Lei Ting, Gu Shiyang, Yu Huiwen
Appl Opt. 2022 Feb 20;61(6):1492-1499. doi: 10.1364/AO.451576.
The keyhole is a specific phenomenon produced by the intense interaction between laser and material. Keyhole morphology can reflect welding stability and welding quality to a certain extent. Nowadays, the keyhole is observed and image processed by a high-speed camera and related algorithms, respectively. However, the binarization threshold is fixed in keyhole extraction, and conventional binarization methods are not adaptive. This will affect the feature extraction of keyhole morphology. In this paper, a dynamic threshold adjustment method is proposed, which can combine the quick positioning of the Otsu method and the weight balance of the average method. Furthermore, seven defined features of the keyhole region are divided into dynamic parameters and shape parameters. The dimension of these parameters is reduced by principal component analysis (PCA). The first three PCs occupy more than 92%, which covers most of the keyhole information. At last, the influence of dynamic parameters and shape parameters on keyhole morphology is presented. This research plays a positive role in monitoring the keyhole morphology of laser welding.
匙孔是激光与材料强烈相互作用产生的一种特定现象。匙孔形态在一定程度上能够反映焊接稳定性和焊接质量。目前，分别通过高速摄像机和相关算法对匙孔进行观察和图像处理。然而，在匙孔提取过程中，二值化阈值是固定的，传统的二值化方法缺乏自适应性。这将影响匙孔形态的特征提取。本文提出了一种动态阈值调整方法，该方法能够结合大津法的快速定位和均值法的权重平衡。此外，将匙孔区域定义的七个特征分为动态参数和形状参数。通过主成分分析（PCA）降低这些参数的维度。前三个主成分占据了92%以上，涵盖了大部分匙孔信息。最后，给出了动态参数和形状参数对匙孔形态的影响。该研究对激光焊接匙孔形态监测具有积极作用。
