Abstract: Recently, soft grippers have garnered considerable interest in various fields, such as medical rehabilitation, due to their high compliance. However, the traditional PneuNet only reliably grasps medium and large objects via enveloping grasping (EG), and cannot realize pinching grasping (PG) to stably grasp small and thin objects as EG requires a large bending angle whereas PG requires a much smaller one. Therefore, we proposed a multi-structure soft gripper (MSSG) with only one vent per finger which combines the PneuNet in the proximal segment with the normal soft pneumatic actuator (NSPA) in the distal segment, allowing PG to be realized without a loss in EG and enhancing the robustness of PG due to the height difference between the distal and proximal segments. Grasping was characterized on the basis of the stability (finger bending angle describes) and robustness (pull-out force describes), and the bending angle and pull-out force of MSSG were analyzed using the finite element method. Furthermore, the grasping performance was validated using experiments, and the results demonstrated that the MSSG with one vent per finger was able to realize PG without a loss in EG and effectively enhance the PG robustness.

Key words: soft robotic grasping, multi-structure, pinching grasping (PG), robustness

摘要： 近年来，软体抓手因其高柔顺性在医疗康复等各个领域引起了广泛的关注。然而，传统的PneuNet仅通过包络抓取（EG）可靠地抓取中大型物体，无法实现捏取（PG）来稳定抓取小而薄的物体，这是由于EG需要大弯曲角度而PG需要相对小很多的弯曲角度。我们提出了一种多结构软体夹持器（MSSG），每个手指只有一个气路，它将近端段的PneuNet与远端段的普通软气动执行器（NSPA）相结合，这样可以在不损失EG的情况下实现PG，并且远端和近端段之间的高度差增强了PG的鲁棒性。基于MSSG的稳定性（指弯曲角度描述）和鲁棒性（拉拔力描述）对抓取进行了表征，并采用有限元方法分析了MSSG的弯曲角度和拉拔力。此外，通过实验验证了抓取性能，结果表明每指单气路的MSSG能够在不损失EG的情况下实现PG，并有效增强了PG的鲁棒性。

关键词: 软机器人抓取，多结构，捏取，鲁棒性