【作者】 周伟；

【导师】 田红旗；

【作者基本信息】 中南大学 ， 载运工具运用工程， 2012， 博士

【摘要】 强风地区铁路接触网的防风安全对确保高速铁路运输安全、提高运输效率具有重要意义,本文采用机器视觉技术对接触网关键部位风偏量、接触网支柱振动量等技术参数进行在线检测,结合有限元静、动力学数值仿真及空气动力学流场分析结果,研究试验现场不同接触悬挂定位方式等条件下接触网风偏响应机理。论文提出并实现了一种基于机器视觉的电气化铁道接触网风偏量检测技术,通过静、动态特征点目标靶面匹配及观测基准失稳运动补偿,以支柱顶端面阵CCD相机的静态特征点靶面动态投影反馈支柱振动响应,结合动态特征点靶面投影中心的像素坐标偏移反推接触悬挂动态特征点的绝对风偏像素偏移,从而实现接触导线、承力索及吊弦等接触悬挂关键部位的横向、抬升风偏及扭转角三分量运动检测。检测算法的实现上,建立了摄像机坐标系下观测基准失稳运动的静态特征点运动反馈数学模型,基于接触网支柱的悬臂梁力学模型分析了最恶劣风环境下支柱在CCD相机安装高度位置的最大挠度及转角值,依据所得参数进一步分析了基准失稳所导致的检测误差构成,同时在此基础上创建并优化了支柱结构的振动检测数学模型和动态特征点的绝对风偏检测数学模型；图形处理算法的实现上,针对现场复杂光照条件和背景干扰,提出了基于改进RGB特征算子的自动阈值寻优分割算法和基于对比度拉伸的一阶亮度矩寻优分割算法,并以彩色图像分割得到的二值化图像为条件构造了基于面积法和几何法的目标偏移及扭转特征提取算法。论文从理论和数值计算两方面分别对铁路接触网风偏数值仿真方法进行了研究。理论建模方面,基于平均风速的静态计算法分别对简单自由悬挂和全补偿链形悬挂的风偏理论公式进行了推导,考虑沿跨长方向吊弦动态作用力变化对风偏理论模型进行了修正。数值仿真方面,针对接触网用多股绞线结构的股间几何协调及材料弹性理论,构造了一种既能精确模拟绞线力学行为、又能最大程度减缩求解自由度的新型有限元分析模型；建立了柔性、大跨距、大变形接触网悬索结构的几何非线性有限元求解列式；考虑接触悬挂与支撑结构的互约束创建了能够反映不同定位方式下不同风偏响应机制的接触网耦合分析体系；基于WAWS谐波合成法生成随机风场作为分析的载荷条件输入。采用提出的风偏视觉检测技术和数值模拟方法,论文通过现场试验、理论模型及有限元分析、三维流场数值仿真分别对试验段接触网特征点风偏响应和现场地形地貌影响下导线部位的流场分布进行了深入研究,针对接触网结构的定位形式等不同条件得出了一系列有意义的结论。结果表明,论文提出的接触网风偏视觉检测技术能够实现对恶劣大风环境下接触悬挂关键部位风偏量、接触网支柱振动量的实时在线可靠检测,创建的接触网数值仿真模型能够合理反映接触网耦合系统的风偏力学特性,分析数据和结论可为风区铁路接触网的设计、运用到维护均提供更为完备的数据支撑和技术保障。更多还原

【Abstract】 Wind safety of electrified railway catenary in strong wind area is of great significance to the requirement of railway transportation safety and efficiency. A novel visual detection technique to detect the wind-deviation of key positions of contact suspension and transverse vibration of column was presented. Combined with static and dynamic FEM simulation results, as well as the flow field analysis conclusions, wind-deviation response mechanism of catenary was studied with different conditions such as anchor mode.Wind deviation detection of railway catenary based on machine vision method was investigated and achieved. Static detecting points are arranged for column vibration detection and dynamic detecting points were distributed at key positions of contact suspension for wind-deviation detection with the help of area CCD camera set on top of catenary column. Detection of transverse, vertical deviation and rotational angle of contact line, catenary wire and dropper can be realized through target matching at static and dynamic testing points, as well as camera motion compensation of observation datum. As for detection algorithm, target projection feedback model of static point was built under camera coordinate system with the moving camera observation datum. The maximum deflection and rotation angle of column at camera height were obtained based on cantilever beam model under worst wind condition, from which the detecting error structure of datum instability was analyzed. Detecting algorithm of column vibration and absolute wind-deviation of dynamic targets was then constructed and optimized. As for image processing algorithm, automatic threshold segmentation method based on improved RGB characteristic operator and intensity-adaptive color image segmentation based on contrast stretching were presented, both of which had good adaptability to complex illumination conditions and background interference. Target offset and rotation were respectively calculated with area method and geometry method uing the segmented image.Wind-deviation simulation model was studied respectively adopting theory method and numerical simulation. Theoretically, sag and wind-deviation of free hanging system and full-compensated chain suspension system were deduced according to statical calculation based on averaged wind velocity. The wind-deviation theoretical model was modified considering the dynamic dropper reation force along the span. Numerically, a novel finite element model of multi-layered wire strand for catenary system was proposed incorporating both material elasticity theory and geometric compatability, which not only can predict its mechanical behavior precisely, but also can reduce solution degrees in the maximal degree. Geometric nonlinearity equations for flexible, large-spanned cable structure of contact suspension was built. The coupled catenary analyzing system was created considering the constraint relations between contact suspension and support structure, which can reflect different wind-deviation response in different anchor mode. Stochastic wind field was generated using WAWS as input load.Adopting the proposed visual detection technique and numerical simulation model, wind-deviation response of catenary targets and wind-flow structure with topography and geomorphology in site taken into account were futher studied through field test, theoretical calculation, finite element simulation and areodynamical simulation. A series of conclusions were obtained about the wind-deviation response with different working conditions. It can be concluded that the proposed visual detection technology can realize real-time wind-deviation detection at key positions of contact suspension and vibration detection of catenary column in strong wind. The established theoretical and numerical simulation model can be helpful in reflecting the wind-deviation behavior of coupled catenary system, and thus provide data support and technical assurance for electrified railway construction, application and maintanance in wind area.更多还原