Cylindrical Surface Inspection via Luminance Profile Positioning
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Solution Overview
Problem
Existing cylindrical-body surface inspection methods face challenges in accurately detecting surface defects, particularly when the relative position between the cylindrical body and the inspection device changes, leading to difficulties in maintaining consistent inspection performance.
Innovation Solution
A cylindrical-body surface inspection device and method that includes a light irradiation unit, a two-dimensional imaging unit, a scanning-position determination unit, a time-series scanning image generator, and an inspection unit, which calculates a luminance profile, determines a scanning position by adjusting the peak luminance position with a coefficient, and generates a time-series scanning image to detect defects, ensuring accurate inspection even with positional changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an automatic inspection device is temporarily installed in the vicinity of the inspection target roll, then the device can be used flexibly without permanent installation, but it becomes difficult to adjust the optical system with high accuracy
Solution Approach 1:
The inspection device automatically determines the scanning position by calculating the luminance profile and identifying the peak position, eliminating the need for manual optical adjustment. The system self-calibrates by using the luminance distribution from the actual inspection target, making the inspection results independent of precise optical alignment.
Solution Approach 2:
The system changes from requiring fixed optical parameters (precise alignment) to using variable parameters (luminance profile shape) that adapt to different installation positions. By using the luminance profile as the basis for position determination, the system accommodates variations in installation position without requiring high-precision optical adjustment.
2Productivity
If a line sensor camera is used for inspection, then continuous conveyance process inspection is enabled, but high accuracy adjustment of sensor distance, angle, and parallelism is required
Solution Approach 1:
The system automatically determines the scanning position based on the luminance profile obtained from the area sensor, eliminating the need for complex manual adjustment of sensor distance, angle, and parallelism. The position determination is performed self-service by the system itself through image processing.
Solution Approach 2:
The patent replaces the mechanical adjustment system (manual positioning of line sensor camera) with an optical-digital system (area sensor with image processing). Instead of mechanically adjusting sensor parameters, the system uses digital image processing to determine position from luminance distribution.
3Ease of operation
If visual inspection by human is performed, then simple setup is possible, but detection of small and varied deformation is difficult
Solution Approach 1:
The patent replaces human visual inspection with an automated area sensor-based inspection system. The area sensor captures images and the system processes luminance profiles to detect surface deformations, providing both ease of operation (automatic setup) and high detection precision.
Solution Approach 2:
The system creates a digital copy (luminance profile) of the surface characteristics and analyzes it to detect deformations. By copying the visual information into digital form and processing it algorithmically, the system achieves both automated operation and precise detection of small variations.
4Ease of operation
If area sensor is used instead of line sensor camera, then adjustment becomes easier, but inspection accuracy may be compromised
Solution Approach 1:
The area sensor system performs self-service by automatically determining the scanning position through luminance profile analysis. This eliminates the need for precise manual adjustment while maintaining inspection accuracy, as the system adapts to its actual installation position through image processing.
Solution Approach 2:
The patent transitions from a one-dimensional line sensor approach to a two-dimensional area sensor approach. By capturing luminance distribution across a two-dimensional field and analyzing profiles, the system gains positional information automatically, compensating for the lack of precise mechanical adjustment.
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 solution allows for stable and highly accurate inspection of cylindrical-body surface defects, facilitating easy adjustment of the optical system and maintaining inspection performance despite changes in the relative position between the cylindrical body and the inspection device.
Implementation Method 1
a light irradiation unit that irradiates the cylindrical body with light; a two-dimensional imaging unit that receives reflected light from a surface of the cylindrical body
Data Source
Figure 1
Figure 2
Figure 3~4(b)
AI summary
The present invention includes a light irradiation unit configured to irradiate a cylindrical body with light; a two-dimensional imaging unit arranged at a position to receive reflected light from the surface of the cylindrical body on which light emitted from the light irradiation unit is reflected; a scanning-position determination unit configured to determine at a predetermined period, with respect to the two-dimensional image data acquired by the two-dimensional imaging unit, a scanning position that is a scanning position in a first direction of the two-dimensional image data and is corresponding to a circumferential direction of the cylindrical body; a time-series scanning image generator configured to perform extraction of image data in a second direction perpendicular to the first direction at a scanning position determined by the scanning-position determination unit, out of the two-dimensional image data, on a plurality of pieces of the two-dimensional image data acquired by the two-dimensional imaging unit and to generate a time-series scanning image by arranging in chronological order in the first direction each piece of extracted image data of the second direction; and an inspection unit configured to inspect the time-series scanning image and detect a defect image.