Fig 1 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Source publication
At present, the operators needs to carry out complicated teaching and programming work on the welding path planning for the welding robot before welding the steel mesh. In this work, an automatic welding path planning method of steel mesh based on point cloud is proposed to simplify the complicated teaching and programming work in welding path plan...
Contexts in source publication
Context 1
... robot welding system of the experimental platform is shown in Fig. 1. It consists of two parts: the welding execution system and the 3D vision system [12]. The welding execution system includes the welding torch, the wire feeder, the manipulator, the robot controller and the cross steel mesh, which is used to complete the welding of the intersections of steel mesh. The 3D vision system includes a 3D ...
Context 2
... background plane point cloud is about 6mm, so set the distance threshold to 6 and keep the outlier point cloud. It should be noted that the background point cloud has the same thickness when shooting at each shooting point. Therefore, the distance threshold can be reused.The steel mesh point cloud after background point cloud removal is shown in Fig. 10. Fig. 9 The filtered steel mesh point cloud display along zaxis in the camera coordinate system Fig. 10 The steel mesh point cloud after background point cloud ...
Context 3
... cloud. It should be noted that the background point cloud has the same thickness when shooting at each shooting point. Therefore, the distance threshold can be reused.The steel mesh point cloud after background point cloud removal is shown in Fig. 10. Fig. 9 The filtered steel mesh point cloud display along zaxis in the camera coordinate system Fig. 10 The steel mesh point cloud after background point cloud ...
Context 4
... Table 3, which jointly determine the straight line. The straight line is also obtained using the RANSAC method (SAC RAN SAC) as the robust estimator of choice. Finally, the interior point and outlier point are determined by setting the distance threshold. According to the point cloud after the segmentation in the camera x-O-y coordinate system in Fig. 11, it can be seen that the diameter of the steel bar is about 10mm. Compared with the actual size 9.8mm, it can be determined that the maximum distance from a point in the same bar to the straight line fitted by the RANSAC method will not exceed 10mm. Hence, the the distance threshold is set to 10, to ensure that all points belonging to ...
Context 5
... points cloud are shown in Fig. 12, where four colors represent four clustered steel ...
Context 6
... the point cloud preprocessing operation, the steel mesh point cloud is divided into independent 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 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 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Fig. 11 The point cloud after the segmentation display in the camera x-o-y coordinate system Fig. 12 The Point cloud after clustering steel bar point cloud. On this basis, we Obtain the welding point coordinates of the steel mesh, finally realizes the welding path planning of the steel ...
Context 7
... operation, the steel mesh point cloud is divided into independent 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 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 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Fig. 11 The point cloud after the segmentation display in the camera x-o-y coordinate system Fig. 12 The Point cloud after clustering steel bar point cloud. On this basis, we Obtain the welding point coordinates of the steel mesh, finally realizes the welding path planning of the steel ...
Context 8
... RANCAC method principle is shown on the left side of Fig. 13, which determines a line by two points on the basis of all sample points, and obtain the line model based on interior points by setting the distance threshold. The algorithm is simple and the calculation speed is fast. However the straight line obtained by the fitting must pass through two of the sample points.It slightly reduces the ...
Context 9
... SVD method principle is shown on the right side of Fig. 13, which determines the line based on sample points in the way of minimizing the distance between all sample points and the fitting line. The fitting process does not need pass through any sample point, leading to a high-accurate fitting results. The purpose of clustering and segmentation of steel mesh point cloud is to obtain ...
Context 10
... shown in Fig. 14, when the angle between the main optical axis of the 3D camera and the plane of the steel mesh is 90 • ± 5 • , the captured point cloud is the upper half of the each steel bar, and the density of the point cloud is gradually sparse along the z-axis. At this point, SVD method is used to carry out linear fitting for each steel bar point ...
Context 11
... sparse along the z-axis. At this point, SVD method is used to carry out linear fitting for each steel bar point cloud. According to the principle of the SVD method, the fitted straight line is located between the central axis and the upper surface of the reinforcing bar point cloud. From the top view of the cross steel bar point cloud shown in Fig. 15, it can be seen that the common vertical line of the cross steel bars point cloud is from the straight line fitted by the upper surface point cloud of the lower steel bar to the straight line fitted by the upper surface point cloud of the upper steel bar. In order to facilitate the accurate solution of the common vertical line, it is ...
Context 12
... 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 sides of the steel by point cloud filtering based on radius outlier removal. The remaining point cloud on the Upper surface of the steel bar are taken as the sample point of the fitting line. According to the principle of radius outlier removal in Fig. 16, calculate the number of other points within the radius d of each point. When the number of other points within the radius is less than the set number, the point will be removed. After repeated debugging in this experiment, the search radius is set to 2.5 and the number of points is set to 12. The point cloud after filtering based on ...
Context 13
... of other points within the radius d of each point. When the number of other points within the radius is less than the set number, the point will be removed. After repeated debugging in this experiment, the search radius is set to 2.5 and the number of points is set to 12. The point cloud after filtering based on radius outlier removal is shown in Fig. 17. The idea of fitting a space line based on SVD method is straightforward, that is, minimizing to minimize the distance from all sample points to the straight line. Firstly, we calculate the arithmetic average of all sample points coordinates (x, y, z) according to Eq. 1. The straight line must pass through the position of the ...
Context 14
... The relation variable t corresponding to all the points between the two endpoints of the line are all the numbers between t 1 and t 2 . The length of the fitting straight line of the steel bar point cloud extending along the y-axis is solved in the same way as extending along the x-axis.The straight line fitting based on SVD method is shown in Fig. ...
Context 16
... obtaining the fitting straight line of the steel bar point cloud, we need to find the common vertical line of the fitting line. As shown in Fig. 19, the fitting straight lines of steel bar 1 and steel bar 3 are AB and CD . The common vertical line of AB and CD is P Q. M is the foot point of AB and N is the foot point of CD . ...
Similar publications
At present, the operators needs to carry out complicated teaching and programming work on the welding path planning for the welding robot before welding the steel mesh. In this work, an automatic welding path planning method of steel mesh based on point cloud is proposed to simplify the complicated teaching and programming work in welding path plan...
Citations
Plane welds are a common type of weld in industrial sites. When the welding robot welds multiple types of plane welds at the same time, the traditional teaching and programming modes become relatively complicated. Therefore, in order to solve the problem of automatic robot welding of various types of plane welds, taking plane V-type butt, plane I-type butt, and plane lap welds as examples, this paper proposes a plane weld extraction method based on 3D vision. Firstly, in order to realize the line and plane segmentation of the workpiece point cloud, we establish the concept of plane point cloud density. Secondly, to segment workpiece edge lines, an iterative segmentation algorithm based on RANSAC is proposed. Then, based on the geometric features of the workpiece, a method for extracting weld feature points based on centroid positioning is proposed. Finally, the least squares method is used to fit the feature points of the welding seam to complete the welding trajectory planning. The experimental results show that the method can well solve the problem of automatic planning welding trajectory of plane V-type butt, plane I-type butt, and plane lap welds, to realize that the welding robot can simultaneously weld various plane welds without teaching and programming.
As a kind of structurally complex workpiece, open impellers made by welding are widely used in mining and light industries. The traditional robot programming method for open impeller welding path planning still requires a long cycle time, and the positioning of the open impeller after clamping is relatively complex and time-consuming. This paper proposes an open impeller welding path planning method for the purpose of improving the automation of open impeller welding by robots and shortening the open impeller welding cycle. From the analysis of the open impeller geometry, the path planning of open impeller welding is realized by extracting the welding seam curve and the blade edge curve. To enhance the open impeller posture detection after clamping on the positioner, a new structural light sensor is used to achieve open impeller alignment positioning by applying an improved iterative closest point (ICP) algorithm. Combined with the detection of the clamping posture, the robot welding path planning procedure of the open impeller is automatically generated. The final simulation and practical experiments verify the effectiveness of the proposed method.
