Stronger at Depth: Jamming Grippers as Deep Sea Sampling Tools

Abstract

Abstract-In this work we experimentally demonstrate (a) that the holding strength of universal jamming grippers increases as a function of the jamming pressure to greater than three atmospheres, and (b) that jamming grippers can be used for deep sea grasping tasks in ambient pressures exceeding one hundred atmospheres, where such high jamming pressures can be readily achieved. Laboratory experiments in a pressurized, water filled test cell are used to measure the holding force of a 'universal' style jamming gripper as a function of the pressure difference between internal membrane pressure and ambient pressure. Experiments at sea are used to demonstrate that jamming grippers can be installed on, and operated from, remotely operated vehicles (ROVs) at depths in excess of 1200m. In both experiments, the jamming gripper consists of a latex balloon filled with a mixture of fresh water and ~200 micron glass beads, which are cheaply available in large quantities as sand blasting media. The use of a liquid, rather than gas, as the fluid media allows operation of the gripper with a closed loop fluid system; jamming pressure is controlled with an electrically driven water hydraulic cylinder in the lab, and with an oil hydraulic driven large-bore water hydraulic cylinder at sea.

Soft Robotic Grippers

“…The universal jamming gripper has been applied to industrial environment, and several research applications have been demonstrated, such as in prosthetic, assembly tasks, and human‐robot cooperation, as well as integration with learning algorithms . Licht et al employed jamming gripper as an end effector of a remotely operated vehicle for deep sea sampling, and showed that the gripper was able to generate over 35 N of pulling force on a sample (stainless steel rod) at a depth of 1200 m (Figure c). When multiple granule‐filled bags are used as end effectors, granular jamming shows improved versatility to deal with an even larger variety of objects.…”

“…c) Holding force test in deep sea (1200 m depth). Reproduced with permission . Copyright 2017, Mary Ann Liebert.…”

Untethered soft robotics

“…Vacuums have also been employed to create strong contraction with minimal change in actuator radius 28 (Fig. 2a) and enable underwater gripping 29 .…”

An Underwater Robotic Manipulator with Soft Bladders and Compact Depth-Independent Actuation

“…Some efforts have been made to address the limitations, from a compact pneumatic system with chemical reactions (not applicable for underwater application) 30 to jamming grippers with ambient water pressure compensation for object picking with primitive dexterity. 31,32 In particular, an accumulator was made by Phillips et al 33 to both counter ambient pressure and increase the flow rate in the actuation level. A spring was used in the accumulator to hold ambient pressure and provide an increased flow rate.…”