Scientists have invented RoboBees that fly and swim, and it’s the first time that tiny robots displaying this double propulsion have ever been created.
The design was achieved by a team of researchers at the Harvard Johnson A. Paulson School of Engineering and Applied Science Microbiotics Lab.
It was imagined after analyzing puffins, one of the few bird species that is capable of employing its wings in order to swim and fly also.
Normally, these types of transport are considered extremely difficult to combine, since they require different mechanisms.
More precisely, flying involves large sails or wings generating enough vertical lift to surpass the effects of gravity. In comparison, swimming requires a smaller surface area, as well as sufficient rear thrust in order to overcome water’s pulling force.
As researchers explain, after conducting several theoretical, experimental and computational studies, they determined that in fact propulsion by flapping occurs almost identically in water and air.
“In both cases, the wing is moving back and forth. The only difference is the speed at which the wing flaps”, explained Kevin Chen, study lead author.
Based on these findings, the researchers designed an upgraded version of RoboBees, which are miniature robots, at the dimensions of a common housefly.
Creating such lightweight and tiny robots has been an incredibly demanding and resource-intensive process. The RoboBees are smaller than a paper clip, so when they create the lift required for moving through the air, they aren’t massive enough to break the water’s surface tension.
Similarly, they can’t leave water without their wings breaking apart. While for now researchers are still working on allowing the microrobot to transition from water to air, a compromise solution was found to deal with the problem of crossing from air into water.
When the robot has to be submerged, it begins to hover at an angle, its flapping stops, and as gravity pulls it deeper into the water the flapping resumes again.
Moreover, the speed of its incredibly fragile and delicate wings varies according to the environment in which it has to move. For example, while in the air, the average speed is at 120 beats per second.
On the other hand, when the RoboBee has to cross distances while being covered by water, the velocity is reduced to a mere 9 beats per second, so as to account for the fact that this medium is around 1,000 times denser.
The fact that these insect-sized robots can move in two alternative ways, by flying and by swimming likewise, gives them much greater versatility, and might allow them to be used more broadly by scientists.
Tiny laser-operated sensors are being designed now to function as eyes for the robot bees, in order give them depth perception and allow them to determine the distance, size and shape of moving objects.
This remote sensing system is called a lidar (light detection and ranging), and is comparable to a radar, with the difference that it emits laser beams, not microwaves.
As researchers explain, the technology is actually similar to that employed when manufacturing autonomous vehicles, but it will be reduced to a miniature scale, resulting in a micro-lidar.
It is expected that in the future the design behind RoboBees will also be employed to create much larger “aerial-aquatic” robots. For now, the invention designed by Kevin Chen’s team was presented and critically acclaimed at the International Conference on Intelligent Robots and Systems in Germany.
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