Drones Stick the Landing on Rolling Runways

Every aspect of a drone, from its control system to its landing gear, is designed to provide a soft and smooth landing — as long as the landing area is flat and level and the winds are calm, that is. If these conditions are not met, then all bets are off. Very often these conditions cannot be guaranteed, which is why nearly half of all drone accidents have been shown to occur during landing.

Given how finicky these aerial vehicles are about landing conditions, you certainly wouldn’t want to rock the boat too much and do something wild, like try to land one on the back of a moving truck. But that is exactly what a trio of engineers at the Université de Sherbrooke set out to do. Given the short battery life of most drones, deploying them from vehicles is a great way to extend their range. They can be driven long distances, only taking to the air when a target is nearby. However, until now, that was very difficult to do.

The team developed an approach that makes it possible to consistently land a quadcopter drone on a vehicle moving at high speed. Their method takes advantage of some rapid changes in pitch — at exactly the right moment — and a novel type of landing gear to safely land on the back of a truck at around 70 miles per hour.

The system, called DART (Direct Approach Rapid Touchdown), rethinks how drones approach the final moments of flight. Traditional drones rely on slow, steady descents and gentle contact with the ground. But that strategy doesn’t work when the landing surface is in motion, especially at highway speeds. DART instead embraces an aggressive, fast approach. The drone dives toward its target, minimizing exposure to turbulence and wind gusts. Then, just before impact, it performs a rapid leveling maneuver that straightens its orientation and aligns it with the surface of the vehicle.

This might sound like a recipe for disaster, but a few tricks keep the drone from bouncing onto the highway. The researchers designed friction shock absorbers (FSAs) that can instantly dissipate the energy of impact, preventing the drone from bouncing or flipping when it hits the moving platform. Simultaneously, the drone’s motors reverse direction to create reverse thrust, pushing it firmly onto the vehicle’s surface.

During testing, a DART drone successfully performed 38 consecutive landings on the flatbed of a pickup truck traveling at speeds up to 68 miles per hour. According to the team, this performance expanded the touchdown envelope (the range of conditions in which a drone can safely land) by a factor of 60 compared to a standard quadcopter. The combination of FSAs and reverse thrust also made the drone far more tolerant of timing errors, pitch angles, and unpredictable environmental factors such as wind gusts or road bumps.

A drone that can land on a fast-moving vehicle opens the door to new mission profiles, such as drones that deploy from and return to moving trucks, ships, or emergency vehicles. With DART, applications like package delivery, military reconnaissance, and search-and-rescue operations may never be the same.