Method and apparatus for refinably accurate localization of devices and instruments in scattering environments
First Claim
1. A method of localizing a device, medical or otherwise, within a three dimensional environment, the method comprising:
- (a) transmitting time varying magnetic fields from at least three transmitters, (b) receiving the transmitted electromagnetic radiation as induced voltage signals from at least one receiver mounted on or within said device, and (c) processing said received voltage signals in order to extract position and orientation localization information for said device, said processing including phase-shifting and correction for conducting materials in the vicinity by the use of information gathered from fitting said phase-shifted induced voltage signals with polynomial functions having terms in powers of freguency using at least three distinct transmission frequencies for each of said transmitters.
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Abstract
A method of localizing a device, medical or otherwise, within a three dimensional environment, the method comprising: (a) transmitting time varying magnetic fields from at least three transmitters, (b) receiving the transmitted electromagnetic radiation as induced voltage signals from at least one receiver mounted on or within said device, and (c) a processing scheme for processing said received voltage signals in order to extract position and orientation localization information for said device, said processing scheme including correction for conducting materials in the vicinity by the use of information gathered from at least three distinct transmission frequencies for each of said transmitters.
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Citations
27 Claims
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1. A method of localizing a device, medical or otherwise, within a three dimensional environment, the method comprising:
- (a) transmitting time varying magnetic fields from at least three transmitters, (b) receiving the transmitted electromagnetic radiation as induced voltage signals from at least one receiver mounted on or within said device, and (c) processing said received voltage signals in order to extract position and orientation localization information for said device, said processing including phase-shifting and correction for conducting materials in the vicinity by the use of information gathered from fitting said phase-shifted induced voltage signals with polynomial functions having terms in powers of freguency using at least three distinct transmission frequencies for each of said transmitters.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for processing signals received by a receiver at multiple frequencies from each of a number of transmitters, where said processing includes, for each pair of receiver and transmitter:
- (a) producing polynomial fits of given order to the signal as a function of frequency, (b) said polynomial fit produced by a fitting procedure, weighted or otherwise, that in the case of a weighted procedure may employ different weights for different frequencies in order to improve the fit over desired frequency ranges, and (c) extracting the coefficient of the linear term in the polynomial fit as the flux in the receiver produced by each said transmitter.
- View Dependent Claims (12, 13, 14)
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15. A system for generating, acquiring and processing signals for the purpose of localizing position and orientation of a device in three dimensional space by electromagnetic means, said system comprising:
- (a) a main computer and programmable interface for refining the accuracy of localization estimation by signal generation, acquisition and processing, (b) a microprocessor controlled signal generation system linked to said main computer, (c) a set of at least three transmitters located at known fixed locations and orientations in three dimensional space, (d) at least one receiver mounted on or within the device at which location position and orientation is desired to be found, said transmitters configured to be driven by said signal generation system at a plurality of frequencies in time and frequency multiplexed fashion to induce voltage signals in the at least one receiver, and (e) processing software for producing polynomial fits to phase-shifted induced voltage signals in powers of frequency using at least three of said frequencies to provide at least three polynomial coefficients for use in correcting the voltage signals for conducting materials present in the surrounding three dimensional space.
- View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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24. A method of localizing a medical device within a three-dimensional environment, the method comprising:
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transmitting time varying magnetic fields at at least three frequencies from each of at least three transmitters; receiving electromagnetic radiation of the transmitted fields as an induced voltage signal from at least one receiver of the device; phase-shifting the induced voltage signal;
curve-fitting the phase-shifted induced voltage signal as a function of frequency to obtain a polynomial expansion in powers of frequency;using the linear term coefficient of the polynomial expansion to determine a flux induced in the at least one receiver from each transmitter; and using the fluxes to determine a position and orientation of the device.
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25. A method of localizing a medical device within a three-dimensional environment, the device including at least one receiver that can receive signals from at least three transmitters in the environment, the method comprising:
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selecting an order of polynomial fit; selecting a plurality of transmission frequencies based on the selected order; driving the transmitters to transmit signals at the selected frequencies in frequency-multiplexed batches; for each of the at least one receiver; receiving voltage signals induced in the receiver by the transmitted signals; curve-fitting at the selected order of fit to components of the voltage signals as a function of frequency to obtain for each receiver at least one polynomial expansion in powers of frequency; extracting a linear term coefficient from each of the polynomial expansions; and using the coefficients to correct device localization for conducting material in the environment. - View Dependent Claims (26)
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27. An apparatus for processing a signal received by a receiver mounted on or within a medical device at a plurality of frequencies from each of a plurality of transmitters, the apparatus comprising, for each pair of the receiver and one of the transmitters:
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means for producing polynomial fits to the signal as a function of frequency, wherein the polynomial fit production means employs different weights for different frequencies to improve the fits over desired frequency ranges; and means for extracting a coefficient of a linear term of each of the polynomial fits to determine flux in the receiver produced by each said transmitter.
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Specification