Patent US4394872A successfully refreshed from Google Patents.
Patent US6980921B2 successfully refreshed from Google Patents.
US6980921B2
Expired / Lapsed
US
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Magnetic tracking system
Assignee: Northern Digital Inc
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Filing: 2003-11-14
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Granted: 2005-12-27
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Expires: 2023-11-14
Abstract
Abstract The present invention provides an electromagnetic tracking system that includes a field generator and a field sensor arranged to generate and detect, respectively, an electromagnetic field. Both the transmitter and receiver coils are connected to signal conditioning and processing circuitry to provide outputs indicative of the coil signals. A processor operates on the signals to determine the coordinates of the sensing assembly relative to the generator assembly. The signal processor produces ratiometric outputs, and applies a mutual inductance model to solve for position/orientation coordinates. In some embodiments, a disturber in the form of a conductive ring or a sheath is disposed about an interfering piece of equipment to moderate and standardize disturbances due to eddy currents.
Inventors
- 👤 Peter T. Anderson
- 👤 Gerald L. Beauregard
- 👤 Christopher D. Cherry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:20
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/06; A61B34/00; A61B34/20; A61B90/00; A61B90/36; A61B34/10; A61B2034/101; A61B2034/102; A61B2034/2046; A61B2034/2051; A61B2034/2055; A61B2034/2068; A61B2034/2072; A61B90/37; A61B2090/376; A61B90/39; A61B2090/3954; A61B2090/3958
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
178 words
An electromagnetic tracking system comprising a magnetic field generating unit driven by a drive signal, a field sensing unit having a sensing signal responsive to a changing magnetic field, said changing magnetic field including a position-dependent field produced by said magnetic field generating unit, the generating and sensing units being arranged to generate and to sense, respectively, an electromagnetic field in an arena of interest, and wherein at least one of said units is movable, signal measurement and conditioning circuitry connected to said units to sample and digitize signal data for the field generating and field sensing units, a distorter having a known structure disposed at a selected location in the arena of interest, and a processor operative on the sampled and digitized signal data to determine relative coordinates and orientations of said field generating or field sensing unit, said processor modeling the distorter and the generating and sensing units to generate modeled signal data and fitting said modeled signal data to measured signal values to determine coordinates and orientations of said field generating and field sensing units.
Claim 2
Dependent Claim
178 words
An electromagnetic tracking system comprising a magnetic field generating unit driven by a drive signal, a field sensing unit having a sensing signal responsive to a changing magnetic field, said changing magnetic field including a position-dependent field produced by said magnetic field generating unit, the generating and sensing units being arranged to generate and to sense, respectively, an electromagnetic field in an arena of interest, and wherein at least one of said units is movable, signal measurement and conditioning circuitry connected to said units to sample and digitize signal data for the field generating and field sensing units, a distorter having a known structure disposed at a selected location in the arena of interest, and a processor operative on the sampled and digitized signal data to determine relative coordinates and orientations of said field generating or field sensing unit, said processor modeling the distorter and the generating and sensing units to generate modeled signal data and fitting said modeled signal data to measured signal values to determine coordinates and orientations of said field generating and field sensing units.
Claim 3
Dependent Claim
22 words
The electromagnetic tracking system of claim 1 , wherein said distorter comprises a shielding device positioned in relation to a fluoroscopic detector.
Claim 4
Dependent Claim
25 words
The electromagnetic tracking system of claim 1 , wherein said processor uses an integral method of correction to compensate for distortion caused by said distorter.
Claim 5
Dependent Claim
20 words
The electromagnetic tracking system of claim 1 , wherein said field sensing unit is movable within the arena of interest.
Claim 6
Dependent Claim
187 words
An electromagnetic tracking system comprising a magnetic field generating unit driven by a drive signal, a field sensing unit having a sensing signal responsive to a changing magnetic field, said changing magnetic field including a position-dependent field produced by said magnetic field generating unit, the generating and sensing units being arranged to generate and to sense, respectively, an electromagnetic field in an arena of interest, and wherein at least one of said units is movable, signal measurement and conditioning circuitry connected to said units to sample and digitize signal data for the field generating and field sensing units, a distorter having a known structure disposed at a selected location in the arena of interest, and a processor operative on the sampled and digitized signal data to determine relative coordinates and orientations of said field generating or field sensing unit, said processor modeling the distorter and the generating and sensing units to generate modeled signal data and fitting said modeled signal data to measured signal values to determine coordinates and orientations of said field generating and field sensing units, said processor modeling said distorter as a ring model.
Claim 7
Dependent Claim
187 words
An electromagnetic tracking system comprising a magnetic field generating unit driven by a drive signal, a field sensing unit having a sensing signal responsive to a changing magnetic field, said changing magnetic field including a position-dependent field produced by said magnetic field generating unit, the generating and sensing units being arranged to generate and to sense, respectively, an electromagnetic field in an arena of interest, and wherein at least one of said units is movable, signal measurement and conditioning circuitry connected to said units to sample and digitize signal data for the field generating and field sensing units, a distorter having a known structure disposed at a selected location in the arena of interest, and a processor operative on the sampled and digitized signal data to determine relative coordinates and orientations of said field generating or field sensing unit, said processor modeling the distorter and the generating and sensing units to generate modeled signal data and fitting said modeled signal data to measured signal values to determine coordinates and orientations of said field generating and field sensing units, said processor modeling said distorter as a ring model.
Claim 8
Dependent Claim
88 words
An electromagnetic tracking system comprising a magnetic field generating unit, a field sensing unit, the generating and sensing units being arranged to generate and to sense, respectively, an electromagnetic field in an arena of interest, a distorter having a known structure disposed at a selected location in the arena of interest, and a processor modeling the generating and sensing units to generate modeled signal data and fitting said modeled signal data to measured signal values to determine coordinates and orientations of said field generating and field sensing unit.
Claim 9
Dependent Claim
88 words
An electromagnetic tracking system comprising a magnetic field generating unit, a field sensing unit, the generating and sensing units being arranged to generate and to sense, respectively, an electromagnetic field in an arena of interest, a distorter having a known structure disposed at a selected location in the arena of interest, and a processor modeling the generating and sensing units to generate modeled signal data and fitting said modeled signal data to measured signal values to determine coordinates and orientations of said field generating and field sensing unit.
Claim 10
Dependent Claim
38 words
The electromagnetic tracking system of claim 6 , wherein the field sensing unit has a sensing signal responsive to a changing magnetic field, said changing magnetic field including a position-dependent field produced by said magnetic field generating unit.
Claim 11
Dependent Claim
33 words
The electromagnetic tracking system of claim 6 , further comprising signal measurement and conditioning circuitry connected to said units to sample and digitize signal data for the field generating and field sensing units.
Claim 12
Dependent Claim
17 words
The electromagnetic tracking system of claim 6 , wherein at least one of said units is movable.
Claim 13
Dependent Claim
22 words
The electromagnetic tracking system of claim 6 , wherein said distorter comprises a shielding device positioned in relation to a fluoroscopic detector.
Claim 14
Dependent Claim
25 words
The electromagnetic tracking system of claim 6 , wherein said processor uses an integral method of correction to compensate for distortion caused by said distorter.
Claim 15
Dependent Claim
18 words
The electromagnetic tracking system of claim 6 , wherein said processor models the distorter as a ring model.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2008-12-26 | 2009-06-27 | 2009-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2012-12-26 | 2013-06-27 | 2013-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2016-12-26 | 2017-06-27 | 2017-12-27 | $7700.00 | Window Closed / Lapsed |