| The ocean,which accounts for 71% of the Earth's surface area,is the hope for the sustainable development of human resources and environment.The strategy of the maritime powers carries the Chinese dream of the great rejuvenation of Chinese clan.However,the current situation of China's oceans is very serious,and national sovereignty and maritime rights and interests are facing enormous challenges.It is especially important to construct a high-precision submarine control network.The underwater positioning technology is monotonous and lacks means.The geospatial information of land,sea and air does not form a unified system.Therefore,it is urgent to carry out in-depth research on underwater positioning.Under the support of the key research and development plan of “Ocean Geodetic Datum and Marine Navigation New Technology”,a series of key technical issues related to underwater acoustic positioning were studied.The main work is summarized as follows:1.The basic principle of underwater acoustic positioning is taken as the entry point.The principle and system composition of the existing underwater acoustic positioning system and combined positioning system are introduced.Based on the principle and practicability,the applicable conditions,advantages and disadvantages of each system are analyzed.2.From the three aspects of water surface error,underwater error and other errors,the error sources in the underwater acoustic positioning process are analyzed in detail,and the main error sources that affect the underwater positioning accuracy are studied.For six classical sound velocity experience models: Dell Grosso,Wilson,Leory,Mackenzie,EM,and Medwin,the applicability of these sound velocity empirical models was analyzed using measured Argo data and a set of simulated data.The experimental results show that the similarity between the Dell Grosso model and the calculation of sound velocity values of other models is low,which is not suitable for the calculation of sound velocity profile in the study area.3?Based on the basic principle of sound line tracking,several commonly used sound velocity correction methods are introduced.A combined sound velocity correction algorithm based on hierarchical isosceles sound line tracking and Taylor series expansion is proposed.The comparative experiments were carried out on the weighted average sound velocitymethod,the equivalent sound velocity profile method,the layered gradient sound line tracking method and the combination method.The conclusions are as follows: the weighted average sound velocity method and the equivalent sound velocity profile method have relatively poor positioning accuracy,and the layered equal-gradient soundtrack tracking method and the combined method have higher precision than the weighted average sound velocity method and the equivalent sound velocity profile method,and the positioning accuracy can reach The centimeter level meets the needs of current high-precision acoustic positioning.Compared with the hierarchical isosceles sound line tracking method,the combination method can determine the initial coordinate value of the seabed transponder position better and faster,reduce the number of iterative calculations,and improve the calculation efficiency.4?The mathematical model of single-difference and double-difference positioning of underwater acoustics based on measuring ship navigation and GNSS-based buoys is deduced in detail,and the main error sources and advantages and disadvantages of the two positioning methods are analyzed.The accuracy and reliability of the two positioning models are verified by using simulation data and measured data,and the influence of systematic errors of different magnitudes(different water depths)on the accuracy of underwater differential positioning is deeply analyzed.The experimental results show that the differential positioning model can effectively eliminate or reduce the influence of system error,especially the system error(deep water depth),which significantly improves the underwater positioning accuracy. |
PDF Full Text Request