New automatic aircraft landing system passes its first test
Ironing out the glitches with GPS negates the need for ground support. Nick Carne reports.
German researchers have demonstrated an automatic landing system for aircraft that they say works without the need for ground-based support systems.
If they’re right, it could change life in the air – or, more accurately, coming down from the air.
Automatic landings are standard procedure at major airports, which have an Instrument Landing System (ILS) to ensure safe navigation. Smaller airports usually aren’t so well equipped, however, which can be a problem in adverse conditions.
"Automatic landing is essential, especially in the context of the future role of aviation," says Martin Kügler, the Chair of Flight System Dynamics at Technische Universität München (TUM).
As part of a project called C2Land, researchers from TUM and Technische Universität Braunschweig (TUB) developed an autopilot system that effectively navigates using GPS.
To do that, they say, they first had to overcome the problem that GPS signals are susceptible to measurement inaccuracies; as such, a GPS receiver in an aircraft can't always reliably detect atmospheric disturbances, for example.
That means, they add, that until now pilots using GPS have had to take over control at an altitude of no less than 60 metres and land the aircraft manually.To address this, a TUB 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 – and 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 TUM team then developed the entire automatic control system for its own research aircraft, a modified Diamond DA42, which is equipped with a fly-by-wire system enabling control by means of an advanced autopilot.
To make automatic landings possible, other functions were integrated into 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.
And it appears to work. Writing in the journal ION, the researchers report that the aircraft successfully made a completely automatic landing during a test flight back in May.
"The cameras already recognise the runway at a great distance from the airport,” says pilot Thomas Wimmer. “The system then guides the aircraft through the landing approach on a completely automatic basis and lands it precisely on the runway's centreline."