An EGNOS Based Navigation System for Highly Reliable Aircraft Automatic Landing

This paper presents the CIRA’s flying test facility for autonomous mid-air flight and landing on runways instrumented by Differential Global Positioning System (DGPS) base station. The aim of the paper is to describe the facility used for testing auto-landing and mid-air flight algorithms, using many different sources to determine a hybrid position of the vehicle with high precision level. Highly precise navigation is the core technology required for many applications, such as automated aerial refuelling, sea-based joint precision approach and landing systems, station-keeping, unmanned aerial vehicles swarming and formation flight, and unmanned ground vehicles convoys. Current navigation efforts presented in literature are focused on carrier-phase differential global positioning system integrated with inertial measurement data, but it must to emphasize that this solution may not be sufficient in certain tactical environments and low-cost Inertial Measurement Units (IMU) may not be able to bridge GPS outages with sufficient accuracy. To overcome this problem, we decided to use additional sensors to improve the integrity and reliability of navigation solutions. The sensors we used are: two GPS, a laser altimeter, an AHRS (Attitude Heading Reference System), and an ADS (Air Data System). By using the above listed sensor measures in a sensor fusion algorithm, we obtained a high precision level in navigation measurements. In the paper, after described the on-board and on-ground architectures of our flight test facility, we present the sensor fusion algorithm we developed and, finally, we describe some results obtained in the validation stages, consisting in both off line simulations and in-flight testing, of the proposed algorithm.