Study On Positioning Method Of Deep Towing System

The 18th and 19th National Congresses of Communist Party of China(CPC)clearly pointed out that it is necessary to accelerate the building of a maritime power,and a comprehensive understanding of the ocean is the primary task of building a maritime power.The deep-sea exploration capability is also a reflection of a country’s scientific and technological level and comprehensive national strength.With the requirements of deep-sea marine research,deep-sea survey platforms,such as Deep Tow,Remotely Operated Vehicle(ROV),Autonomous Underwater Vehicle(AUV),have become routine equipment in deep-sea scientific research.The Deep Tow has become one of the important platforms for deep-sea exploration because of its abundant equipment and high cost performance.The Deep Tow is equipped with acoustic and optical instruments to explore the seabed and obtain various environmental data of the submarine.The body of the Deep Tow is the position datum of all the elements.How to determine the position information of the underwater towing body is the key problem at present.Traditional positioning methods are difficult to realize in water.The positioning error of Doppler and Inertial Navigation System(INS)is accumulated,and the accuracy of the acoustic positioning system in deep sea is not high.Combined positioning technology combines more than two positioning systems to give full play to their advantages,which improve the accuracy and reliability of underwater positioning.It is the development trend of underwater positioning technology.The paper studies the positioning technology of deep-drag system,introduces the principle of each positioning technology,and analyzes the error characteristics to establish the error equation.A single positioning system is difficult to meet the positioning accuracy requirements of the Deep Tow’s body.The accuracy of positioning can be improved by combining more than two systems.A rigorous USBL positioning model is proposed,which improves the positioning accuracy of the USBL by calculating the precise coordinates of the target,using the iterative method for acoustic line tracking and coordinate correction.The INS has high positioning accuracy in a short time,and can output relatively comprehensive navigation information of speed,attitude and position.DVL can provide more accurate speed information.Based on the above three positioning systems,two subsystems,SINS+USBL and SINS+DVL,are designed by kalman filter,and combined positioning data model is established by using federal kalman filter technology.In order to verify the effectiveness of the combined positioning method,a maritime positioning experiment was conducted.By comparing the USBL positioning results with the combined positioning results,it was concluded that the Acoustic Inertial Combined Positioning System(USBL+DVL)effectively improved the positioning accuracy of Deep Tow.The multi-beam data processing-has obtained good results by using position information obtained by combined positioning,indicating that the USBL+DVL can provide robust and reliable positioning for Deep Tow.