Dual Magnetic Sensor Position Calculation Without Conversion Tables

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Solution Overview

Problem

Existing position calculation devices for magnets in pneumatic cylinders require a conversion table specific to each product type due to varying magnet installation positions, making them inefficient for universal application.

Innovation Solution

A position calculation device using two magnetic sensors and a calculation circuit to determine the magnet's position based on the ratios of magnetic flux densities and a predetermined distance, allowing for accurate calculation regardless of product type or installation position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conversion table specific to each product type is used to calculate magnet position, then measurement precision is improved, but device complexity and productivity deteriorate due to requiring multiple conversion tables for different product types

Engineering Contradiction:
Improvemagnet position calculation accuracyVSAvoidconversion table management complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent creates a universal position calculation formula that works across all product types by incorporating the distance between sensor elements as a variable parameter. Instead of requiring separate conversion tables for each product type, the same formula can calculate magnet position by simply inputting the appropriate sensor distance value, making the system multi-functional and adaptable to different products without increasing complexity

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

Solution Approach 2:

The patent changes the approach from using fixed conversion tables to using a dynamic formula where the sensor distance is a variable parameter. By expressing the position calculation in terms of measurable parameters (sensor distances and magnetic field components) rather than pre-fixed tables, the system can adapt to different product configurations by simply changing the input parameter values rather than the entire calculation method

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If a conversion table specific to each individual product installation is used, then measurement precision is improved, but productivity and ease of operation deteriorate due to requiring separate tables for each installation

Engineering Contradiction:
Improvemagnet position calculation accuracyVSAvoidposition calculation efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent develops a universal calculation formula that can handle individual installation variations without requiring separate conversion tables for each installation. The formula incorporates the actual sensor distance as an input parameter, allowing it to adapt to any installation configuration while maintaining a single unified calculation method that improves productivity by eliminating the need to create and manage multiple installation-specific tables

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

Solution Approach 2:

The calculation formula enables the system to automatically adapt to different installations by using the measured sensor distance as an input parameter. Rather than requiring external configuration of installation-specific tables, the system self-adjusts by taking the actual physical parameters as inputs, allowing operators to simply input the sensor distance and obtain accurate results without manual table configuration

Inventive Principle:
Principle #25Self-service

3Measurement precision

If ARCTAN values from two magnetic sensors are used to calculate magnet position, then measurement capability is improved, but device complexity increases due to requiring distance information and conversion tables

Engineering Contradiction:
Improvemagnet position detection capabilityVSAvoidcalculation system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential calculation elements from complex conversion tables and formulates them into a simplified mathematical expression. By taking out only the necessary components (sensor distances and magnetic field components) and expressing them in a direct formula, the system reduces complexity while maintaining measurement precision, eliminating the need for large lookup tables and complex conversion procedures

Inventive Principle:
Principle #2Taking out (Extraction)

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 and universal calculation of magnet position, improving efficiency and adaptability across different product types and individual installations.

Implementation Method 1

a first magnetic sensor and a second magnetic sensor...configured to detect a magnetic flux density of a magnetic field generated by the magnet

Methodology Applied
Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentEP4368950A1Position calculation device
Publication Date: 2024.05.15 SMC CORP
  • EP4368950A1 patent drawingFigure 1
  • EP4368950A1 patent drawingFigure 2
  • EP4368950A1 patent drawingFigure 3

AI summary

A position calculation device (10) calculates a position of a magnet (38) installed on a moving body that is capable of moving relatively in a first direction. The position calculation device includes a first magnetic sensor (52) and a second magnetic sensor (54) arranged apart from each other by a predetermined distance (P) in the first direction, and a calculation circuit that calculates the position of the magnet, using a first ratio (R1) between a first component in the first direction and a second component in a second direction, of a first magnetic flux density (B1) detected by the first magnetic sensor, a second ratio (R2) between a third component in the first direction and a fourth component in the second direction, of a second magnetic flux density (B2) detected by the second magnetic sensor, and the predetermined distance.