Field-Gradient Magnet Orientation Sensing for Disturbance-Robust Joysticks
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Solution Overview
Problem
Magnetic position sensor systems that measure the orientation of a pivotable magnet about a fixed reference point face challenges in achieving high accuracy and robustness against external disturbance fields, especially when the magnet has two degrees of freedom.
Innovation Solution
A sensor device comprising a semiconductor substrate with magnetic sensors configured to determine specific magnetic field gradients, and a processing circuit to calculate the orientation of a cylindrical magnet pivotable about a fixed reference point, using formulas involving two-argument arctangent functions to determine angles based on these gradients, thereby improving accuracy and insensitivity to external disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic sensors measure magnetic field gradients to determine magnet orientation with two degrees of freedom, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system segments the measurement task by using multiple magnetic sensors positioned at different locations to measure different components of the magnetic field gradient. Each sensor measures specific gradient components (dBx/dx, dBy/dy, dBz/dx, dBz/dy), and these segmented measurements are combined through mathematical processing to determine the complete orientation (α, β) of the magnet with high precision.
2Reliability
If the system uses multiple magnetic field gradient measurements to determine orientation angles, then reliability against external disturbance fields is improved, but manufacturing precision requirements increase
Solution Approach 1:
The system uses feedback through mathematical processing of the measured magnetic field gradients. The processing circuit calculates the orientation angles (α, β) based on the measured gradient components using arctangent functions. This mathematical feedback mechanism compensates for variations and errors, making the system reliable against external disturbance fields while reducing the stringency of manufacturing precision requirements.
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 highly accurate and robust method for determining the orientation of a magnet with two degrees of freedom, maintaining precision even in the presence of external disturbance fields, and is applicable in various applications including joysticks.
Implementation Method 1
magnetic sensors configured for determining at least two of the following magnetic field gradients: i) a first magnetic field gradient (e.g. dBx/dx) of a first magnetic field component oriented in a first direction parallel to the semiconductor substrate
Data Source
AI summary
A method of determining an orientation α,β of a magnet which is pivotable about a reference position having a predefined position relative to a semiconductor substrate, comprising: a) determining at least two of the following magnetic field gradients: i) a first magnetic field gradient dBx/dx; ii) a second magnetic field gradient dBy/dy; iii) a third magnetic field gradient dBz/dx; iv) a fourth magnetic field gradient dBz/dy; b) determining a first angle α based on at least one of the magnetic field gradients; c) determining a second angle β based on at least one of the magnetic field gradients. A sensor device is configured for performing this method. A sensor system includes such sensor device and a magnet, optionally connected to a joystick.