For robot arms to perform everyday tasks in unstructured environments, these robots must be able to manipulate a diverse range of objects. Today's robots often grasp objects with either soft grippers or rigid end-effectors. However, purely rigid or purely soft grippers have fundamental limitations: soft grippers struggle with irregular, heavy objects, while rigid grippers often cannot grasp small, numerous items. In this paper we therefore introduce RISOs, a mechanics and controls approach for unifying traditional RIgid end-effectors with a novel class of SOft adhesives. When grasping an object, RISOs can use either the rigid end-effector (pinching the item between non-deformable fingers) and/or the soft materials (attaching and releasing items with switchable adhesives). This enhances manipulation capabilities by combining and decoupling rigid and soft mechanisms. With RISOs robots can perform grasps along a spectrum from fully rigid, to fully soft, to rigid-soft, enabling real time object manipulation across a 1 million times range in weight (from 2 mg to 2 kg). To develop RISOs we first model and characterize the soft switchable adhesives. We then mount sheets of these soft adhesives on the surfaces of rigid end-effectors, and develop control strategies that make it easier for robot arms and human operators to utilize RISOs. The resulting RISO grippers were able to pick-up, carry, and release a larger set of objects than existing grippers, and participants also preferred using RISO. Overall, our experimental and user study results suggest that RISOs provide an exceptional gripper range in both capacity and object diversity. See videos of our user studies here: https://youtu.be/du085R0gPFI

翻译：为使机械臂在非结构化环境中执行日常任务，机器人必须能够操作多样化的物体。目前机器人的抓取常依赖柔性夹爪或刚性末端执行器，但纯刚性或纯柔性夹爪存在根本性局限：柔性夹爪难以处理不规则或重型物体，而刚性夹爪则无法抓取微小或数量众多的物件。为此，本文提出RISOs——一种将传统刚性末端执行器与新型可切换柔性粘附材料相统一的力学与控制方法。抓取物体时，RISOs可单独使用刚性末端执行器（通过非变形手指夹持物体）和/或柔性材料（通过可切换粘附层实现物体的粘附与释放），通过刚性机制与柔性机制的协同与解耦提升操作能力。采用RISOs的机器人能实现从全刚性、全柔性到刚柔耦合的连续谱系抓取，从而实时操作重量跨越六个数量级（从2毫克到2千克）的物体。为研发RISOs，我们首先对可切换柔性粘附材料进行建模与表征，随后将该柔性材料片贴附于刚性末端执行器表面，并开发控制策略以降低机械臂及人类操作员的使用门槛。实验表明，RISOs夹爪在物体抓取、搬运与释放的多样性方面超越现有夹爪，参与者亦更青睐该设计。总体而言，实验与用户研究结果证实RISOs在负载能力与物体多样性上提供了卓越的夹爪适用范围。用户研究视频参见：https://youtu.be/du085R0gPFI