US6172499B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Eddy current error-reduced AC magnetic position measurement system
Assignee: Ascension Technology Corp
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Filing: 1999-10-29
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Granted: 2001-01-09
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Expires: 2019-10-29
Abstract
Abstract A device is disclosed for measuring the position (location and orientation) in the six degrees of freedom of a receiving antenna with respect to a transmitting antenna utilizing multiple frequency AC magnetic signals. The transmitting component consists of two or more transmitting antenna of known location and orientation relative to one another. The transmitting antenna are driven simultaneously by an AC excitation, with each antenna occupying one or more unique positions in the frequency spectrum. The receiving antennas measure the transmitted AC magnetic field plus distortions caused by conductive metals. A computer then extracts the distortion component and removes it from the received signals providing the correct position and orientation output to a high degree of accuracy.
Inventors
- 👤 Westley Ashe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:18
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/12; G01D5/14; G01D5/20; G01D5/204; G01D5/2086; G01D5/2093; F; F41; F41G; F41G3/00; F41G3/22; F41G3/225; G01B; G01B7/00; G01B7/003; G01B7/14; G01B7/30; A; A61; A61B; A61B5/00; A61B5/103; A61B5/11
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
165 words
A device for measuring the position of receiver antennas relative to transmitter antennas comprising: a) transmitter antenna means comprising at least two aparallel antennas adapted to generate at least two AC magnetic field vectors, said fields exhibiting at least two frequency components; b) receiver means comprising at least two aparallel sensors adapted to detect said AC magnetic field vectors; c) a first number of transmitter antennas multiplied by a second number of receiver sensors being at least equal to a total number of degrees of freedom of a desired measurement of position of the receiver means relative to the transmitter antennas; d) signal processing means for ascertaining magnitude of detected AC magnetic field vectors, said signal processing means computing magnitudes of at least two detected AC magnetic field vectors with relative values of phase separated components of said field vectors being employed by said signal processing means to correct detected said AC magnetic field vectors to substantially eliminate position errors caused by eddy current distortion.
Claim 2
Independent Claim
165 words
A device for measuring the position of receiver antennas relative to transmitter antennas comprising: a) transmitter antenna means comprising at least two aparallel antennas adapted to generate at least two AC magnetic field vectors, said fields exhibiting at least two frequency components; b) receiver means comprising at least two aparallel sensors adapted to detect said AC magnetic field vectors; c) a first number of transmitter antennas multiplied by a second number of receiver sensors being at least equal to a total number of degrees of freedom of a desired measurement of position of the receiver means relative to the transmitter antennas; d) signal processing means for ascertaining magnitude of detected AC magnetic field vectors, said signal processing means computing magnitudes of at least two detected AC magnetic field vectors with relative values of phase separated components of said field vectors being employed by said signal processing means to correct detected said AC magnetic field vectors to substantially eliminate position errors caused by eddy current distortion.
Claim 3
Dependent Claim
15 words
A device according to claim 1 , wherein said total number comprises at least six.
Claim 4
Dependent Claim
41 words
A device according to claim 2 , wherein three transmitter antennas are arranged to produce three orthogonal pairs of AC magnetic field vectors, each said pair comprising two parallel field vectors of distinct different frequencies for a total of six vectors.
Claim 5
Dependent Claim
24 words
A device according to claim 2 , comprising three receiver sensors arranged to detect said transmitted AC magnetic field vectors on three orthogonal axes.
Claim 6
Dependent Claim
34 words
A device according to claim 2 , comprising two transmitter antennas arranged to produce two orthogonal pairs of AC magnetic field vectors, each said pair comprising two parallel field vectors of distinct different frequencies.
Claim 7
Dependent Claim
29 words
A device according to claim 3 , including drive means for simultaneously producing said pairs of magnetic field vectors by utilizing a separate instantaneous frequency for each said vector.
Claim 8
Dependent Claim
18 words
A device according to claim 3 , including drive means for producing said transmitted magnetic field vectors sequentially.
Claim 9
Dependent Claim
28 words
A device according to claim 6 , wherein said drive means includes modulation means for generating sidebands in order to separate, in frequency, transmitted AC magnetic field vectors.
Claim 10
Dependent Claim
28 words
A device according to claim 7 , wherein said drive means includes modulation means for generating sidebands in order to separate, in frequency, transmitted AC magnetic field vectors.
Claim 11
Dependent Claim
24 words
A device according to claim 3 , wherein at least one transmit axis is driven with at least two frequencies either simultaneously or sequentially.
Claim 12
Independent Claim
219 words
A device for measuring the position of receiver antennas relative to transmitter antennas comprising: a) transmitter antenna means comprising at least two aparallel antennas adapted to generate at least two AC magnetic field vectors, through frequency division multiplexing with at least two frequency components; b) drive means for driving each of said aparallel antennas with at least one unique frequency, said drive means driving said antennas either simultaneously or sequentially, with a different unique frequency being used for each different axis at any given instant in time; c) receiver means comprising at least two aparallel sensors adapted to detect said AC magnetic vectors; d) a first number of transmitter antennas times a second number of receiver sensors being at least equal to a total number of degrees of freedom of a desired quantitative measurement of position of a receiver sensor relative to said transmitter antennas; e) signal processing means for ascertaining magnitude of detected AC magnetic field vectors, said signal processing means computing the magnitudes of at least two detected AC magnetic vectors comprising at least two frequencies, with relative values of phase separated components of said vectors being used to deduce a compensation coefficient, said compensation coefficient being used to quantitatively correct said detected AC magnetic field vectors to substantially eliminate amplitude errors caused by eddy current distortion.
Claim 13
Independent Claim
219 words
A device for measuring the position of receiver antennas relative to transmitter antennas comprising: a) transmitter antenna means comprising at least two aparallel antennas adapted to generate at least two AC magnetic field vectors, through frequency division multiplexing with at least two frequency components; b) drive means for driving each of said aparallel antennas with at least one unique frequency, said drive means driving said antennas either simultaneously or sequentially, with a different unique frequency being used for each different axis at any given instant in time; c) receiver means comprising at least two aparallel sensors adapted to detect said AC magnetic vectors; d) a first number of transmitter antennas times a second number of receiver sensors being at least equal to a total number of degrees of freedom of a desired quantitative measurement of position of a receiver sensor relative to said transmitter antennas; e) signal processing means for ascertaining magnitude of detected AC magnetic field vectors, said signal processing means computing the magnitudes of at least two detected AC magnetic vectors comprising at least two frequencies, with relative values of phase separated components of said vectors being used to deduce a compensation coefficient, said compensation coefficient being used to quantitatively correct said detected AC magnetic field vectors to substantially eliminate amplitude errors caused by eddy current distortion.
Claim 14
Dependent Claim
14 words
The device of claim 11 , wherein said total number comprises at least six.
Claim 15
Dependent Claim
23 words
The device of claim 11 , comprising three receiver sensors arranged to detect said transmitted AC magnetic field vectors on three orthogonal axes.
Claim 16
Dependent Claim
27 words
The device of claim 11 , wherein said drive means includes modulation means for generating sidebands in order to separate, in frequency, transmitted AC magnetic field vectors.
Claim 17
Dependent Claim
23 words
The device of claim 11 , wherein at least one transmit axis is driven with at least two frequencies either simultaneously or sequentially.
Claim 18
Independent Claim
156 words
A method of measuring the position of receiver antennas relative to transmitter antennas including the steps of: a) providing transmitter antenna means comprising at least two aparellel antennas adapted to generate at least two AC magnetic field vectors, said fields exhibiting at least two frequency components; b) providing receiver means comprising at least two aparallel sensors adapted to detect said AC magnetic field vectors; c) driving said transmitter means to generate said at least two magnetic field vectors; d) receiving signals related to said vectors at said receiver means; e) providing signal processing means for ascertaining magnitude of detected signals; f) computing, with said signal processing means, magnitudes of at least two detected AC magnetic field vectors, relative values of phase separated components of said vectors being obtained; g) calculating from said relative values a compensation coefficient; and h) said signal processing means employing said compensation coefficient to correct vectors to compensate for eddy current distortion.
Claim 19
Independent Claim
156 words
A method of measuring the position of receiver antennas relative to transmitter antennas including the steps of: a) providing transmitter antenna means comprising at least two aparellel antennas adapted to generate at least two AC magnetic field vectors, said fields exhibiting at least two frequency components; b) providing receiver means comprising at least two aparallel sensors adapted to detect said AC magnetic field vectors; c) driving said transmitter means to generate said at least two magnetic field vectors; d) receiving signals related to said vectors at said receiver means; e) providing signal processing means for ascertaining magnitude of detected signals; f) computing, with said signal processing means, magnitudes of at least two detected AC magnetic field vectors, relative values of phase separated components of said vectors being obtained; g) calculating from said relative values a compensation coefficient; and h) said signal processing means employing said compensation coefficient to correct vectors to compensate for eddy current distortion.
Claim 20
Dependent Claim
23 words
The method of claim 16 , further including the step of driving said transmitter means to generate said at least two vectors simultaneously.
Claim 21
Dependent Claim
23 words
The method of claim 16 , further including the step of driving said transmitter means to generate said at least two vectors sequentially.
Claim 22
Dependent Claim
22 words
The method of claim 16 , wherein said driving step includes the step of generating sidebands to separate, in frequency, transmitted vectors.
Claim 23
Independent Claim
132 words
A device for measuring the position of receiver antennas relative to transmitter antennas comprising: a) magnetic field transmitting means for transmitting magnetic field components at desired frequencies, said transmitting means transmitting a plurality of distinct frequencies; b) magnetic field receiving means sensitive to said transmitted field components and outputting a signal to be operated on by a signal processing means responsive to receipt of said field components; c) said signal processing means provided for ascertaining magnitude of detected magnetic field vectors, said signal processing means computing magnitudes of received magnetic field vectors, said magnetic field vectors comprising a plurality of frequencies, said signal processing means utilizing relative values of phase separated components of said field vectors to correct detected said magnetic field vectors to substantially eliminate errors caused by eddy current distortion.
Claim 24
Independent Claim
132 words
A device for measuring the position of receiver antennas relative to transmitter antennas comprising: a) magnetic field transmitting means for transmitting magnetic field components at desired frequencies, said transmitting means transmitting a plurality of distinct frequencies; b) magnetic field receiving means sensitive to said transmitted field components and outputting a signal to be operated on by a signal processing means responsive to receipt of said field components; c) said signal processing means provided for ascertaining magnitude of detected magnetic field vectors, said signal processing means computing magnitudes of received magnetic field vectors, said magnetic field vectors comprising a plurality of frequencies, said signal processing means utilizing relative values of phase separated components of said field vectors to correct detected said magnetic field vectors to substantially eliminate errors caused by eddy current distortion.
Claim 25
Dependent Claim
17 words
The device of claim 20 , wherein said transmitting means comprises a plurality of flat co-planar transmitters.
Claim 26
Dependent Claim
17 words
The device of claim 20 , wherein said receiving means comprises at least one single coil receiver.
Claim 27
Dependent Claim
17 words
The device of claim 21 , wherein said receiving means comprises at least one single coil receiver.
Claim 28
Dependent Claim
17 words
The device of claim 21 , wherein said receiving means comprises a plurality of single coil receivers.
Claim 29
Dependent Claim
17 words
The device of claim 20 , wherein said receiving means comprises at least one gradient field sensor.
Claim 30
Dependent Claim
21 words
The device of claim 25 , wherein said at least one gradient field sensor comprises a plurality of gradient field sensors.
Claim 31
Dependent Claim
38 words
The device of claim 20 , wherein said signal processing means includes means for calculating a compensation coefficient, said compensation coefficient being employed by said signal processing means to compensate for signal errors caused by eddy current distortion.
Claim 32
Independent Claim
179 words
A method of measuring the position of receiver antennas relative to transmitter antennas in a space including the steps of: a) providing transmitter antenna means comprising at least two aparallel antennas adapted to generate at least two AC magnetic field vectors, said fields exhibiting at least two frequency components; b) providing receiver means comprising at least two aparallel sensors adapted to detect said AC magnetic field vectors; c) driving said transmitter means to generate said at least two magnetic field vectors; d) receiving signals related to said vectors at said receiver means; e) providing signal processing means for ascertaining magnitude of detected signals; f) computing, with said signal processing means, magnitudes of at least two detected AC magnetic field vectors, relative values of phase separated components of said vectors being obtained; g) determining a compensation coefficient by measuring a phase shift angle Θ of eddy currents generated by metals in or adjacent said space, said compensation coefficient comprising tan Θ; and h) said signal processing means employing said compensation coefficient to correct vectors to compensate for eddy current distortion.
Claim 33
Independent Claim
179 words
A method of measuring the position of receiver antennas relative to transmitter antennas in a space including the steps of: a) providing transmitter antenna means comprising at least two aparallel antennas adapted to generate at least two AC magnetic field vectors, said fields exhibiting at least two frequency components; b) providing receiver means comprising at least two aparallel sensors adapted to detect said AC magnetic field vectors; c) driving said transmitter means to generate said at least two magnetic field vectors; d) receiving signals related to said vectors at said receiver means; e) providing signal processing means for ascertaining magnitude of detected signals; f) computing, with said signal processing means, magnitudes of at least two detected AC magnetic field vectors, relative values of phase separated components of said vectors being obtained; g) determining a compensation coefficient by measuring a phase shift angle Θ of eddy currents generated by metals in or adjacent said space, said compensation coefficient comprising tan Θ; and h) said signal processing means employing said compensation coefficient to correct vectors to compensate for eddy current distortion.
Claim 34
Dependent Claim
23 words
The method of claim 28 , further including the step of driving said transmitter means to generate said at least two vectors simultaneously.
Claim 35
Dependent Claim
23 words
The method of claim 28 , further including the step of driving said transmitter means to generate said at least two vectors sequentially.
Claim 36
Dependent Claim
22 words
The method of claim 28 , wherein said driving step includes the step of generating sidebands to separate, in frequency, transmitted vectors.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-01-09 | 2004-07-10 | 2005-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-01-09 | 2008-07-10 | 2009-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-01-09 | 2012-07-10 | 2013-01-09 | $7700.00 | Window Closed / Lapsed |