| Under the requirements of task of safe voyage, it is of great significance for the underwater vehicle in military and civilian area, but now the method of the underwater navigation is very limited and it’s impossible for an underwater vehicle to sail safely for a long time. Autonomous navigation technology underwater becomes the bottleneck which imposes restriction on underwater navigation. Autonomy is the characteristic of inertial navigation system, but the navigation errors will be accumulated over time, and the errors need to be calibrated timely. It’s not only needed to send signals to the outside for the gravity matching technology, but also receiving signals is not needed. Autonomy and not to be disturbed is the features of the gravity matching technology. Of course gravity matching aided inertial navigation is the effective solution of underwater autonomous navigation, and it is currently the focal point in underwater navigation research field for every developed country.At present, there is no mature form in the gravity matching aided navigation field yet. The study of this technology is still in the initial stage of development in China and the experiment of the test system just begins for a short time abroad. At the same time, owning to the complexity of the underwater environment, much breakthrough work needs to be done. This paper focuses on the research of gravity matching algorithm, including the following contents:The inertial navigation system is the main part of underwater navigation system. This paper studies the inertial navigation technology. Based on the sufficient research on inertial navigation system, especially the study of strapdown inertial navigation system in principle and navigation algorithm, a simulation system of strapdown inertial navigation has been established, considering the characteristics of the underwater environment and the submarine navigation. This system provides the platform for underwater navigation technology research, and some follow-up study hans been done on this platform.As the navigation error of the inertial navigation system will be accumulated over time, this paper puts forward gravity matching to limit the accumulation of the inertial navigation system. In this paper the structure of gravity matching aided navigation system is analyzed, and the related technologies are briefly introduced. On the research of gravity matching algorithm, much work is done.Gravity matching algorithm is the focal point of gravity matching aided navigation research. This paper studies three kinds of one-dimensional matching algorithm respectively, analyzes the the characteristics of the algorithms and makes navigation experiments in different matching areas, then the adaption of matching algorithm in matching area is analyzed. Through the calculation of the corresponding measure characteristics of regional gravity field, the regional division criteria for gravity method is obtained, and the knowledge is provided for choosing the appropriate gravity matching area and choosing the appropriate matching algorithm.The reliability of the gravity matching technology is the key in the gravity matching aided navigation. This paper introduces two-demensional matching algorithm to improve the navigation matching the reliability of the navigation for the first time. The method of constructing two-dimensional matching data based on the one-dimensional track data is studied first. Then three two-dimensional matching algorithms which are not related are studied. The characteristics and these algorithms and their requirement for matching area are also analyzed. Based on the work which has been done above, integrated navigation could be studied.Mismatch correcting is the important symbol that the gravity matching aided navigation technology could be put into use, and it is also the one of the most important problems for gravity matching aided navigation study. Due to the complexity of the underwater environment, single underwater gravity matching algorithm could not achieve high precision and reliability. This paper puts forward a set of matching strategy, and provides the feasible schemes for gravity matching aided navigation:considering the the spatial relationship of multi-points which is near to each other, suspected matching result can be found and the mismatch could be corrected, then the reliability of the matching result is improved. The relationship of all algorithms is studied. Combining the algorithms there is little correlation between each other, suspected matching result could also be found, and then with these strategies, gravity matching of high accuracy and high reliability can be achieved. At last the simulated system of gravity aided navigation has are established. With the theory research and analysis of experiment in this paper, it can be concluded that gravity matching aided navigation in matching area can achieve high accuracy, high reliability. Employing the matching strategy which is put forward for autonomous navigation in this paper, the mismatch can be effectively eliminated and corrected. Gravity matching aided navigation technology is feasible in technology, but in the research simulation experiment is conducted on the basis of considering limited influence factors. Gravity matching aided navigation technology needs further study. |
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