IOE OpenIR  > 光电技术研究所博硕士论文
天基大视场望远镜内方位元素在轨定标技术研究
聂沛文
Subtype硕士
2019-05-23
Degree Grantor中国科学院大学
Place of Conferral中国科学院光电技术研究所
Degree Name工学硕士
Keyword天基望远镜 内方位元素 星点提取 标定星点 在轨标定
Abstract

太空已成为目前各国激烈竞争的领域,为了应对来自太空的威胁,我们必须对所有在轨目标进行全面监视,天基大视场望远镜作为空间监视的重要载荷有着不可或缺的作用。由于发射时的冲击和震动,以及在轨时恶劣太空环境的影响,天基大视场望远镜在轨后的内方位元素会相对于地面标定时发生了一定的变化,从而影响在轨测量的精度,因此针对天基大视场望远镜内方位元素的在轨标定有着重要的意义。本文将对天基大视场望远镜内方位元素的在轨标定展开探索性研究,主要研究分析了星点的亚像素细分及星图模拟技术,星图预处理及标定星点的筛选过程,以及内方位元素在轨标定算法。

本文通过调研国内外文献对天基大视场望远镜工作原理进行了分析,在此基础上,建立了天基大视场望远镜的在轨测量模型和在轨标定模型。对天基大视场望远镜在轨时拍摄星图进行了高精度的模拟,采用了一种基于高斯分布的模拟星点细分方法,并对星点的能量中心进行了亚像素的灰度修正,结合建立的星库完成了星图的模拟。

在星点的质心提取方面,本文首先对噪声星图进行了预处理,包括滤波去噪、阈值分割和连通域的划分,在分析了三种质心提取算法并对提取结果的偏差进行了仿真后,选取了提取误差最小的方法。针对天基大视场望远镜视场内数量繁多的星点,通过对比不同条件下星点质心提取的平均偏差,对合适的标定星点进行了筛选,从而可以使标定的结果更加准确。

最后,对内方位元素在轨标定算法进行了研究和分析,并进行了仿真实验,计算了标定结果与仿真真值之间的偏差,从而衡量标定结果的准确性,又使用平均星间角距统计偏差对标定结果进行评价。针对随机测量噪声分布不均匀时,错误的选择了标定星点的情况,提出了一种加权剔除的内方位元素在轨标定方法,该方法选取合理的权重对随机测量噪声较大的坏点进行加权处理,将坏点的权重减小甚至消除。对算法的仿真结果表明,使用该方法剔除坏点后,其标定结果相对于扩展卡尔曼滤波算法有明显的提高。在图像中存在焦平面畸变的情况下,建立了畸变模型,并分析了一阶径向畸变下对焦距的影响。建立了畸变补偿模型对星点存在的焦平面畸变进行了补偿。通过仿真分析,在此模型下准确的标定了焦距。

Other Abstract

Space has become a fierce competition in various countries. In order to cope with the threat from space, we must comprehensively monitor all on-orbit targets. The space-based large-field telescope plays an indispensable role as an important load for space surveillance. Due to the impact and vibration during launch, and the influence of the harsh space environment during the orbit, the internal orientation elements of the space-based large-field telescope will change after the orbit with respect to the ground calibration. It may affect the accuracy of the on-orbit measurement. Therefore, it is of great significance for the on-orbit calibration of the orientation elements in the space-based large field of view telescope. This paper will explore the on-orbit calibration of the orientation elements in the space-based large field of view telescope. The main research is to analyze the sub-pixel subdivision and star map simulation technology of star point, the star map preprocessing and the calibration process of the calibration star point. And an on-orbit element on-orbit calibration algorithm.

In this paper, the working principle of space-based large field of view telescope is analyzed by investigating domestic and foreign literatures. On this basis, the on-orbit measurement model and on-orbit calibration model of space-based large field of view telescope are established. A high-precision simulation of the star-shaped image of the space-based large-field telescope was carried out. A simulated star-point subdivision method based on Gaussian distribution was used, and the sub-pixel gray-scale correction was performed on the energy center of the star point. The simulation of the star map was completed in conjunction with the established star library.

In the aspect of centroid point centroid extraction, this paper firstly preprocesses the noise star map, including filtering denoising, threshold segmentation and connected domain partitioning. After analyzing three centroid extraction algorithms and simulating the deviation of the extraction results, the method of extracting the smallest error is selected. Aiming at the large number of star points in the field of view of the space-based large field of view telescope, the appropriate calibration star points are screened by comparing the average deviation of the star point centroid extraction under different conditions, so that the calibration result can be more accurate.

Finally, the on-orbit element calibration algorithm is studied and analyzed, and the simulation experiment is carried out. The deviation between the calibration result and the simulated true value is calculated to measure the accuracy of the calibration result, and the average inter-satellite angular distance is used. Statistical bias is used to evaluate the calibration results. Aiming at the uneven distribution of randomly measured noise, the erroneous selection of the star point is proposed. A method of on-orbit calibration of the inner azimuth element with weighted culling is proposed. This method selects the reasonable weight to carry out the bad points with large random noise. Weighting processing reduces or even eliminates the weight of dead pixels. The simulation results of the algorithm show that after using this method to eliminate the bad points, the calibration results are significantly improved compared with the extended Kalman filter algorithm. In the case of focal plane distortion in the image, the distortion model is established and the influence of the focal length under the first-order radial distortion is analyzed. A distortion compensation model is established to compensate for the focal plane distortion existing in the star point. Through simulation analysis, the focal length is accurately calibrated under this model.

MOST Discipline Catalogue工学 ; 工学::仪器科学与技术
Language中文
Document Type学位论文
Identifierhttp://ir.ioe.ac.cn/handle/181551/9099
Collection光电技术研究所博硕士论文
Corresponding Author聂沛文
Recommended Citation
GB/T 7714
聂沛文. 天基大视场望远镜内方位元素在轨定标技术研究[D]. 中国科学院光电技术研究所. 中国科学院大学,2019.
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