Naval Research Laboratory is teaching drones to use thermals to soar like birds

Everyone reading this has likely seen birds soaring at some point or other, effortlessly moving through the air without flapping their wings. Unlike regular gliding, which gradually results in a bird losing altitude, soaring represents a special type of gliding in which birds fly on rising air currents, known as thermals.

Dr. Dan Edwards of the U.S. Naval Research Laboratory is also familiar with this type of energy-efficient locomotion. He has been fascinated by it since he was in college.

“I was studying autopilots and was hanging out with some of my friends from the robotics club,” Edwards told Digital Trends. “I can’t remember who said it, but someone raised the question of whether it would be possible to catch thermals using an autopilot. That got me thinking.”

Jump forward in time, Edwards and a team of researchers are the brains behind some smart software called ALOFT, short for Autonomous Locator of Thermals. Its goal is to allow unmanned sailplanes to fly for longer than previously thought possible by using algorithms to locate thermals to surf.

“What they’re doing is finding updrafts to keep these autopilots aloft,” Edwards said. “It’s solving the question of how you program an autopilot to be able to emulate a soaring bird’s behavior to increase the endurance of unmanned vehicles.”

The ALOFT system uses sensors already built into aircraft for measuring information related to airspeed, altitude, GPS and other data. It then logs data whenever it senses the plane getting a lift from rising air currents and based on what is called a “nonlinear curve fit,” figures out the GPS points for where it thinks thermals are located. The autopilot then attempts to hitch a ride on these thermals.

“For autonomous soaring, the goal is to be able to fly for longer while using the same amount of battery or fuel — or to be able to redirect that power to do something else instead,” Edwards said.

While early flights using the ALOFT software proved a success, what is even more exciting is the current direction of the project, which aims to get multiple unmanned aerial vehicles sharing information with one another.

“We’ve created cooperative soaring, during which a number of aircraft all do their own localized sensing and then share their data with the others,” Edwards said. “Just like a flock of birds, each bird is independent, but they will also look at their neighbors to find the best thermals for soaring.”

Going forward, Edwards told us he hoped ALOFT may be incorporated into a growing number of autopilot systems. “What we’re doing at the Naval Research Lab is carrying out research that can then transition out to the wider world,” he said. “I think it would be really interesting to get this technology out to industry for both civilian and military uses.”

Given the continued concern about drone battery life, we cannot help but think his research will be gratefully received.