In this work, we discuss the design of soft robotic fingers for robust precision grasping. Through a conceptual analysis of the finger shape and compliance during grasping, we confirm that antipodal grasps are more stable when contact with the object occurs on the side of the fingers (i.e., pinch grasps) instead of the fingertips. In addition, we show that achieving such pinch grasps with soft fingers for a wide variety of objects requires at least two independent bending segments each, but only requires actuation in the proximal segment. Using a physical prototype hand, we evaluate the improvement in pinch-grasping performance of this two-segment proximally actuated finger design compared to more typical, uniformly actuated fingers. Through an exploration of the relative lengths of the two finger segments, we show the tradeoff between power grasping strength and precision grasping capabilities for fingers with passive distal segments. We characterize grasping on the basis of the acquisition region, object sizes, rotational stability, and robustness to external forces. Based on these metrics, we confirm that higher-quality precision grasping is achieved through pinch grasping via fingers with the proximally actuated finger design compared to uniformly actuated fingers. However, power grasping is still best performed with uniformly actuated fingers. Accordingly, soft continuum fingers should be designed to have at least two independently actuated serial segments, since such fingers can maximize grasping performance during both power and precision grasps through controlled adaptation between uniform and proximally actuated finger structures.

中文翻译：

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多段软机器人手指可实现稳健的精确抓取

在这项工作中，我们讨论了用于鲁棒精确抓取的软机器人手指的设计。通过对抓握过程中手指形状和顺应性的概念分析，我们确认当与物体接触发生在手指侧面（即捏抓）而不是指尖时，反足抓握更稳定。此外，我们表明，用柔软的手指对各种物体实现这种捏抓，每个都需要至少两个独立的弯曲段，但只需要在近端驱动。使用物理原型手，我们评估了与更典型的均匀致动手指相比，这种两段式近端致动手指设计在抓握性能方面的改进。通过探索两个手指节段的相对长度，我们展示了具有被动远端节段的手指的力量抓取强度和精确抓取能力之间的权衡。我们根据采集区域、物体大小、旋转稳定性和对外力的鲁棒性来表征抓取。基于这些指标，我们确认，与均匀驱动的手指相比，通过近端驱动的手指设计通过手指捏抓实现了更高质量的精确抓取。然而，力量抓握仍然最好用均匀致动的手指进行。因此，软连续手指应设计为具有至少两个独立致动的串联段，因为通过均匀和近端致动的手指结构之间的受控适应，此类手指可以在强力和精确抓握期间最大限度地提高抓握性能。