Magnetic Field Sensor Error Correction via Lookup Table Injection
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Solution Overview
Problem
Magnetic field sensors face challenges in providing accurate and high-speed output signals for angle measurements due to error components in their signal channels, which affect angular accuracy and speed of response, especially when the magnetic field is rapidly changing or under varying temperature conditions.
Innovation Solution
A magnetic field sensor system that includes multiple x-y output signals from sensing elements, a sequence switch circuit, an electronic filter, a summing circuit, and an error correction signal generator, which processes the signals to reduce error components and improve angular accuracy and speed by using sine lookup table values for error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If error correction techniques are implemented in magnetic field sensors, then angular accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values in lookup tables during the manufacturing process. These correction values compensate for systematic errors in the magnetic field sensor readings. During operation, the sensor simply retrieves and applies the pre-computed correction values based on measured field strengths, avoiding complex real-time error calculation while improving angular accuracy.
Solution Approach 2:
The patent replaces complex mechanical or computational error correction mechanisms with a simplified lookup table approach. Instead of using complex algorithms or additional hardware to calculate and apply corrections in real-time, the system uses pre-stored correction values that can be quickly retrieved and applied, substituting a simple data retrieval operation for what would otherwise require complex processing.
2Measurement precision
If complex error correction processing is applied, then measurement accuracy is improved, but speed of response deteriorates
Solution Approach 1:
The patent performs error correction calculations in advance during manufacturing and stores the results in lookup tables. During actual sensor operation, the system only needs to retrieve pre-computed correction values and apply them to measurements, which is a much faster operation than performing complex error correction calculations in real-time, thus maintaining both high accuracy and fast response speed.
3Measurement precision
If lookup tables with pre-stored correction values are used, then angular accuracy is improved, but memory requirements increase
Solution Approach 1:
The patent applies local quality by creating separate lookup tables for different regions of the measurement space - specifically, different tables for positive and negative magnetic field directions, and potentially different tables for different field strength ranges. Each table contains correction values optimized for its specific region, allowing the system to achieve high accuracy across the entire measurement range while keeping individual table sizes manageable.
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 system effectively reduces error components in the signal channel, providing a high degree of accuracy and rapid response for angle measurements, even under changing conditions, by filtering and correcting error signals, thus enhancing the performance of magnetic field sensors.
Implementation Method 1
Planar Hall elements and vertical Hall elements are known types of magnetic field sensing elements. A planar Hall element tends to be responsive to magnetic field perpendicular to a surface of a substrate on which the planar Hall element is formed. A vertical Hall element tends to be responsive to magnetic field parallel to a surface of a substrate on which the vertical Hall element is formed.
Data Source
AI summary
A magnetic field sensor has an error correction signal generator circuit to inject an error correction signal into a primary signal channel to cancel an error signal component in the primary signal channel.