Limpet II: A Modular, Untethered Soft Robot

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 · 140mm 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.