Robotic "bees" are able dive in and out water, study reports

Researchers from Harvard have developed a robot that is able to both go underwater and come back out of the liquid without breaking.
By Jason Spencer | Oct 27, 2017
A group of scientists from Harvard University have developed a robotic "bee" that can fly, swim underwater, and then move back up into the air.

The machine -- which is apart of the latest generation of so-called RoboBees -- is a big breakthrough. Not only can it do things past models were not capable of, but it is 1,000 times lighter than any previous aerial-to-aquatic robot.

"This is the first microrobot capable of repeatedly moving in and through complex environments," explained lead author Yufeng Chen, a researcher at Harvard University, according to International Business Times. "We designed new mechanisms that allow the vehicle to directly transition from water to air, something that is beyond what nature can achieve in the insect world."

While the new design is effective, creating a robot that can move in and out of water is not easy. That is because water is 1,000 times more dense than air, which means the machine need to flap their wings at different speeds depending on which medium they are in. If they flap too slowly they will not be able to fly, but if their wings move too fast they will break while submerged.

In the study, the team used a combination of computer modelling and experimental data to get the robots to flap their wings between 9 and 13 hertz in water and 220 to 300 hertz in in the air.

Once that problem was solved, they next needed to design the machines in a way that would allow them to dive into water and bring themselves back out.

Past studies have shown that a powerful impact and sharp objects can help machines pierce through the surface of water. However, moving from the liquid -- which has a surface tension that is more than 10 times the weight of the robot and three times its maximum lift -- is a much more difficult process.

To overcome that, scientists fitted the RoboBee with four flotation devices and a special gas chamber filled with combustible fuel. The flotation devices first push the robot up to the surface so that its wings are out of water, and from there a spark ignites the gas to move it out the rest of the way.

"Because the RoboBee has a limited payload capacity, it cannot carry its own fuel, so we had to come up with a creative solution to exploit resources from the environment," said study co-author Elizabeth Helbling, a researcher at Harvard University, according to Tech Radar. "Surface tension is something that we have to overcome to get out of the water, but is also a tool that we can utilize during the gas collection process."

This new design allows the devices to lift more than three times the amount of past models. That enables them to carry the gas chamber, the sparker, and buoyant outriggers. While they are still in early testing, the team hopes the machines will have a wide range of applications across different fields. Not only could they be used forsearch-and-rescue operations, but they could aid environmental monitoring and biological studies as well.

The study is outlined in the journal Science Robotics.

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