激光焊熔池图像三维形态恢复算法分析

Analysis of 3D reconstruction algorithm of laser welding molten pool image

利用熔池图像表面的明暗变化恢复熔池表面三维形态,分析熔高和熔宽等特征与焊接质量的关系.试验装置采用红外激光辅助光源和带有近红外窄带滤波组合系统的高速影像设备实时捕捉熔池动态图像,并根据统计学估计光源位置参数,采用基于单幅熔池灰度图像的明暗恢复形状技术(shape from shading,SFS)中的局部分析算法来恢复熔池三维表面形态,并通过中值滤波和三次样条插值对三维重建后熔池形状进行去噪和平滑处理.结果表明,所采用的方法能有效地恢复熔池表面信息,为大功率盘形激光焊接过程中根据熔池二维图像预测焊缝成形提供了一种方法.

The molten pool in high-power disk laser welding is related to the welding quality. The welding molten pool images were captured by a laser welding monitoring system. In order to reconstruct 3D shapes of the welding molten pools and further analyze the relationship between the shape features such as weld bead height,weld bead width and the welding quality,the shape from shading( SFS) technology based on single welding molten pool image was researched. 3D molten pool shapes could be recovered by the gray variations of welding molten pool image. The experimental apparatus included an auxiliary diode illuminant and a high-speed camera with near infrared filter to capture the welding molten pools in real time. The slant and tilt of illuminant source were estimated by the statistical algorithm. The 3D shape of welding molten pool surface was reconstructed by using the localization method of SFS. Also,the methods of median filter and cubic spline interpolation were applied to remove the noise and smooth the shape of molten pool. Experimental results showed that the proposed method can reconstruct the welding molten pool surface effectively. The 3D molten pool shape can be estimated by the molten pool image during high-power disk laser welding.