High-precision measurement of weld seam based on narrow depth of field lens in laser welding

Wang, P. J.; Shao, Wen; Shuili, Gong; Jia, Pingping; Li, G.

doi:10.1080/13621718.2015.1104094

Cited by 16 publications

(5 citation statements)

References 20 publications

(32 reference statements)

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“…Wei et al [11] designed a monocular vision, dual-position weld tracking system, and proposed an improved Harris algorithm and grayscale scanning method to improve the accuracy of image processing. Wang et al [12] designed a measurement system containing multiple optical amplifiers and combined the narrow depth of field (NDOF) method to solve the narrow weld seam measurement problem. However, these methods are not suitable for narrow butt welds due to significant tracking errors.…”

Section: Introductionmentioning

confidence: 99%

Real-time detection and localization method for weld seam of narrow butt joint based on semantic segmentation

Chen,

Ma,

et al. 2023

Meas. Sci. Technol.

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Structured light measurement is widely used in welding seam tracking because of its high precision and robustness. For the narrow butt joint, the positioning method by reconstructing the weld contour is not suitable for the welding of the narrow butt joint because it is difficult for the laser stripe to produce obvious deformation when projected to the weld. In this study, high-quality images with laser stripes and narrow butt joints are captured by the improved structured light vision sensor, which is equipped with an auxiliary light source. A two-step processing framework, including semantic segmentation and groove positioning, is raised to locate the feature point of the narrow butt joint. Firstly, we design the strip pooling ENet (SP-ENet), a real-time network specifically designed to accurately segment narrow weld images. Our proposed network outperforms other classical segmentation networks in terms of segmentation accuracy and proves to be highly suitable for the detection of narrow butt joint welds. Secondly, a combining method of random sample consensus (RANSAC) and iterative fitting to calculate the sub-pixel coordinates of weld feature points accurately. Finally, a trajectory smoothing model based on the Kalman filter is proposed to reduce the trajectory jitter. The above methods were tested on a self-built robotic welding experimental platform. Experimental results show that the proposed method can be used for real-time detection and positioning of narrow butt joints. The positioning trajectory is smooth, with most positioning errors less than 2 pixels. The mean tracking error reaches 0.207 mm, which can meet the practical welding requirements.

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Section: Introductionmentioning

confidence: 99%

Real-time detection and localization method for weld seam of narrow butt joint based on semantic segmentation

Chen,

Ma,

et al. 2023

Meas. Sci. Technol.

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“…Having been extensively applied to robotic welding due to its high accuracy and non-contact, vision sensing is considered one of the most promising welding seam trajectory recognition technologies [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ]. Great attention has been paid to welding seam detection methods based on structured light vision sensing [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ].…”

Section: Introductionmentioning

confidence: 99%

“…Liu et al [ 31 ] realized the three-dimensional reconstruction of the molten pool surface by projecting a 19-by-19 dot matrix structured light pattern on the weld pool area. Some studies explored welding seam trajectory recognition methods based on passive vision sensing technology [ 38 , 39 , 40 , 41 ]. By visually measuring the offset between the center of a welding seam and a welding gun, Ma et al [ 38 ] proposed a welding seam tracking method that achieved the welding tracking of straight butt-jointed seams.…”

Section: Introductionmentioning

confidence: 99%

“…Mitchell et al [ 39 ] applied reliable image matching and triangulation algorithms to achieve the robust identification and positioning of Z-type and S-type narrow butt-jointed seams. Wang et al [ 40 ] designed a measurement system that consisted of a multi-optical magnifier, a camera, and an external lighting diode lamp, and they devised a welding seam detection method based on narrow depth of field (NDOF) to accurately detect narrow welding seams in laser welding. In some studies, binocular vision sensing technology was used for the 3D reconstruction of welding seam trajectory.…”

Section: Introductionmentioning

confidence: 99%

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Welding Seam Trajectory Recognition for Automated Skip Welding Guidance of a Spatially Intermittent Welding Seam Based on Laser Vision Sensor

Hong

Gao

et al. 2020

Sensors

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To solve the problems of low teaching programming efficiency and poor flexibility in robot welding of complex box girder structures, a method of seam trajectory recognition based on laser scanning displacement sensing was proposed for automated guidance of a welding torch in the skip welding of a spatially intermittent welding seam. Firstly, a laser scanning displacement sensing system for measuring angles adaptively is developed to detect corner features of complex structures. Secondly, a weld trajectory recognition algorithm based on Euclidean distance discrimination is proposed. The algorithm extracts the shape features by constructing the characteristic triangle of the weld trajectory, and then processes the set of shape features by discrete Fourier analysis to solve the feature vector used to describe the shape. Finally, based on the Euclidean distance between the feature vector of the test sample and the class matching library, the class to which the sample belongs is identified to distinguish the weld trajectory. The experimental results show that the classification accuracy rate of four typical spatial discontinuous welds in complex box girder structure is 100%. The overall processing time for weld trajectory detection and classification does not exceed 65 ms. Based on this method, the field test was completed in the folding special container production line. The results show that the system proposed in this paper can accurately identify discontinuous welds during high-speed metal active gas arc welding (MAG) welding with a welding speed of 1.2 m/min, and guide the welding torch to automatically complete the skip welding, which greatly improves the welding manufacturing efficiency and quality stability in the processing of complex box girder components. This method does not require a time-consuming pre-welding teaching programming and visual inspection system calibration, and provides a new technical approach for highly efficient and flexible welding manufacturing of discontinuous welding seams of complex structures, which is expected to be applied to the welding manufacturing of core components in heavy and large industries such as port cranes, large logistics transportation equipment, and rail transit.

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“…Position inaccuracy can cause incomplete joining [1]. Commercial seam trackers [2] measure the weld gap using for example inductive sensors [3,4], structured light triangulating sensors [5][6][7] or image processing [8][9][10]. While optical sensing methods depend on the surface appearance and lighting conditions, inductive methods induce sensing currents into the material itself [11] and interpret the complex impedance response.…”

Section: Introductionmentioning

confidence: 99%

Experimental validation of an inductive probe for narrow gap measurement based on numerical modelling

2019

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Experimental validation of numeric results for an inductive probe shows that narrow gaps between two plates can be measured with accuracy suitable for laser beam welding. A two-coil inductive probe for measurement of the gap was built based on finite element modelling results. The individual coils were calibrated using a complex response method, and results from the physical coils closely match the numerical results regarding distance to gap and lift-off above the plate. The measurement of a realistic gap shows results that can be used in industrial applications for position, plate height and height alignment.

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High-precision measurement of weld seam based on narrow depth of field lens in laser welding

Cited by 16 publications

References 20 publications

Real-time detection and localization method for weld seam of narrow butt joint based on semantic segmentation

Real-time detection and localization method for weld seam of narrow butt joint based on semantic segmentation

Welding Seam Trajectory Recognition for Automated Skip Welding Guidance of a Spatially Intermittent Welding Seam Based on Laser Vision Sensor

Experimental validation of an inductive probe for narrow gap measurement based on numerical modelling

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