【作者】 彭凯；

【导师】 刘书桂；

【作者基本信息】 天津大学 ， 测试计量技术及仪器， 2007， 博士

【摘要】 基于视觉测量技术的便携式三维坐标视觉测量系统具有重量轻、便携性好、组建灵活、操作简单、量程大、精度高、现场测量及测量不受被测物体表面差异影响等优点,代表着坐标测量技术发展的一个方向,相关产品有着极为广阔的应用前景。在对国内外便携式视觉坐标测量系统发展现状和趋势全面分析的基础上,围绕了该类单相机系统的模型存在的轴向定位误差大的问题展开研究,进而设计了基于光靶标的双相机三坐标测量系统,实验表明该系统采用最简的共线三控制点测头模式在测量距离约1500mm处各个方向重复性精度优于0.2mm,与三坐标测量机移动对比测量精度达到±0.15mm。论文的主要工作及创造性研究包括以下几个方面:1、研究测头式视觉坐标测量系统的组成结构,针对测量系统的特点提出了对各个部件的选材及制作要求及原则,并制作了实验室环境样机;2、基于PnP问题,从透视投影学的角度分析论证利用空间控制点和一台摄像机实现空间定位的方式,确定了空间点的分布与摄像机空间定位的关系,提出了空间、平面及直线三种模式的点阵式测头单像机测量模型,从而为测头—摄像机模式的测量系统提供完整的数学模型,为今后类似系统的研究提供了充分的理论基础;进一步提出了光轴正交双摄像机测头坐标测量系统,解决单像机测量系统轴向重复性差的固有问题。3、分析并建立了摄像机标定模型,针对两台面阵视觉传感器,提出了基于坐标测量机的大范围移动靶标双摄像机内外部参数高精度标定方法,通过实验得到了高精度双摄像机的内外部参数。4、研究控制点图像中心的提取,采用两步法定位图像中圆形目标点中心,实验表明该方法快速且定位精度高;设计球目标靶标系统,并提出了基于圆度误差检测的圆形目标检测算法,实现圆形目标高精度定位方法。5、进行了双摄像机—测头模式坐标测量系统的整体精度实验,包括靶标上的球目标中心定位重复性实验,与单像机-测头模式的重复性精度对比实验,双像机视场内多点静态重复性实验,与三坐标测量机对比测量精度实验和不同姿态下同一点测量精度实验。实验结果表明在测量距离1500mm范围内,双像机-测头模式各个方向测量重复性为0.2mm,对比精度显示系统测量精度达到±0.15mm。论文对系统的测量原理、系统结构设计、视觉系统标定模型及算法、控制点图像采集处理、控制点中心像面定位、控制点数量及材质等方面进行了理论研究分析,计算机仿真和实验,取得了相当大的突破,提出了一些新的思想和方法。这些研究工作为使系统进一步朝高精度、实用化方向发展奠定了坚实的基础。更多还原

【Abstract】 The portable vision 3D coordinate measuring system based on photogrammetry technology presents many characteristics such as light and portable device, fast and flexible construction, simple operation, large measuring range, high accuracy, capable of measuring on spot and not affected by the difference of measured surface. So the system has wide prospective applications in many fields. After a comprehensive review on the indoors and overseas current situation and developing tendency of portable 3D coordinate vision measurement system, a dual cameras vision 3D coordinate measuring system using a probe has been proposed to solve the problem of the measuring instability about similar system with one camera. In the dissertation, mathematic models are built up and solved about this kind of system. The experimental result shows that the system with linear points and dual camera has achieved a measuring stability precision of 0.2mm and measuring precision of±0.15mm in the direction of every axis for a distance of 1500mm away from dual camera.The dissertation covers the following aspects concerning the main work and creative research in the project.1. The composing of a probe vision coordinate measurement system has been discussed. The material selection principle and feature requires of system’s parts have been proposed on the basis of system’s characteristics, and the sample system in the laboratory has been composed.2. Based on the principle of Perspective-n-Point Problem (PnP), the system’s mathematic model about the position between n points and one camera has been proposed and established. A system consisting of probe and camera is proposed as line、plane and space system which supply the mathematic basic for similar one. Dual camera with perpendicularity of two axis system is proposed to compensate the instability of one camera system with probe.3. The CCD camera calibration model has been analyzed and established. As for two plane array vision sensors, a high accurate dual cameras’inner and outer parameters calibration method based on CMM has been proposed with a large range moving drone. Using that method, the two cameras’inner and outer parameters in the system can be attained.4. The extraction method for the measured object point’s image center has been studied. The two-stage method is used to position and distill the circular measured object point’s image center, and the experiment result shows that that method is fast and accurate. A drone with spherical object points has been designed, and the circular object point extracting method based on circularity error evaluation is presented to position the circular object points. 5. The experiment has been conducted to test the system’s total measuring precision. Several comparative experiments with the single camera-probe system and CMM are also included. The experiment result shows that the dual camera-probe system is of higher accuracy. The system with three linear points and dual cameras has achieved a measuring stability precision of 0.2mm and measuring precision of±0.15mm in the direction of every axis for a distance 1500mm away from dual cameras.Through theoretical analysis, experiments and computer simulation, 3D coordinates vision measurement system with probe & camera have been studied with emphasis on the system’s composing and measuring principle, the system whole mathematic model and its solution, system image process, objective recognition and position detection, design of objective, camera calibration for single camera and dual camera. In the dissertation, some creative progresses are made and some new methods and conceptions are proposed. The work lays a foundation for further development of the practical portable vision 3D coordinate measuring system with higher measuring stability.更多还原