Photographic Hole Measurement Calibration Using a Reference Sphere
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Solution Overview
Problem
Existing non-contact photographic hole measurement methods in aircraft assembly suffer from elliptical contour distortion of hole edges at different angles, leading to inaccuracies in position calculation, which are not addressed by current calibration methods.
Innovation Solution
A calibration device and method that simulates hole edge contours using a photographic calibration ball measurement, ensuring circular edge contours under any camera angle, and includes a base, installation platform, and illumination compensator to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-contact photographic hole measurement is used for rapid detection, then detection speed is improved, but positioning accuracy deteriorates due to elliptical contour distortion
Solution Approach 1:
The patent uses a calibration ball with known geometric parameters as a copy/reference object to simulate the hole contour. By photographing the calibration ball and comparing its projected elliptical contour with the theoretical circular contour, the system calculates distortion parameters that can be used to correct hole position measurements, thereby maintaining both rapid detection and positioning accuracy.
Solution Approach 2:
The calibration ball serves as an intermediary object between the camera system and the actual hole measurements. It provides a known reference that mediates the distortion introduced by the camera's perspective and lens characteristics, enabling the system to compensate for these distortions when measuring actual hole positions.
2Device complexity
If calibration is performed using existing methods, then calibration process is simplified, but positioning accuracy of hole measurement deteriorates
Solution Approach 1:
The patent employs a spherical calibration ball instead of flat calibration patterns or complex multi-point calibration systems. The spherical geometry provides a simple yet effective reference where the relationship between the 3D sphere and its 2D projected ellipse is well-defined and mathematically tractable, simplifying the calibration process while achieving high positioning accuracy through precise geometric modeling.
Data Source
AI summary
Disclosed are a calibration device for non-contact photographic hole measurement and a calibration method for non-contact photographic hole measurement. The device includes a base, an installation platform, a calibration assembly and an illumination compensator. The installation platform is provided at the base, and the calibration assembly is provided at the installation platform. In a calibration process, the base drives the installation platform to rotate around a Z axis, thereby driving the calibration assembly to rotate around the Z axis. At the same time, the installation platform drives the calibration assembly to rotate around an X axis. The illumination compensator is configured to fill light for a camera during a photography process.