Position Measuring Device Orthogonal Scanning
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Solution Overview
Problem
Existing position-measuring devices face challenges in accurately accounting for temperature-induced displacement of scales in position measurements, particularly in long measuring lengths, where existing methods may not provide precise correction for scale expansion.
Innovation Solution
A position-measuring device design featuring a first assembly with a profiled element bearing a scale and a second assembly with a movable scanning unit, where additional scanning units are positioned orthogonally to the measuring direction to allow collision-free traversal and measure scale displacement relative to the first object, using a resilient connection and sealing to prevent interference with the measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are assigned to the scale to record temperature-induced displacement, then temperature measurement capability is improved, but device complexity increases due to additional sensors and measurement points
Solution Approach 1:
The second scanning unit is designed to serve dual purposes: it scans the second measuring graduation for position reference and simultaneously measures temperature-induced displacement of the scale. This multi-functional design eliminates the need for separate temperature sensors while maintaining measurement precision.
Solution Approach 2:
The patent combines the temperature measurement function with the existing position measurement system by integrating the second scanning unit into the profiled element. The same scanning mechanism that reads the scale also captures thermal expansion data, merging two measurement functions into one component.
2Measurement precision
If additional scanning units are added to measure scale displacement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The second scanning unit performs multiple functions: it scans the second measuring graduation on the scale and simultaneously measures temperature-induced displacement. This multi-functionality improves position measurement precision without requiring separate dedicated components for each measurement task.
Solution Approach 2:
The second scanning unit is positioned at a distance spaced apart from the first scanning unit orthogonally to the measuring direction, utilizing a different spatial dimension. This orthogonal arrangement allows both scanning units to operate independently without interference while contributing to precise position measurement through their combined data.
3Volume of moving object
If the second scanning unit is positioned close to the first scanning unit, then device compactness is improved, but collision-free traversal becomes difficult
Solution Approach 1:
The second scanning unit is positioned at a distance spaced apart from the first scanning unit orthogonally to the measuring direction, utilizing the orthogonal dimension rather than increasing separation along the measuring direction. This maintains device compactness while ensuring collision-free traversal of the first scanning unit along its travel path.
Solution Approach 2:
The profiled element serves as an intermediary structure that carries both scanning units and the second measuring graduation. It provides a stable mounting platform that positions the second scanning unit optimally relative to the first scanning unit, enabling both compact arrangement and unobstructed movement.
4Device complexity
If the second scanning unit is mounted on the profiled element, then device complexity is reduced by using existing structure, but the scanning unit may interfere with measurement operation
Solution Approach 1:
The second scanning unit is positioned orthogonally to the measuring direction, in a dimension that does not interfere with the linear traversal of the first scanning unit. This spatial arrangement ensures that mounting the second scanning unit on the profiled element does not compromise measurement operation reliability.
Solution Approach 2:
The second scanning unit is designed to scan the second measuring graduation which is positioned separately from the first measuring graduation. By extracting the temperature measurement function to a separate scanning operation on a separate graduation, the system avoids interference with the primary position measurement while maintaining reliability.
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
Enables accurate determination of temperature-induced displacement and linear expansion of the scale, ensuring precise position measurement correction without influencing the measurement operation, particularly suited for long measuring lengths.
Implementation Method 1
The temperature-induced displacement of the scale is to be taken into account during the position measurement... the temperature-induced displacement of the scale can be ascertained from the measured temperature and the thermal expansion coefficient of the scale material
Data Source
AI summary
A position-measuring device includes a first assembly and a second assembly. The first assembly, installable on a first object, has a profiled element that bears a scale having a first and second measuring graduation. The second assembly, installable on a second object, has a first scanning unit that is movable along a travel path in a measuring direction to scan the first measuring graduation. A position of the first object relative to the second object is therefore measurable. A second scanning unit is mounted on the profiled element so as to enable the second measuring graduation to be scanned, and is positioned in a way that allows the first scanning unit to traverse collision-free along the travel path at a distance spaced apart from the second scanning unit orthogonally to the measuring direction such that a displacement of the scale relative to the first object is measurable.