Single Channel Soft Robotic Actuator Leveraging Switchable Strain-Limiting Structures for Deep-Sea Suction Sampling

Abstract

Soft Robotics has established itself as an integral field in the broader discipline of general robotics through multiple advantages like inherent safety, adaptable morphology, and energy- and weight efficiency. Especially in environments hostile to humans and classical robots like the deep sea, soft robotic structures made out of silicone and actuated by seawater have numerous advantages. An application with a huge scientific and commercial potential for soft robotic solutions is suction sampling for marine geology in depths of up to 6000 m. In this paper, we propose a single channel soft robotic actuator that is able to bend into six directions while absorbing process forces. By embedding a low melting point alloy (LMPA) acting as switchable strain-limiting structures, the actuator is capable of hexa-planar bending of up to 40° and elongation of 30 % with only one valve used for actuation. In addition, the LMPA chambers enable a stiffening factor of 4.1 and locking the actuator in its bending state for energy efficient usage in robotic deep-sea suction sampling.