Magnetic Tracking Distortion Correction via IMU Field Mapping
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Solution Overview
Problem
Magnetic tracking systems face challenges in accurately determining the position and orientation of objects in distorted magnetic fields, particularly due to environmental objects like metallic structures, which cause variations in magnetic field strength and shape.
Innovation Solution
The system employs an inertial measurement unit (IMU) and multiple magnetic receivers to measure and correct distortions by comparing low-distortion regions to higher-distortion areas, estimating undistorted magnetic fields, and generating a model of the distortions to accurately determine object position and orientation without requiring additional tracking means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If magnetic tracking systems operate in environments with metallic objects, then the system can function in diverse settings, but tracking precision deteriorates due to magnetic field distortions
Solution Approach 1:
The system performs preliminary distortion mapping by moving the receiver through various positions and orientations to pre-characterize the magnetic field distortions caused by metallic objects. This pre-acquired distortion information is stored and later used to correct tracking measurements, allowing the system to maintain precision in environments with metallic objects present
2Measurement precision
If distortion mapping is performed by moving the receiver throughout the volume, then distortion correction accuracy improves, but the time required for system setup and calibration increases
Solution Approach 1:
The system performs distortion mapping at a limited set of discrete positions and orientations rather than continuously throughout the entire volume. This partial sampling approach reduces calibration time while still capturing the essential distortion characteristics needed for correction, balancing accuracy requirements with practical setup time constraints
3Measurement precision
If the magnetic field model is updated continuously, then tracking accuracy in distorted regions improves, but computational load and processing time increase
Solution Approach 1:
The system pre-computes distortion correction values during a calibration phase and stores them in lookup tables. During actual tracking operations, the system quickly retrieves pre-computed correction values based on the current receiver position and orientation, avoiding the need for continuous complex calculations and maintaining high processing efficiency
4Measurement precision
If multiple receivers are used to map distortions, then the coverage and accuracy of distortion modeling improve, but device complexity increases
Solution Approach 1:
The system uses a single receiver that can be moved to multiple positions and orientations to collect distortion data for the entire volume. This multi-functional approach allows one device to perform the work that would otherwise require multiple fixed receivers, reducing system complexity while maintaining comprehensive distortion mapping capability
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 allows for direct absolute position reference in distorted regions, expanding the trusted region of the magnetic field, and reducing errors in position determination, enabling accurate tracking without additional tracking systems.
Implementation Method 1
The magnetic tracking system includes an inertial measurement unit (IMU) configured to provide motion data representing motion of the tracked device
Implementation Method 2
a magnetic sensor, a first value for each of one or more characteristics of a magnetic field at a first position in the magnetic field
Implementation Method 3
An Electromagnetic Tracking (EMT) system can be used to track a device
Data Source
AI summary
A system is configured to model a magnetic field by measuring a first value for characteristics of a magnetic field at a first position in the magnetic field. The system measures a second value characteristics of the magnetic field at a second position in the magnetic field. The system determines a distance between the first position and the second position. The system estimates a distortion component of the magnetic field at approximately the second position in the magnetic field based on each of the distance, the first value for each of the one or more characteristics, and the second value for each of the one or more characteristics. The system outputs a model of at least a region of the magnetic field.