“Right now GPS is the one ring to rule them all: Without it, tiny drones all the way up to commercial aircraft can’t do their jobs. It’s a huge liability,” said Christopher Lum, a UW research assistant professor of aeronautics and astronautics and the director of the Autonomous Flight Systems Laboratory. “Before GPS was widely used, pilots had myriad other techniques for navigation. Now we need to fall back to some of those older techniques to keep unmanned vehicles like drones in the air without GPS.”
The team’s unmanned drones carry transponders on board that send signals to operators and any surrounding aircraft about their whereabouts.
“A transponder is like Twitter for aircraft,” said Lum. “It blabs out information to anyone who’s listening, such as: ‘Here’s my GPS position, here’s my GPS position.’ Then everyone else knows where the aircraft is.”
If GPS is knocked out, the transponder doesn’t know its location, but it will still send signals. So the team used a large ground-based antenna array to pick up the signals and then triangulate the position of the aircraft.
“The ground station is smarter than the aircraft at that point,” said Lum. “We’re just modifying the autopilot onboard the aircraft. Instead of using GPS information to navigate, it’s listening to this message coming from the ground to figure out where it is.”
Welcome to drone day on the Adafruit blog. Every Monday we deliver the latest news, products and more from the Unmanned Aerial Vehicles (UAV), quadcopter and drone communities. Drones can be used for video & photography (dronies), civil applications, policing, farming, firefighting, military and non-military security work, such as surveillance of pipelines. Previous posts can be found via the #drone tag and our drone / UAV categories.
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