本文選題：旋轉(zhuǎn)式合成孔徑雷達　切入點：三維成像　出處：《西安電子科技大學》2014年博士論文　論文類型：學位論文

【摘要】：旋轉(zhuǎn)式合成孔徑雷達(ROSAR)是一種新型的雷達成像模式，它既保留了傳統(tǒng)合成孔徑雷達(SAR)全天候、全天時、電磁穿透等優(yōu)點，又具有重訪周期短、全視域成像等卓越性能，廣泛應用于自然災難應急救援、地下資源勘探、公共場所無損安檢、戰(zhàn)場監(jiān)視以及低空火力支援等領(lǐng)域。直升機等旋翼飛行器是ROSAR模式最為典型的應用平臺，ROSAR天線固定在剛性支架上，并指向外圍隨機翼一起做勻速圓周運動，天線旋轉(zhuǎn)一周即能完成周圍場景一次探測。該技術(shù)巧妙地利用了機翼旋轉(zhuǎn)特性，僅需要一個天線的旋轉(zhuǎn)運動，就能形成方位向圓弧形合成孔徑，從而實現(xiàn)周圍場景二維成像，極大地提高了飛行器的飛行安全。但是面對低空飛行任務(wù)，周圍場景通常非常復雜，而獲取的二維圖像將可能錯誤地反映潛在威脅物的空間信息，為此開展ROSAR三維成像研究顯得尤為必要。 本文以滿足低空空域安全飛行為目的，針對ROSAR三維成像中的關(guān)鍵問題和技術(shù)難點，圍繞973項目“復雜低空飛行的自主避險理論與方法研究”、國家自然科學基金“機載毫米波雷達旋轉(zhuǎn)合成孔徑成像處理方法研究”等項目的研究任務(wù)，從ROSAR三維成像模型和三維成像方法等方面展開研究。具體的工作和貢獻如下： 1.介紹了傳統(tǒng)的二維ROSAR模型，為后續(xù)的三維成像理論奠定基礎(chǔ)。針對現(xiàn)有的二維成像方法運算量大、大方位角散焦問題，提出了一種基于頻譜重構(gòu)的二維ROSAR成像方法。通過分析ROSAR回波信號形式，對其直接進行傅立葉變換，獲取二維精確頻譜表達式。由于精確頻譜的形式過于復雜，導致后續(xù)處理無法進行，折中考慮頻譜的精確性和可操作性，采用四階頻譜重構(gòu)的方法，獲取形式簡潔、保留較多信息的高階頻譜，并基于該頻譜提出ROSAR距離徙動算法(RMA)和調(diào)頻變標算法(CSA)。仿真實驗表明，在方位角不大于90度情況下，頻譜重構(gòu)方法都能實現(xiàn)高精度快速成像。 2.建立了ROSAR干涉成像模型，并重點分析了非理想情況載機平臺的軸偏移問題。通過ROSAR技術(shù)和干涉方法相結(jié)合，要求載機平臺在不同高度上進行懸停，每懸停一次獲取一組場景數(shù)據(jù)，對錄取的數(shù)據(jù)進行成像和干涉處理，可實現(xiàn)周圍場景全視域三維成像。針對平臺運動非理想情況，討論了軸偏移對方位帶寬、圖像位置和干涉相位的影響。軸偏移導致干涉相位中增加一項附加相位，通過推導和分析附加相位形式，構(gòu)建了一個相位補償函數(shù)，由于該函數(shù)需要場景高度這一未知信息，預先假設(shè)所有場景高度為零，然后通過構(gòu)建相位加權(quán)因子來消除高度置零的影響。最后對軸偏移的影響進行仿真實驗，，并獲取了仿真場景三維高程圖。 3.建立了旋轉(zhuǎn)上升合成孔徑雷達(SSAR)三維成像模型，并提出一種適用于該模型的三維成像算法。在現(xiàn)有的二維ROSAR技術(shù)的基礎(chǔ)上，SSAR利用載機平臺上升在高度向上形成第二個合成孔徑，天線受水平旋轉(zhuǎn)和勻速上升的共同作用，在空中形成一個圓柱形合成陣面，同時結(jié)合距離向發(fā)射的寬帶信號，使得該模型具有三維成像能力。關(guān)于三維成像算法，為了降低成像處理難度，首先分析方位向采樣和高度向上升對天線位置的影響，并構(gòu)建位置偏移補償函數(shù)，將“旋轉(zhuǎn)上升”模式簡化為沿高度向“一步一懸�！蹦Ｊ�。然后分析了簡化模式的相位歷程，計算高度向中心頻率偏移量，推導波數(shù)域三維匹配函數(shù)，構(gòu)建波數(shù)域插值函數(shù)，進而實現(xiàn)簡化模式的三維成像。最后對該模型進行了性能分析，并通過仿真實驗驗證成像算法的有效性。 4.建立了前行ROSAR(FMROSAR)三維成像模型，并針對該模型提出了一種三維成像算法。在前行狀態(tài)下，天線指向前方區(qū)域發(fā)射寬帶信號，同時受到平臺前行和機翼旋轉(zhuǎn)的共同影響，在空中形成一個水平合成陣面，結(jié)合距離向高分辨能力以及二維陣面分辨能力，F(xiàn)MROSAR可實現(xiàn)三維前視成像。FMROSAR成像算法包括模式簡化和簡化模式三維成像兩大步驟。首先通過方位向偏移補償和順軌向偏移補償，將前行模式簡化為沿順軌向“一步一�！蹦Ｊ�。針對“一步一停”模式，又細分為距離-方位成像和距離-順軌成像兩個子步驟。在后者的成像過程中，分析了平臺運動對方位角變化的影響，并給出了順軌向有效聚焦的約束條件。同時考慮順軌向大斜視成像情況，提出了一種改進的距離多普勒算法(RDA)。最后分析了上述模型的性能，并驗證了成像算法的有效性。
[Abstract]:Rotary synthetic aperture radar (ROSAR) is a new radar imaging mode, it retains the traditional synthetic aperture radar (SAR) all-weather, all day long, and has advantages of electromagnetic penetration, revisit period, full horizon imaging, superior performance, are widely used in natural disaster emergency rescue, underground resources exploration. Public security surveillance and nondestructive, low fire support and other fields. Helicopter rotor aircraft is the most typical application platform for ROSAR mode, the ROSAR antenna is fixed in a rigid frame, and point to the periphery of the random wing do uniform circular motion, antenna rotation can be completed around the scene of a detection. This technology skillfully the wing rotation characteristics, rotational motion requires only one antenna, can form azimuth circular synthetic aperture, so as to realize the scene around two-dimensional imaging, greatly improve the vehicle Flight safety. But in the face of low altitude missions, the surrounding scenes are usually very complex. The two-dimensional images acquired will probably reflect the spatial information of potential threats wrongly. Therefore, it is necessary to carry out ROSAR 3D imaging research.
In this paper, in order to meet the low altitude airspace flight safety for the purpose, aiming at the key problem of ROSAR three-dimensional imaging and technical difficulties, around the 973 project "complex low flying self hedging theory and research method, research project of National Natural Science Foundation of airborne imaging rotating synthetic aperture millimeter wave radar research method", and carries out the research on ROSAR 3D imaging model and 3D imaging methods. The specific work and contributions are as follows:
The 1. introduces the traditional two-dimensional ROSAR model, lay the foundation for the subsequent three-dimensional imaging theory. According to the calculation of two dimensional imaging method of existing large amount of large azimuth defocus problem, proposed a two-dimensional ROSAR imaging method based on spectral reconstruction. By analyzing the form of the ROSAR echo signal and the Fu Liye transform directly to obtain two-dimensional the precise spectrum expression. Due to the precise spectrum form is too complex, resulting in subsequent processing can not be carried out, the trade-off between accuracy of spectrum and maneuverability, by using the method of four order spectrum reconstruction, obtain simple form, high order spectrum retain more information, and based on the proposed ROSAR spectrum range migration algorithm (RMA) and FM scaling algorithm (CSA). Simulation results show that the azimuth angle of not more than 90 degrees, the spectrum reconstruction method can achieve fast imaging with high precision.
2. an imaging model of ROSAR interference, and analyzes the problem of non ideal axis aircraft platform. Through the combination of ROSAR technique and the interference method, requirements of aircraft platform were hovering at different heights, each one gets a set of hovering scene data, on admission according to the number of imaging and interferometric processing. Can realize the full view around the scene of 3D imaging. Based on the ideal of non platform movement, discusses on the azimuth bandwidth axis offset, affect the image position and the interference phase. The shaft offset resulted in increased an additional phase interferometric phase, through the derivation and analysis of the additional phase form, construct a phase compensation function, because the function the height of the unknown scene information, presupposes all the scenes height is zero, then through the construction phase weighting factor to eliminate the influence of height zero. Finally simulation effect on axial offset The experiment was carried out and the 3D elevation map of the simulation scene was obtained.
3. the establishment of a spin up of synthetic aperture radar (SSAR) imaging model, 3D imaging algorithm and propose a suitable for this model. Based on two-dimensional ROSAR technology on the SSAR based aircraft platform increased form second in height to the synthetic aperture, the interaction of antenna by horizontal rotation and uniform rising and form a cylindrical synthetic array in the air, combined with the distance to transmit broadband signal, makes the model has three-dimensional imaging capabilities. A 3D imaging algorithm, in order to reduce the difficulty of image processing, the first analysis of azimuth sampling and height to the impact of rising position of the antenna, and construct the offset compensating function, simplified spin up "mode to" step along the height of a hover mode. And then analyzes the simplified phase process model, calculating the height to the center frequency offset, derived 3D wavenumber domain The matching function is used to construct the interpolation function in wavenumber domain, and then the simplified mode of 3D imaging is realized. Finally, the performance of the model is analyzed, and the effectiveness of the algorithm is verified by simulation experiments.
4. established ROSAR before (FMROSAR) 3D imaging model, and presents a 3D imaging algorithm based on this model. In the moving state, the antenna pointing to the front region to transmit broadband signals, at the same time by the platform forward and wing rotating joint effects of the formation of a water level synthesis array in the air, with high range resolution two dimensional array capability and resolution, FMROSAR can realize three-dimensional forward-looking imaging.FMROSAR imaging algorithm including model simplification and model of 3D imaging of two steps. Firstly, the azimuth offset compensation and orbit to offset compensation, will walk along the track model is simplified as "a step in a stop mode. According to the" one step one stop "mode, and subdivided into range azimuth imaging and imaging distance along track two sub steps. In the imaging process, analyzes the influence of platform motion azimuth changes, and gives the travel direction Considering the constraint condition of effective focusing, an improved range Doppler algorithm (RDA) is proposed considering the situation of imaging along the track to the large squint. Finally, the performance of the above models is analyzed, and the effectiveness of the imaging algorithm is verified.

【學位授予單位】：西安電子科技大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TN957.52

【參考文獻】

相關(guān)期刊論文 前10條

1 任笑真;楊汝良;;機載前視SAR三維成像原理及分辨率分析[J];電子科技大學學報;2010年05期

2 井偉;張磊;邢孟道;保錚;;聚束式SAR的寬場景成像算法[J];電子學報;2009年03期

3 孫兵周;蔭清;陳杰;李春升;;廣域觀測圓軌跡環(huán)掃SAR成像模式研究[J];電子與信息學報;2008年12期

4 任笑真;楊汝良;;機載前視SAR三維成像算法研究[J];電子與信息學報;2010年06期

5 林峗;譚維賢;洪文;王彥平;吳一戎;;圓跡SAR極坐標格式算法研究[J];電子與信息學報;2010年12期

6 廖軼;周松;邢孟道;保錚;;一種基于級數(shù)反演的機載圓跡環(huán)掃SAR成像算法[J];電子與信息學報;2012年11期

7 ;Synthetic aperture radar tomography sampling criteria and three-dimensional range migration algorithm with elevation digital spotlighting[J];Science in China(Series F:Information Sciences);2009年01期

8 洪文;;圓跡SAR成像技術(shù)研究進展[J];雷達學報;2012年02期

9 李清泉,李必軍,陳靜;激光雷達測量技術(shù)及其應用研究[J];武漢測繪科技大學學報;2000年05期

10 吳雄峰;王彥平;吳一戎;洪文;;圓周合成孔徑雷達投影共焦三維成像算法[J];系統(tǒng)工程與電子技術(shù);2008年10期

相關(guān)博士學位論文 前5條

1 胡銳;慣性輔助GPS深組合導航系統(tǒng)研究與實現(xiàn)[D];南京理工大學;2010年

2 曾齊紅;機載激光雷達點云數(shù)據(jù)處理與建筑物三維重建[D];上海大學;2009年

3 姚春靜;機載LiDAR點云數(shù)據(jù)與遙感影像配準的方法研究[D];武漢大學;2010年

4 王金峰;SAR層析三維成像技術(shù)研究[D];電子科技大學;2010年

5 李文超;雙基地前視合成孔徑雷達運動補償[D];電子科技大學;2012年

本文編號：1582074