A team from the University of California has developed an eel-like robot capable of exploring the deep, operating in salt water, and silently propelling itself using artificial muscles.
The foot-long robot also looks the part. Because it’s connected via tether to an electronics board above the surface, its body is thin and translucent, rather than full of components.
Exploring in silence
Following in the wake of a similar marine robotics project from MIT’s CSAIL lab – which disguised an underwater camera as a robotic fish – the University of California team is seeking to find a solution to a problem that marine biologists have grappled with for years. Namely, how to monitor the deep and gather data without disturbing, damaging, or disrupting the ecosystem.
Detailing their work in the April 25 issue of Science Robotics, the researchers point out that the majority of scientific underwater vessels are closer to submarines in nature, with rigid structures and electric motors that ensure they are heard coming.
Their alternative is a soft robot that can swim in complete silence.
Powered by the environment
“Instead of propellers, our robot uses soft artificial muscles to move like an eel underwater without making any sound,” said Caleb Christianson, a Ph.D. student at the Jacobs School of Engineering at UC San Diego.
The robot eel is able to do that by using the salt water in which it swims to generate enough electrical force to push it forwards.
Cables apply an electric current to the salt water around the robot eel, as well as to pouches of water inside its artificial muscles. Electronics inside the robot then push a negative charge through the water outside and positive charges through its internal pouches. The result is power, activating the eel’s artificial muscles.
The electrical charges cause the robot’s muscles to bend one way then the other, enough for the eel to glide along underwater.
“Our biggest breakthrough was the idea of using the environment as part of our design,” said Michael T Tolley, the paper’s corresponding author and a professor of mechanical engineering at the Jacobs School at UC San Diego. “There will be more steps to creating an efficient, practical, untethered eel robot, but at this point we have proven that it is possible.”
“This is, in a way, the softest robot to be developed for underwater exploration,” he added.
The next stage for the research team will be to improve the eel’s ballast so that it can dive deeper. They have also been experimenting with fluorescent dye, loading it into the eel’s internal chambers as a prelude to an underwater communication system.
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While aerial robotics tends to grab the headlines, alongside humanoid and industrial models and autonomous transport, marine robotics is a thriving area. Among the many applications are environmental monitoring, extreme-weather mapping, tidal studies – to predict the movement of plastic waste, for example – and the surveillance and repair of remote installations.
But with the marine environment – on the surface or beneath it – comes a range of additional challenges, such as the need to protect the natural ecosystem from the machines. This forces researchers to get creative with power sources and materials, as this university project has done. An impressive achievement, with more to follow, no doubt.