Scientists have developed a vision-assisted navigation system which lets smaller aircraft land without assistance from ground-based systems. Automatic landings have long been standard procedure for commercial aircraft, said researchers at the Technical University of Munich (TUM) in Germany.
While major airports have the infrastructure necessary to ensure the safe navigation of the aircraft, this is usually not the case at smaller airports. At large airports, the Instrument Landing System (ILS) makes it possible for commercial aircraft to land automatically with great precision.
Antennas send radio signals to the autopilot to make sure it navigates to the runway safely. Procedures are also currently being developed that will allow automatic landing based on satellite navigation. A ground-based augmentation system is required, researchers said.
However, systems like these are not available for general aviation at smaller airports, which is a problem in case of poor visibility — then aircraft simply cannot fly, they said.
“Automatic landing is essential, especially in the context of the future role of aviation,” said Martin Kugler, a research associate at the TUM.
This applies for example when automated aircraft transport freight and when passengers use automated flying taxis. The researchers partnered with Technische Universitat Braunschweig in Germany to develop a landing system which lets smaller aircraft land without assistance from ground-based systems.
The autopilot uses global positioning system (GPS) signals to navigate. However, GPS signals are susceptible to measurement inaccuracies, for example, due to atmospheric disturbances.
The GPS receiver in the aircraft can’t always reliably detect such interferences. As a result, current GPS approach procedures require the pilots to take over control at an altitude of no less than 60 metres and land the aircraft manually.
In order to make completely automated landings possible, the team designed an optical reference system: A camera in the normal visible range and an infrared camera that can also provide data under conditions with poor visibility.
The researchers developed custom-tailored image processing software that lets the system determine where the aircraft is relative to the runway based on the camera data it receives.
The team developed the entire automatic control system of its research aircraft, a modified Diamond DA42. The aircraft is equipped with a Fly-by-Wire system enabling control by means of an advanced autopilot, researchers said.
In order to make automatic landings possible, additional functions were integrated with the software, such as comparison of data from the cameras with GPS signals, calculation of a virtual glide path for the landing approach as well as flight control for various phases of the approach.
In late May, the research aircraft made a completely automatic landing.
