微间隙焊缝磁光成像检测及跟踪方法

Approach of Detecting and Tracking Micro Weld Joint Based on Magneto Optical Imaging

在激光对接焊过程中,必须精确检测焊缝位置并控制激光束始终对中焊缝。针对小于0.05 mm的微间隙对接焊缝,通过对焊件施加感应磁场,利用法拉第磁旋光原理构成磁光传感器,获取焊缝磁光图像。针对焊缝磁光图像,以焊缝磁光图像的灰度直方图为特征模版,研究一种基于均值漂移算法的激光焊焊缝检测与跟踪方法。通过均值漂移与粒子滤波相结合的算法,利用粒子滤波能够对图像大范围搜索目标的特点,实现焊缝全自动跟踪。同时,根据相似度Bhattacharyya系数对焊缝特征模版进行更新,提高焊缝跟踪精度。试验结果表明,利用均值漂移与粒子滤波相结合的算法能够从焊缝磁光图像中有效检测焊缝特征,实现焊缝的自动跟踪。

It is required that the weld joint position should be detected and the laser beam focus should be controlled to follow the weld joint accurately during butt joint laser welding. For micro butt joint whose width is less than 0.05 mm, the weldments are magnetized by using an excitation magnetic field. Meanwhile, a magneto optical sensor based on the principle of Faraday magneto effect is applied to acquire the magneto optical images of weld joint. By using the histogram of weld joint magneto optical image as the feature template, and being based on the algorithm of mean shift, a new method for weld detection and seam tracking of laser welding is proposed. Through the study of combining algorithm of particle filter and mean shift, it is found that the weld image target can be searched with the large scale by using particle filter, and the seam tracking can be realized. Also, the feature template of weld joint is updated according to the similarity coefficient of Bhattacharyya to improve the accuracy of seam tracking. Experimental results have showed that the micro weld joint position can be effectively detected from the magneto optical images by using the combining algorithm of mean shift and particle filter, and automatic seam tracking has been realized.