3 hours ago
5
Engineers have designed an “invisible” drone that nearly disappears before the eye, by using a visual illusion rather than traditional camouflage.
Drones may offer photographers a bird’s-eye view, but they can also give away the shot. A drone filming a couple’s wedding day can make guests wave or freeze up, while one photographing nesting birds can unintentionally disrupt the very behavior it was sent to record.
For years, scientists have tried to design invisible drones and robots using camouflage, transparent materials, or light-bending optical systems. But instead, engineers at Northwestern University decided to focus on how people — and many animals — see drones. These researchers used a concept called “motion blur” — the same effect that makes fast-spinning fans and propellers seem to disappear — to create a drone that blurs itself into near-invisibility.
According to a news release by Northwestern University, the feature — called the “Phantom Twist ”– allows the drone to spin up to 25 times per second, which is too fast for the human eye to see clearly. While the drone isn’t completely invisible, it morphs into a ghostly smudge that seamlessly blends into the background.
“The human eye takes time to accumulate signals, roughly analogous to the exposure time of a camera,” Alexander, an expert in computer vision, says in a statement. “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.”
Whether monitoring nesting birds, surveying wetlands or inspecting aging infrastructure, drones often alter natural behavior simply because people or animals notice them. The disruption can cause wildlife to scatter and people to behave differently. The engineers believe that a drone that’s harder to see, on the other hand, could perform the same tasks while blending into its surroundings. The researchers hope their work eventually could lead to nearly-invisible drones that monitor wildlife, survey the environment, and inspect infrastructure with less visual disruption.
“Most efforts to hide drones focus on making them look like their surroundings,” Northwestern University’s Michael Rubenstein, who led the work, says. “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.”
However, the researchers note that their invisible drone still has several limitations. The propeller makes audible noise, and the drone’s wires and support rods are still somewhat visible. Rubenstein says his team plans to design future iterations with more transparent materials or quieter propulsion to make the Phantom Twist even less noticeable.
English (US) ·