Visual Sensor Auto-Focusing Using Pattern-Based Robot Calibration
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Solution Overview
Problem
Existing methods for calibrating visual sensors on industrial robots require complex processing and may fail to accurately determine the placement information and focusing of workpieces with varied shapes.
Innovation Solution
An image processing system that includes a visual sensor, a visual pattern, and a focusing operation control unit to automatically focus on the visual pattern by adjusting the relative position between the sensor and pattern based on determined positional relations, using a calibration jig to enhance precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex processing is used to determine workpiece placement status and normal lines, then focusing accuracy may be improved, but device complexity and processing time increase significantly
Solution Approach 1:
A visual pattern serves as an intermediary object placed on the workpiece surface. Instead of directly analyzing complex workpiece geometry to determine placement status and normal lines, the system uses the standardized visual pattern as a mediator. The pattern's known geometry and high-contrast features enable straightforward detection of placement position and surface orientation, significantly simplifying the processing while maintaining focusing accuracy.
Solution Approach 2:
The visual pattern acts as a simplified copy or representation of the workpiece surface characteristics. By detecting the pattern's position and orientation, the system infers the workpiece placement status without needing to process the actual workpiece geometry. This copying approach reduces computational complexity while preserving the essential information needed for focusing.
2Productivity
If manual adjustment by users is used to focus the camera, then device complexity is reduced, but productivity and time efficiency deteriorate
Solution Approach 1:
The system performs automatic focusing without requiring user intervention. The visual sensor detects the visual pattern's position and orientation, the image processing unit calculates the normal line and optimal focal distance, and the focusing operation control unit automatically adjusts the camera. This self-service capability eliminates manual adjustment steps, significantly improving productivity while the automation is achieved through software processing rather than complex mechanical systems.
3Extent of automation
If visual patterns are placed on workpieces for automatic focusing, then focusing automation and productivity improve, but the method must handle various workpiece shapes and placements
Solution Approach 1:
The visual pattern is designed as a universal element that can be placed on workpieces of various shapes and sizes. The pattern's standardized geometry and high-contrast features enable consistent detection regardless of the underlying workpiece characteristics. The image processing unit adapts to different placements by detecting the pattern's position and orientation, making the automated focusing system versatile across different workpiece types while maintaining high automation.
Data Source
AI summary
An image processing system includes: an industrial machine; a visual sensor; a visual pattern arranged on a part to be detected, for identifying a relative positional relationship between the visual sensor and the visual pattern; an image processing unit that determines the relative positional relationship between the visual sensor and the visual pattern on the basis of an image of the visual pattern captured by the visual sensor; and a focusing operation control unit that, with the visual pattern within the field of view of the visual sensor, causes the visual sensor to capture the visual pattern while changing the relative positions of the visual sensor and the visual pattern in a predetermined direction with reference to the visual pattern, on the basis of the determined relative positional relationship to obtain a focus degree of the visual pattern, whereby the visual sensor is focused on the visual pattern.