Acquisition method for terrain referenced navigation using terrain contour intersections

Abstract

This study presents a contour intersection-based acquisition method for fast and robust terrain referenced navigation (TRN). Due to advances in highly accurate sensors, such as in radar and lasers, the shortcomings of past TRN could be overcome. High-performance sensors have made it possible to estimate the true terrain height limited to narrow error intervals. Digital terrain elevation data is employed for the purpose of inversely obtaining the measurement area - the area created by contours - corresponding to the height interval. Since the measurement area is a bundle of contour lines, the intersection area, which is the intersection of measurement areas, consists of a set of intersections of contour lines. Intersection areas are sequentially obtained to estimate the actual aircraft position. While batch processing is computationally expensive and it is hard to produce solutions until the position is fixed, the proposed method is fast enough to provide a rapid solution without an initial break. Sequential processing is sensitive to initial position errors, whereas the proposed method proves to be robust. The simulation results show that the contour intersection-based acquisition method provides improved navigation performance for various terrain samples.