Clock-free synchronous localization method of deep-sea UUV based on sound ray correction with grazing angle and differential iteration

基于掠射角声线修正及微分迭代的深海UUV免时钟同步定位方法

¹ School of Marine Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China
² Key Laboratory of Ocean Acoustics and Sensing, Northwestern Polytechnical University, Xi'an 710072, China
³ School of Electronic Information and Artificial Intelligence, Shaanxi University of Science and Technology, Xi'an 710021, China

Received: 25 April 2024

Abstract

The underwater acoustic localization of deep-sea UUV in the underwater acoustic sensor networks is mainly based on the geometric principle. Due to the uneven underwater sound speed, the propagation of sound ray is bent. It will produce great error to calculate the distance between the node and the UUV with constant sound speed. At the same time, the complexity of underwater environment makes it difficult to achieve accurate clock synchronization between the underwater node and the UUV, and the cost of maintaining clock synchronization is very high. Aiming at the clock asynchrony between the node and the UUV and sound ray bending, a clock-free synchronous localization method for deep-sea UUV based on sound ray correction with grazing angle and differential iteration was proposed. When the sound speed profile and the grazing angle of the node are known, the horizontal distance between the node and UUV can be obtained more accurately, and the UUV localization accuracy can be improved by differential iteration method. The performance is verified by Matlab simulation and simulation experiment with Bellhop. The results show that the traditional sound ray correction methods are no longer suitable for clock asynchronous situation between the node and the UUV, but the clock-free synchronous localization method for deep-sea UUV based on sound ray correction with grazing angle and differential iteration proposed in this paper can significantly improve the localization accuracy of UUV under the condition of grazing angle estimation error. In addition, the performance of the sound correction based grazing angle is simulated in the presence of grazing angle estimation error, which has practical guiding significance for the setting of node depth and the selection of nodes within the communication range.

摘要

水声传感器网络深海无人水下航行器(unmanned underwater vehicle, UUV)主要根据几何原理进行水声定位。水下声速不均匀会导致声线传播发生弯曲, 用恒定声速来计算节点和UUV之间的距离会产生很大的误差, 同时水下环境的复杂性使水下节点和UUV之间很难做到精确的时钟同步, 且维持时钟同步的成本很高。针对节点、UUV间时钟异步和声线弯曲情况, 提出了一种基于掠射角声线修正及微分迭代的深海UUV免时钟同步定位方法。该方法在声速剖面和节点接收端掠射角已知的情况下, 可以获得比较精确的节点和UUV间水平距离, 采用微分迭代方法提高UUV定位精度。通过Matlab仿真和Bellhop模拟实验进行了性能验证, 结果表明传统声线修正方法已经不适用节点、UUV时钟异步情况, 文中所提基于掠射角声线修正及微分迭代的深海UUV免时钟同步定位方法在掠射角估计误差存在的情况下可以明显提高UUV的定位精度。此外, 在掠射角估计误差存在情况下仿真了基于掠射角的声线修正效果, 对节点深度的设置和通信范围内节点的选择具有实际的指导意义。