Imaging Sensor Alignment via Convex Reflective Reference Surface
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Solution Overview
Problem
Coordinate measuring machines with multiple sensors face challenges in calibrating imaging sensors due to sensitivity to illumination types, leading to uncertainty in relative positions and orientations, especially when detecting artifact boundaries.
Innovation Solution
A convex reflective reference surface, such as a spherical reflector, is integrated into the coordinate measuring machine to allow the imaging sensor to capture images of a fiducial marker, which is either internally or externally illuminated, enabling alignment and calibration within the machine's reference frame by providing a consistent image across various positions and orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If different types of illumination are used to detect artifact boundaries, then image contrast can be achieved, but detection accuracy becomes sensitive to illumination type and calibration uncertainty increases
Solution Approach 1:
The patent uses a reflective reference surface that creates a virtual copy of the fiducial marker. The imaging sensor captures an image of the fiducial marker reflected in the convex reflective surface, effectively creating a consistent optical copy that can be imaged from multiple positions and orientations without being affected by illumination sensitivity issues of physical artifacts.
Solution Approach 2:
The convex reflective surface acts as an intermediary between the fiducial marker and the imaging sensor. Instead of directly imaging the artifact boundary, the system images the fiducial marker through its reflection, which provides consistent contrast and eliminates the need for complex illumination setups while maintaining measurement precision.
2Adaptability or versatility
If imaging sensors are positioned at multiple orientations to collect measurements, then comprehensive data can be gathered, but calibration complexity and uncertainty increase
Solution Approach 1:
The fiducial marker with convex reflective surface serves multiple functions: it provides a consistent reference target for calibration, creates a virtual image that can be captured from any orientation, and eliminates the need for different illumination setups for different sensor positions. This universal reference solution simplifies calibration across multiple sensor orientations.
Solution Approach 2:
The convex reflective surface, typically spherical or curved, provides consistent reflective properties from all viewing angles. This curvature ensures that the fiducial marker's reflected image maintains consistent characteristics regardless of the imaging sensor's position or orientation, greatly simplifying multi-orientation calibration compared to flat or irregular surfaces.
3Loss of information
If traditional artifact boundary detection is used, then measurement data can be collected, but illumination sensitivity causes calibration uncertainty
Solution Approach 1:
Instead of directly measuring artifact boundaries that are sensitive to illumination, the system creates and images a reflected copy of the fiducial marker. This virtual image in the reflective surface provides consistent visual information for calibration that is independent of illumination variations, thereby improving reliability while maintaining data collection capability.
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
This approach allows for precise determination of the imaging sensor's position and orientation relative to other sensors, improving calibration accuracy and reducing uncertainty by using a fiducial marker that can be imaged through the convex reflective surface, facilitating the alignment of the imaging sensor within the machine's reference frame.
Implementation Method 1
a reflective reference sphere or other convex reflective surface shape can be arranged in accordance with certain embodiments disclosed herein
Data Source
AI summary
An alignment system for an imaging sensor of a coordinate measuring machine incorporates a reference surface associated with a stage of the measuring machine but instead of imaging the reference surface as a location marker, the reference surface is incorporated into a combined imaging system together with the imaging sensor for imaging a feature associated with the imaging sensor. The imaged feature can be an internal part of the imaging sensor, such as an internal aperture, or an external feature in a fixed relationship with the imaging sensor, such as a lens hood.