Simulation For Underwater Navigation System Based On Gravity Gradient

Submarine needs a precise, passive and autonomous navigation system to cruise hiddenly under water for a long period of time. Inertial Navigation System meets the requirements well. But it actually is a dead reckoning navigation method which is involved with accumulated errors and needs to verify data regularly to ensure precise navigation during its long time working. Usually, we take Inertial Navigation System as the main navigation system and another navigation method as a supplement to correct errors regularly that brought form INS.The measurement of gravity gradient doesn't need to receive or send signals and is hardly detected and disturbed. So the navigation method based on gravity gradient is a high-precision, independent and autonomous method which can bring to a maximum of secrecy and autonomy of submarine. The significance of this method is great.The underwater navigation system based on gravity gradient is composed of gravity gradient map, gravity gradient sensor, navigation algorithm and so on. This paper focuses on gravity gradient map and navigation algorithm. The specific content are as follows: Firstly, I summarized the research status about the technology of gravity gradient modelling, discussed the impact of density error on gravity gradient map, analyzed the effects of isostasy in gravity gradient map modelling, and proposed an advanced method of gravity gradient map modelling based on isostatic model. Secondly, I discussed the navigation methods based on gravity or gravity gradient, develops a associative underwater navigation and positioning method based on gravity gradient. Thirdly, I developed a software system for underwater navigation system. In the end,I made a summary of the whole dissertation and points out the directions of future research.