Magnetometer Calibration Using Natural Motion and Least Squares
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Solution Overview
Problem
Existing magnetometer calibration methods are inefficient and require significant user involvement, as they often necessitate full rotations of devices to account for errors caused by ferrous materials, which is impractical for daily use in portable devices.
Innovation Solution
A method and apparatus for fast magnetometer calibration using natural motion with minimal space coverage, allowing for automatic calibration in both 2D and 3D environments without requiring specific user movements or full rotations, utilizing external heading sources, pitch, and roll angles to calculate calibration parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional magnetometer calibration methods are used (requiring full rotations), then calibration accuracy is improved, but user involvement and time consumption increase significantly
Solution Approach 1:
The patent applies partial action by collecting magnetometer readings over a limited period during natural device motion rather than requiring complete full rotations. The system accumulates sufficient calibration data from partial motion segments, using statistical methods to compute calibration parameters without demanding the full calibration sequence, thus reducing time while maintaining accuracy
Solution Approach 2:
The calibration system performs self-service by automatically processing magnetometer readings from natural device motion without user intervention. The processor autonomously collects data, determines sufficient space coverage, computes calibration parameters using least squares or estimation methods, and applies corrections, eliminating the need for users to manually rotate the device through specific sequences
2Reliability
If full rotation calibration is required to account for ferrous material effects, then calibration completeness is improved, but ease of operation deteriorates
Solution Approach 1:
The system implements self-service calibration by automatically detecting when sufficient spatial coverage has been achieved during natural device motion. The processor monitors reading variations, determines when calibration data sufficiency is met, and initiates parameter calculation without requiring users to understand or perform rotation sequences, making the process as easy as normal device usage
Solution Approach 2:
The patent applies dynamics by transitioning from static, predetermined calibration sequences to dynamic, adaptive calibration that responds to actual device motion patterns. The system continuously evaluates whether collected readings provide sufficient space coverage and adjusts the calibration process accordingly, allowing calibration to complete as soon as adequate data is gathered during natural use rather than requiring fixed rotation protocols
3Measurement precision
If magnetometer calibration is performed frequently for accurate heading, then heading accuracy is improved, but device complexity increases
Solution Approach 1:
The calibration system demonstrates multi-functionality by serving multiple purposes: it calibrates magnetometer sensors, determines when sufficient calibration data is collected, computes calibration parameters, applies corrections to readings, and validates calibration quality—all through a unified automated process that leverages existing processor and sensor resources without requiring additional dedicated hardware
Solution Approach 2:
The patent replaces complex mechanical calibration mechanisms (physical rotation stages, precision positioning systems) with computational methods. The processor uses mathematical algorithms (least squares, estimation approaches) to extract calibration parameters from magnetometer readings taken during natural motion, substituting mechanical complexity with software-based solutions that achieve the same calibration goal
Data Source
AI summary
A method and apparatus for fast magnetometer calibration with little space coverage is described herein. The present method and apparatus is capable of performing both 2-dimensional (2D) and 3-dimensional (3D) calibration for a magnetometer (magnetic sensor) and calculating calibration parameters. The present method and apparatus does not need the user to be involved in the calibration process and there are no required specific movements that the user should perform. The present method and apparatus performs magnetometer calibration in 2D or 3D depending on the natural device movements whatever the application that the magnetometer is used in.