基于无衍射光莫尔条纹的三维角度误差测量方法

发布时间：2018-01-31 06:57

本文关键词： 三维角度误差测量轴锥镜莫尔条纹无衍射光图像处理　出处：《湖北工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着现代工业的发展,各行业对于零件加工精度的要求越来越高,而测量工作台在加工过程中的运动误差(包括直线度误差和角度误差)是保证加工精度的重要环节。本文利用无衍射光中心光斑能量集中、强度分布在传输过程中不随距离改变等特性,再结合莫尔条纹对微小位移的高敏感性研究了一种针对单轴工作台三维角度运动误差的测量方法。主要研究内容如下:首先,在无衍射光及其干涉理论的基础上,对无衍射光莫尔条纹的形成机理和特性进行了分析。根据菲涅尔衍射公式,得到轴锥镜后的光强分布,再结合干涉理论,得出了两束无衍射光叠加产生莫尔条纹的数学模型,并给出了莫尔条纹数目与光斑中心距离的关系。将其与普通光栅莫尔条纹进行了对比,说明无衍射光莫尔条纹能精确检测微小误差。其次,设计了误差测量光路,并利用空间矢量运算法则推导了误差测量公式。测量光路采用双CCD对比的检测方法,对不同位置处CCD接收到的无衍射光斑,通过对光斑中心位置的变化量进行比较和计算,最终得到三维角度误差(俯仰角、偏摆角、滚转角),并用ZEMAX软件对光路进行了仿真,得到的结果与理论推导的结果一致,证实了理论模型的合理性。第三,根据推导出的无衍射光莫尔条纹模型,设计了相应的图像处理方法以提取莫尔条纹信息。对采集到含有背景噪声的无衍射光莫尔条纹,采用图像增强手段提高图像对比度,通过选择合适的低通滤波器对无衍射光图像中的高频噪声信号加以消除,再经过二值化和平滑处理,使莫尔条纹的轮廓清晰,然后采用坐标变换,将莫尔图像转换到极坐标域,根据莫尔条纹在一周内的突变特性,利用多次间隔扫描法对条纹数目进行计数。最后,利用精密角度运动台对测量系统进行了验证实验,通过误差测量公式和图像处理算法计算出了最终结果,在1°范围内的测量误差不超过0.05°。实验结果表明本文提出的方法能准确测量三维角度误差。
[Abstract]:With the development of modern industry, the requirement of parts machining precision is more and more high. The motion error (including straightness error and angle error) of the measuring table in the machining process is an important link to ensure the machining accuracy. In this paper, the energy concentration of the spot in the center of the non-diffractive light is used. The intensity distribution does not change with distance during transmission. Combined with the high sensitivity of moire fringes to the small displacement, a measurement method for the three-dimensional angular motion error of the single-axis worktable is studied. The main contents are as follows: first. On the basis of non-diffractive light and its interference theory, the formation mechanism and characteristics of moire fringe of non-diffractive light are analyzed. According to Fresnel diffraction formula, the intensity distribution behind axial cone mirror is obtained, and then the interference theory is combined. The mathematical model of producing moire fringes by superposition of two nondiffractive beams is obtained, and the relationship between the number of moire fringes and the distance between the center of the spot is given, which is compared with that of ordinary grating moire fringes. It shows that non-diffractive light moire fringes can accurately detect small errors. Secondly, an error measuring optical path is designed. The error measurement formula is derived by using the space vector algorithm. The measurement path uses the double CCD contrast detection method to detect the non-diffractive spot received by the CCD at different positions. Through the comparison and calculation of the center position of the spot, the three-dimensional angle error (pitch angle, deflection angle, roll angle) is obtained. The optical path is simulated with ZEMAX software. The obtained results are consistent with the theoretical results, which confirm the rationality of the theoretical model. Thirdly, according to the derivation of the non-diffractive light moire fringe model. The corresponding image processing method is designed to extract the moire fringe information. The image contrast is improved by image enhancement for the non-diffractive moire fringe with background noise. By selecting the appropriate low-pass filter to eliminate the high-frequency noise signal in the non-diffractive light image, the contour of moire fringe is made clear by binary and smooth processing, and then coordinate transformation is adopted. The moire images are converted to polar coordinates and the number of moire fringes is counted by multiple interval scanning method according to the abrupt change of moire fringes within one week. The precision angular motion table is used to verify the measurement system, and the final results are calculated by error measurement formula and image processing algorithm. The measurement error in the range of 1 掳is not more than 0.05 掳. The experimental results show that the proposed method can accurately measure the three-dimensional angle error.
【学位授予单位】：湖北工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP391.41;O436

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