Geomagnetic Sensor Calibration via Motion-Triggered Parameter Selection
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Solution Overview
Problem
Geomagnetic sensors in electronic devices are susceptible to external interference, particularly hard iron distortion caused by objects within and outside the device, leading to inaccurate magnetic field measurements in indoor environments.
Innovation Solution
An electronic device equipped with a geomagnetic sensor, motion sensor, and processor that identifies user motion to determine calibration parameters, allowing for automatic calibration of the geomagnetic sensor based on daily user motion, even without specific user instruction, to provide accurate geomagnetic data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If geomagnetic sensor is used for indoor location tracking, then position and azimuth can be measured, but measurement accuracy deteriorates due to hard iron distortion from surrounding objects
Solution Approach 1:
The system performs preliminary calibration by detecting user motion patterns (walking, running, vehicle movement) and identifying periods when the device is in stable conditions. During these stable periods, the system pre-calculates correction parameters for hard iron distortion before actual navigation or location tracking begins, ensuring accurate measurements from the start.
Solution Approach 2:
The system continuously monitors geomagnetic sensor data and compares it against calibrated reference values. When distortion is detected (deviation from expected circular pattern during rotation), the system automatically adjusts calibration parameters in real-time based on the detected motion state and environmental conditions, providing continuous feedback to maintain measurement accuracy.
2Measurement precision
If calibration is performed continuously to maintain accuracy, then measurement precision improves, but energy consumption increases
Solution Approach 1:
Instead of continuous calibration, the system performs calibration periodically based on detected motion events. It identifies specific moments when the device undergoes characteristic motions (complete rotations, vehicle stops, pedestrian pauses) and triggers calibration only at these discrete intervals, significantly reducing computational load and energy consumption while maintaining accuracy.
Solution Approach 2:
The system automatically detects motion patterns and determines when calibration is needed without user intervention. It self-manages the calibration process by monitoring sensor data, identifying stable periods, performing calibration autonomously, and updating correction parameters without requiring explicit user commands or continuous processing.
3Measurement precision
If adaptive calibration is performed for external hard iron distortion, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The system uses existing motion sensors (accelerometer, gyroscope, GPS) already present in the device for their primary navigation functions to also detect motion patterns for calibration purposes. The processor leverages existing data streams from multiple sensors to identify calibration opportunities and perform corrections, avoiding the need for additional dedicated calibration hardware or complex specialized systems.
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 enables accurate geomagnetic value measurement and calibration in indoor environments, reducing current consumption and performing accurate corrections using filtered and parameter-applied geomagnetic data.
Implementation Method 1
A geomagnetic sensor is a sensor that detects geomagnetism by measuring a voltage value induced by a geomagnetism using a flux-gate
Data Source
AI summary
An electronic device may include: a geomagnetic sensor; a motion sensor for sensing a signal associated with a motion of a user; and a processor operatively connected, directly or indirectly, to the geomagnetic sensor and the motion sensor, wherein the processor determines whether to perform calibration of the geomagnetic sensor based on a signal measured by the geomagnetic sensor; in response to the determination to perform the calibration, identifies the motion of the user based on motion data obtained from the motion sensor; based on the identified motion of the user, determines a parameter including a range of data to be used for calibrating the geomagnetic sensor among data obtained from the geomagnetic sensor; and calibrates the geomagnetic sensor based on data extracted based on the parameter. Other various embodiments are possible.