Inclined Magnet Encoder for Absolute Position Detection
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Solution Overview
Problem
Industrial control systems face challenges in accurately determining the position of moving carts along tracks, especially when power is removed, as traditional encoder systems fail to provide immediate and precise position feedback.
Innovation Solution
An encoder system utilizing an angled or inclined magnet pair with magnetic field sensors that detect varying magnetic field angles to determine absolute positions, allowing for continuous position measurement and immediate power-up position availability, which can be adapted for both linear and rotary encoders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional encoder systems are used to determine cart positions, then the system structure is simple, but the position determination fails when power is removed and immediate position feedback is not available
Solution Approach 1:
The patent changes the magnetic field detection parameter from measuring field strength to measuring field angle. By using the angle of the magnetic field vector relative to the inclined scale, the system can determine absolute position immediately upon power-up without requiring power continuity, thus improving reliability while maintaining reasonable system complexity
Solution Approach 2:
The patent replaces traditional mechanical or simple magnetic field strength-based encoding systems with a magnetic field angle detection system. This substitution enables the system to provide immediate absolute position feedback by measuring the angular orientation of the magnetic field from the inclined magnet pair, resolving the contradiction between reliability and complexity
2Measurement precision
If magnetic field strength measurement is used, then the system is simple to implement, but position determination is inaccurate when the cart is away from sensors
Solution Approach 1:
The patent transitions from measuring magnetic field strength (which diminishes with distance) to measuring magnetic field angle (which remains consistent regardless of distance). This parameter change ensures that position measurement accuracy is maintained whether the cart is near or far from the sensors, improving measurement precision without significantly increasing system complexity
Solution Approach 2:
The patent moves the measurement from a one-dimensional field strength measurement to a two-dimensional magnetic field vector angle measurement. By utilizing the angular dimension of the magnetic field rather than just its magnitude, the system achieves accurate position determination independent of distance, resolving the contradiction between measurement precision and system complexity
3Loss of information
If incremental encoders are used, then the system is simpler, but absolute position information is lost during power interruptions
Solution Approach 1:
The patent uses the angular parameter of the magnetic field instead of incremental position counting. The angle of the magnetic field directly encodes absolute position information, which is retained even during power interruptions. This approach provides absolute position capability without the complexity of multi-turn incremental encoders or battery-backed memory systems
Solution Approach 2:
The magnetic field angle measurement system inherently provides absolute position information without requiring external power during measurement or complex backup systems. The physical orientation of the inclined magnet pair continuously encodes position information that is immediately readable upon power-up, eliminating information loss without adding significant complexity
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 precise and immediate determination of cart positions, enhancing the accuracy and reliability of industrial control processes by providing linearly changing angle measurements with position, suitable for both incremental and absolute position determination.
Implementation Method 1
multiple sensors arranged along a path, each sensor being configured to detect a magnetic field produced from the encoder scale
Implementation Method 2
a magnetic field sensor, such as an Anisotropic Magnetoresistance (AMR) sensor, with a sensing element perpendicular to a magnet in a travel path, can be used to continuously measure magnetic field direction
Data Source
AI summary
By configuring an encoder scale as an angled or inclined magnet or pair of oppositely arranged, adjacent magnets, a magnetic field sensor in a travel path of the scale can detect an absolute position of the scale for use in an industrial control system. Due to the angle or incline, when a first side of the scale is proximal to the sensor, the sensor can detect an angle of −180°. As the scale moves to center with respect to the sensor, the sensor can detect an increasing angle to 0°. Then, as a second side of the scale becomes proximal to the sensor, the sensor can detect an increasing angle to +180°. The angle changes linearly with position. In one aspect, the pair of oppositely arranged magnets can be rotated with respect to the travel path to provide the angle. In another aspect, the pair of oppositely arranged magnets can be magnetized diagonally to provide the angle.