基于数字图像的扫描镜动态精度测量方法研究

发布时间：2018-05-28 01:36

  本文选题：数字图像 + 扫描镜　； 参考：《中国科学院研究生院(上海技术物理研究所)》2016年博士论文

【摘要】：新一代静止气象卫星“风云四号”是三轴稳定平台卫星,其载荷之一扫描成像辐射计采用二维扫描成像技术实现对地成像。在18°×18°地球视场范围内,扫描镜的动态运动精度指标高达1″(1σ)。如何评价扫描镜在工作模式下的动态运动精度成为一个技术难题。针对这个技术难题,本课题进行了基于数字图像的扫描镜动态精度(扫描精度)测量方法的研究,分别从方法原理提出、系统构建、成像信息处理、方法精度论证、方法实施这几个层次进行了研究和探讨。首先,本文提出了基于数字图像的扫描镜动态精度测量方法,即在扫描镜动态扫描模式下,给定一个精密标准图案进行扫描成像,通过检测所成图像上像点与理想像点位置之间的偏差反演扫描镜的动态精度。本文选用带有13*13阵列菱形图案的目标板作为精密标准图案场景,采用积分球作为照明系统对目标板进行照明,目标板发出的光线经过平行光管(投影系统)输出平行光到达扫描辐射计进行成像。文中关于目标板的标准图案选取、尺寸参数设计、材质选型,以及照明系统的选取、投影系统的指标分别进行了详细论证。其次,对于成像的信息处理是该方法基于数字图像的含义所在。本文采用角点和质心点作为扫描图像的特征点进行位置检测,进而反演扫描精度。选取Harris Affine角点检测算法进行角点检测,选取了传统质心检测算法进行质心点检测。针对每一个检测算法,文中进行了详细的精度仿真论证。再次,本文对该方法分别从仿真和试验这两个方面进行了方法本身精度的分析和标定。本课题通过可控亚像素偏移成像序列进行测角方法精度的试验标定,得出基于角点的测角方法精度为0.56~0.91urad(1σ),基于质心点的测角方法精度为0.56~0.84urad(1σ),可以满足FY-4扫描镜动态精度检测需求。最后,基于搭建的测试平台,在扫描镜10°/s的运动模式下,采用该测角方法对扫描镜进行动态精度测试。测得在局部小视场范围(0.33°×0.33°)内,扫描镜的动态指向角位置精度为2.64urad(1σ,0.54″)。通过以上四个层次的研究工作,本文提出并论证了基于数字图像的扫描镜动态精度测量方法,并取得了良好的测试结果和精度,为扫描镜在大视场扫描工作模式下的动态精度测量提供了有效参考。本方法研究的创新之处在于基于辐射计扫描成像工作原理,对扫描数字图像进行处理和像点信息获取,实现了扫描镜在动态运动过程中的动态精度测量,并通过数字图像处理技术提高了测角精度。
[Abstract]:The new generation geostationary meteorological satellite "Fengyun 4" is a triaxial stabilized platform satellite. One of its payloads, scanning imaging radiometer, uses two-dimensional scanning imaging technology to realize earth imaging. In the range of 18 掳脳 18 掳Earth field of view, the dynamic motion accuracy index of scanning mirror is as high as 1 "/ 1 蟽". How to evaluate the dynamic motion accuracy of scanning mirror in working mode has become a technical problem. In view of this technical problem, this subject has carried on the research based on the digital image scanning mirror dynamic precision (scanning precision) measurement method, respectively from the method principle, the system construction, the imaging information processing, the method precision demonstration, Methods the implementation of these levels was studied and discussed. Firstly, the dynamic precision measurement method of scanning mirror based on digital image is proposed, that is, in the dynamic scanning mode of scanning mirror, a precise standard pattern is given for scanning imaging. The dynamic accuracy of the scanning mirror is inversed by detecting the deviation between the image points and the ideal image points. In this paper, the target board with 1313 array diamond pattern is selected as the precision standard pattern scene, and the integrated sphere is used as the lighting system to illuminate the target board. The light emitted from the target plate passes through a parallel tube (projection system) and reaches the scanning radiometer for imaging. In this paper, the standard pattern selection, dimension parameter design, material selection, lighting system selection and projection system index of the target board are discussed in detail. Secondly, the information processing of imaging is the meaning of the method based on digital image. In this paper, the corner and centroid are used as the feature points of the scanning image to detect the position, and then the scanning accuracy is retrieved. Harris Affine corner detection algorithm is selected for corner detection, and traditional centroid detection algorithm is selected for centroid detection. For each detection algorithm, a detailed accuracy simulation is presented in this paper. Thirdly, this paper analyzes and calibrates the accuracy of the method from two aspects: simulation and experiment. In this paper, the precision of angle measurement method is calibrated by using controllable sub-pixel migration imaging sequence. It is concluded that the precision of angle measurement method based on corner point is 0.56~0.91urad(1 蟽, and the precision of angle measurement method based on centroid point is 0.56~0.84urad(1 蟽, which can meet the need of dynamic precision detection of FY-4 scanning mirror. Finally, based on the test platform, the dynamic precision of the scanning mirror is tested by the angle measuring method under the motion mode of 10 掳/ s. In the range of local small field of view (0. 33 掳脳 0. 33 掳), the position accuracy of the dynamic pointing angle of the scanning mirror is 2.64urad(1 蟽 0. 54 ". Through the above four levels of research work, this paper puts forward and demonstrates the dynamic precision measurement method of scanning mirror based on digital image, and obtains good test results and accuracy. It provides an effective reference for dynamic precision measurement of scanning mirror in large field scanning mode. The innovation of this method is that, based on the principle of radiometer scanning imaging, the scanning digital image is processed and the image point information is obtained, and the dynamic precision measurement of scanning mirror in the dynamic motion process is realized. The precision of angle measurement is improved by digital image processing technology.
【学位授予单位】：中国科学院研究生院(上海技术物理研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TP391.41
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本文编号：1944709