Barometer-free Aircraft Terrain-aided Navigation System: Prototype Design and Flight-Test Validation

This paper deals with terrain-aided navigation (TAN) for aircraft. In particular, the radar-altimeter-based TAN (RATAN) recently developed by Honeywell laboratories is described and validated. The RATAN fuses data from inertial measurement unit, radar altimeter, and map, only, using a robust state estimator based the point-mass method and provides the estimate of the full navigation information including the three-dimensional position, velocity, attitude, and heading. As such, the RATAN is a all-weather navigator suitable for GNSS-denied environments, which was validated in the helicopter flight test campaign with trajectories flown in different altitudes above terrain, varying dynamics, and sensor properties. The RATAN provides consistent horizontal position estimate with accuracy below thirty meters in terms root-mean-square-error over a common terrain.