Robot grasping is subject to an inherent tradeoff: Grippers with a large span typically take a longer time to close, and fast grippers usually cover a small span. However, many practical applications of soft grippers require the ability to close a large distance rapidly. For example, grasping cloth typically requires pressing a wide span of fabric into a graspable cusp. Here, we demonstrate a human-finger-inspired snapping gripper that exploits elastic instability to achieve reversible rapid closure over a wide span. Using prestressed semi-rigid material as the skeleton, the gripper fingers can widely open (86 ~) and rapidly close (46 ms) following a trajectory similar to that of a thumb-index finger pinching which is 2.7 times and 10.9 times better than the reference gripper in terms of span and speed, respectively. We theoretically give the design principle, simulatively verify the method, and experimentally test this gripper on a variety of rigid, flexible, and limp objects and achieve good adaptivity and mechanical performance. This research helps bridge the gap between strong industry manipulators and safe human-interactive robotic hands.

翻译：机器人抓取存在固有的权衡：跨度大的抓取器通常闭合时间较长，而快速抓取器通常覆盖的跨度较小。然而，软体抓取器的许多实际应用需要具备快速闭合大距离的能力。例如，抓取布料通常需要将大范围的织物压成可抓取的褶皱。在此，我们展示了一种受人类手指启发的弹射式抓取器，它利用弹性不稳定性实现宽跨度上的可逆快速闭合。采用预应力的半刚性材料作为骨架，抓取器手指能够大幅张开（86°）并快速闭合（46毫秒），其运动轨迹类似于拇指和食指的捏合动作，在跨度和速度上分别比参考抓取器提升了2.7倍和10.9倍。我们从理论上给出了设计原理，通过仿真验证了该方法，并在多种刚性、柔性和易变形物体上实验测试了该抓取器，展现出良好的适应性和力学性能。这项研究有助于缩小强力工业机械手与安全人机交互机器人手之间的差距。