顾及波束入射角的常梯度声线跟踪水下定位算法

海水声速的时空变化会使声波沿传播方向发生折射，有效消除声波的折射效应对提高水下声学定位精度至关重要。在声速剖面已知的情况下，声线跟踪是削弱折射效应的有效方法。但现有的声线跟踪方法要求波束入射角为已知，而基于距离交会原理的水下声学定位系统通常未对波束入射角进行直接观测。针对上述问题，提出了顾及波束入射角的常梯度声线跟踪水下定位算法，采用搜索法确定波束入射角，通过对声线跟踪与定位解算的迭代计算，实现波束入射角和目标坐标的渐次修正。为进一步提高计算效率，提出了迭代求解超越方程的解算法。试验结果表明，本文方法有效利用声速剖面消除了声线折射效应的影响，且解算法计算效率优于搜索法。

A constant gradient sound ray tracing underwater positioning algorithm considering incident beam angle

The spatial and temporal variation of sound velocity in sea water can make sound waves refract along the propagation direction, and effective elimination of refraction artifacts is very important to improve the accuracy of underwater acoustic positioning. When the sound velocity profile is known, sound ray tracing is an effective method to reduce the refraction artifacts. The existing sound ray tracing methods require that the incident beam angle is known, while the underwater acoustic positioning systems based on the distance intersection principle usually do not directly measure the incident beam angle. A constant gradient sound ray tracing underwater positioning algorithm considering incident beam angle is proposed, which can trace sound ray and estimate target position respectively by iterative calculation, and the incident beam angle is determined by a search method. In order to improve the calculation efficiency, a transcendental equation solution method is proposed to determine the incident beam angle iteratively. The experimental results show that the proposed method effectively eliminate the effect of the refraction artifacts by using sound velocity profile, and the calculation efficiency of the transcendental equation solution method is better than the search method.