The manta ray’s biomechanics inspired researchers to develop an energy-efficient soft robot that can swim 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.
“Even today, Soft swim bots They weren’t able to swim faster than one body length per second, but marine animals — such as manta rays — are able to swim much faster, and with greater efficiency, says corresponding study author Ji Yin, associate professor of mechanics and aerospace engineering at Carolina State University. North.
“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 developed are doing very well.”
Researchers have developed two types of butterfly robots. One, specifically designed for speed, was capable of reaching average velocities of 3.74 body lengths per second. The second is designed to be highly maneuverable and 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 first author Yiding Qi, a recent PhD graduate from NC State. Peak propulsion efficiency occurs when an animal is swimming or flying with a Strohal number between 0.2 and 0.4. Both butterfly bots had Strohal numbers in this range.”
Butterfly robots derive their swimming power from their wings, and they are “Bistable,” which means that wings have two stable states. A wing is similar to a snapped hair clip. A 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, too stable.
In butterfly robots, hair clip-inspired bistable wings are attached to a soft silicone body. Users control the switching between the two steady states in the wings by pumping air into the chambers inside smooth. As these chambers inflate 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 Robots flutter They focused on using actuators to directly provide power to the wings,” Yin says. “Our approach uses bistable wings that are actuated passively by moving the central body. This is an important distinction, as it allows for a streamlined design that reduces weight.”
The faster butterfly robot has a single “command 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 a standalone, unconstrained version.”
The paper appears in the journal Science advances.
The National Science Foundation funded the work.
source: North Carolina State
#Butterfly #Bot #swims #times #faster #previous #bots