Electromagnetic Tracking Distortion Suppression via Multi-Frequency Signal Design
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Solution Overview
Problem
Electromagnetic tracking systems in medical procedures face errors due to field distortions caused by conductors in the environment, which existing methods struggle to accurately mitigate without significant hardware constraints or computational demands.
Innovation Solution
The system employs a parameter selection process to dynamically control the frequencies and amplitudes of electromagnetic signals transmitted by field transmitters, ensuring that the distortion component of the received field includes residual errors only from specified higher-order frequency terms, thereby suppressing distortions without needing to identify or adjust for specific conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods are used to mitigate tracking errors, then measurement precision is improved, but device complexity and computational costs increase
Solution Approach 1:
The patent changes the parameters of the electromagnetic signals by transmitting multiple frequencies simultaneously rather than a single frequency. This allows the system to suppress distortion components through frequency-based differentiation without requiring complex calibration procedures or detailed knowledge of conductor properties, thereby improving tracking accuracy while maintaining system simplicity
Solution Approach 2:
The patent replaces the mechanical/calibration-based approach with a signal processing approach. Instead of physically calibrating the system based on conductor models, the method uses mathematical processing of multi-frequency signals to automatically separate and suppress distortion components, reducing both device complexity and computational burden
2Measurement precision
If conventional calibration methods are used to mitigate tracking errors, then measurement precision is improved, but productivity decreases due to increased computational demands
Solution Approach 1:
By transmitting multiple frequencies and using frequency-based signal separation, the patent achieves distortion suppression through efficient mathematical operations that are less computationally intensive than conventional calibration methods requiring repeated evaluations of conductor properties and transmission parameter adjustments
Solution Approach 2:
The patent performs preliminary signal transmission at multiple frequencies and pre-processes the received signals to separate distortion components before final position calculation. This preliminary processing reduces the computational burden during real-time tracking operations, improving overall productivity
3Measurement precision
If conventional calibration methods are used to mitigate tracking errors, then measurement precision is improved, but adaptability decreases due to inflexibility to conductor changes
Solution Approach 1:
The patent uses multiple transmission frequencies that can be dynamically adjusted based on the received signal characteristics. This allows the system to adapt to changing conductor configurations in the environment without requiring recalibration, as the frequency-based distortion suppression automatically adjusts to new conditions
Solution Approach 2:
The patent employs feedback by analyzing the received multi-frequency signals to identify distortion components and adjusting the transmission parameters accordingly. This continuous feedback loop enables the system to automatically adapt to environmental changes involving conductors while maintaining high tracking 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 effectively reduces tracking errors by eliminating lower-order distortion terms, maintaining system flexibility and minimizing computational and hardware requirements, ensuring accurate position and orientation tracking during medical procedures.
Implementation Method 1
transmitting, using a field transmitter of the plurality of field transmitters, a set of electromagnetic signals
Implementation Method 2
The transmitted fields can drive eddy currents in metals or other conductors in the environment around the transmitters, and these eddy currents in turn result in distortions of the transmitted fields
Implementation Method 3
one or more field sensors associated with a medical device that can measure signals from the set of transmitters
Data Source
AI summary
A method uses an electromagnetic tracking system, including a number of field transmitters and at least one receiver, to determine location information associated with a medical device. The method includes transmitting a set of electromagnetic signals, each signal having a frequency that is different than a frequency associated with each of the other signals, where each signal corresponds to a sum of sinusoidal functions, each of which includes an amplitude and a frequency. A field signal is received, and includes an undistorted field component and a distortion component. The amplitudes and frequencies of the sinusoidal functions are selected such that the distortion component includes a residual error arising from terms of at least a specified order in frequency. Field components corresponding to the field transmitters are extracted from the received signal, and the location information is determined based on the field components.