Pneumatically driven soft robotic grippers have been extensively studied in recent years. A majority of the grippers, especially those entirely composed of soft materials, can adapt to and handle various objects. However, there are limited studies regarding the realization of arbitrary grasping postures and twisting manipulation. Furthermore, the handling efficiency or the takt time of a handling task has not been investigated frequently. Therefore, this article proposes a circular shell gripper that consists of a rigid external shell and four soft internal air chambers. The soft chambers can be pneumatically inflated, thereby enabling it to grasp an object with a large contact area. The rigid shell allows the gripper to generate a large grasping force, while providing rigidity. This allows it to achieve arbitrary handling postures and twisting manipulations. A finite element model was constructed to simulate the chamber inflation, contact area upon grasping, lifting force, and twisting torque. An analytical model was formulated to quickly predict the lifting force and the twisting torque required to manipulate a known object. The models were validated via experimental tests on the lifting and twisting of a rigid cylinder. The experimental results indicate that the shell gripper can generate a maximum lifting force and twisting torque of 50.97 N and 0.73 Nm, respectively, with an input pressure of 10 kPa. Experimental tests on a variety of food and drink products revealed that the gripper could handle deformable, heavy, and irregularly shaped objects as well as realize arbitrary manipulation posture and twisting motion. The takt time for a pick-and-place task was found to be ∼2–5 s, using an SCARA robot; this time can be further optimized (less than 1 s) by using a parallel robot. However, the gripper was unable to handle low-profile objects, due to the downward pressing force; this was identified as a limitation of the proposed design.

中文翻译：

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用于处理食品的圆形外壳夹持器

近年来，气动驱动的软机器人夹具得到了广泛的研究。大多数抓手，尤其是完全由软材料制成的抓手，可以适应和处理各种物体。然而，关于实现任意抓取姿势和扭转操作的研究有限。此外，没有经常研究处理任务的处理效率或节拍时间。因此，本文提出了一种圆形外壳夹持器，它由一个刚性外壳和四个柔软的内部气室组成。软室可以气动充气，从而使其能够抓住具有大接触面积的物体。刚性外壳允许夹持器产生较大的抓取力，同时提供刚性。这使得它可以实现任意处理姿势和扭转操作。构建了一个有限元模型来模拟腔室膨胀、抓握时的接触面积、提升力和扭转扭矩。制定了一个分析模型，以快速预测操纵已知物体所需的提升力和扭转扭矩。通过对刚性圆柱体的提升和扭转的实验测试对模型进行了验证。实验结果表明，在输入压力为 10 kPa 的情况下，壳抓手可产生的最大提升力和扭转扭矩分别为 50.97 N 和 0.73 Nm。对各种食品和饮料产品的实验测试表明，该夹具可以处理可变形、重、不规则形状的物体，并实现任意操纵姿势和扭转运动。使用 SCARA 机器人，拾取和放置任务的节拍时间约为 2-5 秒；这个时间可以通过使用并联机器人进一步优化（小于 1 秒）。然而，由于向下的压力，夹持器无法处理低矮的物体；这被确定为拟议设计的限制。