【作者】 黄海波；

【导师】 艾勇；

【作者基本信息】 武汉大学 ， 通信与信息系统， 2011， 博士

【摘要】 本文研究内容是在某重大课题的支持下展开的,目的是为了解决空间光通信在我国尤其是在国防应用的信息传输带宽瓶颈和传输安全问题。空间光通信由于具有通信码率高、容量大、高保密性、低功耗、体积小、重量轻及抗干扰能力强等优点,使之成为将来通信领域最具潜力的通信方式,已经或即将受到了越来越多关注。正是基于这种需求,我们和中国科技大学、清华大学组成的科研团队对空间光通信的关键技术展开了深入的研究和开发。我们课题组主要侧重于激光通信中的ATP关键技术和激光通信机展开理论研究和系统设计,尤其是在ATP关键技术方面获得了一些有意义的理论成果,并在样机设计上也取得了较好的结果。本文针对空间光通信ATP系统中的精跟踪子系统展开了理论研究和系统开发工作。首先对空间光通信的念、关键技术、发展现状和趋势进行介绍,并重点介绍了武汉大学在空间光通信方面的研究成果。进而对空间光通信ATP技术中的精跟踪关键技术发展概况进行了总结,包括精跟踪探测器、精密光束偏转机构、精跟踪图像处理技术和精跟踪伺服控制技术等。然后对空间光通信ATP系统的两个主要组成部分：粗跟踪和精跟踪的构成及其视场匹配和带宽匹配进行论述,指出粗精伺服单元带宽比越大,精跟踪伺服单元对于粗跟踪控制残差能力越强。分析了ATP精跟踪系统带宽的影响因素,并对四种误差源进行误差分配,在此基础上讨论精跟踪系统的带宽补偿校正技术,采用按照期望传输特性对精跟踪系统带宽进行串联优化补偿,使得精跟踪系统的开环和闭环传输带宽大大增加,稳定裕度满足要求,系统超调量小,响应速度快,达到精跟踪系统的稳态和动态指标。接着对精跟踪图像处理的常规步骤进行阐述,即光斑图像滤波、光斑图像分割、光斑质心定位技术。建立了基于小波多尺度卡尔曼光斑质心动态系统,基于该系统利用多尺度卡尔曼滤波、改进的质心算法和经典卡尔曼预测对光斑质心进行滤波、分割和定位综合一体的算法处理,实验分析表明,采用该算法处理后的光斑质心标准差大大减小,定位精度相对于传统算法提高了80%以上。介绍了模糊控制的基本术语和基础理论,在此基础上论述了模糊控制器的基本结构和设计过程。然后详细论述了两种自适应模糊控制器的设计方法,对直接自适应模糊控制在精跟踪系统的应用进行研究,采用自适应预测与模糊控制相结合的控制算法。仿真结果表明,自适应预测模糊PID控制比传统模糊PID控制具有更好的稳态性能,并且能够更快地适应被控对象参数的变化,是一种非常理想的控制策略。最后详细论述了开发的以DSP+FPGA为核心的嵌入式精跟踪控制系统,在单片FPGA中实现了全部精跟踪有关的camera link接口技术、图像处理技术和跟踪控制技术,实现了高带宽高精度的嵌入式精跟踪样机产品设计。实验测试表明,该系统抗噪能力强,跟踪精度高,可以满足空间光通信的一般应用需求。系统的跟踪带宽达到200Hz以上,对低频抖动的压缩比达到80%以上,抖动均方差小于一个像素,定位精度约为1μrad。更多还原

【Abstract】 The research content in this dissertation is developed under the sustentation fund of certain important task, the purpose is solve the application of space optical communication in our nation, especially the problem of information transmission band limitation and information security in the area of national defence and military affairs. Space optical communication has the characteristic of high communication rate, high capacity, high secrecy, low power consumption, small volume, light weight and high ability of anti-jamming, it will become the most potential communication style in the future communication domain, and attracts more and more attention in the world. Based on the need of space optical communication, we constitute the scientific group with Chinese science and technology university and Tsinghua University to develop thorough research and exploitation on space optical communication. The main function of our research team is declined on academic research and system design of ATP (Acquisition. Tracking and Pointing) key technology and laser communication device, especially have gained some significative research fruit, and achieved fair result of prototype laser communication device. This paper aims at the academic research and system design of fine tracking system of ATP system in space optical communication.above all. the concept of space optical communication, key technology, development status and trend is introduced, and the research fruits of Wuhan University laser communication lab is particularly presented, then key technology and development general situation of fine tracking of ATP system has been summed up. which consists of fine tracking detector, precise beam gauche setup, fine tracking image process technology and servo tracking technology.Then two main components of space optical communication ATP system, namely coarse tracking system and fine tracking system, are discussed, including their formation, visual field match and band match. The analysis shows that the bandwidth ratio is more lager, the inhibition residual error ability of coarse tracking is much higher. The influencing factors of ATP fine tracking system bandwidth is analyzed, and provides error distribution for four error sources, on the basis of which, bandwidth compensation correction technology of fine tracking system is discussed, adopting expectation transmission character for optimization compensation to fine tracking system bandwidth, which largely increases open loop and closed loop bandwidth of fine tracking system, stabilization margin meets the challenge, overshoot is small. response speed is rapid, steady and dynamic indicator of fine tracking system is achieved.In succession. traditional steps of fine tracking image processing is elaborated. including facula image filtering. facula image segmentation. facula centroid positioning. facula centroid dynamic system based on wavelet multi-scale kalman filter. on which multi-scale kalman filter, improved centroid algorithm and traditional kalman predictor are used to filter and segment and position the facula centroid. Experimental analysis indicates that standard deviation of facula centroid is largely reduced with this algorithm:poisoning precision increases 80% higher than traditional algorithm.Basic terminology and basic theory of fuzzy control are introduced, disserts on basic structure and design process of fuzzy controller. Then the design method of two kinds of self-adATPing fuzzy controller is disserted in detail, the application of direct self-adATPing fuzzy controller in fine tracking system is take in study, which algorithm adopts self-adATPing predictor and fuzzy controller. Simulation result shows that self-adATPing predictor fuzzy PID controller has better steady performance than traditional fuzzy PID controller. and rapidly adATPs to parameter change of controlled object, approves that it is fair ideal control strategy for fine tracking system.Finally the developed embedded fine tracking control system with the core of FPGA is dissertated in detail, all the technologies are assembled in single chip FPGA. including cameral ink interface technology, image processing technology and tracking and control technology, high bandwidth and high precision embed fine tracking prototype is designed. Experiment test indicates that this system has strong ability to cancel noise and high tracking precision, and meets the general application demand of space optical communication. The tracking bandwidth is up to 200Hz. the reduction ratio to low frequency dithering is more than 80%. the dithering mean square deviation is lower than 1 pixel, poisoning precision is about 1μrad.更多还原