Outlines Regularization Method for Laser Cleaning Based on Grid Filling

doi:10.12382/bgxb.2024.0185

Abstract

Abstract:

The accurate positioning of cleaning area is one of the key factors to reduce the cleaning area and improve the cleaning efficiency.In order to solve the problem of positioning an irregular paint layer area in laser cleaning applications,a outlines regularization method based on grid filling is proposed.The paint layer region image is obtained by the K-means image segmentation method based on L×a×b× color space.The paint layer region image is rasterized to determine the external raster vertices of the paint layer region,and the 4-neighborhood boundary tracking algorithm is used to search for the external raster vertices of the paint layer region in accordance with certain judgment criteria.The searched raster vertices are sequentially connected as regularized shapes,the redundant points and self-intersecting parts of the regularized shapes are deleted,and the regularized shapes with different raster widths are evaluated by using the intersection over union (IOU) as an index,and the raster width corresponding to the largest IOU at the ratio of the area of a single raster to the area of lacquer layer region ranging from 0.025 to 0.04 is selected,and the right-angled polygons generated by this raster width are considered to be the optimal regularized shapes.The regularizations of various contours are compared and analyzed.The results show that the right-angled polygon obtained by the contour regularization method based on raster filling can more accurately express the contour shape of the paint layer and reduce the cleaning area compared with the minimum outer rectangle.

Key words: laser cleaning, outlines regularization, image segmentation, boundary tracking, machine vision

CLC Number:

TN249

LIU Weijun, LI Qiang, LIU Shuai, ZHANG Kai, XING Fei. Outlines Regularization Method for Laser Cleaning Based on Grid Filling[J]. Acta Armamentarii, 2025, 46(3): 240185-.

Figures/Tables 14

Table 1 Main chemical composition of 2A12 aluminum alloy

化学成分	质量分数/%
Si	≤0.5
Fe	0.5
Cu	3.8~4.9
Mn	0.3~0.9
Mg	1.2~1.8
Ni	0.1
Zn	≤0.3
Ti	≤0.15
Al	余量

Fig.1 Cross-section of composite paint layer specimen

Fig.2 Laser cleaning and visual inspection system

Fig.3 Schematic diagrams of spot overlap rates for different working paths

Table 2 Process parameters of laser cleaning the gray primer

工艺参数	数值
激光能量密度/(J·cm^-2)	7.96
重复频率/kHz	20
脉宽/ns	60
激光光斑直径/mm	0.4
机械臂扫描速度/(mm·s^-1)	1
振镜扫描速度/(mm·s^-1)	3000~6000

Fig.4 Schematic diagram of K-Means image segmentation in L×a×b× color space

Fig.5 Determining whether a grid vertices is inside or outside the paint area

Fig.6 Schematic diagram of grid vertices position relationship

Fig.7 Four cases of judging criteria

Fig.8 Problems to be optimized during regularization

Fig.9 Area ratios(left) and regularized shapes(right)of experimental samples

Fig.10 Area ratios(left) and regularized shapes(right)of 6 samples

Fig.11 Comparison of different regularization methods

Fig.12 Regularized results and cleaning effect

References 24

[1]	WANG Z Z, ZHANG L J, JIANG J, et al. Mechanism and parametric control of laser-layered paint removal for aircraft skin[J]. Optics & Laser Technology, 2023, 165:109612.
[2]	ZHU G D, WANG S R, CHENG W, et al. Corrosion and wear performance of aircraft skin after laser cleaning[J]. Optics & Laser Technology, 2020, 132:106475.
[3]	ZHU G D, XU Z H, JIN Y, et al. Mechanism and application of laser cleaning:a review[J]. Optics and Lasers in Engineering, 2022, 157:107130.
[4]	BERTASA M, KORENBERG C. Successes and challenges in laser cleaning metal artefacts:a review[J]. Journal of Cultural Heritage, 2022, 53:100-117.
[5]	BRAND J, MAXIMOVA K, MADDEN S, et al. Femtosecond pulse laser cleaning of Makrana marble[J]. Applied Surface Science, 2023, 641:158484.
[6]	李悦, 吴卓颐, 储德谱, 等. 激光清洗监测技术研究进展(特邀)[J]. 红外与激光工程, 2023, 52(2):50-68.
	LI Y, WU Z Y, CHU D P, et al. Research progress of laser cleaning monitoring technology (invited)[J]. Infrared and Laser Engineering, 2023, 52(2):50-68. (in Chinese)
[7]	佟艳群, 张昂, 符永宏, 等. 碳纤维复合材料的激光清洗等离子体光谱在线检测研究[J]. 光谱学与光谱分析, 2019, 39(8):2388-2394.
	TONG Y Q, ZHANG A, FU Y H, et al. Research on on-line detection of plasma spectroscopy in laser cleaning of the carbon fiber reinforced polymer[J]. Spectroscopy and Spectral Analysis, 2019, 39(8):2388-2394. (in Chinese)
[8]	WANG W J, SUN L X, LU Y, et al. Laser induced breakdown spectroscopy online monitoring of laser cleaning quality on carbon fiber reinforced plastic[J]. Optics & Laser Technology, 2022, 145:107481.
[9]	TSEREVELAKIS G J, POZO-ANTONIO J S, SIOZOS P, et al. On-line photoacoustic monitoring of laser cleaning on stone:evaluation of cleaning effectiveness and detection of potential damage to the substrate[J]. Journal of Cultural Heritage, 2019, 35:108-115.
[10]	ZOU W F, SONG F, LUO Y. Characteristics of audible acoustic signal in the process of laser cleaning of paint on metal surface[J]. Optics & Laser Technology, 2021, 144:107388.
[11]	史天意, 周龙早, 王春明, 等. 基于机器视觉的铝合金激光清洗实时检测系统[J]. 中国激光, 2019, 46(4):83-89.
	SHI T Y, ZHOU L Z, WANG C M, et al. Machine vison-based real-time monitor system for laser cleaning aluminum alloy[J]. Chinese Journal of Lasers, 2019, 46(4):83-89. (in Chinese)
[12]	HU Q C, WEI X L, LIANG X Q, et al. In-process vision monitoring methods for aircraft coating laser cleaning based on deep learning[J]. Optics and Lasers in Engineering, 2023, 160:107291.
[13]	刘伟军, 田泽琦, 卞宏友, 等. 基于机器视觉的钢材锈蚀表面激光清洗检测方法[J]. 应用激光, 2021, 41(6):1287-1292.
	LIU W J, TIAN Z Q, BIAN H Y, et al. Laser cleaning detection method for rust layer of steel based on machine vision[J]. Applied Laser, 2021, 41(6):1287-1292. (in Chinese)
[14]	ZHANG G X, HUA X M, HUANG Y, et al. Investigation on mechanism of oxide removal and plasma behavior during laser cleaning on aluminum alloy[J]. Applied Surface Science, 2020, 506:144666.
[15]	ZHAO Z J, LIU X, CHEN Z Y, et al. Evaluation of laser cleaning effect for the removal of paint on aluminum alloys[J]. The International Journal of Advanced Manufacturing Technology, 2023, 126(7/8):3193-3203.
[16]	WANG L K, ZHAO Y, YANG Y, et al. Experimental investigation on ablation of 4H-SiC by infrared femtosecond laser[J]. Micromachines, 2022, 13(8):1291.
[17]	张天刚, 段俊杰, 刘天翔, 等. y向搭接率对铝合金表面复合漆层激光清洗的影响[J]. 中国激光, 2023, 50(16):130-141.
	ZHANG T G, DUAN J J, LIU T X, et al. The effect of y-direction overlap rate on laser-cleaned composite paint layer over aluminum alloy[J]. Chinese Journal of Lasers, 2023, 50(16):130-141. (in Chinese)
[18]	SUN Q, ZHOU J Z, MENG X K, et al. Mechanism and threshold fluence of nanosecond pulsed laser paint removal[J]. Rare Metals, 2022, 41(3):1022-1031.
[19]	王蔚, 沈杰, 刘伟军, 等. 激光清洗中振镜扫描速度对7075铝合金表面质量和摩擦特性的影响[J]. 兵工学报, 2023, 44(10):2995-3005. doi: 10.12382/bgxb.2022.0437
	WANG W, SHEN J, LIU W J, et al. Effect of galvanometer scanning speed on surface quality and friction characteristics of 7075 aluminum alloy during laser cleaning[J]. Acta Armamentarii, 2023, 44(10):2995-3005. (in Chinese) doi: 10.12382/bgxb.2022.0437
[20]	ZHENG X, LEI Q Y, YAO R, et al. Image segmentation based on adaptive K-means algorithm[J]. EURASIP Journal on Image and Video Processing, 2018, 2018(1):1-10.
[21]	ZHOU Z P, ZHAO X X, ZHU S W. K-harmonic means clustering algorithm using feature weighting for color image segmentation[J]. Multimedia Tools and Applications, 2018, 77:15139-15160.
[22]	王荣军, 黄明明, 马立东. 基于单边跟踪与中点预测的线结构光中心提取算法研究[J]. 中国激光, 2024, 51(13):108-118.
	WANG R J, HUANG M M, MA L D. Research on center extraction algorithm of line structured light based on unilateral tracking and midpoint prediction[J]. Chinese Journal of Lasers, 2024, 51(13):108-118. (in Chinese)
[23]	钟康, 高贤君, 杨元维, 等. 建筑物轮廓双向驱动自适应分割重构的规则化方法[J]. 激光与光电子学进展, 2023, 60(20):200-209.
	ZHONG K, GAO X J, YANG Y W, et al. A regularization method for building contour based on bidirectional-driven adaptive segmentation and reconstruction[J]. Laser & Optoelectronics Progress, 2023, 60(20):200-209. (in Chinese)
[24]	王伟玺, 杜靖, 李晓明, 等. 基于栅格填充的直角多边形建筑物轮廓规则化方法[J]. 武汉大学学报(信息科学版), 2018, 43(2):318-324.
	WANG W X, DU J, LI X M, et al. A grid filling based rectangular building outlines regularization method[J]. Geomatics and Information Science of Wuhan University, 2018, 43(2):318-324. (in Chinese)