基于Snell窗及偏振模式的水下载体航姿测量  

A method for underwater vehicle attitude measurement based on Snell’s window and its polarization mode

作　　者：辛润宏 张然[1,2] 褚金奎 巩文哲[1] 李云鹏 程潇欧 XIN Runhong;ZHANG Ran;CHU Jinkui;GONG Wenzhe;LI Yunpeng;CHENG Xiaoou(Technology Liaoning Provincial Key Laboratory of Micro Nanosystems,Dalian University,Dalian 116024,China;Technology Ningbo Research Institute,Dalian University,Dalian 116000,China;Dalian Shipbuilding Industry Group Co.,Ltd.,Dalian 116011,China)

机构地区：[1]大连理工大学辽宁省微纳米系统重点实验室,辽宁大连116024 [2]大连理工大学宁波研究院,辽宁大连116024 [3]大连船舶重工集团有限公司,辽宁大连116011

出　　处：《光学精密工程》2024年第12期1801-1811,共11页Optics and Precision Engineering

基　　金：国家自然科学基金资助项目(No.52275281,No.52175265);中央高校基本科研业务费资助项目(No.DUT21ZD101,No.DUT21GF308)。

摘　　要：提出了一种在水下通过Snell窗获得偏振分布模式与天顶点坐标,进而得到水下载体的航姿信息(即航向角、横滚角与俯仰角)的方法。在载体上安装鱼眼镜头与偏振相机,在水下拍摄天空,得到偏振角分布模式。建立小孔成像模型得到相机的内外参数矩阵以及镜头畸变系数,对偏振角分布模式进行畸变校正,进而得到太阳子午线特征区域,使用Canny算子检测得到特征区域边缘,由霍夫直线检测算法计算出太阳子午线与水下载体体轴夹角,得到航向角。通过实验得到不同光入射角与偏振角误差的函数关系,进行误差补偿,减小由于鱼眼镜头改变入射光偏振态带来的偏振角测量误差,进而提高太阳子午线与水下载体体轴夹角的测量精度。利用灰度阈值检测算法筛选出图像中的天顶点坐标,进而计算载体的横滚角与俯仰角,经过实验验证了算法的准确性。搭建了模拟水下环境的实验平台,实验结果表明:该方法得到的航向角平均绝对误差为0.5303°。在[-50°,50°]角度范围内,横滚角与俯仰角平均绝对误差为0.7544°与0.6213°,满足水下导航的精度需求。This paper proposed a method to observe the celestial polarization pattern and the coordinate of zenith through Snell’s window,which consequently yields the navigation information of the carrier,i.e.,yaw angle,roll angle,and pitch angle.A fish-eye lens and an imaging polarimeter were installed on the carrier to capture the sky and obtain the celestial polarization pattern.First,a pinhole imaging model was established to obtain both the internal and external parameter matrices of the camera and the distortion coefficients of the lens.A distortion correction was applied to the polarization pattern to obtain the solar meridian characteristic region.A Canny operator was used to detect the edge of the characteristic region,after which a Hough line detection algorithm was used to calculate the angle between the solar meridian and the carrier′s axis,yielding the Yaw angle.Second,the relationship between incidence angles and the error of polarization angle was abstracted as a function through experiments.Error compensation based on the function was performed to reduce the measurement error of the polarization angle caused by changes in the incident light polarization state of the fish-eye lens,hence improving the accuracy of measuring the angle between the solar meridian and the carrier axis.Third,the grayscale threshold detection algorithm was used to calculate the coordinates of the zenith in the image,and therefore the roll and pitch angles of the carrier.The accuracy of the algorithm was verified through experiments.Lastly,an experimental platform was constructed to simulate an underwater environment.Results show that the mean absolute error of the yaw angle calculated by this method is 0.5303°.Within the range of[-50°,50°],the mean absolute error of the roll angle and pitch angle are 0.7544°and 0.6213°,respectively,which meets the accuracy requirements of underwater navigation.

关 键 词：水下导航 Snell窗 偏振分布 图像处理 

分 类 号：TN967.2[电子电信—信号与信息处理] U666.1[电子电信—信息与通信工程]