SerpApi.Org
A spinning drone that turns transparent as it rotates has been invented to provide less invasive wildlife monitoring.
Called the “Phantom Twist”, the machine exploits a quirk of human vision that blurs an object if it spins faster than the brain’s processing speed.
It is the same phenomenon that appears to make whirring fan blades vanish.
“The human eye takes time to accumulate signals, roughly analogous to the exposure time of a camera,” said Dr Emma Alexander, an assistant professor of computer science at Northwestern’s McCormick School of Engineering, in Illinois.
“When an object spins quickly, we perceive it as blurring out and losing distinct features.
“Because this new drone is almost entirely transparent, its few opaque components are visually averaged with the background for an overall appearance of a slight haze.”
Drones have become invaluable tools for reaching remote areas, and monitoring wildlife without the need for human intervention.
But animals notice them and their presence often causes changes to their behaviour, and sometimes prompts groups to scatter.
Researchers have been trying for years to create a drone that is camouflaged, using transparent materials or light-bending optical systems, but none have proved particularly successful.
The new design spins up to 25 times per second, which is too fast for the human eye to see clearly, morphing into a ghostly smudge that blends into the background.
Unlike a typical quadcopter with four separate rotors, Phantom Twist has one motor and one propeller. The propeller spins in one direction, and the rest of the drone spins in the opposite direction, turning it into a semi-transparent cloud rather than a distinct shape.
The drone is about 10 times less visually perceptible than a conventional quadcopter.
“Most efforts to hide drones focus on making them look like their surroundings,” said Dr Michael Rubenstein, who led the work.
“Instead, we asked whether we could design the drone itself around the way humans perceive motion. This idea of low visibility through persistent motion is something few people have explored.
“For a typical quad-rotor drone, the propellers are spinning, but the robot is stationary, so you still see its body. For our drone, the whole thing is rotating, so there are no stationary parts.”
To design the drone, the Northwestern team first used a computational model to generate roughly 20,000 drone configurations capable of stable flight, then determined the ideal placement of the components to minimise visibility.
After selecting promising candidates, the engineers simulated each drone spinning in flight and overlaid the images with a hundred real-world backgrounds, before using a human vision perception model to see how noticeable each was.
They then kept repeating the process, adjusting the components until the drone was as invisible as possible.
However, the new drone still has several limitations. The propeller makes noise, and the drone’s wires and support rods are still somewhat visible.
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Dr Rubenstein said his team plans to design future iterations with more transparent materials or quieter propulsion to make the Phantom Twist even less noticeable.
The drone was presented at the Robotics: Science and Systems 2026 in Sydney, Australia.
