旋转测量状态下光斑中心定位方法

Spot Center Positioning Method Under Rotational Measurement State

目前,对管道内腔为自由曲面的截面轮廓进行高精度测量是行业难题。拟将多个不同测量范围的激光位移传感器放置于管道内腔中,采用旋转的方式对内腔进行测量,将得到的测量数据进行归一化处理后获得被测管道内腔截面轮廓形状。分析测量过程中激光光斑的变化情况,针对光斑图像的多峰、散斑、平顶与形状变化等现象,提出了一种基于传统灰度重心法进行粗定位的距离倒数加权多项式插值亚像素光斑中心定位方法。采用中值滤波对光斑图像进行预处理,通过自适应阈值分割法从环境背景光强中分离出光斑中心定位区域。通过MATLAB仿真与灰度重心法、加权灰度重心法与高斯拟合法传统光斑中心定位方法相比,结果表明,光斑中心定位精度达到0.01 pixel,在激光光斑中心定位精度和稳定性方面有一定的改善,明显优于传统的光斑中心定位算法。

At present,the high-precision measurement of the cross-section profile of a pipe whose inner cavity is a free-form surface is a difficult problem in the industry.Several laser displacement sensors with diverse measuring ranges are placed in the inner cavity of the pipe by this paper.The inner cavity is measured through rotation,and after normalizing the obtained measurement data,the shape of the cross-section profile of the pipe's measured inner cavity is obtained.Through the analysis of the laser spot changes during the measurement,a distance inverse weighted polynomial interpolation sub-pixel spot center localization method based on the traditional grayscale center-of-gravity method for coarse localization is proposed for the shape of the spot image such as multiple peaks,scattering,flat tops,and changes of shape.The median filter is used to preprocess the spot image,and the spot center localization region is separated from the ambient background light intensity by the adaptive threshold segmentation method.Compared with the traditional spot center localization methods of grayscale center of gravity method,weighted grayscale center of gravity method and Gaussian fitting method through MATLAB simulation,the results show that the spot center localization accuracy reaches 0.01 pixel,which is a certain degree of improvement in the accuracy and stability of laser spot center localization,and is obviously better than the traditional spot center localization algorithm.