Hybrid Triangulation and Photometric Stereo Welding Joint Tracking
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Solution Overview
Problem
Existing automatic welding techniques face challenges in achieving robust joint tracking, especially when the weld joint is being filled, as traditional methods like triangulation become less effective due to the increasing difficulty in detecting joint edges.
Innovation Solution
Combining triangulation with photometric stereo imaging to determine joint edges, using a welding device with a line illumination member, a camera for registering line images, and a stereo image member for photometric stereo images, allowing for simultaneous control of the welding head based on both image types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If triangulation is used for joint tracking, then measurement speed is improved, but measurement precision deteriorates when the joint is being filled
Solution Approach 1:
The patent combines triangulation-based line image registration with photometric stereo imaging to create a hybrid joint tracking system. The line illumination member scans a light beam across the joint line while the stereo image member captures photometric stereo images from multiple angles. This merging allows the system to use triangulation for fast initial positioning and photometric stereo for precise edge detection when the joint is filled, resolving the contradiction between speed and precision.
2Device complexity
If traditional triangulation is used, then device complexity is reduced, but reliability of joint tracking deteriorates when weld beads are applied
Solution Approach 1:
The patent introduces photometric stereo imaging as an intermediary detection method that works reliably when triangulation fails. The line illumination member and camera system capture images from multiple angles, and the processing member uses these photometric stereo images to determine joint geometry even when weld beads are present. This intermediary approach maintains tracking reliability without significantly increasing overall system complexity.
3Measurement precision
If photometric stereo imaging is used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The line illumination member and camera system serve multiple functions: they capture both triangulation-based line images for fast positioning and photometric stereo images for precise edge detection. The processing member processes both image types to determine joint geometry. This multi-functionality allows the system to achieve high measurement precision without proportionally increasing device complexity, as the same hardware components perform multiple detection tasks.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and robust joint tracking throughout the welding process, ensuring precise placement of weld beads even as the joint fills, by leveraging the strengths of both triangulation and photometric stereo imaging.
Implementation Method 1
a line illumination member which is arranged to illuminate the joint by scanning a light beam across the joint line
Implementation Method 2
at least one camera arranged for registering line images of the joint when it is illuminated with the scanned light beam
Implementation Method 3
a stereo image member arranged to register photometric stereo images of the joint substantially simultaneously with the registration of the line images
Implementation Method 4
a processing member for determining at least the location of the edges of the joint by means of triangulation based on the registered line image
Data Source
Figure 1~2
Figure 3
AI summary
Welding device (1) and a method for automatic multiple-bead welding are described. A line illumination member (10) is arranged to illuminate the joint by scanning a light beam across the joint line (8). A camera (16) is arranged for the registration of line images of the joint when it is illuminated with the scanned light beam. The locations of the edges (12, 13) of the joint are determined by means of triangulation based on the registered line image. The welding device (1) comprises a stereo image member arranged to register photometric stereo images of the joint substantially simultaneously with the registration of the line images. The welding device (1) is arranged to, during welding of a weld joint with a plurality of weld beads, control the welding head (9) in dependence on both stereo images and line images.