Underwater Robot Moves Like an Eel
Matthew Greenwood posted on May 05, 2018 | | 942 views

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A team of engineers and marine biologists at the University of California, San Diego has created an eel-like robot that can swim silently in saltwater without using an electric motor—and it’s is virtually transparent.

The eel-bot uses the water to help generate the electrical forces it needs to move. The robot contains cables that apply voltage to both the saltwater it is immersed in and pouches of water inside its artificial muscles. The robot’s electronics deliver negative charges in the water and positive charges inside the robot to activate the device’s muscles.

The charges cause the muscles to bend, allowing the robot to swim in an undulating motion—much like its natural counterpart. The electrical discharge carries very little current and occurs in the water just outside the eel-bot’s surface, making it harmless to nearby aquatic life.

Previous efforts by other researchers used similar technology but relied on materials that needed to be held in constant tension by semirigid frames. The eel-bot, however, does not require such frames. “Our biggest breakthrough was the idea of using the environment as part of our design,” said Michael T. Tolley, professor or mechanical engineering at the Jacobs School of Engineering at UC San Diego.

The robot’s designers say it provides an important step toward developing soft robots that can swim alongside sea creatures without scaring them away or harming them with a noisy and dangerous propeller—allowing scientists to observe and study sea life in more detail. "It's really hard to sneak up on a fish, especially if you're a robot," said Caleb Christianson, one of the robot’s developers.

The robot has been tested inside saltwater tanks containing jellyfish, coral and fish in Tolley’s lab and at the Birch Aquarium at the Scripps Institution of Oceanography at UC San Diego. The development team knows that more work is needed: its next objective is to improve the robot’s reliability and geometry. The team also needs to improve ballast, equipping the robot with weights that will allow it to dive deeper. In addition, researchers plan to design and build a head that could house a variety of sensors. The conductive chambers within the robot’s artificial muscles could also be loaded with fluorescent dyes, which could be used to transmit signals.

Eventually, researchers could potentially use these soft and stealthy robots to study the marine environment at a much greater level of detail than is currently possible.

To see other ocean research robots, check out Underwater Drone Fits in a Backpack.

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