基于光栅的贴片机对准系统的精度标定

贴片机对准系统的精度标定是视觉定位的关键环节，直接影响贴片精度与贴片质量。传统的标定方法往往需要进行大量的矩阵计算和分析，来确定相机的坐标系与世界坐标系和图像坐标系之间的关系，因此要掌握大量的三维几何知识与投影理论，并且计算繁杂。本文提出的基于光栅的精度标定方法，将光栅图像灰度值之和形成一组周期固定的准正弦信号，通过像元平移把图像条纹灰度值变为李萨如图。通过对李萨如图及其数据进行分析与处理，直接计算出光学系统的分辨率，实现光学系统的精度标定。实验结果表明这种标定方法的精度高，偏差小于0.2微米,精度达到亚微米级，满足贴片机的对准精度要求。

Accuracy calibration of alignment system of chip mounter based on grating

Accuracy calibration is the key of high-precision chip mounter vision alignment system, affects the precision and quality of chip mounting. The traditional calibration usually requires a large number of matrix calculation to define the relation of camera coordinate, world coordinate and image coordinate . This paper presents a new calibration method based on grating , a group of data being similar to sinusoid is gotten by calculating the sum of gray-value of pixels in each column. These calculated data are elaborately showed a Lissajous figure by translation for pixel. The size mapping coefficient between the grating groove and their image pixels of the optical alignment system is calculated to realize the accuracy calibration . The result of experiments indicates that the error of the new calibration method is little ,it can meet the precision needs of an automatic chip mounter vision alignment system.