Magnetic Sensor Calibration via Optical Tracking

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Solution Overview

Problem

Conventional magnetic sensor calibration methods for soft- and hard-iron interference are complex, impractical for certain applications, and lack auto-correction capabilities, especially when the interference characteristics of the object change over time.

Innovation Solution

The system uses optical data from a camera to track orientation changes and calculate magnetic calibration parameters in real-time, allowing for auto-calibration as a background process and real-time adjustments, eliminating the need for pre-operation procedures and enabling continuous operation without manual recalibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional magnetic calibration methods are used, then magnetic sensor calibration can be performed, but the calibration process becomes complex and impractical for certain applications

Engineering Contradiction:

Improvemagnetic sensor calibration accuracyVSAvoidcalibration process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical movement-based calibration system with an optical tracking system. Instead of requiring physical rotation and positioning of the object through complex mechanical movements, the system uses optical tracking (cameras) to monitor and record the object's orientation and position changes. This substitution eliminates the need for complex mechanical calibration procedures while maintaining calibration accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an optical tracking system as an intermediary between the magnetic sensor and the calibration process. The optical tracker serves as a mediator that captures the object's orientation data, which is then used to compute calibration parameters. This intermediary approach simplifies the direct interaction between the user and the calibration process, making it more practical and less complex.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If conventional magnetic calibration methods are used, then initial calibration can be achieved, but the system lacks auto-correction capabilities when interference characteristics change

Engineering Contradiction:

Improvecalibration stabilityVSAvoidreal-time adaptation to changing conditions

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements a feedback mechanism where the optical tracking system continuously monitors the object's orientation during operation. This continuous feedback allows the system to detect changes in interference characteristics and automatically update calibration parameters in real-time, providing both stability and adaptability to changing conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent transitions from a static calibration approach to a dynamic one. Instead of performing calibration once during setup, the system continuously updates calibration parameters based on real-time optical tracking data. This dynamic approach enables the system to adapt to changing interference characteristics while maintaining reliable operation.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If pre-operation calibration procedures are required, then accurate calibration parameters can be obtained, but the system cannot perform calibration as a background process

Engineering Contradiction:

Improvecalibration parameter accuracyVSAvoidoperational convenience

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent enables continuous calibration throughout the operational lifetime of the system. The optical tracking system operates continuously in the background, constantly gathering data and updating calibration parameters without interrupting the system's normal operation. This eliminates the need for separate pre-operation calibration procedures while maintaining high accuracy.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system performs calibration automatically using its own operational data. The optical tracking system and magnetic sensors work together to self-calibrate the system during normal operation, eliminating the need for external calibration equipment or manual intervention. The system serves itself by utilizing its own operational movements and environmental data for calibration.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS10444030B1Automatic calibration of magnetic sensors based on optical image tracking

Publication Date: 2019.10.15 INERTIAL LABS INC

AI summary

The present invention provides the ability to calibrate magnetic sensors for magnetic distortions caused by soft- and hard-iron magnetic interference without a use of any conventional means of magnetic calibration. The system utilizes data collected from an attached camera to track orientation changes during operation that are, then, used to calculate magnetic calibration parameters. The system embodiment allows for calibration to be performed as a background process while the system is in operation. Additionally, the system automatically corrects calibrations in applications where the interference characteristics of the object under measure change. Moreover, the system can be used with unknown absolute heading which may be estimated based on optical data at the same time with magnetometer auto-calibration as an extension to the estimation algorithm.