Magnetic Field Mapping Using Freely Moving Detector
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Solution Overview
Problem
Existing magnetic tracking systems face inaccuracies due to interferences from ferromagnetic objects and electromagnetic devices, which are not adequately accounted for in the magnetic field maps, leading to distorted field models and incorrect pose determination of tracked objects.
Innovation Solution
A system and method for mapping magnetic fields by freely moving a magnetic field detector within the volume of interest, using a processor to estimate the entire set of parameters of a magnetic field model, including coefficients, order, and centers of expansion, to create an accurate magnetic field model that accounts for interferences and distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic field map is created using conventional methods without accounting for interferences, then the mapping process is simpler and faster, but the accuracy of pose determination deteriorates due to distorted field models
Solution Approach 1:
The system performs preliminary mapping of the magnetic field by moving the detector through the volume and storing the measured field vectors in a look-up table before actual tracking operations. This pre-characterization of the magnetic field environment, including interference patterns, enables accurate pose determination during tracking without requiring complex real-time calculations
Solution Approach 2:
The patent introduces an intermediary processing layer that uses the measured magnetic field vectors from the look-up table to interpret and correct distorted field models caused by ferromagnetic objects and electromagnetic devices. This intermediary mapping data serves as a reference to compensate for interferences during pose determination
2Reliability
If the magnetic field map accounts for interferences from ferromagnetic objects and electromagnetic devices, then the reliability of tracking improves, but the mapping process becomes more complex and time-consuming
Solution Approach 1:
The system performs the complex task of mapping the magnetic field environment, including all interference sources, in advance and stores the results in a look-up table. This preliminary action captures the complete magnetic field characteristics once, allowing rapid and reliable tracking operations subsequently without repeating the complex mapping process
Solution Approach 2:
The patent creates a copy of the magnetic field environment characteristics by measuring and storing field vectors at multiple locations in a look-up table. This copied representation of the magnetic field map serves as a reference model that can be quickly queried during tracking without requiring real-time remapping
3Productivity
If a look-up table with sparse sampling points is used for magnetic field mapping, then the mapping process is faster and simpler, but the interpolation accuracy between entries deteriorates
Solution Approach 1:
The system performs excessive sampling by measuring magnetic field vectors at more locations and with greater density than the minimum required for basic mapping. This excessive action captures finer details of the magnetic field variations, improving interpolation accuracy between sample points while still maintaining reasonable mapping speed
Solution Approach 2:
The patent optimizes the interpolation scheme by adjusting sampling density and distribution based on the specific characteristics of the magnetic field environment. Parameters such as the number of sampling points, their spatial distribution, and the interpolation function characteristics are tuned to achieve optimal balance between mapping speed and accuracy
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 enables precise determination of the magnetic field model, improving the accuracy of pose tracking by incorporating interference effects, thus enhancing the reliability of magnetic tracking systems in complex environments.
Implementation Method 1
a magnetic field transmitter (502) which generates a magnetic field (576) in a volume of interest (578)
Implementation Method 2
a magnetic field detector (504) which measures a magnetic flux at a plurality of poses
Data Source
AI summary
System for mapping a magnetic-field including a magnetic-field-transmitter, a freestanding magnetic-field-detector operative to freely move within a volume of interest and acquire measurements of the flux of the magnetic-field at a plurality of poses, a pose-information-acquisition-module for measuring information related to the pose of the magnetic-field-detector and a processor, coupled with the magnetic-field-detector and with said pose-information-acquisition-module and determines pose-related-information respective of each of at least a portion of the magnetic-flux-measurements, according to said information related to the pose of said magnetic-field-detector, the processor further estimating the entire set of parameters of a magnetic-field-model-template according to the magnetic-flux-measurements and the respective pose-related-information the magnetic flux measurements, the processor incorporates the entire set of parameters into said magnetic field model template, thereby determining said magnetic field model, the entire set of parameters includes the coefficients, the order, the number and location of the centers of expansion of the model.