共查询到18条相似文献,搜索用时 140 毫秒
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APS星跟踪器亚像素质心定位 总被引:1,自引:0,他引:1
APS像元结构和大小制约APS星跟踪器精度,采用散焦技术使星光成像在几个相邻像素(窗)上,以窗内灰度重心作为星点质心可以得到亚像素定位精度。APS具有多种噪声源,它们直接影响质心定位精度。根据星点模型和质心误差计算模型量化分析了窗大小、星点模型方差、噪声源对APS亚像素质心定位的影响。分析结果表明5×5窗为最优窗,星点模型方差最优值为0.62个像素,精度为0.0016个像素;固定模式噪声、暗电流对质心定位影响较大,读噪声较小,提高信噪比可以改善质心定位精度。 相似文献
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CMOS APS噪声对星斑质心定位精度的影响 总被引:2,自引:0,他引:2
CCD作为星敏感器探测器的技术已经比较成熟,但其瓶颈限制也日渐显露.本文以IBIS5-B-1300A探测器为例,具体分析CMOS APS各种噪声对星敏感器星像质心定位精度的影响,在理论上分析CMOS探测器所能达到的质心定位精度上限,并通过建模仿真验证理论分析结果,得出弥散斑束腰宽度为0.7,开窗大小为5×5时质心算法精度最高,固定模式噪声(FPN)对质心定位精度影响最大等结论,为星敏感器探测器的选型以及提高系统星点定位精度的潜力提供理论上的依据和支持. 相似文献
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2.中国科学院大学,北京100049)摘要:为了提高星敏感器的测角精度,提出了一种采用系统辨识法对星敏感器模型进行修正以及测角精度检测的方法。首先分析了星敏感器的理论测量模型以及像面坐标与星点目标的空间位置关系,然后给出了用模型修正来提高星敏感器测角精度的原理和数学模型。修正模型由系统辨识方法得到,同时为了提高辨识精度,文中采用将星敏感器像面划分为多个区域,每个区域单独建模辨识的方式。最后利用某星敏感器进行了实验,利用该方法进行模型修正后,星敏感器的测角精度为σx=1.68″、σy=1.91″,而修正前的测角精度为σx=17.43″、σy=23.46″。结果表明,采用该方法可以使星敏感器测角精度得到大幅提高,同时也完成了测角精度的检测。 相似文献
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一种无需乘法器的光斑质心定位方法 总被引:2,自引:0,他引:2
光斑质心定位在光学精密跟踪和精密测量中是一项关键技术,其精度和速度直接影响了光学测量的精度和响应速度.在实际应用中,往往把灰度重心法与图像预处理方法结合起来,以提高光斑质心计算的可靠性.运用图像预处理技术有效地抑制了噪声的影响,同时也会消耗大量的逻辑资源.针对在资源受限的条件下采用灰度重心法计算光斑质心的问题,本文提出了一种无需乘法器的光斑质心计算方法,用加法运算代替乘法运算,使用递推方法完成质心计算所需的低阶矩的运算.该方法的硬件仅为5个累加器,结构简单,能够以更低的资源消耗实现光斑质心定位.通过并行技术和流水线技术,其工作频率达到515 MHz.实验证明:本文的结构在FPGA内实现,在100 MHz的工作频率下,完成一帧质心计算的延时为0.35μs,误差与传统质心方法一致,占用214个Slices,其资源消耗仅为常规灰度重心法的50%. 相似文献
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We describe modeling and simulation results for the Thirty Meter Telescope on the degradation of sodium laser guide star Shack-Hartmann wavefront sensor measurement accuracy that will occur due to the spatial structure and temporal variations of the mesospheric sodium layer. By using a contiguous set of lidar measurements of the sodium profile, the performance of a standard centroid and of a more refined noise-optimal matched filter spot position estimation algorithm is analyzed and compared for a nominal mean signal level equal to 1000 photodetected electrons per subaperture per integration time, as a function of subaperture to laser launch telescope distance and CCD pixel readout noise. Both algorithms are compared in terms of their rms spot position estimation error due to noise, their associated wavefront error when implemented on the Thirty Meter Telescope facility adaptive optics system, their linear dynamic range, and their bias when detuned from the current sodium profile. 相似文献
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本文构建了基于CMOS图像传感器的高精度定位系统,并且研究光源、被测目标、测量系统与亚像元定位算法等因素对定位精度的影响.研究结果表明:光源与测量环境的稳定性是高精度测量的必要前提与关键因素;带阈值的质心算法对系统白噪声抑制能力基本相同,但对具有一定规律缓慢变化的干扰信号杭干扰能力不同,且带活动阈值的质心算法杭干扰能力... 相似文献
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Gregory F. Piepel 《技术计量学》2013,55(3):279-283
In constrained mixture experiments the centroid of a constraint region has traditionally been defined as the average of all extreme vertices of the region. This differs from the classical physics definition of a centroid as the center of mass (or volume) of a region. An algorithm for calculating a centroid based on the center of mass definition is discussed and illustrated with an example. This centroid calculation technique can be used to calculate centroids of various dimensional faces and edges of the constraint region as well as of the overall centroid. Results of the center-of-mass and averaged-extreme-vertices centroid computation techniques are compared using examples from the literature. 相似文献
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Shen J Zhang G Wei X 《Journal of the Optical Society of America. A, Optics, image science, and vision》2010,27(12):2638-2647
The elongated imaging track pertaining to a star spot recorded in the image sensor of a star tracker will diffuse over several pixels at a high angular velocity, leading to an inaccurate, even false, attitude value. A computer simulation of the attitude determination from a dynamic star tracker is developed first, based on a dynamic mathematical model of the star-spot imaging and an efficiency validation of the star centroiding algorithm in the dynamic condition. Then major error sources affecting the attitude accuracy in the dynamic condition are analyzed and discussed systematically based on the simulation results. A mathematical model calculating the average star number detected in the field of view is also deduced, using simulation results and signal processing theory, with image trailing ranging from 0 to 20 pixels during exposure. The summarized regularity is helpful in the system design and accuracy evaluation of a star tracker. 相似文献
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《成像科学杂志》2013,61(5):436-446
AbstractA novel hybrid technique of combining an improved morphological gradient operator and Zernike moments, named MGZ edge detection algorithm, is developed to meet the stringent requirements for measuring accuracies of charge coupled device metrology system. The mathematical morphological gradient and Zernike moment algorithm are discussed based on the pixels grey-scale and spatial structure information of the images. To improve the algorithm process, the image edge is oriented and extracted by using improved morphological gradient operator firstly; then, the calculation errors of the typical ideal step edge model are analysed and corrected by the proposed error compensation formula. The edge point is relocated with sub-pixel accuracy by means of Zernike moment operator based on the edge point vectors and the threshold value. Finally, the sub-pixel edge detecting of the image is attained. The extensive experimental results show that the measuring error of the edge point is compensated reliably and accurately, and the new algorithm has short operation time, more precise and stronger robustness to noise than the prior similar algorithms. Meanwhile, the proposed method can well meet the need of charge coupled device metrology system for sub-pixel edge detection. 相似文献