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This robotic manta ray may speed underwater search and rescue

The underwater bot can swim for up to 10 hours.
by Denise Chow /
Image: MantaDroid
MantaDroidNational University of Singapore
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Manta rays are some of the sea’s most graceful creatures, capable of gliding almost effortlessly and able to swim efficiently even in turbulent water. Now, researchers at the National University of Singapore have created a robot that mimics the manta.

Dubbed “MantaDroid,” the cute little bot is about 14 inches long and 25 inches wide and weighs 1.5 pounds. Using its pair of flexible pectoral fins, each powered by a single electric motor, it’s able to swim for up to 10 hours.

“Manta rays are known to be extremely efficient swimmers,” Chew Chee Meng, an associate professor in the university’s department of mechanical engineering, told NBC News MACH in an email. “We wanted to explore an alternative solution to traditional propeller-based thrusters that are used by most autonomous underwater vehicles.”

The robot could be used for search and rescue operations, as well as to perform underwater surveys and inspections, like those conducted by environmental groups. It could even be deployed in swarms for faster, more efficient searches and surveys, according to the researchers.

The engineers spent two years testing 40 different fin designs, aiming to recreate how real-life manta rays thrust forward by flapping their fins to drive water backwards. They say the MantaDroid achieved “good maneuverability” when tested in a pool. The bot was able to swim at a top speed of 2.3 feet per second — equivalent to almost 1.6 miles per hour.

Like its real-life counterpart, the MantaDroid has a wide, flat body, which means it could be equipped with multiple sensors on its “belly.” And the fins seem to have big benefits over propellers, Meng said. In addition to being less likely to get tangled in aquatic plants, they cause less turbulence than props.

“As a whole, MantaDroid tends to have less environmental impacts on marine ecosystems,” Meng said.

Meng and his colleagues want to test the MantaDroid in a marine environment to study its swimming ability at various depths, and to gauge its ability to handle currents.

The engineers are also working to make the bot autonomous.

“We plan to incorporate sensors and implement perception algorithms on the current prototype to make MantaDroid autonomous after we have completed the maneuverability study and design optimization,” Meng said.

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