Magnetic Field Mapping via 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 effectively accounted for in pre-determined magnetic field maps, leading to distorted field models and incorrect pose determination of tracked objects.
Innovation Solution
A system and method for freely moving a magnetic field detector within a volume of interest to acquire measurements, allowing a processor to estimate the entire set of parameters of a magnetic field model, including coefficients, order, and centers of expansion, thereby determining an accurate magnetic field model that incorporates interference effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a pre-determined magnetic field map is used, then the system complexity is reduced, but the measurement precision deteriorates due to interferences from ferromagnetic objects and electromagnetic devices
Solution Approach 1:
The system performs preliminary measurement of the actual magnetic field in the volume of interest before tracking operations. This measured field map is obtained by moving the detector through the volume and recording magnetic flux at multiple poses, then processing these measurements to create an accurate reference map that accounts for all interference sources present in the specific environment.
Solution Approach 2:
The system changes the parameters of the magnetic field model by estimating the entire set of parameters including coefficients, order, and centers of expansion of a magnetic field model template. This allows the model to adapt to the specific interference conditions in the measurement volume rather than using fixed pre-determined parameters.
2Measurement precision
If the magnetic field detector is moved through a plurality of known poses to determine the magnetic field map, then the measurement precision improves, but the loss of time increases due to the calibration process
Solution Approach 1:
The magnetic field map determination is performed as a preliminary calibration step before actual tracking operations. By completing this time-consuming measurement process once, the system establishes an accurate reference that can be reused for multiple subsequent tracking operations, amortizing the time cost over many uses.
Solution Approach 2:
The system creates a digital copy of the magnetic field distribution in the form of a stored map or model. This copied representation allows the system to reference the measured field characteristics without repeatedly performing the physical measurements, significantly reducing time for subsequent operations.
3Adaptability or versatility
If ferromagnetic objects and electromagnetic devices are present in the volume of interest, then the adaptability of the system to real-world environments improves, but the measurement precision deteriorates due to magnetic field interferences and distortions
Solution Approach 1:
The system converts the harmful effect of ferromagnetic objects and electromagnetic devices into beneficial information by measuring their actual magnetic field contributions. By including these interference sources in the measurement process, the system creates a comprehensive field map that accounts for all sources, allowing accurate pose determination even in their presence.
Solution Approach 2:
The system estimates the entire set of parameters of a magnetic field model template, including coefficients, order, and centers of expansion. This flexible parameter estimation allows the model to adapt to and characterize the complex magnetic field environment created by various objects, transforming the variable interference conditions into a solvable parameter set.
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 mapping of magnetic fields, accounting for interferences and distortions, resulting in improved accuracy of pose determination for tracked objects within the magnetic tracking system.
Implementation Method 1
The magnetic field detector measures the magnetic flux at that pose. The magnetic tracking system determines the magnetic field vector according to the measured magnetic flux
Implementation Method 2
The magnetic field transmitter may employ several magnetic field generators (e.g., coils with electric current flowing there through)
Implementation Method 3
The processor estimates the entire set of parameters of a magnetic field model template according to the magnetic field flux measurement and the respective poses related information thereof
Data Source
AI summary
A system for mapping a magnetic-field in a volume-of-interest comprising a magnetic-field transmitter, generating a magnetic-field in the volume-of-interest, a freestanding magnetic-field detector operative to freely move within the volume-of-interest, a pose-information-acquisition-module and a processor. The detector acquires measurements of flux of the magnetic-field at a plurality of poses. The pose-information-acquisition-module measures information related to the pose of the detector. The processor determines pose-related-information respective of at least a portion of the measurements according to the information related to the pose of the detector. The processor estimates the entire set of parameters of a magnetic-field model template according to the magnetic-field flux measurement and the respective poses-related-information thereof. The processor incorporates the entire set of parameters into the magnetic-field model template, thereby determining the magnetic-field model. The entire set of parameters includes the coefficients, the order the number and location of the centers of expansion of the magnetic-field model.