FO-DIAS Project: an Overview and the Development Status

摘要

The navigation segment of the FO-DIAS avionics system and test results from a mobile test-rig are presented. The Aerospace Laboratories of the Forli (FO) branch of the University of Bologna, in collaboration with Italian Public Authorities and Industry, are developing a DGNSS Instrument Approach System (called FO-DIAS) following the MASPS of RTCA/DO-217 and RTCA/DO-245. In particular, FO-DIAS is devoted to General Aviation (GA) which, in the near future, is also supposed to comply, as Commercial Aviation does, with the Required Navigation Performance (RNP) of the DIAS MASPS. On the other hand, even if Inertial Reference Systems could easily augment the RNP continuity parameter of the system, nevertheless their cost for G.A. suggests to implement a cheaper Avionics Dead Reckoning (ADR) with inputs from the onboard Air Data System (ADS) and the Attitude and Heading Reference System (AHRS). Since the vertical channel is the most critical one as to accuracy integrity and continuity, an accurate baro-inertial channel has to be synthesized so that its altitude information can augment the DGNSS pseudorange information. As to the horizontal channel of the ADR, it is continuously updated, whenever the DGNSS solution is available, but it guaranties the continuity of the accuracy, in case the signal of some satellites or of DIAS ground station fails, by means of the True Airspeed Data (TAS) from the ADS. First test data taken on ground pathes simulating the approach profile show promising results. Obviously, before validating the whole concept further work is to be done to define the Airplane Integrity Monitoring (AIM) function and to test the system in flight.