Position Measuring Device Dynamic Reference Value Adjustment

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Solution Overview

Problem

Existing absolute position measuring devices face reliability issues due to increased error signals when scanning signal amplitudes decrease, and adaptive threshold methods can misinterpret code elements, leading to incorrect position measurements.

Innovation Solution

A position measuring device with a code consisting of irregular sequences of fields with inverse properties, where each code element is formed by a single field, and a scanning device with detector elements generates analog signals for evaluation units to derive absolute position information by comparing signals with dynamically adjusted reference values based on scanning signal amplitudes, ensuring accurate bit value assignment and error checking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a fixed reference value is used for comparing scanning signals, then the device complexity is reduced, but the reliability deteriorates due to increased error signals when signal amplitudes decrease

Engineering Contradiction:
Improvereference value determinationVSAvoidmeasurement reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The reference value is changed from a fixed predetermined value to a dynamically determined value that adapts to current scanning conditions. The evaluation unit determines the reference value based on the actual scanning signals, allowing the system to adjust to varying signal amplitudes and reduce error signals while maintaining reasonable complexity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system uses feedback from the scanning signals themselves to determine the reference value. The evaluation unit analyzes the scanning signals and uses this information to set an appropriate reference value, creating a closed-loop system that improves reliability without requiring additional external reference sources.

Inventive Principle:
Principle #23Feedback

2Ease of operation

If the reference value is permanently specified, then the ease of operation is improved, but the adaptability deteriorates when signal amplitudes change during operation

Engineering Contradiction:
Improvereference value settingVSAvoidsignal amplitude adaptation
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The reference value transitions from a static predetermined value to a dynamic value that automatically adjusts to changing signal conditions. This allows the system to maintain ease of operation while adapting to varying signal amplitudes during operation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system determines its own reference value automatically based on the scanning signals without requiring external intervention or manual adjustment. The evaluation unit performs self-adjustment, making the system both easy to operate and adaptable to changing conditions.

Inventive Principle:
Principle #25Self-service

3Adaptability or versatility

If an additional detector is used to adapt the comparison threshold, then the adaptability is improved, but the device complexity increases and measurement precision deteriorates due to misinterpretation of code elements

Engineering Contradiction:
Improvethreshold adaptationVSAvoiddetector arrangement
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The existing evaluation unit is made multi-functional by enabling it to both evaluate scanning signals and determine the reference value. This eliminates the need for a separate additional detector, maintaining adaptability while reducing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The functions of signal evaluation and reference value determination are merged into a single evaluation unit. This integration avoids the problems of additional detectors while maintaining the ability to adapt to changing signal conditions.

Inventive Principle:
Principle #5Merging (Combining)

4Manufacturing precision

If the comparison range is specified by a fixed reference value, then the manufacturing precision is improved, but the reliability deteriorates when signal amplitudes are reduced

Engineering Contradiction:
Improvecomparison range specificationVSAvoiderror signal generation
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The comparison range is changed from a fixed specification to a dynamic range that adjusts with signal amplitudes. The reference value determined from actual scanning signals creates a comparison range that maintains manufacturing precision while preventing error signals when amplitudes are reduced.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2040041B1Position measuring device and method for measuring position
Publication Date: 2014.10.29 DR JOHANNES HEIDENHAIN GMBH
  • EP2040041B1 patent drawingFigure 1
  • EP2040041B1 patent drawingFigure 2~3
  • EP2040041B1 patent drawingFigure 4

AI summary

The invention provides a position measuring device in which information (B1, B2, B3, F) is obtained for each code element (C1, C2, C3) of a sequential pseudorandom code (C). This information (B1, B2, B3, F) of a code element (C1, C2, C3) is determined by comparing at least one sample signal (S1A to S3B) of this code element (C1, C2, C3) with a reference value (+V, -V). The reference value (+V, -V) is derived from and adjusted based on the sample signals (S1A to S3B) of the code elements (C1, C2, C3).