Research On Key Techniques Of Underwater Acoustic Positioning Algorithm

The ocean is the hope of sustainable development of human resources and environment.Ocean power strategy carries the Chinese dream of great rejuvenation of the Chinese nation.The situation of our country's oceans is very grim.Underwater autonomous navigation and long-term observation are basically blank.Therefore,there is an urgent need to study underwater positioning.Research on key techniques of underwater acoustic positioning algorithm is carried out under the support of the national key R & D project "Marine Geodetic Standards and New Technologies for Marine Navigation".The main research and conclusions are as follows:1.The progress at home and abroad about underwater positioning technology and sound speed correction model are summarized.The underwater acoustic positioning system and the combination positioning system are introduced,and the applicable conditions,advantages and disadvantages of various systems are analyzed.The sources of errors in underwater acoustic positioning and the corresponding error correction methods are introduced.The ARGO data for sound velocity calculation and the sound speed empirical model for indirect measurement are systematically studied,including six kinds of models such as Dell Grosso,Wilson,Leroy,Mackenzie,EM and Medwin.The real data calculations show that the sound velocity calculated by the Dell Grosso model has a large deviation from other models.Except for the Dell Grosso model,there is a good agreement between the sound velocity values and temperature and salinity changes in other models.2.The data format and interpretation method of p2/94 original file for underwater long baseline positioning system are introduced.The underwater acoustic zero-difference and single-difference positioning models were studied.On the basis of the classical least-squares solution,the least-squares method based on weighted iteration of IGG scheme was introduced into underwater acoustic positioning.The underwater acoustical zero-difference and single-difference positioning models based on robust estimation are presented.Taking into account the underwater positioning geometry and the actual situation,it is proposed to adopt the method of neglecting the vertical direction and changing the slant distance to thehorizontal distance to perform two-dimensional positioning,thereby improving the horizontal positioning accuracy.3.According to the real data of the South China Sea,the underwater positioning method proposed in this paper is verified and compared.Four kinds of schemes were adopted to conduct underwater acoustic positioning experiments: zero-difference three-dimensional positioning,zero-difference two-dimensional positioning,single-difference three-dimensional positioning,and single-difference two-dimensional positioning.The results show that the algorithm of two-dimension positioning by changing the slant range to horizontal distance is feasible and the accuracy is improved obviously.The positioning results are equivalent to the three-dimensional difference positioning method.Robust least squares method based on IGG scheme can effectively eliminate gross errors and greatly improve positioning accuracy and reliability.The single-difference method can reduce the influence of some systematic errors and spatial correlation errors,and the positioning accuracy is better than that of the zero-difference method.The horizontal positioning accuracy using the two-dimensional positioning method by neglecting the vertical direction is better than that of the three-dimensional positioning.4.Sound speed tracking algorithm in underwater acoustic positioning was studied.The velocity tracking method using Taylor series expansion method instead of weighted average velocity method is proposed.The calculation results show that the improved ray tracing method has obviously improved accuracy compared with other methods,and can meet the positioning requirements of centimeter-level accuracy.On this basis,the algorithm of speed-of-sound correction based on the single-difference model is proposed.The simulation example shows that the speed-of-sound correction algorithm based on the single-difference method improves the accuracy and reliability of the sound speed correction.