Prediction of GTAW penetration state based on enhanced knowledge of dynamic morphology molten pool
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摘要:
为了实现对焊接熔透状态的在线监测,保障焊缝质量并推动机器人智能化技术发展,提出了一种熔池动态形变知识增强的钨极惰性气体保护焊(gas tungsten arc welding, GTAW)熔透状态预测方法. 采用高速高动态范围工业相机获取熔池图像,利用DeepLabv3 + 语义分割模型进行熔池动态分割以获取精准的熔池区域,在此基础上进行多帧熔池轮廓图像融合,以描述熔池在焊接过程中的动态形变. 将融合后熔池轮廓图像和原始熔池图像合成输入CNN,学习同一位置熔池轮廓像素变化,指导CNN预测熔透状态. 结果表明,基于熔池动态形变知识增强的CNN能够准确识别部分熔透、适度熔透和过度熔透三种典型焊缝状态,分类准确率可达到97.1%,单帧预测时间0.86 ms. 与未融合熔池动态形变特征专家知识的深度学习方法相比,该方法在少样本数据情况下表现出更高的鲁棒性和准确率.
Abstract:To achieve online monitoring of welding penetration status, ensure weld quality, and promote the development of robotic intelligent technology, a knowledge-enhanced prediction method for Gas Tungsten Arc Welding (GTAW) penetration status based on molten pool dynamic deformation is proposed. High-speed, high-dynamic-range industrial cameras are employed to capture molten pool images, and the DeepLabv3 + semantic segmentation model is utilized for dynamic segmentation of the molten pool to obtain precise molten pool regions. On this basis, multi-frame molten pool contour image fusion is performed to describe the dynamic deformation of the molten pool during the welding process. The fused molten pool contour images and original molten pool images are combined and input into a CNN to learn pixel-level changes in the molten pool contours at the same location, guiding the CNN to predict penetration status. Experimental results demonstrate that the CNN enhanced with molten pool dynamic deformation knowledge can accurately identify three typical weld states: partial penetration, adequate penetration, and excessive penetration, achieving a classification accuracy of 97.1% with a single-frame prediction time of 0.86 ms. Compared to deep learning methods without the integration of expert knowledge on molten pool dynamic deformation features, this method exhibits higher robustness and accuracy in scenarios with limited sample data.
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图 12 不同输入下t-SNE可视化
Figure 12. Visualization of t-SNE with different inputs. (a) single-frame raw molten pool image; (b) multi-frame raw molten pool image fusion; (c) knowledge enhancement for single-frame molten pool contour image; (d) knowledge enhancement for multi-frame molten pool contour image fusion
表 1 焊接试验参数
Table 1 Welding experiment paraments
焊件尺寸
(L × W × H)/mm氦气流量
q/(L·min−1)焊接电流
I/A焊接速度
v/(mm·s−1)钨极直径
d/mm300 × 150 × 5 12 155 ~ 175 270 5.0 表 2 CNN架构
Table 2 Architecture of the proposed CNN
模型 输入大小 卷积核1 卷积核2 卷积核3 卷积核4 全连接层 CNN-1 360*360 16 32 64 128 [23*23*128,3] CNN-2 224*224 16 32 64 128 [14*14*128,3] CNN-3 224*224 32 64 128 256 [14*14*256,3] CNN-4 128*128 32 64 128 256 [8*8*256,3] 表 3 不同分割网络性能对比
Table 3 Quantifying the performance of different segmented networks
方法 平均交并比 平均像素精度 检测速度
v/(帧·s−1)FNC 0.722 0.791 22 SegNet 0.754 0.786 25 U-Net 0.783 0.824 24 DeepLabv3 + 0.812 0.836 19 表 4 数据集分布(个)
Table 4 Distribution of dataset
数据集 部分熔透 适度熔透 过度熔透 总计 训练集 301 623 350 1 274 测试集 129 268 150 547 总计 430 891 500 1 821 表 5 CNN测试结果
Table 5 CNN test results
输入图像 准确率
A(%)精度
P(%)召回率
R(%)F1值
F1(%)单帧原始熔池图像 83.5 81.4 83.3 83.8 多帧原始熔池图像融合 90.4 91.5 90.4 90.5 单帧熔池轮廓图像知识增强 93.2 93.4 93.2 93.2 多帧熔池轮廓图像融合知识增强 97.1 98.5 97.4 97.3 -
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