Adaptive Weighting for Magnetic Tracking Eddy Current Distortion
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Solution Overview
Problem
Electromagnetic tracking systems face challenges in accurately determining the position and orientation of a tracked object due to eddy current distortion and signal strength variability, which can lead to unreliable source-sensor pair correlations.
Innovation Solution
The system constructs matrices from electrical signals received by multiple receiver elements aligned at different axes, distinguishing between magnetic fields generated by separate transmitter circuits using differences in timing and frequency, and assigns weights based on the quality of the electromagnetic field structure and signal strength to determine the position and orientation of the receiver circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If signal strength is used as the sole indicator to determine reliability of source-sensor pairs, then the selection process is simple, but the accuracy of position and orientation determination deteriorates due to inaccurate correlation between signal strength and eddy current distortion
Solution Approach 1:
The system changes from using a single parameter (signal strength) to using multiple parameters (signal strength, eddy current distortion metrics, quality indicators) to evaluate source reliability. This allows more accurate assessment of source-sensor pair quality while maintaining automated operation.
Solution Approach 2:
The reliability assessment combines multiple different types of measurements and metrics into a composite evaluation system. By integrating signal strength data with eddy current distortion analysis and quality indicators, the system creates a more robust and accurate reliability determination than any single metric could provide alone.
2Area of stationary object
If multiple transmitter circuits with overlapping magnetic fields are used to expand tracking coverage, then the tracking region is improved, but the complexity of distinguishing and processing signals from different sources increases
Solution Approach 1:
The system segments the overlapping magnetic field signals by identifying and separating contributions from individual transmitter circuits. By evaluating each source-sensor pair independently and assigning weights based on their respective qualities, the system can process multiple overlapping fields without excessive complexity.
Solution Approach 2:
The system uses partial information from multiple transmitter circuits rather than attempting to process all signals equally. By selecting and weighting the most reliable source-sensor pairs, the system achieves accurate tracking with reduced processing complexity compared to using all available signals.
3Measurement precision
If sources are positioned close to the sensor to maximize signal strength, then signal strength is improved, but eddy current distortion increases reducing measurement accuracy
Solution Approach 1:
The system uses feedback by continuously evaluating the quality indicators and eddy current distortion metrics for each source-sensor pair. This real-time assessment allows the system to identify when a nearby source is causing excessive distortion and adjust the weighting accordingly, selecting alternative sources when necessary.
Solution Approach 2:
The system changes the evaluation criteria from relying solely on signal strength to incorporating multiple parameters including eddy current distortion metrics and quality indicators. This allows the system to identify optimal sources that balance signal strength with acceptable distortion levels.
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 enhances the accuracy of position and orientation determination by accounting for distortion and signal strength variations, providing a reliable method for tracking objects within a common region with overlapping magnetic fields.
Implementation Method 1
each receiver element configured to detect a magnetic field along its respective receiver axis
Implementation Method 2
the first transmitter circuit and the second transmitter circuit being spaced apart from one another within a common region such that the respective first and second magnetic field portions overlap one another within the common region
Implementation Method 3
distinguishable from one another by differences in at least one of timing and frequency
Data Source
AI summary
An apparatus and method for implementing a technique for adaptively assigning weighting factors to position and orientation determinations in an electromagnetic or hybrid tracking system having multiple transmitters or multiple receivers. The apparatus may reduce the impact of eddy current distortion to the position and orientation determinations.