Laser Weld Vision Inspection With Shielded Composite Imaging
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Solution Overview
Problem
Vision-based inspection systems struggle to accurately analyze laser welds due to shadowing effects caused by deep concavities, making it difficult to assess the narrow widths and depths of laser welds in automotive and other applications.
Innovation Solution
A vision inspection system with a scanning station and vision sensing assembly that includes a light source, sensor, and a shield, where the sensor generates multiple images using different exposure periods and combines them into a composite image, while a light shield reduces light dimensions to create a buffer zone around the welds, and a robot delivers the workpiece to the scanning station, ensuring accurate inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a vision-based inspection system is used to analyze laser welds, then the inspection can be performed automatically, but the accuracy is reduced due to shadowing effects from deep concavities
Solution Approach 1:
The patent transitions from 2D planar illumination to 3D conformal illumination by wrapping the light source around the workpiece. This dimensional change allows light to reach into deep concavities and weld geometries that traditional overhead lighting cannot illuminate, eliminating shadowing effects while maintaining automated inspection capability
Solution Approach 2:
The patent introduces a conformal light source as an intermediary element that physically contacts or closely follows the workpiece surface. This intermediary mediates between the inspection system and the complex weld geometry, providing uniform illumination across varying surfaces and eliminating direct line-of-sight shadowing problems
2Device complexity
If traditional overhead lighting is used, then the system is simple, but shadowing effects occur in deep concavity areas
Solution Approach 1:
The lighting system evolves from simple overhead (1-point) illumination to conformal wrapping illumination that follows the 3D geometry of the workpiece. This dimensional transformation enables light to penetrate deep concavities and eliminate shadowing, justifying the increased system complexity through superior inspection capability
Solution Approach 2:
The conformal light source provides localized illumination quality that adapts to different regions of the workpiece. By conforming to the local geometry at each point on the surface, the lighting system ensures uniform illumination quality across varying depths and angles, eliminating shadowing in previously dark areas
3Measurement precision
If the vision sensor is positioned close to the workpiece, then detailed morphology can be captured, but artificial noise increases
Solution Approach 1:
The conformal light source acts as an intermediary that enables the sensor to capture detailed morphology without excessive noise. By providing uniform, shadow-free illumination, the light source allows the sensor to be positioned closer to the workpiece while maintaining signal quality and reducing the need for high-gain amplification that would introduce noise
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
The system effectively reduces shadowing and improves the accuracy of laser weld inspection by capturing detailed morphology and avoiding artificial noise, enabling precise analysis of weld dimensions and normal production variations.
Implementation Method 1
The light source illuminates the workpiece while the sensor generates an image of the one or more laser welds
Implementation Method 2
the sensor generates an image of the one or more laser welds
Data Source
AI summary
A vision inspection system for laser welds includes a scanning station to support a workpiece including one or more laser welds. A vision sensing assembly includes a top surface, a bottom surface, side surfaces, a light source, and a sensor. The light source illuminates the workpiece while the sensor generates an image of the one or more laser welds of the workpiece. A shield is arranged around the top surface and the side surfaces of the vision sensing assembly. The bottom surface of the vision sensing assembly is arranged above a lower edge of the shield by a first predetermined distance.