AC Magnetic Tracking with Wireless Source Inversion
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Solution Overview
Problem
Classical AC magnetic tracking systems face limitations in extending operating range due to signal attenuation and distortion caused by eddy currents, which are exacerbated by the need for high-energy sources and tethered configurations, and existing systems lack the ability to efficiently track wireless sources with phase coherency in three-dimensional space.
Innovation Solution
The system employs multiple, low-power, wireless multi-axis field sources operating at different frequencies, with receivers detecting and synchronizing these sources using phase-adjusted matrices to compute position and orientation, allowing for simultaneous tracking of sources and sensors without requiring harmonic relationships or initial presence, and enabling phase synchronization and coherency without special start-up constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a larger magnetic field source is created and driven at high energy levels to cover more distance, then the operating range is extended, but eddy current distortion increases and signal-to-noise ratio deteriorates
Solution Approach 1:
The patent inverts the traditional magnetic tracking configuration by making the source movable and sensors static. Instead of having a large stationary source covering a volume, a small portable source moves through the field of distributed static sensors. This inversion allows the source to remain small and low-power while still achieving large-volume tracking coverage through its movement, thereby avoiding eddy current distortion that would result from high-energy stationary sources.
Solution Approach 2:
The system transitions from a static source configuration to a dynamic one where the source moves freely through three-dimensional space while sensors remain stationary. This dynamic configuration enables the source to access different spatial regions without requiring a large stationary field-generating structure, maintaining low power levels while extending effective operating range through motion.
2Length of stationary object
If multiple static sensors are distributed along the periphery of a large volume to track a source, then the source-sensor coupling range is extended, but maintaining phase coherency between distributed sensors becomes complex
Solution Approach 1:
The system employs self-service mechanisms where each static sensor independently detects and processes signals from the moving source. The phase coherency is automatically maintained through the system's signal processing architecture that references all sensor measurements to a common coordinate system, eliminating the need for complex external synchronization hardware between distributed sensors.
Solution Approach 2:
The static sensor array serves multiple functions simultaneously: each sensor acts as both a position detector and an orientation reference point. The system universally processes signals from all sensors through a common computational framework that handles both localization and attitude determination, simplifying the overall phase coherency maintenance across the distributed sensor network.
3Ease of operation
If a portable wireless source is used to track position and orientation in three-dimensional space, then the ease of operation is improved, but the ability to maintain phase coherency with static sensors without radio links is challenged
Solution Approach 1:
The system replaces radio frequency communication links with direct magnetic field coupling for phase synchronization. The portable source and static sensors maintain phase coherency through electromagnetic induction in the magnetic near field, eliminating the need for wireless radio communication while preserving synchronization accuracy. This mechanical/electromagnetic substitution provides more reliable phase tracking than radio links would offer.
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 efficient tracking of sources and sensors in a large volume with reduced distortion, enabling wireless operation and extended range without the need for radio links, and allows for the use of pseudo-sensors and sources powered by other systems, enhancing the flexibility and accuracy of position and orientation calculations.
Implementation Method 1
AC magnetic tracking system with non-coherency between sources and sensors
Implementation Method 2
receivers detecting and synchronizing these sources using phase-adjusted matrices to compute position and orientation
Implementation Method 3
multiple, low-power, wireless multi-axis field sources operating at different frequencies, with receivers detecting and synchronizing these sources
Data Source
AI summary
In an AC magnetic tracker one or more multi-axis field sources, each operating at a different frequency, or frequency set, are detected and tracked in three-dimensional space, even when wireless or otherwise not physically connected to the tracking system. Multiple sources can be tracked simultaneously as they each operate with their own unique detectable set of parameters. The invention not only provides the ability to uniquely identify one or more sources by their frequencies, but also to synchronize with these frequencies in order to measure signals that then allow tracking the position and orientation (P&O) of the source(s). Further, these sources need not be present at the time of system start-up but can come and go while being detected, discriminated and tracked. It also should be noted that application of such systems in multiples with more sensors not synchronized to a source or sources also could be employed to give the reverse appearance of a known source phase and incoherency with the sensors.