E-mail Alert
RSS
The auto guiding system combined with sub-pixel real-time gray projection algorithm
-
摘要:
服务于现代天文望远镜的导行系统通常会受到大气和风载等干扰而引起导行信标重心位置计算不准确。为了有效解决这种问题，本文提出将具备亚像元和实时性的灰度投影算法嵌套到导行系统的重心算法中，从而在几乎不失时间分辨率的前提下减小一个导行闭环周期内的重心误差，达到提高导行系统性能的目的。首先，分析了高实时小偏差的导行信标重心计算是实现高性能导行系统的重要前提，并指出灰度投影算法在其中所起的重要作用。其次，分析了灰度投影算法能够与重心算法结合提高导行系统性能的原因，并针对传统灰度投影算法进行速度和分辨率的改进，以实现使用亚像元实时灰度投影算法与重心算法结合提高导行系统性能的目的。最后，将所提出的结合亚像元实时灰度投影算法的导行系统在400 mm口径望远镜上进行了测试，测试结果表明，本文所提出的方法能够在几乎不失时间分辨率的前提下较好地抑制风载的干扰，从而达到了提高导行系统性能的目的。
-
关键词:
- 导行系统 /
- 风载抑制 /
- 亚像素实时灰度投影算
Abstract:Guiding systems serving modern astronomical telescopes are usually subjected to atmospheric and wind-borne disturbances that result in inaccurate calculation of the center of gravity of the guiding beacon. In order to solve this problem effectively, the sub-pixel real-time gray projection algorithm is nested into the algorithm of center of gravity of auto guiding system, which reduces the jitter of the center of gravity in a closed-loop cycle of auto guiding system without losing time resolution and achieves the goal of improving the performance of auto guiding system. First of all, in the paper, we analyze that to implement high performance auto guiding system, obtaining high real-time and small error guiding beacon's center of gravity is significant, and point out that gray projection algorithm plays an important role in the course of obtaining the guiding beacon's center of gravity. Furthermore, after analyzing the reason that classic gray projection algorithm is able to be combined with the center of gravity to increase the performance of auto guiding system, we modify the classic gray projection algorithm in the speed and accuracy so as to combine the modified algorithm with the algorithm of center of gravity of auto guiding system and achieve the goal of improving the performance of auto guiding system. Finally, we test our auto guiding system with the algorithms mentioned above in a 400 mm aperture telescope, and conclude that our system can obviously decrease the random jitter caused by wind load at the cost of less decreasing temporal resolution, and achieve the goal of improving its performance.
-
Overview: Guiding systems serving modern astronomical telescopes are usually subjected to atmospheric and wind-borne disturbances that result in inaccurate calculation of the center of gravity of the guiding beacon. In order to solve this problem effectively, the sub-pixel real-time gray projection algorithm is nested into the algorithm of center of gravity of auto guiding system, which reduces the jitter of the center of gravity in a closed-loop cycle of auto guiding system without losing time resolution and achieves the goal of improving the performance of auto guiding system. First of all, in the paper, we indicate that the atmospheric turbulence and wind are two things that have a bad influence on the performance of auto guiding system, and then describe some existing methods used to suppress the two things. Afterwards, we have a knowledge about that to suppress the influence of the atmospheric turbulence, in a closed-loop cycle of auto guiding system, the time of calculating guiding beacon's center of gravity is significant, and to suppress the influence of wind, reducing the error of guiding beacon's center of gravity is indispensable. Therefore, we propose an efficient method that takes advantages of gray projection algorithm to calculate the displacement vector between adjacent images of auto guiding system in the time when the guiding beacon's center of gravity is computed, and then compensates the displacement vector for the center of gravity so that the influences from atmospheric turbulence and wind are suppressed, simultaneously. On the other hand, we are aware of that the performance of our method mentioned above can be further improved through rectifying three aspects of our method in algorithm. One is that making use of the structural similarity between gray projection algorithm and the algorithm of guiding beacon's center of gravity, some combinations between the two algorithms can be conducted to speed up their execution. Two is that through comparing with existing searching algorithms of minimum value of correlation function, which are an important part of gray projection algorithm, an efficient searching algorithm named as three point searching is further improved in order to obtain a promotion of computational speed of gray projection algorithm. Three is that based on the characteristic of correlation function of gray projection algorithm, an efficient fitting method in possession of a sub-pixel accuracy is applied to the correlation function so that the gray projection algorithm can obtain a sub-pixel accuracy. Finally, some experiments are conducted, and corresponding results show that our method can efficiently improve the performance of auto guiding system.
-
-
图 1 导行系统重心偏移图像。(a)参考帧图像及两帧重心；(b)当前帧图像及其重心
Figure 1. The deviation of center of gravity of the auto guiding system. (a) Reference image and the centers of gravity of reference image and current image; (b) Current image and its center of gravity
图 3 水平和垂直方向的相关函数曲线。(a) RX(mp)的曲线；(b) RY(mq)的曲线
Figure 3. Correlation function curves of horizontal and vertical direction. (a) The curve of RX(mp); (b) The curve of RY(mq)
图 4 重心算法和灰度投影算法嵌套伪代码
Figure 4. The pseudo code embedded in the algorithm of center of gravity and gray projection algorithm
图 5 相关函数搜索算法搜索示意图。(a)全局搜索算法的搜索过程；(b)中间向两边的三点搜索算法的搜索过程；(c)本文算法的搜索过程
Figure 5. The schematic diagrams of the searching algorithm of correlation function. (a) The global searching algorithm; (b) The three point searching algorithm from center to both sides; (c) Algorithm in this paper
图 7 随机风载作用下导行系统重心抖动对比测试。(a)测试时的随机风载测量值；(b)风载下重心坐标在X方向上的相对抖动；(c)风载下重心坐标在Y方向上的相对抖动
Figure 7. The auto guiding system's jitter of the center of gravity in the random wind load. (a) The measured values of wind load in our experiment; (b) The relative jitter of the center of gravity in the x direction; (c) The relative jitter of the center of gravity in the y direction
表 2 随机风载作用下重心抖动对比测试
Table 2. The comparison among jitters of the center of gravity accused by random wind load
方向 没有结合 结合本文的 结合传统的 X 均方根RMS/(″) 2.46 0.61 0.61 峰值PV/(″) 11.30 1.48 1.65 帧频/(f×s-1) 10.67 8.67 7.32 Y 均方根RMS/(″) 3.01 0.48 0.41 峰值PV/(″) 11.38 1.52 1.68 帧频/(f×s-1) 10.67 8.67 7.32 
下载: 导出CSV
-
[1] Mandrini C H, Schmieder B, Démoulin P, et al. Topological analysis of emerging bipole clusters producing violent solar events[J]. Solar Physics, 2014, 289(6): 2041-2071. doi: 10.1007/s11207-013-0458-6
[2] 邓林华. 一米红外太阳望远镜光电导行系统的研究[D]. 昆明: 中国科学院研究生院云南天文台, 2009.
Deng L H. Study on the auto guide unit system of one-meter infrared solar telescope in yunnan observatory[D]. Kunming: Yunnan Observatories, Chinese Academy of Sciences, 2009.
http://cdmd.cnki.com.cn/Article/CDMD-80023-2010042478.htm [3] 郭晶晶, 杨云飞, 冯松, 等.太阳望远镜高精度导行方法[J].科学通报, 2016, 61(10): 1112-1120. http://www.irgrid.ac.cn/handle/1471x/1049020
Guo J J, Yang Y F, Feng S, et al. High precision guide method for the solar telescope[J]. Chinese Science Bulletin, 2015, 61(10): 1112-1120. http://www.irgrid.ac.cn/handle/1471x/1049020
[4] 柳光乾. 一米红外太阳望远镜控制系统研制[D]. 昆明: 中国科学院研究生院云南天文台, 2011.
Liu G Q. Research and realization on control system of one meter infrared solar teleseope[D]. Kunming: Yunnan Observatories, Chinese Academy of Sciences, 2011.
[5] 柳光乾, 杨磊, 邓林华, 等.大气湍流对天文望远镜光电导行精度的影响[J].光学学报, 2013, 33(1): 7-11. http://www.cnki.com.cn/Article/CJFDTotal-GXXB201301001.htm
Liu G Q, Yang L, Deng L H, et al. Influence of atmospheric turbulence on the accuracy of astronomical telescope auto-guiding system[J]. Acta Optica Sinica, 2013, 33(1): 7-11. http://www.cnki.com.cn/Article/CJFDTotal-GXXB201301001.htm
[6] 柳光乾, 程向明, 宋腾飞, 等.一米太阳望远镜风载对伺服系统的影响及控制[J].光电工程, 2011, 38(6): 50-58. doi: 10.3969/j.issn.1003-501X.2011.06.009
Liu G Q, Cheng X M, Song T F, et al. The influence and control of wind loading on the one meter solar telescope servosystem[J]. Opto-Electronic Engineering, 2011, 38(6): 50-58. doi: 10.3969/j.issn.1003-501X.2011.06.009
[7] 李玉艳, 柳光乾.摆镜图像稳定控制系统在NVST中的应用研究[J].天文研究与技术, 2016, 13(1): 82-92. http://www.irgrid.ac.cn/handle/1471x/1061451?mode=full&submit_simple=Show+full+item+record
Li Y Y, Liu G Q. The study on the application of the stabilized control system for the tip-tilt mirror image in NVST[J]. Astronomical Research & Technology, 2016, 13(1): 82-92. http://www.irgrid.ac.cn/handle/1471x/1061451?mode=full&submit_simple=Show+full+item+record
[8] Close L M, McCarthy D W. High resolution imaging with a tip-tilt Cassegrain secondary[J]. Publications of the Astronomical Society of the Pacific, 1994, 106(695): 77-86.
[9] Didkovsky L V, Dolgushyn A, Marquette W, et al. High-order adaptive optical system for big bear solar observatory[J]. Proceedings of SPIE, 2003, 4853: 630-639. doi: 10.1117/12.471341
[10] 敦广涛, 屈中权.光纤阵列太阳光学望远镜偏振分析器设计[J].天文学报, 2012, 53(4): 342-352. http://www.irgrid.ac.cn/handle/1471x/1049492?mode=full
Dun G T, Qu Z Q. Design of the polarimeter for the fibre arrayed solar optical telescope[J]. Acta Astronomica Sinica, 2012, 53(4): 342-352. http://www.irgrid.ac.cn/handle/1471x/1049492?mode=full
[11] Qu Z Q. A fiber arrayed solar optical telescope (FASOT)[C]//Proceedings of 6th Solar Polarization Workshop, 2011, 437: 423.
[12] 李长松, 姜爱民.空间太阳望远镜相关计算的FPGA实现技术[J].宇航学报, 2008, 29(4): 1350-1357. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-ZGTW201110001160.htm
Li C S, Jiang A M. The realization of sst's correlation calculation based on FPGA[J]. Journal of Astronautics, 2008, 28(4): 1350-1357. http://cpfd.cnki.com.cn/Article/CPFDTOTAL-ZGTW201110001160.htm
[13] 汪小勇. 基于灰度投影的实时电子稳像算法研究[D]. 杭州: 浙江大学, 2006.
Wang X Y. The research of real-time electronic image stabilization algorithm based on gray projection[D]. Hangzhou: Zhejiang University, 2006.
http://cdmd.cnki.com.cn/Article/CDMD-10335-2006041830.htm [14] 张艳超, 王芳, 赵建, 等.投影特征峰匹配的快速电子稳像[J].光学精密工程, 2015, 23(6): 1768-1773. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=gxjmgc201506034
Zhang Y C, Wang F, Zhao J, et al. Fast digital image stabilization based on characteristic peak of projection matching[J]. Optics and Precision Engineering, 2015, 23(6): 1768-1773. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=gxjmgc201506034
[15] 孙辉.快速灰度投影算法及其在电子稳像中的应用[J].光学精密工程, 2007, 15(3): 412-416. https://www.wenkuxiazai.com/doc/0c56c91355270722192ef75d.html
Sun H. Fast gray projection algorithm and its application to electronic image stabilization[J]. Optics and Precision Engineering, 2007, 15(3): 412-416. https://www.wenkuxiazai.com/doc/0c56c91355270722192ef75d.html
[16] 张永祥, 赵晓旭, 张伟功, 等.一种基于灰度投影的电子稳像改进算法[J].微电子学与计算机, 2008, 25(11): 212-215. http://www.cqvip.com/qk/92040X/200811/28772113.html
Zhang Y X, Zhao X X, Zhang W G, et al. An improved electronic image stabilization algorithm based on gray projection algorithm[J]. Microelectronics & Computer, 2008, 25(11): 212-215. http://www.cqvip.com/qk/92040X/200811/28772113.html
[17] 李博, 王孝通, 杨常青, 等.电子稳像的灰度投影三点局域自适应搜索算法[J].光电工程, 2004, 31(9): 69-72. doi: 10.3969/j.issn.1003-501X.2004.09.018
Li B, Wang X T, Yang C Q, et al. Three-point locally adaptive searching in gray scale projection algorithm for electronic image stabilization[J]. Opto-electronic Engineering, 2004, 31(9): 69-72. doi: 10.3969/j.issn.1003-501X.2004.09.018
[18] 孙辉, 张永祥, 熊经武, 等.高分辨率灰度投影算法及其在电子稳像中的应用[J].光学技术, 2006, 32(3): 378-380. http://www.cqvip.com/QK/92835A/200703/24038757.html
Sun H, Zhang Y X, Xiong J W, et al. The application of high resolution gray projection algorithm in electronic image stabilization technology[J]. Optical Technique, 2006, 32(3): 378-380. http://www.cqvip.com/QK/92835A/200703/24038757.html
-
点击扫一扫
图(7)
表(2)
计量
- 文章访问数: 7438
- PDF下载数: 2682
- 施引文献: 0
