Position Measuring Device Single Scanning Head Calibration
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Solution Overview
Problem
Existing position-measuring devices face challenges in achieving high accuracy due to systematic measurement errors, such as eccentricity and local geometric deviations, which are exacerbated by phase differences between scanning units, leading to increased complexity and cost in implementation.
Innovation Solution
A position-measuring device that uses a single scanning head with stored correction values determined during calibration, allowing for accurate detection of relative positions by correcting measurement values with a nonvolatile memory, eliminating the need for additional scanning heads and reducing computing power, while maintaining accuracy similar to multi-head systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple scanning heads are used to suppress measurement errors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by performing error characterization during a calibration phase before actual measurement. Multiple scanning heads are used temporarily to characterize errors and store correction values, then a single scanning head performs measurements using these pre-computed corrections, eliminating the need for continuous multi-head operation.
Solution Approach 2:
The patent uses copying by creating a digital replica of the multi-head measurement capability through correction values stored in memory. The single scanning head effectively copies the error-compensation functionality of multiple heads by applying pre-determined correction factors, achieving multi-head precision with single-head hardware.
2Measurement precision
If additional scanning heads are used for error compensation, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The calibration phase performs preliminary error characterization using additional scanning heads, storing the results as correction values. This one-time preliminary action eliminates the need for permanent installation of multiple expensive scanning heads, reducing manufacturing cost while maintaining precision.
Solution Approach 2:
The additional scanning heads used during calibration serve a temporary, disposable function. After calibration, they can be removed or deactivated, and their role is replaced by inexpensive memory storage containing correction values, significantly reducing the permanent hardware requirements and manufacturing cost.
3Measurement precision
If phase difference between scanning units is reduced, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the phase synchronization problem from the operational measurement phase and relocates it to the calibration phase. During calibration, phase relationships are characterized and stored as correction values. During operation, a single scanning head eliminates phase difference issues entirely while applying these pre-determined corrections, separating the complexity from the measurement process.
Solution Approach 2:
The correction values copied from the multi-head calibration phase enable a single scanning head to achieve the same measurement precision without requiring phase synchronization hardware or software, copying the functional outcome without the operational complexity.
4Device complexity
If computing power is reduced to a single scanning head, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The calibration phase performs preliminary error characterization and computation, storing correction values that compensate for systematic errors. This shifts the computational burden from real-time operation to setup phase, allowing a simple single-head system to achieve high precision through pre-computed corrections rather than real-time multi-head processing.
Solution Approach 2:
The patent replaces the mechanical/multi-sensor system with a computational approach using a single sensor. Instead of physically combining multiple scanning heads to achieve precision, the system uses electronic correction values applied by a single head, substituting mechanical complexity with computational correction.
Data Source
AI summary
A position-measuring device for detecting the relative position of two bodies capable of motion relative to each other includes a measurement standard with a scale division connected to one of the bodies and a scanning head (MK) connected to the other body for reading the scale division, wherein the scanning head is connected to an electronic evaluation unit. The electronic evaluation unit has a nonvolatile memory in which correction values for the measurement values recorded by the scanning head are stored, wherein the correction values are determined during a preceding calibration of the position-measuring device together with the use of at least one other scanning head to scan the same measurement standard.