Robust guidance and navigation for airborne vehicles using GPS/terrain aiding

The emergence of new technologies for terrain elevation data collection allows the possibility of much improved terrain elevation model resolution and accuracy. This presents an opportunity for high accuracy navigation of airborne vehicles at modest cost and at the same time, less reliance on GPS navigation. In this paper, we present a concept for airborne en route and terminal navigation using both terrain aiding and GPS. Simulation of an air vehicle navigation system using terrain data, ladar sensor, and inertial measurement unit shows precise terrain aiding in the terminal area can result in a terrain-relative CEP of less than 1 foot. Furthermore, to deal with the large amount of terrain data that is available, a recursive nonlinear Bayesian filter is developed. Compared to a traditional minimum absolute difference algorithm, it is shown to provide much improved performance for the same computational load