Researchers from Germany have successfully tested an air traffic management system which coordinated the flight of two drones around the Köhlbrand Bridge in Hamburg last month.
The City Air Traffic Management (City-ATM) project demonstrated the drones cooperating with one another around the bridge, amid active shipping and road traffic, while inspecting it for cracks.
The City-ATM project was conducted by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) and industrial and academic partners to provide a test scenario for the future use of drones in urban airspace.
The project’s leader Stefan Kern, from the DLR Institute of Flight Guidance, said, “Under highly realistic conditions we demonstrated how two camera drones can work in parallel – from flight planning to detection and identification, through to flight monitoring and conflict detection and avoidance.
“The use case of a bridge flight provided an ideal test scenario, as it required the drones to work together particularly closely and in a very dynamic way.”
It is anticipated that parcel-delivery drones, air taxis and uncrewed inspection aircraft will fly over cities and interact with one another in the future. They must be able to recognize and avoid one another, ideally before even taking off.
During the flight test, which was conducted during April, both drones flew along pre-set routes to the side of and underneath the Köhlbrand Bridge. Two of three drones available were in the air simultaneously.
The drones, which were provided by the DLR institutes of Flight Guidance, Flight Systems and Communications and Navigation, were equipped with telemetry and communications technology to enable the determination of their location and status. The equipment also facilitated the sharing of information between the drones and the control station.
Deutsche Flugsicherung (DFS), the company responsible for air traffic control in Germany, tracked the drone’s locations and provided an integrated air situation display. This continuous transmission of the drones’ locations gave the pilots at the control station a picture of the situation in the air, including any conflicts.
In addition to testing the overall system during several flights, the researchers also successfully demonstrated the detection of hairline cracks in the bridge.
The system developed for City-ATM involves several steps. First, the pilots and drones are electronically registered for take-off clearance and authenticated. At the same time, the flight missions are planned, taking spatial flight restrictions (geofences) into consideration.
Once the basic waypoint planning has been completed, this information is used to generate flightpaths. The system also takes account of the flight performance of the equipment, as well as local conditions and time constraints.
This allows potential conflicts to be identified before take-off. It is particularly important that drone flights covering large distances – as in the case of drones that fly out of the line of sight of those controlling them – should be able to detect and avoid other airspace users at an early stage.
The U-Fly ground control station for drones, belonging to the Institute of Flight Guidance, was used for the test flights.
The City-ATM system will be tested for other use cases until late 2020. The researchers will also investigate areas such as the optimal use of drones for rescue workers.
The flight testing was carried out in partnership with the Hamburg Port Authority (HPA) and the project partners NXP, KopterKraft OÜCity Air Traffic Management, FlyNex, DFS Deutsche Flugsicherung GmbH, and the Center of Applied Aeronautical Research (Zentrum für Angewandte Luftfahrtforschung GmbH; ZAL).