UAV achieves full-speed autonomous landing

In the most critical phase of the landing maneuver, the UAV flight control system must compensate for the accelerated air flow above the ground vehicle. (Photo: DLR)

Moving at 75 kilometers an hour (47 mph) an unmanned, electric, autonomous aircraft settled gently on the roof of a moving car.

Scientists from the German Aerospace Center (DLR) Institute of Robotics and Mechatronics combined robotics and unmanned aerial vehicles (UAVs) to develop a system where a fixed-wing aircraft automatically lands on a moving ground vehicle.

The DLR system is designed for commercial applications such as remote sensing and communication. It could be applied to ultra-lightweight solar aircraft that complement traditional satellite systems in the stratosphere. Or, it could support crisis management, such as aiding disaster-communications networks or providing data on climate change.

Losing weight

Ultralight solar aircraft can reach more than 20 kilometers in altitude. The weight factor is crucial to how long the ultralight can stay in the air.

The Demonstrator Platform Penguin BE UAV is equipped with redundnant landing hardware. (Photo: DLR)

By omitting the traditional landing gear, the dead weight of these UAVs can be significantly reduced. This allows more load capacity, greater range and better performance. A lighter craft also increases payload capacity, creating more space for scientific instruments.

In flight tests on an airfield in Swabia Mindelheim-Mattsies, the DLR system was successfully tested with a 3-meter, 20-kilogram, electric fixed-wing UAV. A net was provided on the roof of a car, along with optical markers. The UAV can position itself up to half a meter over the 4 x 5 meter landing platform. The optical multi-marker tracking system detects the landing apparatus and determines the relative position of the ground vehicle with high accuracy. The computer-controlled landing is then carried out.

Movement of UAV and the vehicle are adjusted with the help of special algorithms. With the car and the UAV moving at the same speed, the landing is more like a settling, making the landing safer and easier. Though designed for both autonomous car and UAV, a driver remained in the car for safety during the tests. A robotic vehicle without a driver will be tested next.

The work was supported by the EU project EC-Safe Mobile Support and complement the activities of the Flight Robotics Group.

In the semi-autonomous landing vehicle, the driver receives control commands via a graphical display. The crosshairs indicate the location of the UAV. (Photo: DLR)