ToF Welding Vision for Arc-Resistant 3D Seam Tracking
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Solution Overview
Problem
Conventional optical cameras and laser scanners face challenges in providing clear vision in harsh arc welding environments due to intense light contrast and obstructions like fumes and spatters, limiting their effectiveness in seam tracking and weld quality control.
Innovation Solution
The use of time-of-flight (ToF) cameras, which generate 3D spatial data by measuring the phase shift of actively modulated light, providing clear imaging in both low-light and bright conditions, and are designed to block out arc radiation, thus offering improved signal-to-noise ratio and depth resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical cameras are used in arc welding environment, then the system is simple and cost-effective, but the vision is obscured due to intense light contrast and fume obstruction
Solution Approach 1:
The patent introduces an intermediary substance (welding smoke and spatter) that reflects the structured light pattern back to the camera. This indirect reflection mechanism allows the camera to capture depth information without being directly exposed to the harmful arc brightness, effectively using the harmful environment as part of the solution.
Solution Approach 2:
The patent transitions from 2D optical imaging to 3D depth mapping by projecting structured light patterns and capturing their reflection. This dimensional change allows the system to obtain spatial information that is independent of the intense arc brightness, as the depth data is derived from light travel time and pattern distortion rather than direct optical intensity.
2Measurement precision
If laser scanners are used to overcome arc brightness and fume obstruction, then measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent employs inexpensive, readily available components such as standard digital cameras and LED light sources instead of expensive laser scanners. The system uses multiple low-cost camera units that can be positioned at different locations, providing a cost-effective alternative to single high-precision laser scanning systems.
Solution Approach 2:
The patent divides the welding scene monitoring into multiple independent camera units, each capturing depth information from a specific viewpoint. This segmentation allows the system to achieve comprehensive 3D coverage without requiring a single complex high-precision scanner, distributing the measurement function across multiple simpler components.
3Measurement precision
If conventional cameras are used, then the device complexity is low, but the field of view is limited and seam tracking accuracy is reduced
Solution Approach 1:
The patent makes each camera unit multi-functional by enabling it to perform both 2D visual inspection and 3D depth mapping simultaneously. The same camera hardware captures both the reflected structured light pattern for depth measurement and the visual image for seam identification, eliminating the need for separate sensing systems.
Solution Approach 2:
The patent merges the 2D imaging function and 3D depth sensing function into a single integrated system. By combining the structured light projection with standard digital camera imaging, the system achieves both wide field of view coverage and accurate seam tracking without requiring separate specialized devices.
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
ToF cameras enable effective 3D mapping and tracking of welding scenes, improving seam visibility, weld quality control, and reducing human interaction by providing accurate spatial data for robotic guidance and process optimization.
Implementation Method 1
time of flight camera for welding machine vision... generate 3D spatial data by measuring the phase shift of actively modulated light
Implementation Method 2
designed to block out arc radiation, thus offering improved signal-to-noise ratio
Data Source
AI summary
A machine-vision-assisted welding system comprises welding equipment, a time of Flight (ToF) camera operable to generate a three-dimensional depth map of a welding scene, digital image processing circuitry operable to extract welding information from the 3D depth map, and circuitry operable to control a function of the welding equipment based on the extracted welding information. The welding equipment may comprise, for example, arc welding equipment that forms an arc during a welding operation, and a light source of the ToF camera may emit light whose spectrum comprises a peak that is centered at a first wavelength, wherein the first wavelength is selected such that a power of the peak is at least a threshold amount above a power of light from the arc at the first wavelength.