Compact Magnetic Sensor Using Arctangent Evaluation
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Solution Overview
Problem
Current contactless magnetic sensors for pneumatic cylinders are limited by their length matching the measuring range, requiring complex control systems, being expensive, and offering slow measurement due to digital interfaces and high signal noise, making accurate and quick position determination difficult.
Innovation Solution
A sensor with at least two elements detecting perpendicular magnetic field components, using an evaluation unit to calculate a monotonic position signal through arctangent functions and correction, allowing for a shorter sensor length than the measuring range, high resolution, and interference suppression, compatible with both axially and diametrically magnetized magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of Hall elements are positioned at a fixed distance along the measuring area to achieve larger measuring ranges, then the measuring range is improved, but the overall length of the sensor must correspond to the measuring range, increasing device length and complexity
Solution Approach 1:
The patent transitions from a one-dimensional array of Hall elements along the measuring range to a two-dimensional configuration where two sensor elements detect perpendicular magnetic field components (axial and radial). By using the arctangent function of the ratio between these two components, the sensor achieves a measuring range independent of its physical length, effectively adding a dimensional aspect to the measurement approach.
Solution Approach 2:
The patent changes the evaluation parameters by using the ratio and arctangent of magnetic field components instead of direct position mapping. This parameter transformation allows the sensor to determine position over a large measuring range while maintaining a compact sensor structure, as the mathematical evaluation creates a monotonic position signal independent of sensor length.
2Loss of information
If 3D Hall elements with digital interface are used to transmit measured values, then data transmission is achieved, but the measurement speed is slow and signal noise is high, reducing measurement precision and speed
Solution Approach 1:
The patent replaces the digital interface transmission system with an analog evaluation approach. Instead of using digital 3D Hall elements that require microcontroller processing, the invention uses two sensor elements with analog magnetic field component detection and processes the signals through arctangent calculation, achieving faster response and lower noise.
Solution Approach 2:
The patent extracts only the essential measurement information by using two sensor elements that directly detect the magnetic field components needed for position calculation. This eliminates the need for complex digital processing and microcontroller interfaces, removing the source of measurement delay and noise while retaining the core position detection function.
3Measurement precision
If individual Hall elements are selected using a relatively complex control system, then position measurement is achieved, but the device complexity and cost increase
Solution Approach 1:
The patent merges the functions of multiple Hall elements into a simplified two-element configuration. By combining the detection of axial and radial magnetic field components with a single evaluation unit that performs arctangent calculation, the system achieves position measurement with minimal components, eliminating complex control systems while maintaining measurement capability.
Solution Approach 2:
The patent creates a universal sensor design where two sensor elements can detect both axial and radial magnetic field components, and the evaluation unit processes these signals to determine position regardless of magnetization direction. This multi-functional approach eliminates the need for complex control systems that would be required to manage multiple specialized Hall elements.
4Adaptability or versatility
If the sensor length corresponds to the measuring range, then full measuring range coverage is achieved, but the sensor becomes expensive and complex with many required components
Solution Approach 1:
The patent uses perpendicular magnetic field component detection to create a two-dimensional measurement space from two sensor elements. The arctangent evaluation of the component ratio provides position information across the full measuring range without requiring the sensor length to match the measuring range, dramatically reducing component count while maintaining coverage.
Solution Approach 2:
The patent transforms the measurement parameters by using the ratio and arctangent of magnetic field components instead of direct spatial mapping. This parameter change allows full measuring range coverage with a compact sensor structure, reducing the number of components needed while maintaining adaptability to the entire measuring range.
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
The solution provides a compact, cost-effective sensor with high resolution and fast measurement capabilities, capable of accurate position determination over large ranges with minimal linearity errors and interference, suitable for various magnet configurations.
Implementation Method 1
at least two sensor elements (4.1, 4.2), each detecting two components (6, 7) of a magnetic field (5)
Data Source
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AI summary
Sensor for non-contact magnetic detection of linear relative motion of a sensor magnet (2) along a measuring section (3) with at least two sensor elements (4), wherein the sensor elements (4) each detect two mutually perpendicular components (6, 7) of a magnetic field (5) of the sensor magnet, wherein the sensor elements (4) and the sensor (1) are shorter than the measuring section (3), wherein a first component (6) is an axial component (Bx), wherein a second component (7) is a radial component (By), wherein an evaluation unit (9) is provided, wherein the axial component (Bx) and the radial component (By) can be evaluated in the evaluation unit (9) according to a mathematical function, wherein the mathematical function is ARCTAN (radial component/axial component) or ARCTAN (axial component/radial component).wherein a section-wise monotonic position signal (10) with a value (11) of a value range (12) is formed for each position (13) along the measuring section (3) of the encoder magnet (2), wherein the evaluation unit is configured to correct the respective position signal (10) in at least one area (14) of the measuring section (3) with a constant correction value (21), so that a monotonic position signal (10) with a monotonic value range (12) is formed over the entire measuring section (3).