Researchers have been trying to make invisible drones and camouflaged robots for years; before that, it was cars and planes. They have used everything from transparent materials to light-bending optical systems or cloaks, but haven't been able to make it happen.
But now, engineers at Northwestern University have created a drone that appears to vanish in plain sight after it takes flight.
The team created the Phantom Twist, a drone that uses a concept called "motion blur" — the effect that makes fast-spinning fans and propellers look like a ghostly smudge.
The drone spins up to 25 times per second, which is too fast for the human eye to see clearly. While it isn’t completely invisible, it appears to seamlessly blend into the background. The work could lead to drones that monitor wildlife, survey the environment and inspect infrastructure with less visual disruption.
To design the drone, the engineers first used a computational model to generate some 20,000 drone configurations capable of stable flight. Next, they used AI and optimization algorithms to rearrange the drones’ major components, including a motor, propeller, circuit board, counterweight and batteries. It was the algorithms that determined the ideal placement of the drone’s components to minimize its visibility from virtually every viewing angle while allowing for stable flight.
Northwestern’s Michael Rubenstein, who led the project, said, "The design process was fully automated ... Then, when we were confident that a drone met all our criteria, we built it."
According to the visibility metric, the optimized drone is about 10 times less visually perceptible than a conventional quadcopter.
The new drone still has several limitations. For example, the propeller still makes noise, and some wires and support rods are still somewhat visible. Next, the team is working on new iterations with more transparent materials or quieter propulsion to make the Phantom Twist truly disappear.
