The Butterfly Robot is the fastest swimming robot yet!

Inspired by the biomechanics of the manta ray, researchers at North Carolina State University have developed an energy-efficient soft robot that can swim more than four times faster than previous soft-swimming robots. The robots are called “butterfly robots,” because their swimming motion is similar to the way a person’s arms move when they swim the butterfly stroke.

“Until now, soft-swimming robots have not been able to swim faster than one body length per second, but marine animals—like the manta ray—are able to swim much faster, and with much greater efficiency,” says Ji Yin. Paper author and associate professor of mechanical and aerospace engineering at NC State. “We wanted to draw on the biomechanics of these animals to see if we could develop faster, more energy-efficient soft robots. The prototypes we’ve developed are doing very well.”

Researchers have developed two types of butterfly robots. One was built specifically for speed, and was capable of average velocities of 3.74 body lengths per second. The second is designed to be highly maneuverable, capable of making sharp turns to the right or left. This highly maneuverable prototype was capable of reaching speeds of 1.7 body lengths per second.

“Researchers who study aerodynamics and biomechanics use something called the Strohal number to evaluate the energy efficiency of flying and swimming animals,” says Yiding Qi, first author of the paper and a recent Ph.D. North Carolina State graduate. “Peak propulsion efficiency occurs when an animal is swimming or flying with a Strouhal number between 0.2 and 0.4. Both butterfly robots had Strouhal numbers in this range.”

Butterfly robots derive their swimming power from their wings, which are “distable,” meaning the wings have two stable states. The wing is similar to a sudden hair clip. The hair clip remains stable until you apply a certain amount of energy (by bending it). When the amount of energy reaches a critical point, the hair clip snaps into a different shape—which is also stable.

In butterfly robots, hair clip-inspired bistable wings are attached to a soft silicone body. Users control the switching between the two stable states of the wings by pumping air into the chambers inside the soft body. As these chambers swell and deflate, the body bends up and down – forcing the wings to flip back and forth with them.

“Most of the previous attempts to develop flapping robots focused on using motors to power the wings directly,” says Yin. “Our approach uses bi-stabilized wings that are passively actuated by moving the central body. This is an important distinction, as it allows for a streamlined design, which reduces weight.”

The faster butterfly robot has only one “drive unit” – the soft body – that controls both of its wings. This makes it very fast, but difficult to turn left or right. The maneuverable butterfly robot basically has two driving units, which are connected side by side. This design allows users to manipulate the wings on both sides, or “flap” just one wing, which enables it to make sharp turns.

“This work is an exciting proof-of-concept, but it has limitations,” says Yin. “Obviously, the current prototypes are constrained by thin tubes, which is what we use to pump air into the central bodies. We are currently developing an independent, unconstrained version.”

The paper, “Snapping the High-Speed, High-Efficiency Soft Swimmer, Similar to the Butterfly Stroke,” will be published November 18 in the open access journal Science advances. The paper was co-authored by Yaoye Hong, PhD. student at North Carolina State; and by Yao Zhao and Yanbin Li, two postdoctoral researchers at NC State. The work was done with support from the National Science Foundation under grants CMMI-2005374 and CMMI-2126072.

A video of the butterfly robots can be found at

Story source:

Materials Introduction of North Carolina State University. Original by Matt Shipman. Note: Content can be modified by style and length.

Source link

Related Posts