Limpet II: A Modular, Untethered Soft Robot

Abstract

The ability to navigate complex unstructured environments and carry out inspection tasks requires robots to be capable of climbing inclined surfaces and to be equipped with a sensor payload. These features are desirable for robots that are used to inspect and monitor offshore energy platforms. Existing climbing robots mostly use rigid actuators, and robots that use soft actuators are not fully untethered yet. Another major problem with current climbing robots is that they are not built in a modular fashion, which makes it harder to adapt the system to new tasks, to repair the system, and to replace and reconfigure modules. This work presents a 450 g and a 250 • 250 • 140 mm modular, untethered hybrid hard/soft robot-Limpet II. The Limpet II uses a hybrid electromagnetic module as its core module to allow adhesion and locomotion capabilities. The adhesion capability is based on negative pressure adhesion utilizing suction cups. The locomotion capability is based on slip-stick locomotion. The Limpet II also has a sensor payload with nine different sensing modalities, which can be used to inspect and monitor offshore structures and the conditions surrounding them. Since the Limpet II is designed as a modular system, the modules can be reconfigured to achieve multiple tasks. To demonstrate its potential for inspection of offshore platforms, we show that the Limpet II is capable of responding to different sensory inputs, repositioning itself within its environment, adhering to structures made of different materials, and climbing inclined surfaces.

Soft Robots for Ocean Exploration and Offshore Operations: A Perspective

“…Evidence that these strategies represent viable solutions is the extensive work performed on compliant, tendon-driven manipulators capable of performing robust and firm grasp with minimal actuation [134][135][136][137] and by recent work on advanced adhesion technologies. [138][139][140] The performances of reversible adhesive systems suitable for operating on wetted and irregular surfaces are improving remarkably, and as suction forces in the order of 300 kPa become achievable, 141 the chance to use these technologies to enable soft robots to work in the wave slamming region of an offshore platform becomes a reality.…”

Soft Lattice Modules that Behave Independently and Collectively

“…The "Click-e-bricks" components [16] are reminiscent of plastic brick toys which are constructed and then glued together with additional elastomer. The Limpet II [23] is described as modular, but this term is used to describe interchangeable components, such as sensors or actuators, and not that the individual robots work together as a collective. The Omniskins Prior "robotic skins" (or omniskins) [2] are described as modular, but are better understood as reconfigurable components that afford new shapes than they are as collective robot swarms that can link together.…”

Propaedeutic Study of Biocomposites Obtained With Natural Fibers for Oceanographic Observing Platforms

“…Perhaps the most appealing field for biodegradable materials is soft robotics, i.e., a field of robotics that raised significant interest among scientists in the last 20 years (Trivedi et al, 2008). Among many of the applications of soft robots there are offshore operations (Sayed et al, 2018(Sayed et al, , 2021 and ocean exploration (Aracri et al, 2021), which both entail a significant risk of losing the device performing the task. More specifically, elastomers such as Ecoflex TM 00-30 are widely used in aquatic soft robotics (Giorgio-Serchi and Weymouth, 2017;Armanini et al, 2021;Bujard et al, 2021), because they have a density very close to that of water and an elasticity vaguely similar to that of living tissue.…”