Integrated Navigation System Based on Correlation between Gravity Gradient and Terrain

The passive gravity aided inertial navigation system has been proven to improve submarine´s navigation accuracy by matching the measured gravity field data to the pre-surveyed reference map. However, it has a lack of such prepared reference maps at present. In this paper, an integrated navigation system based on the correlation between gravity gradient and terrain fluctuation is proposed, and the system can avoid any use of gravity maps. According to the correlation between gravity gradient and terrain, the calculating value of gravity gradient abnormal at the estimated position of the submarine can be obtained by high-precision digital elevation model, and the measurement value can also get from gradiometer. By using the difference of them, the system optimal filter generates real-time adjustment to the navigational errors. This method avoids the shortage of gravity field data presently. In addition, the system guarantees the safety of submarine at the same time because there is no transmission of signals outward from the vehicle during measurements of the gravity gradient.