Engineers at the Harvard John A. Paulson School of Engineering and Applied Science (SEAS) have developed an insect-sized robot than can swim and fly. The robot has been able to fly for some time, and recently the engineers implemented a flapping technique to give it swimming capabilities as well.
This led to the first-ever demonstration of a robot capable of aerial and aquatic movement. Taking inspiration from seabirds and the puffin, the engineers used theoretical, computational and experimental studies, to find that the only major difference between a puffin’s flying and swimming is the speed at which the wings move. Researchers applied this discovery to modify the flapping motion of the wings, giving it the ability to swim.
“Water is almost 1,000 times denser than air and would snap the wing off RoboBee if we didn’t adjust its snapping speed,” said co-author E. Farrell Helbling.
“Through various theoretical, computational and experimental studies, we found that the mechanics of flapping propulsion are actually very similar in air and in water,” said Kevin Chen, a graduate student in the Harvard Microrobotics Lab at SEAS. “In both cases, the wing is moving back and forth. The only difference is the speed at which the wing flaps.”
Smaller than a paper-clip, the RoboBee weighs 80-mg, is made up of laser-cut carbon fiber that is joined together by plastic to shape like a frame. The robot uses piezoelectric actuators to flap gossamer-looking plastic wings at the rate of 120 beats per second. The robot is powered by an external source through wire tether, and also for optimizing weight.
Initially, the lightweight factor posed a problem for researchers as it was not capable of diving into the water. Researchers then set up RoboBee at an angle above the surface of water and turned off the power, allowing it to dive into the water and swim. The water was also deionized, to prevent any short-circuit while the robot swims. Several improvements such as insulating the coating to protect electrical connections are being worked out. However, this demonstration has opened the possibility of flying and swimming insect-sized robots or larger flying submarines.