基于二次多项式拟合的超短基线声线修正方法

超短基线定位解算中的距离观测值是指换能器与水下应答器之间的直线距离，而海水声速的不均匀分布导致声波在海水中的实际传播路径为连续弯曲的曲线，需要结合实测声速剖面进行声线修正。根据声速在分层介质中的传播特性，本文提出了一种基于二次多项式拟合的声线跟踪算法，采用线性插值方法对声速剖面数据进行合理加密并按等深度进行分层，设定每层声速梯度是不断变化的，用二次多项式拟合声速，基于运动学原理建立了完整的数学解算模型。仿真结果表明，该方法修正后的水下目标分布具有明显的收敛性，且优于等梯度声线跟踪算法和等效声速剖面法，显著提高了超短基线水声定位系统的定位精度。

Ultra-short baseline sound ray correction method based on quadratic polynomial fitting

The observed distance in the ultra-short baseline positioning is the linear distance between the transducer and the underwater transponder, while the uneven distribution of sound speed in seawater leads to the actual propagation path of sound wave in seawater being continuous curve, which needs to be corrected in combination with the measured sound speed profile. According to the propagation characteristics of sound speed in the layered medium, this paper proposes a sound ray tracing method based on quadratic polynomial fitting. Using linear interpolation method encrypts the sound speed profile reasonably. The sound speed profile is stratified by equal depth, and the gradient of sound speed in each layer is set to be constantly changing. Using quadratic polynomial method fits the sound speed, and the complete mathematical model is established based on the principle of kinematics. The simulation results show that the distribution of modified underwater target has obvious convergence. The method in paper is superior to the equal gradient sound ray tracing method and equivalent sound speed profile method, which significantly improves the positioning accuracy of the ultra-short baseline underwater acoustic positioning system.