Soft-shell robot uses snailfish features to sail though Mariana Trench stress test

Deep sea submersible may help humans explore deepest oceans

Researchers in China have developed flexible submersible robots that experts say might one day help humans reveal the secrets to unexplored depths of the Earth's vast oceans.

Using flexible materials such as silicone, embedded and distributed electronic controls, and a bio-mimicking propulsions system, Zhejiang University professor Tiefeng Li and his colleagues have shown how engineers might overcome the limitations of rigid robots in deep sea research.

Published in Nature this week, the study shows soft machines were able to operate in the famous Mariana Trench at a depth of 10,900m, further under the ocean's surface than the peak of Mount Everest is above it.

Youtube Video

Under pressure

Rigid robots in underwater environments struggle to withstand ever-increasing stress the further down they go. Their conventional control systems need to be encased and protected from pressures of more than a thousand times standard atmospheric pressure at sea level. They require watertight enclosures made of metallic materials the thickness and dimensions of which need to increase to cope with greater depths.

“To explore depths ranging between 3,000m and 11,000m, rigid robots and machines require pressure vessels or pressure-compensated systems. However, deep-sea exploration remains challenging, given the risk of structural failure under extreme conditions,” the researchers said.

Youtube Video

Instead of engaging in this war of attrition against the elements, the research team took inspiration from nature.

“Soft-bodied organisms living at medium ocean depths [of more than 1,000m] such as octopuses and jellyfish, have been widely studied; their adaptability has inspired the design of underwater soft robots. Elegant soft robot designs present promising approaches to deep-sea exploration,” the paper – "Self-powered soft robot in the Mariana Trench" – said.

In particular, the researchers looked at how evolution had solved the thorny control system problem in the hadal snailfish, which has recently been discovered at ocean depths around 8,000m. Its body features a distributed, partly open skull and flapping pectoral fins, both of which guided the mechanical design of the researchers’ deep-sea soft robot with onboard power, control and dielectric elastomer actuators.

Hence, in the deep sea floppy bot, the electronics, including a battery, a micro-control unit and a voltage amplifier, are encapsulated in a matrix within a polymer. “If the electronic components are densely packed together on a single printed circuit board, pressure tests indicate that failures occur at their interfaces,” the research paper said.

The soft robot next to the snailfish that inspired its construction. Pic: Nature

The soft robot next to the snailfish that inspired its construction. Pic: Nature

To enhance the pressure resilience, the boffins mitigated the shear stress by using a decentralised design in which the components were wire-connected with or separated onto several smaller printed circuits. They also detached the transformer from the circuit board, and increased the distance between microchips by removing of direct rigid contacts among electronic components.

Meanwhile, for propulsion, the fins are attached to artificial muscles which are made of a soft material that converts electrical energy into mechanical work. Tiny solid structures mechanically connect the contracting muscles to the fins, making them flap.

Results from lab tests showed the stresses, under the same pressure on the components was much less than in the centralised, rigid robot design.

The robot was successfully tested in the South China Sea, where it free-swam by flapping locomotion. It also came through tests in the Mariana Trench where it was tethered to a conventional underwater robot, which also took images of the mission.

It's not exactly fast though, swimming at roughly 5cm per second.

Still, the remarkable progress in robot design for extreme underwater environments could help reveal more of this largely unexplored expanse of Earth. The number of people that have descended to the Mariana Trench can be counted on one hand, fewer than have stepped on the Moon.

In an accompanying article, professor Cecilia Laschi of the Department of Mechanical Engineering at the National University of Singapore, and Marcello Calisti, senior lecturer at the University of Lincoln in the UK, said: “Li and co-workers’ research now pushes the boundaries of what can be achieved: the replacement of rigid protective enclosures for electronic components by distributed electronics embedded in a soft material paves the way to a new generation of deep-sea explorers.”

Such robots could “help researchers to explore the vast uncharted depths of the oceans,” the commentators said.

But clearly work needs to be done on the robot’s speed. It could not withstand sizeable disturbances and could easily be swept away by underwater currents. ®

Similar topics

Other stories you might like

  • Experts: AI should be recognized as inventors in patent law
    Plus: Police release deepfake of murdered teen in cold case, and more

    In-brief Governments around the world should pass intellectual property laws that grant rights to AI systems, two academics at the University of New South Wales in Australia argued.

    Alexandra George, and Toby Walsh, professors of law and AI, respectively, believe failing to recognize machines as inventors could have long-lasting impacts on economies and societies. 

    "If courts and governments decide that AI-made inventions cannot be patented, the implications could be huge," they wrote in a comment article published in Nature. "Funders and businesses would be less incentivized to pursue useful research using AI inventors when a return on their investment could be limited. Society could miss out on the development of worthwhile and life-saving inventions."

    Continue reading
  • Declassified and released: More secret files on US govt's emergency doomsday powers
    Nuke incoming? Quick break out the plans for rationing, censorship, property seizures, and more

    More papers describing the orders and messages the US President can issue in the event of apocalyptic crises, such as a devastating nuclear attack, have been declassified and released for all to see.

    These government files are part of a larger collection of records that discuss the nature, reach, and use of secret Presidential Emergency Action Documents: these are executive orders, announcements, and statements to Congress that are all ready to sign and send out as soon as a doomsday scenario occurs. PEADs are supposed to give America's commander-in-chief immediate extraordinary powers to overcome extraordinary events.

    PEADs have never been declassified or revealed before. They remain hush-hush, and their exact details are not publicly known.

    Continue reading
  • Stolen university credentials up for sale by Russian crooks, FBI warns
    Forget dark-web souks, thousands of these are already being traded on public bazaars

    Russian crooks are selling network credentials and virtual private network access for a "multitude" of US universities and colleges on criminal marketplaces, according to the FBI.

    According to a warning issued on Thursday, these stolen credentials sell for thousands of dollars on both dark web and public internet forums, and could lead to subsequent cyberattacks against individual employees or the schools themselves.

    "The exposure of usernames and passwords can lead to brute force credential stuffing computer network attacks, whereby attackers attempt logins across various internet sites or exploit them for subsequent cyber attacks as criminal actors take advantage of users recycling the same credentials across multiple accounts, internet sites, and services," the Feds' alert [PDF] said.

    Continue reading

Biting the hand that feeds IT © 1998–2022