A new aquatic robot inspired by Manta rays has broken the world record for the fastest swimming soft robot. The robot, designed by a team of engineers from North Carolina State University and the University of Virginia, was able to reach speeds of 6.8 body lengths per second. That comes out to a swim speed of 156.4 mm per second or about 0.35 mph. That time blows past the previous record of 3.74 body lengths per second record previously set by the same researchers. Researchers behind the machine, who published their findings today in Science Advances, told Popular Science the new design could be useful for future deep-sea exploration efforts.
The researchers initially set out to create a soft, aquatic robot that was simultaneously fast, energy efficient, and highly maneuverable. As is often the case, they looked to nature for inspiration. Though one might initially think to model such a design of a Marlin or other notoriously fast fish, the researchers were instead drawn to Mana rays and, in particular, their unique “wing-like pectoral fins.”
North Carolina State PhD student and Paper co-author Haitao Qing told Popular Science he is fascinated by the ways rays and other marine animals propel themselves with remarkable energy efficiency. Their natural biological designs, in his view, seem “inherently optimized” for tasks like navigating through unstructured environments, an ability traditional rigid robots typically struggle with. After observing the animal further, Qing realized its elegant flapping motions and swimming patterns “aligns perfectly with the goals of soft robotics.”
“Manta rays became a natural source of inspiration because of their unique swimming mechanics, which combine efficiency, speed, and maneuverability,” Qing said. “Their wing-like pectoral fins generate oscillatory motions that are not only graceful but also highly effective for propulsion, allowing them to glide effortlessly through water surface and underwater.”
Video: Researchers designed a soft-bodied robot with flapping fins that spontaneously snap back to their initial state. Credit: Haitao Qing, North Carolina State University
Two flaps for the price of one
Armed with that inspiration, the researchers designed a swimming robot made out of a flexible silicone body with flexible finds that resemble those found on rays. This new robot, building off of the team’s previous design, introduced what Qing calls a “monostable snapping mechanism.” Previously, researchers would have to pump compressed air into the robot’s body to make its wings flap in both directions. This new approach would still require air to flap the wings at once but then they would passively snack back on the robot’s recovery stroke. The result: a simpler, more energy-efficient robot swimmer.
“This simplification enhanced energy efficiency, reduced mechanical complexity, and increased overall swimming speed,” Qing said.
[Related: Why animals run faster than their robot doppelgängers… for now]
The researchers refined the robot’s wing design from past versions with a new geometry that Qing says achieved a better overall balance of speed and efficiency. They similarly switched to a single-input pneumatic system which helped make the robot easier to control and more adaptable to potential changes in its environment. They also adjusted the buoyancy of the robot so that it could swim both near the water’s surface and deeper down.
Manta ray robots could explore oceans and survey marine life
The researchers navigated their soft swimmer through two underwater obstacle courses, one near the surface and one towards the bottom of a water tank. One of the researchers remotely controlled the robot, guiding it and adjusting the amount of times its wings flapped using the pneumatic control system. The Manta ray design helped the robot swim past obstacles in the course and do it in a world record-breaking time for a soft-bodied robot. Now, according to a statement from North Carolina State University student Jie Yin, the team is looking into improving the robot’s lateral movement and adding new models of actuation to propel it forward.
“Our goal is to do this with a design that retains that elegant simplicity,” Yin said.
The real beauty of the robot’s design,’ Qing said, rests on its simplicity. Looking to the future, he could see real-world scenarios where researchers use swimming robots with this streamlined locomotion for prolonged deep-sea exploration, underwater marine surveillance, or even to monitor water quality levels for signs of pollution and environmental changes. There’s nothing necessarily limiting this design to oceans either. Qing said a similar flapping wing approach could also potentially be applied to robots operating in the land and in the air.
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