Gravity based navigation of AUVs

A class of autonomous navigators, termed gravity gradiometer navigation systems (GGNS), is introduced. These systems use measurements of the spatial gradients of the local gravity field and compare them with a presurveyed gravity gradient map. The convergence problem is easily solved because, unlike the terrain data, the gravity signal has significant low-frequency (geological) content. Hence, with appropriate processing the low-frequency content can be used for initial large position adjustments and the high frequencies to maintain good steady-state accuracy. Added benefits are that the system provides vertical as well as horizontal position updates and is nonemanating and thus completely covert. The basic principles of this technology and the application to the navigation/guidance of autonomous underwater vehicles are described