Quantitative prediction of laser-cut slag adhesion by integrating image and frequency domain features
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摘要:
为实现激光切割熔渣附着精准量化与工艺优化,本研究探索一种基于图像与频域特征的卷积神经网络(CNN)预测方法。构建包含
2160 张1 mm厚304不锈钢切割端面图像数据集。基于该数据集,采用高斯模糊、自适应阈值及形态学闭运算等图像处理算法,精确提取了挂渣的面积、高度及周长作为量化特征。为评估不同特征预测潜力,采用了RGB图像及其经二值化处理小波包分解(WPD)频域图像作为输入,并系统对比了VGG16、ResNet50和DenseNet121三种CNN架构回归性能。结果表明,在RGB图像输入路径下,VGG16网络对挂渣面积和高度预测最为精准,其平均绝对误差(MAE)分别达到0.019 mm2和0.044 mm。而对于更能反映动态过程状态轮廓周长特征,WPD频域输入路径预测效果显著提升,MAE降至0.094 mm,归一化平均误差(nMAE)为5.25%,且其预测值与真实值间拟合斜率与决定系数R2分别为0.83与0.86,呈现强线性关系。本研究证实,VGG16网络在熔渣特征预测中具备良好适用性,且WPD频域特征更有效地捕捉激光切割过程瞬态信息,所提出方法为工艺智能评估与闭环优化提供了可靠量化工具。Abstract:To achieve precise quantification of slag adhesion and process optimization in laser cutting, this study investigates a convolutional neural network (CNN)-based prediction method that integrates both image and frequency-domain features. A dataset of
2160 cross-sectional images of 1 mm thick 304 stainless steel was constructed. From these images, key dross characteristics-area, height, and perimeter were accurately extracted using a combination of image processing techniques including Gaussian blur, adaptive thresholding, and morphological closing operations. To evaluate the predictive potential of different input representations, both RGB images and binarized images transformed via wavelet packet decomposition (WPD) were used as model inputs. The regression performance of three CNN architectures-VGG16, ResNet50, and DenseNet121 was systematically compared. Experimental results demonstrate that VGG16 achieved the highest prediction accuracy for dross area and height using RGB images, with mean absolute errors (MAE) of 0.019 mm2 and 0.044 mm, respectively. For predicting the perimeter, which better reflects dynamic process behavior, the WPD frequency-domain input path yielded a significantly improved MAE of 0.094 mm and a normalized MAE (nMAE) of 5.25%. The regression fit between predicted and actual values showed a slope of 0.83 and a coefficient of determination (R2) of 0.86, indicating a strong linear correlation. This study confirms the effectiveness of VGG16 in predicting dross-related features and demonstrates the capability of WPD-derived frequency-domain features in capturing transient process information during laser cutting. The proposed methodology offers a reliable quantitative tool for intelligent process evaluation and closed-loop optimization. -
图 7 三种网络架构RGB模型预测-真实散点对比。(a)、(b)、(c)分别为面积、高度、周长ResNet50预测结果;(d)、(e)、(f)分别为面积、高度、周长VGG16预测结果;(g)、(h)、(i)分别为面积、高度、周长DenseNet121预测结果
Figure 7. Comparison of Predicted vs. Actual Scatter Plots for Three CNN Architectures with RGB Image Input. (a), (b), (c) Scatter plots of predicted vs. actual values for area, height, and perimeter using ResNet50;(d), (e), (f) Scatter plots of predicted vs. actual values for area, height, and perimeter using VGG16;(g), (h), (i) Scatter plots of predicted vs. actual values for area, height, and perimeter using DenseNet12
表 1 三种CNN模型基于RGB图像挂渣特征预测MAE与nMAE对比
Table 1. Comparison of MAE and nMAE for dross feature prediction using three CNN models on RGB images
网络架构 挂渣面积MAE
(mm2)挂渣高度MAE
(mm)挂渣周长MAE
(mm)挂渣面积nMAE
(%)挂渣高度nMAE
(%)挂渣周长nMAE
(%)ResNet50 0.023 0.046 0.106 8.48 9.72 5.91 VGG16 0.019 0.044 0.117 7 9.38 6.49 DenseNet121 0.029 0.054 0.106 10.6 11.4 5.91 表 2 频域训练下挂渣周长预测MAE与nMAE
Table 2. MAE and nMAE for slag perimeter in frequency-domain training
模型 频域MAE(mm) 频域nMAE(%) ResNet50 0.145 8.11 VGG16 0.094 5.25 DenseNet121 0.131 7.31 表 3 三种模型RGB与WPD支路熵对比
Table 3. Comparison of entropy between RGB and WPD branches in three models
模型 RGB 支路熵 WPD 支路熵 VGG16 2.62 2.41 ResNet50 3.12 3.68 DenseNet121 2.80 2.96 表 4 随机森林模型三种挂渣特征预测性能
Table 4. Prediction performance of three slag sticking features in the random forest model
挂渣特征 RMSE MAE R2 面积 0.029 0.022 0.901 高度 0.055 0.040 0.810 周长 0.215 0.157 0.629 表 5 激光切割工艺参数优化结果
Table 5. Optimization results for laser cutting process parameters
离焦量 (mm) 速度(m/s) 预测挂渣面积平均值( mm2) 超标率(%) −0.8 10 0.18 0 −1 10 0.18 0 −0.6 10 0.19 20 −0.8 12 0.19 20 −1 12 0.20 30 -
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