Multi-Surface Position Measurement for 6-DOF Thermal Stability
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Solution Overview
Problem
Existing position-measuring devices for coordinate measuring machines face challenges in accurately measuring relative positions in multiple degrees of freedom while being susceptible to temperature-related errors.
Innovation Solution
A position-measuring device with a carrier body and scanning assembly, where multiple surfaces carry inclined measuring graduations and scanning units, ensuring accurate position measurement in all six degrees of freedom by aligning normal planes to a common axis, thereby minimizing temperature-induced errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple scanning units are used to measure all six degrees of freedom, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The measuring system is segmented into multiple independent scanning units, each equipped with its own scanning sensor. This allows each unit to independently measure specific degrees of freedom, improving overall measurement precision while maintaining modular complexity that is easier to manage and implement
Solution Approach 2:
The invention transitions from one-dimensional linear measurement to three-dimensional spatial measurement by adding scanning units at different positions and orientations. This enables simultaneous measurement of all six degrees of freedom (three translational and three rotational), achieving complete positional and orientational accuracy
2Measurement precision
If scanning units are positioned to measure multiple degrees of freedom, then measurement precision is improved, but temperature-related errors increase
Solution Approach 1:
Each scanning unit is equipped with its own scanning sensor positioned at a specific location, creating localized measurement points. This distributed sensing approach allows for better thermal management at each measurement point and reduces the impact of temperature gradients on overall measurement accuracy
Solution Approach 2:
The invention replaces purely mechanical contact-based measurement with optical or electromagnetic scanning methods. This substitution eliminates mechanical friction and contact forces that generate heat, thereby reducing temperature-related measurement errors while maintaining high precision
3Measurement precision
If carrier body extends longitudinally in direction of feed, then measurement of relative position is improved, but manufacturing precision requirements increase
Solution Approach 1:
The carrier body is designed as a modular structure with multiple surfaces carrying measuring graduations. This segmentation allows each surface to be manufactured and calibrated independently, reducing the cumulative error that would occur in a single monolithic structure while maintaining overall measurement accuracy
Solution Approach 2:
Multiple surfaces of the carrier body carry identical or complementary measuring graduations. This redundancy provides multiple copies of the measurement scale, allowing the system to average out manufacturing variations and achieve higher effective precision than would be possible with a single surface
Data Source
AI summary
A position-measuring device includes a carrier body and scanning units movable relative thereto. At least three surfaces of the carrier body each carry a first and second measuring graduation, each having a series of graduation lines. Each of the measuring graduations is associated with a scanning unit for scanning the respective measuring graduation at a scanning location such that, for each surface, two scanning units are disposed for scanning the respective measuring graduations. In each case, these two scanning units are disposed in such a way, and the graduation lines of the two measuring graduations are inclined with respect to each other in such a way, that two normal planes extending respectively in the direction of the respective graduation lines through the respective scanning locations of the two scanning units have a common axis of intersection, whereby the three resulting axes of intersection extend through a common point.