Hydraulically Actuated Soft Tubular Gripper

There is an increasing interest in soft robotic grippers as they exhibit an ability to grip objects of differing shapes, sizes, textures, and even deformable materials, all of which present a difficult challenge to traditional rigid grippers. An ideal soft gripper would exhibit universal gripping with high gripping force and consists of low-cost materials with simple fabrication processes. This paper investigates the development of a strong and scalable hydraulic soft tubular gripper (HSTG) using facile fabrication method and low-cost materials. The HSTG which consists of a single long hydraulically actuated artificial muscle, soft 3D printed element, and commercial weaving yarn can expand and contract its orifice to grasp objects using a miniature hydraulic syringe. Grasping experiments show that the new HSTG can successfully grasp convex, nonconvex, and flat objects as well as the ones with cavity. The soft gripper uniquely exhibits high normal contact force at minimal pressure and energy use due to the nature of its working principle. A 26 g HSTG can produce at least 40 N of gripping force, can hold at least 88 N in external gripping mode (~346 times of its weight), 0.34 N in internal mode, and 1.74 N in suction gripping mode. The design and mechanical properties of its components can be fine-tuned to produce tailored performance for different grasping tasks.