In lubro 3D measurement of oil film thickness at the interface between tool and workpiece in sheet drawing using a fluorescence microscope

In order to understand quantitatively the micro-contact and lubricant behavior at the interface between a tool and a workpiece in sheet drawing, a method for mapping the oil film thickness in lubro has been developed. This is based on the use of a fluorescence microscope. It is shown, firstly, that the in situ oil film thickness between the tool and the workpiece can be measured three dimensionally, and, secondly, that the in situ surface topography of the workpiece can be visualized clearly. From the 3D surface topography, the permeation of the trapped lubricant into the real contact area can be observed.     

光学三维测量技术与应用

光学三维测量技术是一种可视化的测量技术,能完成复杂形体的点、面、形的三维测量,能实现非接触测量,在制造业和航空航天领域得到广泛应用。航空三维激光扫描与摄影测量技术利用激光测距原理和航空摄影测量原理,与基于全球定位系统(GPS)和惯性测量装置(IMU)的机载定位定向系统(POS)联接,可以快速获取大面积地球表面三维数据。本文对光学三维测量技术和航空三维激光扫描技术做一简单介绍,给出三维激光扫描技术在航空航天领域的几个应用。     

基于三维技术的发电机组监测系统的开发

介绍了某型发电机组监测系统的设计,着重阐述了Direct3D技术在发电机组的三维仿真中的应用.提出一种基于判别投影原点与鼠标点击点形成的射线,与三维仿真模型是否存在交点来实现模型拾取的方法,探讨了射线与三角形、球体以及长方体相交的判别实现.研究发现,当模型采用长方体或球体近似描述时,本方法具有计算量小、拾取准确率高的优点.实际应用表明,运用Direct3D技术开发的发电机组监测系统具有良好的交互性和实用性.     

光学非接触三维形貌测量技术新进展

三维物体表面轮廓测量是获取物体形态特征的一种重要手段,在机器视觉、自动加工、工业检测、产品质量控制领域具有重要意义和广阔的应用前景.光学非接触测量由于其高分辨率、无破坏、数据获取速度快等优点而被认为是最有前途的三维形貌测量方法. 介绍了光学非接触测量方法中的光切法、基于调制度测量的原理及优缺点,重点介绍了光栅投射法的测量原理,并分析了其研究热点与发展方向.     

格雷码与相移结合的结构光三维测量技术

提出一种应用于结构光三维测量系统投射角求取的格雷码与相移结合的编码、解码方法。该方法首先利用相移图案,确保采样点的相位在（π,-π]范围内周期变化,再将该相位与采样点对应的格雷码结合得到绝对相位,最后将绝对相位在相位空间中的位置线性映射到投射角空间,对其进行连续划分,从而确定采样点的投射角,最后依据三角法原理实现三维测量。本文具体介绍了编码、解码原理,分析了解码过程中格雷码和相移周期错位问题,并通过判断相邻像素点的格雷码值增加和相位突变是否一致进行了调整,给出了3dsMAX和MATLAB环境下的仿真重构实验结果。     

圆弧金刚石砂轮三维几何形貌的在位检测和误差评价

针对非球面光学元件加工对圆弧金刚石砂轮形状误差测量的需求,提出了砂轮三维几何形貌在位检测与误差评价方法。建立了砂轮外圆面螺旋扫描轨迹测量数学模型,利用位移传感器获取了砂轮表面轮廓数据;对得到的数据匀滑滤波后沿圆周展开并进行插值处理,得到砂轮三维几何形貌。然后,根据非球面平行磨削加工特点,提出评价圆弧砂轮形状精度的指标。通过提取三维几何形貌轴截面轮廓,进行最小二乘圆弧拟合得到不同相位处的圆弧半径与圆心坐标,并由误差分离获得砂轮表面圆弧的圆度误差、圆周跳动误差及轮廓圆心轴向偏差。最后,对非球面加工圆弧金刚石砂轮进行检测,获得了砂轮的三维几何形貌以及多个关键尺寸及其误差数据:即圆弧金刚石砂轮的平均圆弧半径为55.442 3mm,半径波动极差为0.16mm,中央±8mm环带内圆弧的圆度误差约为5μm,圆周跳动误差约为2μm,截面轮廓圆心轴向位置相对偏差为0.008mm。根据检测结果,进行了大口径复杂非球面磨削实验,得到的元件面形P-V值为4.62μm,RMS值优于0.7μm,满足工程的实际需求。     

三维光电振动测量技术的校准方法研究

为了分析三维光电振动测量仪测量的三维数据准确性,提出了一种利用标准小球做相对校准的简便方法。组成三维光电振动测量仪的5台激光测振仪发出的5束激光同时经过1个透镜,聚焦在位于透镜焦点处且安装在振动源上的标准小球球面上,软件处理小球振动时的三维分量,并与小球3个正交方向放置的3台激光测振仪测得的数据对比。通过微调小球的摆放位置,测量小球不同振动方向的三维振动信息,最后对数据进行误差分析,测量结果验证了该校准方法的可行性和适用性。     

动态三维测量中图像同步高速投影与采集的原理及实现

基于结构光的动态物体三维面形测量对航空航天、能源和汽车等领域的科学研究与工程应用具有重要作用。然而现有测量设备单次测量时间过长,难以实现对动态物体三维面形的测量,其中主要的难点在于图像高速同步投影与采集。提出了一种图像精确同步高速投影与采集的方法,该方法通过实验测定出数字微镜翻转延时和触发曝光延时,设计了帧触发信号、数字微镜翻转、LED光源点亮和相机曝光之间耦合工作的精确时序,从而实现了220帧/秒图像的精确投影与采集,为动态物体三维面形测量设备的开发提供了良好的技术基础。     

In situ observation and interferometric characterization of solid–liquid interface morphology in directionally growing transparent model systems

The performance of a new directional solidification device dedicated to the characterization of solid–liquid interface morphology by means of optical methods is presented in this paper. In contradiction to usual solidification studies on transparent materials carried out on thin films, which eliminates the complex coupling between solidification and convection, this device enables in situ and real time studies on bulk transparent materials. The alloy is contained in a cylindrical crucible and observation is performed in two perpendicular directions: the growth one and the transverse one. In addition to direct observation by light transmission in those directions, an interferometer is also set up in the growth direction to provide information on the shape and the motion of the interface through an analysis of the interferometer fringes. The combined determination of solidification front characteristics by these three observation modes has already given critical information on interface dynamics: front recoil measurements during initial transient, formation of microstructure patterns, and influence of convection on the triggering of instabilities.     

基于激光扫描的足部三维测量仪设计

个性化鞋楦设计是社会发展的必然趋势,足部测量仪的研制成为了一个重要课题.提出了个性化足部扫描测量仪的设计方法,介绍了仪器的测量原理以及标定方法,设计出控制系统、光学系统、移动平台和图像采集模块来实现快速足部扫描.经过自行开发的软件控制系统执行图像提取与数据分析,即可在短时间内重建出所测量的足部轮廓.最后,对足部进行了实际扫描,该过程可在10s之内完成,测量误差小于0.5%.得到了很好的结果,满足工业设计的要求.     

3D measurement of gears based on a line structured light sensor

Gears are core components of transmission systems. The current trend of gear measurements is the rapid and full digitization. To rapidly obtain information on the three-dimensional (3D) shape of the gear tooth flank, a 3D point cloud measurement system based on a line structure light sensor and high precision air floating rotary table is proposed. The system can acquire more than 1.5 million 3D data points on one side of the gear tooth flank within less than 5 s. In this study, the measured 3D point cloud data is used to calculate the profile error, pitch error, then compared to those obtained from traditional contact measurements. In addition, tooth flank error was evaluated. The results show that the 3D point cloud measurement system can perform fast and accurately in 3D measurements of gears and it is a novel system for gear measurement and error calculation.     

形貌视觉测量中立体拼接靶标的设计及应用

设计了一种正六棱柱形状的立体拼接靶标,以靶标侧面6个棋盘格的角点作为全局控制点。基于近景摄影测量技术,建立立体靶标的6个单元模型,通过计算模型内摄站间的相对位姿,推导出棋盘格角点在所属单元模型的局部坐标。以公共棋盘格为中介,确立相邻单元模型的坐标系转换关系。建立靶标的全局坐标系于1号棋盘格,推导该棋盘格平面与其像平面间的单应性矩阵,从而确立全局坐标系和1号棋盘格所处单元模型的坐标系的转换关系。依次递推实现全局坐标系和每个单元模型坐标系的转换,进而计算出全部靶标角点的全局坐标,再经光束平差算法获取精确值。以玻璃表面棋盘格的角点间距作为评价指标,拼接精度优于0.15 mm/m。基于立体拼接靶标的拼接试验表明,实体模型表面4个子区域的局部点云可被精确地拼接成整体点云。与基于全局控制点和平面靶标的拼接方法相比,本方法亦具有更高的拼接精度。     

Stereo vision for 3D measurement: accuracy analysis, calibration and industrial applications

This paper evaluates the accuracy of different camera calibration and measurement methods used in 3D stereo vision with CCD cameras. These methods are evaluated by means of several precision tests, determining their error limits under specified conditions of operation. To check the precision of such systems, a CMM and some calibration objects, such as grids, plates, spheres, etc. are used. Two practical applications are described: a cost-effective system for the measurement of free-form surfaces, able to generate CAD models and measuring programs for CMMs. The system aims to reduce some difficulties associated with stereo vision and to speed up the traditional digitizing process. The other application involves car frame measurement. A new automatic measuring system has been developed, allowing contactless car frame measurement through two rotating CCD cameras.     

矩形脉冲涡流传感器的三维磁场量与缺陷定量评估

脉冲涡流是一种有效的电磁无损检测技术。基于脉冲涡流检测原理设计了脉冲涡流检测系统,并对矩形脉冲涡流传感器的三维磁场量进行了研究。分别在传感器的不同走向下,使用三维检测传感器获得了三维磁场量的Bx、By与Bz曲线。在传感器的不同走向下,提出使用三维蝶形图对缺陷进行检测识别。对三维信号进行特征分析后,分别在不同走向下,通过Bz曲线评估缺陷的深度。通过By与Bz曲线的特征可以测量缺陷的长度。为进一步实现飞机机身缺陷的成像检测提供了有价值的参考。     

用于提琴琴弦三维振动测量的高速摄影系统

分析了琴弦的亥姆霍兹运动,设计了一个基于高速摄影的非接触式光学测量系统,用于测量真实小提琴上琴弦的振动。通过特殊的光路设计和在琴弦上设置标定点,以7 000 frame/s的速度和336×480的图像分辨率拍摄了拉弦和拨弦时琴弦上标定点的三维振动形态。采用圆形霍夫变换图像处理算法、奇异值分解算法和自动批处理,对记录的大量序列图像进行处理,提取了弦振动的位移和轨迹等数据。实验结果表明,该测量系统能够精确跟踪小提琴琴弦的振动状态和包络轨迹,振动位移曲线的图像处理精确度达到0.03 mm。该系统为进一步研究提琴琴弦的振动机理和建立精确的琴弦振动理论模型提供了一种有效的实验方法。     

Statistic optics discussion on the formula of digital holographic 3D surface profiling measurement

Based on the theories of statistic optics and scalar diffraction, this paper derived the digital holography formula for 3D object surface profile measurement. The results indicate that random changes of the scattering light phase will cause error in measurement when the detected object surface is optically rough. Moreover, more precise calculation formula should theoretically be used in case of there is a short distance between the CCD and the measured object, both for a smooth object and an optically rough object.     

采用可编程逻辑控制器的大型物体三维扫描重建

本文提出了一种新颖且实用的三维重建系统,以获取大型物体的三维数据。文中对该系统的组成以及所采用的方法和原理进行了研究。该系统由一个基于红外的三维扫描仪、两个导轨和一个基于PLC(可编程逻辑控制器)模块的高精度运动控制系统组成。运动控制系统控制安装在导轨上的三维扫描仪做匀速运动;三维扫描仪向物体投射红外线,并重建物体上所投射的红外线段;接着,系统根据三维扫描仪的运动速度,拼接局部重建数据,最终获得大型物体完整的三维重建数据。实验结果表明:与基于激光测距拼接的方法相比,该方法的测量速度约提高了7倍,测量精度约提高了2.5倍。基本满足工业生产中大型物体自动三维重建的稳定可靠、精度高、速度快等要求。     

基于矢量补偿技术精密测量三维空间曲面及逆向工程

为使测量机完成空间旋转曲面及3D轮廓面的测量,提出等分度测量法及等距测量法。关闭测针半径补偿按技术要求测量空间曲面上4个测量点,利用其中3个测量点在空间曲面上建立投影面为"正三角形"的"微型三角形",另一个测量点的投影在该正三角形中为重心点,以该测针中心坐标为其测量目标点,即方法1;也可以计算出该"微型三角形"的重心坐标为测量目标点,即方法2。应用向量计算该"微型三角形"法矢量,启动测针半径补偿做该空间轮廓的精密测量;用标准球作3D实验探讨"正三角形高"的取值;应用DEAPPL语言设计程序,一次性快速完成空间曲面上4条曲线的测量及其8个数据文件的生成,该文件组可应用于逆向工程、计量检定及曲面的分析研究和改进。按上述方法设计的程序经标准球实验,测量精度可达平均偏差0.001 mm以内,对应标准偏差在0.002 mm以内,能广泛用于高速烟机设计中对空间旋转曲面或3D轮廓面的测量及制造;在我国制造行业,能完成对叶片、叶轮的测试和反求,并为三维空间曲线面的测量提出一种新方法。     

In situ observation of the initial growth process of carbon nanotubes by time-resolved high resolution transmission electron microscopy

We succeeded in plan-view dynamic observation of the initial formation process of carbon nanotubes from β-SiC( 1 1 1 ) surfaces by time-resolved high resolution transmission electron microscopy. At 1360 °C, the flakes of graphite layers of a fibre orientation were formed on the SiC( 1 1 1 ) surfaces. From the graphite layers, carbon nanotubes were formed perpendicular to the ( 1 1 1 ) plane of the SiC. A scanning tunnelling microscopy observation showed that the end of carbon nanotube was closed. These results indicate that the caps of the carbon nanotubes are formed by a lift of a part of the graphene along the [ 1 1 1 ] direction of the SiC through generation of pentagons and heptagons. Two types of carbon nanotube, single-wall and double-wall, were observed in plan-view images. Different image intensity between an outer ring and an inner ring in double-wall nanotubes suggests that the inner layers of multiwall nanotubes are formed after the outer ones.