Position Determination Using Analog Differential Circuits

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Solution Overview

Problem

Existing devices for determining position, length, or angle require additional incremental coding and readout devices to achieve high-resolution relative position measurements, which increases installation space and costs.

Innovation Solution

Incorporating differential circuits in the readout device to calculate differences between measured values from adjacent sensors, allowing for precise determination of relative position without additional coding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional incremental coding and readout devices are used to achieve high-resolution relative position measurements, then measurement precision is improved, but device complexity and installation space increase

Engineering Contradiction:
Improverelative position measurement resolutionVSAvoidcoding and readout device structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the measurement function into multiple sensors that detect different code sections, with each sensor contributing to the overall position determination. The evaluation unit processes signals from multiple sensors to achieve high-resolution measurements without requiring additional incremental coding tracks.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from one-dimensional incremental encoding to utilizing the temporal dimension by evaluating signals over time from multiple sensors. The evaluation unit determines relative position by analyzing the temporal progression of measured values from multiple sensors detecting the same absolute code, thereby achieving high resolution without additional spatial encoding dimensions.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If additional incremental coding and readout devices are installed to improve measurement resolution, then measurement precision is improved, but manufacturing costs increase

Engineering Contradiction:
Improverelative position measurement resolutionVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent makes the absolute code and its readout device serve multiple functions: they provide both coarse position information and, through temporal signal evaluation, fine position information. The same hardware components (sensors and absolute code) are used for both absolute position detection and high-resolution relative position measurement, eliminating the need for separate incremental coding infrastructure.

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

Solution Approach 2:

The evaluation unit extracts high-resolution position information from the signals already generated by the sensors reading the absolute code. By analyzing the temporal progression of measured values and identifying signal edges, the system derives fine position data from the existing absolute coding structure without requiring additional dedicated components for incremental measurement.

Inventive Principle:
Principle #25Self-service

3Speed

If digital subtraction is used to process sensor signals, then processing speed is improved, but measurement precision may be compromised due to distortion from prior digitization

Engineering Contradiction:
Improvesignal processing speedVSAvoidmeasurement accuracy
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The patent replaces digital signal processing with analog differential circuits that perform subtraction in the analog domain. This substitution of the processing mechanism (from digital to analog) allows for distortion-free differentiation of sensor signals, maintaining measurement precision while still achieving fast processing through dedicated analog circuitry.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4571269A1Device and method for determining position, length or angle
Publication Date: 2025.06.18 SICK AG
  • EP4571269A1 patent drawingFigure 1
  • EP4571269A1 patent drawingFigure 2
  • EP4571269A1 patent drawing

AI summary

A device for determining position, length, or angle, comprising a first and a second part that are movable relative to one another. An absolute code consisting of a plurality of consecutive code sections of the first type and a second type is attached to the first part. A readout device for detecting the code is attached to the second part, wherein the readout device comprises a plurality of sensors, each of which is designed to detect the code sections and output a corresponding measured value. The device further comprises an evaluation unit designed to determine a relative position between the first and the second part. The readout device comprises at least one, in particular a plurality of, preferably analog, differential circuits. Said differential circuits are designed to form a difference between the measured values ​​of two adjacent sensors and to output this difference as a differential signal.The evaluation unit is designed to determine the relative position between the first and second parts, taking these differential signals into account. Furthermore, a corresponding method for determining position, length, or angle is described.