Magnetometer Calibration Using Sphere Model for Internal Field Compensation
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Solution Overview
Problem
Magnetometers in portable electronic devices often inaccurately detect magnetic vectors due to internal magnetic fields from electrical circuitry and ferromagnetic components, leading to errors in positioning and orientation functionality.
Innovation Solution
A method and device for calibrating magnetometers by obtaining and processing measurement values to estimate and compensate for internal magnetic fields, using a sphere model to calculate a center and radius, and continuously calibrate the magnetometer output based on this estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetometer calibration is performed using traditional methods with multiple measurement points, then measurement precision improves, but device complexity and computational burden increase
Solution Approach 1:
The patent applies the sphere model principle by representing the magnetic field distortion caused by internal components as a spherical deviation. The calibration process calculates a sphere center and radius from measurement values, then uses this spherical model to compensate for internal magnetic field interference. This geometric abstraction simplifies the complex calibration process while maintaining high measurement precision.
2Measurement precision
If continuous calibration is performed to maintain measurement accuracy, then measurement precision improves, but power consumption increases
Solution Approach 1:
The patent implements preliminary calibration by establishing a sphere model from initial measurement values. This pre-established model is then used for continuous compensation without requiring repeated full calibration processes. The sphere center and radius calculated in advance enable ongoing correction of magnetic field measurements, maintaining precision while reducing power consumption.
Solution Approach 2:
The calibration system uses feedback by continuously comparing new measurement values against the established sphere model. The deviation from the spherical pattern is used to adjust and refine the calibration parameters, ensuring measurement accuracy is maintained while avoiding the energy-intensive process of complete recalibration.
3Measurement precision
If comprehensive calibration checks are performed to ensure accuracy, then measurement precision improves, but processing time increases
Solution Approach 1:
The patent extracts the essential calibration information into a simplified sphere model defined by center coordinates and radius. This extraction process separates the critical calibration parameters from the full set of measurement data, enabling rapid compensation calculations. By focusing only on the sphere center and radius, the system achieves comprehensive calibration accuracy with reduced processing time.
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
This approach efficiently and accurately calibrates magnetometers, reducing computational burden and power consumption, thereby improving the performance and efficiency of navigational and orientation functions in electronic devices.
Implementation Method 1
a magnetometer may be used to provide positioning information for a device in relation to the vector of an external magnetic field
Data Source
AI summary
A method of calibrating a magnetometer may include; obtaining at least four measurement values using the magnetometer, calculating a center and a radius of a sphere in accordance with the measurement values, wherein the center and the radius of the sphere correspond to an internal magnetic field associated with an electronic device including the magnetometer, and calibrating an output of the magnetometer in accordance with the center of the sphere.