Test Element Pose Variation for Coordinate Measuring Machine Calibration
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Solution Overview
Problem
Existing methods for calibrating rotation axes in coordinate-measuring machines and machine tools face limitations due to the high costs, limited calibration accuracy, and sensitivity to external influences of mirror polygons, as well as the inability to correct higher-order errors and provide flexible support locations.
Innovation Solution
A method involving a test element, such as a mirror or polygon, is moved into various poses within the coordinate-measuring machine or on a rotating apparatus using a movement device, allowing for precise error determination of the rotation position system without the need for expensive, highly accurate calibrated polygons, enabling any number of measurements with small angle changes and overcoming the limitations of traditional polygon-based calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a mirror polygon with many surfaces is used to improve calibration accuracy, then measurement precision increases, but device complexity and cost increase significantly
Solution Approach 1:
The patent divides the measurement process into multiple discrete measurement positions around the rotation axis. Instead of using one complex high-precision polygon, the system performs multiple measurements at different angular positions (e.g., every 30 degrees for 12 positions) to comprehensively characterize the rotation axis errors throughout the full rotation range.
Solution Approach 2:
The patent uses a simple mirror or reflector that can be positioned at multiple locations rather than a single complex calibrated polygon. The measurement system captures images of the mirror at different positions to determine rotation axis errors, effectively copying the measurement function across multiple positions rather than relying on one complex reference object.
2Measurement precision
If a calibrated polygon is used to achieve accurate error determination, then measurement precision improves, but purchase costs and delivery time increase
Solution Approach 1:
The patent replaces expensive, hard-to-obtain calibrated polygons with simple, inexpensive mirrors or reflectors that can be easily manufactured and obtained. These simple reflective elements serve the same measurement function without requiring costly certification processes or long delivery times associated with precision calibration laboratories.
Solution Approach 2:
The measurement system performs self-calibration by capturing images of the mirror at multiple positions and computationally determining the rotation axis errors from the geometric relationships in the captured images. The system derives its own calibration data without requiring external calibration services or pre-calibrated reference objects.
3Ease of manufacture
If a polygon with fixed number of surfaces is used, then manufacturing is simplified, but adaptability to different measurement needs is reduced
Solution Approach 1:
The patent introduces dynamic positioning capability where a simple mirror can be moved to multiple different angular positions around the rotation axis during measurement. This dynamic repositioning allows the same simple mirror to provide measurement data for characterizing rotation errors at all positions, replacing the need for fixed multi-surface polygons with different numbers of surfaces for different measurement requirements.
Solution Approach 2:
The simple mirror or reflector serves multiple functions: it can be positioned at any angular location, it provides reflection for image capture, and it enables determination of rotation axis errors throughout the full rotation range. This single versatile element replaces multiple specialized polygons that would be needed to cover different measurement scenarios.
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 provides a cost-effective and accurate method for determining movement or rotation position errors, allowing for flexible pose changes and increased measurement capabilities beyond the limitations of traditional polygon systems, thereby improving calibration accuracy and reducing operational costs.
Implementation Method 1
A method involving a test element, such as a mirror or polygon, is moved into various poses within the coordinate-measuring machine
Data Source
AI summary
A method for performing measurements using a test element, comprising:arranging a test element in a measurement region of a coordinate-measuring apparatus, wherein the test element is arranged on a base of the coordinate-measuring apparatus or at/on a first, rotatable part of a rotating apparatus arranged within the measurement region, and wherein the test element is arranged in a first pose relative to the base or to the first part.performing a measurement by incorporating the test element in the first pose,arranging the test element with the movement device in a second pose on the base or on the first part using the movement device,performing a measurement by incorporating the test element in the second pose.