Cyborg Smellicopter Drone navigates with a Reside Moth antenna
A big advantage of drones is that these little robots can reach places humans can’t live, including areas that may be too dangerous, like unstable structures after a natural disaster or an area with unexploded devices.
Researchers are keen to develop devices that can control these situations by detecting chemicals in the air to locate survivors from disasters, gas leaks, explosives, and more. Most man-made sensors, however, are not sensitive or fast enough to find and process certain smells as they fly through the mottled plumes of odor these sources create.
Now, a team led by the University of Washington has developed a smellicopter: an autonomous drone that uses a live antenna from a moth to navigate in the direction of smells. Smellicopter can also detect and avoid obstacles on its way through the air. The team published these results on October 1st in the journal IOP Bioinspiration & Biomimetics.
“Nature really blows our man-made odor sensors out of the water,” said lead author Melanie Anderson, a UW graduate student in mechanical engineering. “By using a moth antenna with a smellicopter, we can get the best of both worlds: the sensitivity of a biological organism on a robot platform on which we can control its movement.”
The moth uses its antennae to sense chemicals in its environment and to navigate to food sources or potential partners.
“Cells in a moth antenna amplify chemical signals,” said co-author Thomas Daniel, a UW professor of biology who supervised Anderson’s doctoral thesis. “The moths do this really efficiently – a scent molecule can trigger a lot of cellular reactions, and that’s the trick. This process is super efficient, specific and fast.”
The team used antennas from the Manduca sexta hawkmoth for smellicopters. The researchers put moths in the refrigerator to numb them before removing an antenna. Once separated from the living moth, the antenna remains biologically and chemically active for up to four hours. This time could be increased by storing the antennas in the refrigerator.
By adding tiny wires to either end of the antenna, the researchers were able to connect it to a circuit and measure the average signal from all the cells in the antenna. The team then compared it to a typical man-made sensor by placing both at one end of a wind tunnel and blowing scents that both sensors would respond to: a floral scent and ethanol, a type of alcohol. The antenna responded faster and took less time to recover between pulls.
To develop smellicopters, the team added the antenna sensor to a commercially available open-source quadcopter drone platform that allows users to add special functions. The researchers also added two plastic fins to the back of the drone to create drag so it can be constantly pointed against the wind.
“This is a genius from a robotics standpoint,” said co-author and consultant Sawyer Fuller, an UW assistant professor of mechanical engineering. “The classic approach in robotics is to add more sensors and possibly create a fancy algorithm or use machine learning to estimate wind direction. It turns out all you have to do is add a fin.”
Smellicopter doesn’t need any help from researchers to look for smells. The team created a “cast and surge” protocol for the drone, mimicking the way moths search for scents. Smellicopter begins its search by moving left for a certain distance. If nothing exceeds a certain odor threshold, the Smellicopter will move the same distance to the right. As soon as it detects an odor, it changes its flight pattern to approach it.
With the help of four infrared sensors, the Smellicopter can also avoid obstacles, with which it can measure what is around it ten times per second. If something is within about eight inches of the drone, it changes direction by moving on to the next stage of its cast and surge protocol.
“So if Smellicopter has thrown to the left and there is now an obstacle on the left, they switch to the right,” said Anderson. “And if the Smellicopter smells a smell but there is an obstacle in front of it, it will keep throwing to the left or right until it can shoot forward if there is no obstacle in its path.”
Another advantage of the smellicopter is that it doesn’t require GPS, the team said. Instead, it uses a camera to examine its surroundings, much like insects use their eyes. This makes smellicopters well suited for exploring indoor or underground spaces such as mines or pipes.
During the tests in the UW research laboratory, the Smellicopter was of course tuned to fly for smells that moths find interesting, such as B. floral fragrances. However, the researchers hope that in future work the moth antenna could sense other smells, such as the exhalation of carbon dioxide from someone trapped under rubble or the chemical signature of a device that has not exploded.
“Finding spring sources is a perfect job for small robots like the Smellicopter and the Robofly,” said Fuller. “Bigger robots are able to carry around a bunch of different sensors and use them to create a map of their world. We can’t really do that on a small scale. But to find the source of a cloud, a robot really needs everything to avoid obstacles and stay It in the cloud while moving against the wind. No sophisticated sensor suite is required – it just has to be able to smell good. And that is exactly what the smellicopter is really good at. “
Reference: Anderson MJ, Sullivan JG, Horiuchi T., Fuller SB, Daniel TL. A palm-sized, palm-sized, odor-controlled autonomous handheld vehicle. Bioinspir Biomim. 2020. doi: 10.1088 / 1748-3190 / abbd81
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