路面检测车新型主动悬架LQG控制的研究

为弥补路面检测车车身振动位移所导致的图像偏移,提出了设计新型主动悬架系统来抑制车身振动位移方法。根据极小值原理推导了新型主动悬架LQG控制规律,利用Matlab软件仿真分析了被动悬架、传统主动悬架LQG控制器和新型主动悬架LQG控制器对图像偏移量补偿的效果。仿真结果表明,新型主动悬架LQG控制器对图像偏移量进行补偿的效果最好,优于电子稳像技术所取得的效果。     

偏流角误差对TDI CCD相机成像的影响与仿真

本文分析了TDI CCD相机的偏流角调整过程和偏流角误差匹配的影响因素,依据偏流角误差导致的姿态稳定度偏差对相机成像质量的影响,建立推扫相机像点与物点一一对应的数学模型,根据TDI CCD成像时超出对应像素的横向与纵向偏移量的累加计算,仿真卫星姿态稳定度改变时相机的成像;同时,利用单轴气浮转台和面阵CCD进行成像实验,将实验条件的像移速度与仿真条件的像移速度匹配,并对面阵CCD成像进行偏移量的累加,模拟推扫CCD成像,最后利用图像对比度和互相关相似性测度分析仿真成像与实验成像质量。仿真成像与实验成像在对比度和互相关相似性测度上相差为0．03左右,能较好满足地面卫星相机连调试验的图像仿真。     

航空相机的像移计算及其补偿分析

航空相机拍照时难免会产生像移,要提高成像质量和相机分辨力必须进行像移补偿。推导出前向像移、飞行器俯仰、滚动和偏航产生的像移及其误差计算公式,以美国 KS-146 航空侦察相机为例,计算出前向像移的大小数量级在 10-3,而其它像移量大小则为 10-4数量级,提出在航空垂直拍照时前向像移占主导地位,应作为像移补偿的主要方向,同时提出在航空相机设计中通过缩短曝光时间和提高快门精度等途径来减小像移、增强航摄图像的清晰度。     

一种彩色大面阵航空遥感相机前向像移补偿机构设计及精度分析

提高彩色大面阵航空遥感相机地面分辨力需设计像移补偿环节以消除工作时CCD像面的像移,本文在分析航空遥感器4种像移补偿方式及像移补偿机构设计原则的基础上,针对某航空遥感器的要求设计了一种前向像移补偿机构,利用等径共轭凸轮机构将电机旋转转化为直线运动,并配合精密直线导轨约束运动自由度。具有传动简单,精度较高的优点,可有效的避免传动误差。分析了原动件输入速度波动、制造误差对像移补偿残差的影响,并对像移补偿总体效果进行了评价。试验数据及数据分析表明,像移补偿机构的补偿残差小到600μm/s,动态目标发生器及外场航拍图像良好,满足使用要求。     

大面阵数字航测相机像移补偿的实现

航空拍摄时,由于飞机与地面景物存在相对速度等原因的存在,发生像移是难免的。为了提高航拍图像的成像质量及相机分辨率,大面阵数字航测相机设计开发了像移补偿装置。采用了由步进电机驱动凸轮机构从而推动CCD平动的像移补偿方法。依据相应的补偿原理,得出航拍过程中的理论像移量。经过航拍实验验证,设计的补偿装置实际补偿后的地物位移量小于1/3像元。     

像移和采样共同作用下的TDICCD探测器像质

CCD探测器的像元尺寸一般来说是光学系统弥散斑的几倍,因此以CCD探测器为接收器的光学成像系统在理论上可以近似看作是空间移不变系统。采用计算机仿真的方法来研究在空间移变条件下的TDICCD遥感相机的影像分辨力和像质问题,结果是：在目标条带宽度一定时,像元尺寸为a,像移量为a/3,a/2,a,MTF分别下降为0．918,0．876,0．753;当MTF基本相等时,像移量为a/3,a/2,a,条带宽度为36,38,44。通过模拟,认识到在像移大于a/3时,Angle=0和Angle≠0的肘阡相差小于1％;并在像移量大于a/3的条件下得到了适用于工程应用的像元尺寸、像移量、分辨力、MTF的一个简洁函数。     

刃边法计算在轨卫星图像MTF的仿真分析

调制传递函数（MTF）较之仅凭借某一个数字量（分辨率、清晰度等）来对成像系统进行质量评价更具有权威性。刃边法适合卫星在轨的特性，易于实现，无需人工对在轨遥感器输入激励信号。本文在实现刃边法计算图像MTF的算法的基础上，通过仿真，分析了像移、刃边角度、噪声对MTF计算结果的影响，并对算法精度进行了检验。仿真结果表明，本文的计算在轨卫星图像MTF的方法具有较高的精度，并且能较好地抵抗噪声。     

飞机大坡度转弯对航空相机成像的影响

飞机姿态变化是影响航空相机成像质量的关键因素,尤其是飞机进行大坡度转弯将影响航空相机照相分辨率和重叠率。采用公式推理、坐标旋转变换等方法详细分析了飞机大坡度转弯对相机照相分辨率和重叠率的影响,并以摆扫型全景相机为例,给出了飞机大坡度转弯时相机的像移模型,分析结果表明:飞机大坡度转弯过程中相机产生的最大前向像移量接近4个像素,需要进行像移补偿;而垂直飞行方向上的最大像移量小于1/8像元,对成像分辨率影响不大。依据分析结果对像移模型进行了简化,为像移补偿提供了理论依据。针对飞机大坡度转弯对照相重叠率的影响,提出了依据转弯半径和转弯角速率调整曝光时间的方法加以解决。上述分析为摆扫相机在大坡度转弯时获取高质量图像提供了理论依据。     

LCD谱熵及其在滚动轴承退化状态识别中的应用

针对滚动轴承在出现故障时其振动信号呈现出非线性、非平稳特性,以及退化特征难以提取等问题,将局部特征尺度分解法应用到轴承振动信号分析中,并与信息熵理论融合提出局部特征尺度分解谱熵的滚动轴承退化特征指标。该方法首先对不同故障程度的轴承振动信号做局部特征尺度分解,基于得到的内禀尺度分量计算振动信号得能谱熵、奇异谱熵和包络谱熵用于表征轴承故障程度,仿真信号分析结果表明以上特征指标能够较好地反映滚动轴承的退化状态。对内圈故障和外圈故障模式下不同程度故障的轴承振动信号进行分析,结果表明该文提出的退化特征能够有效表征轴承的退化状态,并采用灰关联分析法构建轴承退化状态识别模型,可有效实现轴承退化状态识别。     

某型航侦CCD相机姿态扰动像移计算

根据某型推扫式航侦相机的工作原理,利用共线方程,以坐标系旋转代替姿态变化,得出像移与姿态扰动和成像倾角的解析表达式.并在此基础上结合工作参数对成像倾角和姿态扰动共同作用下的像移进行仿真,分析其结果知当成像倾角在0.13 rad范围内变化时,像移与成像倾角无关,与姿态扰动量成线性关系;当成像倾角超过这个范围时,像移与成像倾角之间存在非线性,但整体趋势仍然是随着各扰动量的增加而增加.这为同类相机及像移补偿装置的设计提供理论依据.     

Enhanced-resolution image restoration from a sequence of low-frequency vibrated images by use of convex projections

An algorithm to increase the spatial resolution of digital video sequences captured with a camera that is subject to mechanical vibration is developed. The blur caused by vibration of the camera is often the primary cause for image degradation. We address the degradation caused by low-frequency vibrations (vibrations for which the exposure time is less than the vibration period). The blur caused by low-frequency vibrations differs from other types by having a random shape and displacement. The different displacement of each frame makes the approach used in superresolution (SR) algorithms suitable for resolution enhancement. However, SR algorithms that were developed for general types of blur should be adapted to the specific characteristics of low-frequency vibration blur. We use the method of projection onto convex sets together with a motion estimation method specially adapted to low-frequency vibration blur characteristics. We also show that the random blur characterizing low-frequency vibration requires selection of the frames prior to processing. The restoration performance as well as the frame selection criteria is dependent mainly on the motion estimation precision.     

振动条件下的尼龙拉链厚度尺寸视觉在线测量算法

针对尼龙拉链厚度尺寸的视觉在线测量过程中,振动对测量结果影响较大的问题,通过对拉链振动的机理分析,建立并求解出被测拉链横向振动模型的运动方程,再结合LK(Lucas Kanade)光流法测量原理,求取出某一时刻的拉链全局振动信息。在此基础上,提出了一种振动条件下的尼龙拉链厚度尺寸的视觉在线测量算法。首先提取出待补偿图像中被测拉链的边缘点坐标,其次根据运动补偿算法修正边缘点坐标,接着利用最小二乘法将边缘点坐标拟合成平行直线并求出其间距,最后根据像素当量转换为拉链厚度的实际尺寸。实验结果表明:该算法测量结果的不确定度为0.00051mm,远优于无运动补偿的视觉测量方法测量结果,能有效地抑制拉链振动对测量结果的影响。     

Motion feature extraction for stepped frequency radar based on Hough transform

The high resolution range profile can be obtained through coherent pulse compression processing in every coherent processing interval (CPI) for stepped frequency radars (SFR). The radar observation time can be divided into multiple CPIs. By utilising the temporal information inherent to a sequence of these range profiles, a time-range image containing the target motion information can be synthesised. Through analyses of the point scatterer targets with the radial uniform motion, radial uniformly accelerated motion, rotation and vibration, this study indicates that there is a certain correlation between the target motion features and the time-range image features in the limited observation time. Based on this result, we propose a motion feature extraction method for SFR without any assistant information using the conventional and well-known feature extraction tool, Hough transform. The authors give detailed analyses and explanation of this method, and verify them by outfield experiments, demonstrate the motion feature extraction results using real radar data. The proposed method enables the motion feature extraction through space non-coherent integration, which fully utilises the radar data information under low signal-to-noise ratio conditions.     

运动模糊不变量研究

图像的运动模糊是摄像机在曝光期间与场景间相对运动而造成的图像退化,但现有算法对运动模糊的恢复精度有限.本文分析了图像运动模糊的退化模型,提出了运动模糊不变量的概念,证明了图像零阶矩、第一个Hu不变矩和SIFT为运动模糊不变量,并给出了测试和应用.结果表明运动模糊不变量是存在的,而且可以用于不确定性运动模糊图像的匹配和识别领域.     

一种基于印刷图像处理技术的模糊图像复原方法

根据印刷图像处理技术的基本原理,针对印前的电子出版图像处理中存在的原稿图像运动模糊现象,介绍了约束最小二乘方滤波复原技术消除图像模糊方法.阐述了运动模糊图像的退化模型和复原模型,利用二值图的信息来估计模糊方向,通过对二值图的矩阵变换来估计模糊尺度,再利用约束最小二乘方滤波的方法复原图像.实验表明,该方法行之有效.     

图像插值分析的交互式分层复原

为了复原模糊图像以得到可辨识的目标,分析相机与目标高速相对运动时产生的两种模糊性质,针对其退化函数难以确定的特点,提出一种基于图像插值分析的交互式分层复原方法,该方法首先对图像进行插值,以提高对低分辨率图像退化机理的分析能力,并在分析的基础上进行图像预处理.然后在图像复原的优化准则下,交互地选择出降质模型的最优参数组合,以得到两个降质函数,最后对原图像实施分层复原.对仿真图像进行实验,基本上恢复了目标图像的特征,证明该方法复原效果比较理想.     

A stretching transform‐based automatic nonrigid registration system for cerebrovascular digital subtraction angiography images

In the cerebrovascular digital subtraction angiography (DSA), patient motion is the primary cause of image quality degradation. In this article, we describe a nonrigid image registration system for motion artifact reduction in DSA which is fully automatic, effective, and computationally very efficient. In this system, the mask image is partitioned to generate the appropriate control points. The energy of histogram of differences method is adopted as similarity measurement, and the Powell algorithm is utilized for acceleration. A forward stretching transformation is used to complete the motion estimation, and an inverse stretching transformation is used to generate the target image by pixel mapping strategy. The method of this system is effective to maintain the topological relationships of the gray value before and after the image deformation. Preliminary experiments on the cerebrovascular DSA images illustrate the applicability of the system. After the deformation, the mask image remains clear and accurate contours, and the quality of the subtraction image after the registration is favorable. © 2013 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 23, 171–187, 2013     

滚动轴承的振动性能退化过程与保持可靠性研究

为了分析滚动轴承的振动性能退化过程与保持可靠性之间的关系,提出一种基于最大熵法和相似度法的滚动轴承振动性能退化模型,并对滚动轴承的退化过程进行评估;然后基于最大熵法和泊松过程建立滚动轴承振动性能保持可靠性模型;最后基于灰关系理论对滚动轴承的性能退化序列和保持可靠性序列进行分析。实验结果表明,所提出的滚动轴承振动性能退化模型能够有效地识别滚动轴承的退化状态,并且滚动轴承振动性能保持可靠性的演变历程与振动性能退化过程之间有明显的灰关系,可信水平均达到80%以上。     

General restoration filter for vibrated-image restoration

Mechanical vibrations are often the principal cause of image degradation. Low temporal-frequency mechanical vibrations involve random image degradation that depends on the instant of exposure. Exact restoration requires the calculation of a specific filter unique to each vibrated image. To calculate the restoration filter for each image, one needs the specific optical transfer function unique to the motion in the image. Therefore the instant of exposure and the motion function have to be measured or estimated by some other means. We develop a restoration filter for individual images blurred randomly by low-frequency mechanical vibrations. The filter is independent of the instant of exposure. The filter is designed to give its best performance averaged over a complete ensemble of vibrated images. Although when applying the new filter to any vibrated image the restoration achieved is slightly poorer than that achieved with an exact filter unique to the specific motion function, the new filter has the advantage of simplicity.     

Vision method of inspecting missing fastening components in high-speed railway

The increasing train speed on railways generates an urgent need for more powerful automatic inspection of railway tracks, including real-time fastening component inspection. To obtain better high-speed performance with lower cost, this paper has proposed a novel structured light method based on motion image (SLMMI) for moving object inspection. The motion images in the proposed method are insensitive to motion, abundant with information, and easy to process, resulting in a low performance requirement of the hardware. Compared to the conventional unstructured light method and structured light method, the proposed method inherits the virtues of both thus offering a fresh perspective when inspecting missing fastening components on high-speed railways. By using the SLMMI and the recognition method based on a neural network, the experimental results yield good performance in terms of speed and accuracy. Furthermore, the robustness of the proposed method is also discussed and simulated by adding typical interferences, such as ambient light, vibration, and obstacles.