that increase mechanical complexity. This paper presents a novel design of an active elastic bandbased gripper, that can achieve translation and rotation of grasped objects with passive adaptive wrapping and active conveyor motion. The design utilizes pre-tensioned elastic bands that function simultaneously as an adaptive grasping mechanism and an active surface, conforming to the shape of the object shape and providing evenly distributed gripping forces. The principles of grasping and manipulation, as well as the fabrication process of the gripper are presented in this work, and the kinematics and workspace of the gripper with cylindrical objects are analyzed. Based on experiments, the contact stiffness model of the elastic band finger with cylindrical objects was established. To evaluate the performance of the gripper, we carried out experiments on manipulation objects with different shapes and sizes, such as boiled eggs, and fruits. Experimental results illustrated the adaptable grasping and stable in-hand manipulation ability of the gripper.