Seafloor Baseline Transfer Control Network Optimization And Underwater Positioning Nonlinear Adjustment

About 71% of the Earth's surface area is covered by the ocean.The marine spatial datum is an important infrastructure for underwater marine navigation and positioning,oceanographic surveys,and resource development.Marine datum also plays an important role in scientific research field,such as marine environment and marine geology.However,the underwater positioning accuracy mainly depends on the geometric configuration and acoustic ranging accuracy of the sea surface and the subsea control network.Therefore,the optimal design of the underwater positioning control network is meaning for improving the underwater positioning accuracy.In addition,for the nonlinearity of very short distance measurement in underwater positioning,complicated error sources of positioning and observational quality control in underwater positioning are relatively need to be taken into account compared to conventional ground positioning.For this reason,we perform relevant research on the optimization of long-baseline arrays on the sea surface and the nonlinear least squares for solving the underwater positioning equation.The main research contents and innovations include:(1)Studying the system working principle and underwater positioning mathematical models for the underwater positioning.The principle and method of the optimal design of underwater positioning control network are given,and then the underwater ranging positioning model is discussed based on the linearization parameter estimation model.(2)With the newly developed analytical method for GDOP optimization,the analytical optimization for the deployment of underwater positioning buoys on the sea surface was studied.Besides,the optimization objective was established by introducing the proposed regional GDOP mean and variance.The optimal configuration solution is given by taking five sea surface buoys as an example,considering the constraints of the underwater positioning with elevation angle constraints,the GDOP minimum positioning configuration solutions were given by applying the analytical optimization on underwater positioning buoys array.In addition,considering the navigation and positioning should be performed in a certain region,the sea buoy array optimization design method is carried out with the al GDOP mean and variance minimization,and then search algorithm is proposed to obtain a regional GDOP mean minimum configuration.Simulation experiments show that the best positioning performance of the GDOP minimum positioning configuration found in the paper indicates that optimizing the surface submarine array control network array is an important approach to improve underwater positioning accuracy.(3)Since the underwater ranging equation is a nonlinear function model,and in most cases it is a ranging positioning problem of short-distance.Due to the complexity of the nonlinear problem,the solution of the ranging equation may not be unique.It shows that,when the equation is ill-conditioned,the solution of the equation will become more complicated.At the same time,the nonlinearity of the short range ranging equation is relatively large.We solve this problem by using direct solution,Gauss-Newton method and closed-form of Newton method to solve ill-conditioned ranging equations.The experiment verifies the local convergence properties of analytical solution,Gauss-Newton method and closed-form of Newton iteration method.The results show that the Newton method has the best local convergence.Experiment shows that,the analytic method and Gauss-Newton method get two solutions,while the closed-form of Newton method gets three solutions.(4)Utilizing the measured underwater positioning data,we carried out research on underwater data processing and analysis.