Position Measuring Device Eccentricity Correction via Duty Cycle Analysis
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Solution Overview
Problem
Existing position measuring devices face challenges in achieving high accuracy due to measurement errors caused by eccentricity, which often require additional components and increased complexity, leading to higher costs.
Innovation Solution
A position measuring device that uses a single scanning chip or receiving unit, with a material measure that varies in width along its orientation, allowing for precise determination of angular or linear positions by analyzing the duty cycle of signal pulses, thereby accounting for eccentricity without additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional receivers or code tracks are arranged on the modulator to determine eccentricity, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts the eccentricity determination function from the mechanical/optical structure and relocates it to the evaluation unit through signal processing. By analyzing the duty cycle of signals already present in the system, the evaluation unit calculates eccentricity without requiring additional physical components like receivers or code tracks on the modulator.
Solution Approach 2:
The patent replaces the mechanical/optical approach of determining eccentricity (which would require additional physical components) with an electronic signal processing approach. The evaluation unit uses electronic analysis of signal duty cycles to determine eccentricity, substituting mechanical complexity with electronic computation.
2Measurement precision
If additional receivers or code tracks are arranged on the modulator to determine eccentricity, then measurement accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the eccentricity determination function from the mechanical/optical structure and relocates it to the evaluation unit through signal processing. By analyzing the duty cycle of signals already present in the system, the evaluation unit calculates eccentricity without requiring additional physical components like receivers or code tracks on the modulator.
Solution Approach 2:
The patent replaces the mechanical/optical approach of determining eccentricity (which would require additional physical components) with an electronic signal processing approach. The evaluation unit uses electronic analysis of signal duty cycles to determine eccentricity, substituting mechanical complexity with electronic computation.
3Measurement precision
If the modulator is arranged very precisely with respect to the receiver to ensure high accuracy, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the evaluation unit continuously analyzes the duty cycle of received signals to determine the actual eccentricity between modulator and receiver. This measured eccentricity information is then used to correct position measurements in real-time, creating a closed-loop system that compensates for misalignment without requiring precise mechanical arrangement.
Solution Approach 2:
The patent changes the approach from controlling physical position parameters (precise mechanical arrangement) to controlling signal processing parameters (duty cycle analysis and eccentricity calculation). By shifting from spatial precision to signal parameter analysis, the system achieves high accuracy without complex mechanical arrangements.
Data Source
Figure 1~2A
Figure 2B
Figure 3~4
AI summary
To enable improved measurement accuracy in position determination, a position measuring device (1) for determining the position of a first object (2) relative to a second object (3) movable relative to the first object (2) is provided, comprising a measuring body (2a) connected to the first object (2), which is configured such that first and second signal-modulating elements (4, 5) are arranged adjacent to each other on the measuring body (2a), each first and second element (4, 5) having a respective orientation (AR), and the first elements (4) change in their circumference along their orientation (AR) such that a ratio of a width (Br1, Br2) between the width of the first element (4) and the second element (5) changes along the orientation (AR) of the first and second element (4, 5), respectively, a receiving unit (E) connected to the second object (3),which generates a first and a second sine signal (A1, A2) and a first and a second cosine signal (B1, B2), and an evaluation unit for evaluating the signals of the receiving unit (E), wherein the evaluation unit is designed to: perform a first difference calculation from the first sine signal and the first cosine signal to obtain a first difference signal (Δ1) and a second difference calculation from the second sine signal and the second cosine signal to obtain a second difference signal (Δ2), perform a sum and/or a third difference calculation (Δ1+Δ2, Δ1-Δ2) from the first and second difference signals (Δ1, Δ2), and compare a result of the sum and/or the third difference calculation (Δ1+Δ2, Δ1-Δ2) in order to determine a change in a duty cycle resulting from the changing ratio of the width (Br1, Br2) and a to derive a position signal that depends on the change in duty cycle.