| Aiming at the characteristics of the automatic underwater gravity navigation system, the fundamental theories and methods are mainly studied in this dissertation. Gravity map reconstruction, data preprocessing, analysis of matching algorithms and capability evaluation are made with the information obtained by various gravitational sensors. Then, the intelligentized data is syncretized, and the simulation design of the automatic underwater navigation modules is completed so as to correct the inertial navigation errors and improve the positioning precision. Thus, it could be a reliable technology for the precise navigation of underwater carriers in the ocean. The main works and innovative ideas are listed as follows:1. The basic skeleton of the automatic underwater gravity aided inertial navigation system is summarized in this thesis, while the correlative fundamental theories are discussed, the basic principle of the Satellite Altimetry and the oceanic gravity anomaly map based on satellite altimetry data are given. The gravity and gravity gradient sensor surveying systems are introduced. What's more, the principles and characteristics of the classical matching algorithms are summed up as well.2. With the oceanic gravity map data at the level of 2′×2′, the reconstruction method of oceanic gravity anomaly map based on coons curved surface is put forward. Besides, the gravity anomaly model of double one order or three orders coons curved surface are established. The precision are much better than that of the mobile curve surface interpolation. The method of establishing high precision and high resolution gravity datum map based on the depth of the ocean at the level of 30"×30" is studied.3. The feasibility of the real time underwater gravity measurement and the implement method of gravity disturbing correction based on the output of INS are studied. Then, the physical characteristics of the underwater gravity sensor measurement errors are analyzed and the magnitude is discussed by corresponding mathematical models. Also, the pre-process, continuation reduction as well as the mathematical transformation of the gravity sensor measurement data are discussed.4. The influence of the statistical characteristics of the oceanic gravity field to the precision of automatic gravity navigation is analyzed. Based on the thought that the correction of the navigation system mostly determined by the variable characteristics of space properties, statistical calculation analysis of local gravity field characteristic parameters is made. The gravity matching zone is discussed by simulation gravity experiments of different sea areas.5. Aimed at the inertial navigation system, which is the study object of the noise transmission characteristics of the main error sources such as gyroscopes drift in inertial navigation, zero position errors of the acceleration, initial adjustment errors and so on are discussed. A simulated model of sailing path errors that fulfilling the characteristics of inertial navigation is established. Furthermore, a suggestion that the eastern correction precision should be paid more attention to in the matching result is put forward when considering the unbounded characteristic of the eastern position errors.6. In order to eliminate the influence of the inertial errors in the calculation of E?tv?s effect and the normal gravity in gravity measurement, differential descending correlative extremum matching algorithm is put forward with new observational series comprised of the differential adjacent gravity anomaly observations. Probabilistic data association filtering algorithm is put forward with the fact that multi-available positions are resulted from the disturbing errors of the real position, and the reliability and robustness of the matching algorithm is improved.7. The ICCP matching algorithm based on Fibonacci number series is studied. As for its localization, the following strategy is taken in this thesis. With serial relevant extremum matching algorithm, the inertial flight path is corrected to close to the real one before the ICCP is taken to the matched path to obtain the best sailing path.8. With the help of SITAN, the random linearization technology of the double two orders curved surface of gravity anomaly is discussed. Optimized gravity anomaly measurement functions are constructed by the discussion of all the items magnitude. Parallel Kalman filtering technology is studied, and how to determine the sampling period for the inverse of the visible matrix is considered to ensure the stability of the Kalman filtering.9. A compositive gravity gradient aided inertial navigation system working mode is designed, which is based on the thought that the close-loop compensation of the random inertial navigation errors is corrected through the matching of gravity information and the open loop compensation of the disturbing gravity and the deflection of the vertical arranged by the inertial navigation mechanic functions. In addition, the method of variable gravity cells matching method without gravity map is discussed preliminarily.10. The error transmission model of the position and velocity in the inertial navigation system by the disturbing gravity vector is studied, of which the magnitude and characteristics are analyzed to validate the necessity of the gravity open loop compensation qualitatively and quantitatively.11. Experiments present that the frequency domain continuation of the gravity gradient could satisfy the precision as well as the real time requirements of the underwater gravity gradient matching navigation. Kalman filtering matching algorithm with independent diagonal element Txx and Tyy, which both have obvious characteristics variance, is put forward based on the magnitude and variance statistical characteristics analysis of the gradient data.12. The data processing flow of the automatic underwater gravity aided navigation is designed, of which the object-oriented compositive simulation experiments platform is established.
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