Position and orientation measuring with magnetic fields
First Claim
Patent Images
1. A remote object location determining system comprising:
- a generation subsystem having at least one transducer operable to produce an electromagnetic field;
a sensing subsystem having at least one transducer operable to measure an electromagnetic field produced by the generation subsystem;
a driver operable to apply excitation waveforms to the generation subsystem; and
a processor operably connected to receive sensor signals from the sensing subsystem, and to determine at least two location parameters by comparing measured magnetic field values to a function of splines corresponding to magnetic field values; and
wherein at least one of the generation subsystem and the sensing subsystem has a plurality of transducers.
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Abstract
Splines of magnetic field values are used by a processor to determine location parameters in a remote location determination system. The location determination system is used on a laser catheter that is operable to perform myocardial revascularization. An automatic calibration technique compensates for any variations in gain in a sensor and related components. Methods for reducing the effects of eddy currents in surrounding conductive objects are used in electromagnetic position and orientation measurement systems.
355 Citations
35 Claims
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1. A remote object location determining system comprising:
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a generation subsystem having at least one transducer operable to produce an electromagnetic field;
a sensing subsystem having at least one transducer operable to measure an electromagnetic field produced by the generation subsystem;
a driver operable to apply excitation waveforms to the generation subsystem; and
a processor operably connected to receive sensor signals from the sensing subsystem, and to determine at least two location parameters by comparing measured magnetic field values to a function of splines corresponding to magnetic field values; and
wherein at least one of the generation subsystem and the sensing subsystem has a plurality of transducers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A remote object location determining system comprising:
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a generation subsystem having at least one transducer operable to produce an electromagnetic field;
a sensing subsystem having at least one transducer operable to sense an electromagnetic field produced by the generation subsystem;
a driver operable to apply excitation waveforms to the generation subsystem; and
a processor operably connected to receive sensor signals from the sensing subsystem, the processor operable to determine at least two location parameters of a relationship between the generation subsystem and the sensing subsystem, and wherein the processor determines gain in the sensing subsystem automatically and determines location parameters independent from any variations in the gain of the sensing subsystem; and
wherein at least one of the generation subsystem and the sensing subsystem has a plurality of transducers. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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24. A remote object location determining system comprising:
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a generation subsystem having at least one transducer operable to produce an electromagnetic field;
a sensing subsystem having at least one transducer operable to sense an electromagnetic field produced by the generation subsystem;
a driver operable to apply excitation waveforms to the generation subsystem, the excitation waveforms being selected from the group consisting of a ramp waveform and a triangular waveform; and
a processor operably connected to receive sensor signals from the sensing subsystem, the processor operable to determine at least two location parameters of a relationship between the generation subsystem and the sensing subsystem; and
wherein at least one of the generation subsystem and the sensing subsystem has a plurality of transducers and wherein the processor minimizes inaccuracies in the location parameters by performing eddy current compensation, thus reducing or eliminating inaccuracies that would otherwise be introduced by eddy currents in the vicinity of the sensing subsystem and the generation subsystem. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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31. A method of determining the position and orientation of a remote object, comprising the steps of:
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measuring a magnetic field so as to generate first measurement values;
characterizing said magnetic field with splines using said first measurement values;
measuring said magnetic field at a selected location so as to generate second measurement values; and
determining at least two location parameters relative to said selected location by comparing said second measurement values with said splines. - View Dependent Claims (32, 33)
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34. A system for determining the location of a remote object, comprising:
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a generation subsystem having at least one transducer operable to produce a magnetic field;
a sensing subsystem having at least one transducer operable to measure a magnetic field produced by the generation subsystem;
a driver operable to apply excitation waveforms to the generation subsystem;
a processor operably connected to receive sensor signals from the sensing subsystem, and to determine at least two location parameters by comparing measured magnetic field values to a plurality of polynomials fit together to characterize said electromagnetic field; and
wherein at least one of the generation subsystem and the sensing subsystem has a plurality of transducers.
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35. A remote object location determining system, comprising:
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first means for producing a magnetic field;
second means for measuring a magnetic field produced by said first means and providing an output signal containing magnetic field values obtained from measurement of said magnetic field;
third means for applying excitation waveforms to said first means; and
fourth means, operably connected to said second means, for receiving said output signal and for determining at least two location parameters by comparing said magnetic field values in said output signal to a function of splines characterizing said magnetic field produced by said first means.
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Specification