The ‘Smellicopter’ drone sniffs its way around

There is considerable interest in developing drones that can detect chemicals in the air, locate survivors of disasters, gas leaks, explosives, narcotics, and other objects of interest. However, most human-made sensors are not sensitive or fast enough for these applications.

Engineers at the University of Washington worked around this by incorporating a live antenna from a moth to create a drone that can navigate to smells.

https://www.youtube.com/watch?v=8SGx2qmo9M4

“Nature really pulls our human-made odor sensors out of the water,” said mechanical engineer and doctoral candidate Melanie Anderson. “By using a real moth antenna with Smellicopter, we can get the best of both worlds – the sensitivity of a biological organism on a robotic platform where we can control its movement.”

Moths use their antennae to detect chemicals in their environment and navigate to food sources or potential mates: “Cells in a moth antenna amplify chemical signals. Moths do this really efficiently – one scent molecule can trigger a lot of cellular responses, and that’s the trick. This process is super efficient, specific and fast, ”said Professor Thomas Daniel, a biologist at the University of Washington.

The researchers used antennas from the falcon moth Manduca sexta; They placed live moths in the refrigerator to anesthetize them before removing an antenna. Once separated from the moth, the antenna remains biologically and chemically active for up to four hours.

The antenna was connected to a circuit so that the researchers could measure the average signal from their cells. They compared it to a typical human-made sensor by placing it in a wind tunnel and releasing various scents into the tunnel; the antenna reacted and recovered more quickly than the conventional sensor.

Then the antenna sensor was incorporated into an open source quadcopter drone platform that allows users to add custom functions, creating Smellicopter. Two plastic fins were attached to the rear of the drone to orient it upward during flight.

The researchers created a “launch and magnify” protocol for the drone that mimics how moths search for scents. Smellicopter begins by moving to the left for a specific distance. If nothing goes above a certain odor threshold, it moves to the right by the same distance. When it detects an odor, it changes its flight pattern to emerge towards the source.

Smellicopter is also capable of obstacle avoidance with the help of four infrared sensors, which scan its surroundings 10 times per second. When an object is 20cm from the drone, it changes direction, moving to the next stage of its launch and magnification protocol.

“So if Smellicopter was pitching left and now there’s an obstacle to the left, it will switch to pitching right,” Anderson said. “And if Smellicopter smells a smell but there is an obstacle in front of him, he will continue to dart left or right until he can move forward when there is no obstacle in his way.”

In laboratory tests, the drone naturally flew toward smells that moths find interesting, such as flower scents. However, the researchers hope that in the future it can be adapted to detect other aromas, such as carbon dioxide or the chemical signature of an unexploded device.

“Finding fountain pens is a perfect task for small robots like the Smellicopter,” said Professor Sawyer Fuller, a mechanical engineer. “Larger robots are capable of carrying a number of different sensors and using them to build a map of their world. We really can’t do that on a small scale. “

“But to find the source of a column, all a robot needs to do is avoid obstacles and stay on the column while moving against the wind. You don’t need a fancy sensor suite for that, you just need to be able to smell good. And that’s what the Smellicopter is really good for. “