Claims
- 1. A correction system for determining an effect of an interfering object on a field sensor within a navigational domain, the system comprising:
a first transmitter configured to project, into said navigational domain, field energy in a first waveform sufficient to induce a first signal value in said field sensor, said first signal value being influenced by said interfering object; a second transmitter configured to project, into said navigational domain, field energy in a second waveform sufficient to induce a second signal value in said field sensor, said second signal value being influenced by said interfering object; and, a signal processor configured to receive said first signal value and said second signal value and to determine said influences of said interfering object on said field sensor, to thereby permit a substantially precise location of the field sensor to be determined despite the presence of said interfering object.
- 2. The correction system of claim 1, wherein said field energy is magnetic field energy.
- 3. The correction system of claim 1, wherein said interfering object is an electrically conductive object.
- 4. The correction system of claim 1, wherein said field sensor includes an electrically conductive sensing coil.
- 5. The correction system of claim 1, wherein said first waveform is a sinusoidal waveform at a first frequency, and
wherein said second waveform is a sinusoidal waveform at a second frequency.
- 6. A correction system according to claim 5, wherein said first transmitter and said second transmitter include (i) three unidirectional coil sets, each said set being driven by a drive unit capable of driving said unidirectional coil set at said first frequency and at said second frequency, and (ii) six delta coil sets, each said set being driven by a drive unit capable of driving said delta coil set at said first frequency and said second frequency, such that said three unidirectional coil sets and said six delta coils sets produce said field energy at said first and second frequencies.
- 7. A correction system according to claim 6, wherein said three unidirectional coil sets include a first unidirectional coil set oriented so as to produce a substantially uniform amplitude field directed in an x direction, a second unidirectional coil set oriented so as to produce a substantially uniform amplitude field directed in a y direction, and a third unidirectional coil set oriented so as to produce a substantially uniform amplitude field directed in a z direction, such that said x, y and z directions are substantially mutually orthogonal.
- 8. A correction system according to claim 7, said first unidirectional coil set having (i) a first coil pair including a first coil element and a second coil element, and (ii) a second coil pair including a third coil element and a fourth coil element, said first coil element and said third coil element being disposed in a major surface of a platform, said second coil element being disposed in a first lateral wall of said platform, and said fourth coil element being disposed in a second lateral wall of said platform, wherein said first lateral wall and said second lateral wall are substantially normal to said major surface and substantially parallel to one another.
- 9. A correction system according to claim 7, said second unidirectional coil set having a first coil element and a second coil element disposed within a platform, said coil elements being spaced apart and substantially parallel to one another.
- 10. A correction system according to claim 7, said third unidirectional coil set having (i) a first coil pair including a first coil element and a second coil element, and (ii) a second coil pair including a third coil element and a fourth coil element, said first coil element and said third coil element being disposed in a major surface of a platform, said second coil element being disposed in a first lateral wall of said platform, and said fourth coil element being disposed in a second lateral wall of said platform, wherein said first lateral wall and said second lateral wall are substantially normal to said major surface and substantially parallel to one another.
- 11. A correction system according to claim 6, wherein said six delta coil sets include a first pair of coil elements, a second pair of coil elements, and a third pair of coil elements, said coil elements being disposed so as to be substantially mutually coplanar within a major surface of a platform.
- 12. A correction system according to claim 11, wherein each of said pairs of coil elements includes a long coil and a short coil, and said pairs of coils are disposed at equal angles on a circle about an axis extending substantially perpendicular to said major surface, such that for each of said pairs of coils, a radius of said circle extends perpendicular to a direction of elongation of said pair, proceeding from said long coil to said short coil.
- 13. A correction system according to claim 12, wherein each of said pairs of coil elements further includes at least one compensation coil, constructed and arranged to modify at least one termination point of said coil elements, so as to provide relatively a high spatial field gradient along two orthogonal axes, and substantially zero field amplitude along a third orthogonal axis.
- 14. The correction system of claim 6, wherein said signal processor comprises:
(i) a first sequencer configured to (a) sequentially activate each of said three unidirectional coil sets and said six delta coil sets at said first frequency, and to measure said first signal value corresponding to each of said unidirectional and delta coil sets at said first frequency, and (b) to sequentially activate each of said three unidirectional coil sets and said six delta coil sets at said second frequency, and to measure said second signal value corresponding to each of said unidirectional and delta coil sets at said second frequency; and, (ii) a processor configured to calculate, for each of said unidirectional and delta coil sets, and adjusted signal value as a predetermined function of said first signal value and said second signal value, so as to produce nine adjusted signal values, each corresponding to field energy from one of said unidirectional coil sets and said delta coil sets.
- 15. A correction system according to claim 1, further including a third transmitter configured to project into said navigational domain a third waveform sufficient to induce a third signal value in said field coil, said third signal value being influenced by said interfering object; and
wherein said signal processor is further configured to receive said third signal value.
- 16. A correction system according to claim 15, further including a fourth transmitter configured to project into said navigational domain a fourth waveform sufficient to induce a fourth signal value ins aid field coil, said fourth signal value being influenced by said interfering object; and
wherein said signal processor is further configured to receive said fourth signal value.
- 17. A correction system according to claim 16, further including N-4 transmitters configured to project into said navigational domain N waveforms sufficient to induce N signal values in said field coil, said N signal values being influenced by said interfering object; and
wherein said signal processor is further configured to receive N signal values.
- 18. A correction system for determining an effect of an interfering object on first and second field sensors in a navigational domain, the system comprising:
a transmitter configured to project into said navigational domain, field energy sufficient to induce a first signal value in said first field sensor, and to induce a second signal value in said second field sensor; and, a signal processor configured to receive said first signal value and said second signal value and to determine the effect of said interfering object on said first field sensor, to thereby permit a substantially precise location of said first field sensor to be determined despite the presence of said interfering object.
- 19. The correction system of claim 18, wherein the field energy is magnetic field energy.
- 20. The correction system of claim 18, wherein said interfering object is a ferromagnetic and electrically conductive object.
- 21. The correction system of claim 18, wherein said field sensor includes an electrically conductive sensing coil.
- 22. The correction system of claim 18, wherein said transmitter includes
(i) three unidirectional coil sets, each said unidirectional coil set being driven by a unit capable of driving said unidirectional coil set at a first sinusoidal waveform at a first frequency, and (ii) six delta coil sets, each said delta coil set being driven by a drive unit capable of driving said delta coil set at said first sinusoidal waveform at said first frequency, such that said three unidirectional coil sets and said six delta coil sets produce said field energy at said first frequency.
- 23. A correction system according to claim 22, wherein said three unidirectional coil sets include a first unidirectional coil set oriented so as to produce a substantially uniform amplitude field directed in an x direction, a second unidirectional coil set oriented so as to produce a substantially uniform amplitude field directed in a y direction, and a third unidirectional coil set oriented so as to produce a substantially uniform amplitude field directed in a z direction, such that said x, y and z directions are substantially mutually orthogonal.
- 24. A correction system according to claim 23, said first unidirectional coil set having (i) a first coil pair including a first coil element and a second coil element, and (ii) a second coil pair including a third coil element and a fourth coil element, said first coil element and said third coil element being disposed in a major surface of a platform, said second coil element being disposed in a first lateral wall of said platform, and said fourth coil element being disposed in a second lateral wall of said platform, wherein said first lateral wall and said second lateral wall are substantially normal to said major surface and substantially parallel to one another.
- 25. A correction system according to claim 23, said second unidirectional coil set having a first coil element and a second coil element disposed within a platform, said coil elements being spaced apart and substantially parallel to one another.
- 26. A correction system according to claim 23, said third unidirectional coil set having (i) a first coil pair including a first coil element and a second coil element, and (ii) a second coil pair including a third coil element and a fourth coil element, said first coil element and said third coil element being disposed in a major surface of a platform, said second coil element being disposed in a first lateral wall of said platform, and said fourth coil element being disposed in a second lateral wall of said platform, wherein said first lateral wall and said second lateral wall are substantially normal to said major surface and substantially parallel to one another.
- 27. A correction system according to claim 22, wherein said six delta coil sets include a first pair of coil elements, a second pair of coil elements, and a third pair of coil elements, said coil elements being disposed so as to be substantially mutually coplanar within a major surface of a platform.
- 28. A correction system according to claim 27, wherein each of said pairs of coil elements includes a long coil and a short coil, and said pairs of coils are disposed at equal angles on a circle about an axis extending substantially perpendicular to said major surface, such that for each of said pairs of coils, a radius of said circle extends perpendicular to a direction of elongation of said pair, proceeding from said long coil to said short coil.
- 29. A correction system according to claim 28, wherein each of said pairs of coil elements further includes at least one compensation coil, constructed and arranged to modify at least one termination point of said coil elements, so as to provide relatively a high spatial field gradient along two orthogonal axes, and substantially zero field amplitude along a third orthogonal axis.
- 30. A correction system according to claim 22, wherein said signal processor further comprises:
(i) a first sequencer configured to sequentially activate each of three unidirectional coil sets and six delta coil sets at said first frequency, and to measure said first signal value and said second signal value corresponding to each of said unidirectional and delta coil sets at said first frequency; and, (ii) a processor configured to calculate, for each of said unidirectional and delta coil sets, an adjusted signal value as a predetermined function of said first signal value and said second signal value, so as to produce nine adjusted signal values, each corresponding to field energy from one of said unidirectional coil sets and said delta coil sets.
- 31. A correction system for determining an effect of a field influencing shield device on a field sensor in a navigational domain, said correction system comprising:
a transmitter configured to project into said navigational domain field energy sufficient to induce a signal value in said field sensor; a storage device containing information corresponding to said field energy in said navigational domain at selected locations within said navigational domain, said information including shield information incorporating the effect of said field influencing shield device at said selected locations; and, a processor for accessing said storage device and said signal value to determine the effect of said shield device on said field sensor, to thereby permit a substantially precise location of said field sensor to be determined despite the presence of said field influencing shield device.
- 32. The correction system of claim 31, wherein said field energy is magnetic field energy.
- 33. The correction system of claim 31, wherein said field sensor includes an electrically conductive sensing coil.
- 34. The correction system of claim 31, wherein said transmitter includes
(i) three unidirectional coil sets, each said unidirectional coil set being driven by a unit capable of driving said unidirectional coil set at a first sinusoidal waveform at a first frequency, and (ii) six delta coil sets, each said delta coil set being driven by a drive unit capable of driving said delta coil set at said first sinusoidal waveform at said first frequency, such that said three unidirectional coil sets and said six delta coil sets produce said field energy at said first frequency.
- 35. A correction system according to claim 34, wherein said three unidirectional coil sets include a first unidirectional coil set oriented so as to produce a substantially uniform amplitude field directed in an x direction, a second unidirectional coil set oriented so as to produce a substantially uniform amplitude field directed in a y direction, and a third unidirectional coil set oriented so as to produce a substantially uniform amplitude field directed in a z direction, such that said x, y and z directions are substantially mutually orthogonal.
- 36. A correction system according to claim 35, said first unidirectional coil set having (i) a first coil pair including a first coil element and a second coil element, and (ii) a second coil pair including a third coil element and a fourth coil element, said first coil element and said third coil element being disposed in a major surface of a platform, said second coil element being disposed in a first lateral wall of said platform, and said fourth coil element being disposed in a second lateral wall of said platform, wherein said first lateral wall and said second lateral wall are substantially normal to said major surface and substantially parallel to one another.
- 37. A correction system according to claim 35, said second unidirectional coil set having a first coil element and a second coil element disposed within a platform, said coil elements being spaced apart and substantially parallel to one another.
- 38. A correction system according to claim 35, said third unidirectional coil set having (i) a first coil pair including a first coil element and a second coil element, and (ii) a second coil pair including a third coil element and a fourth coil element, said first coil element and said third coil element being disposed in a major surface of a platform, said second coil element being disposed in a first lateral wall of said platform, and said fourth coil element being disposed in a second lateral wall of said platform, wherein said first lateral wall and said second lateral wall are substantially normal to said major surface and substantially parallel to one another.
- 39. A correction system according to claim 34, wherein said six delta coil sets include a first pair of coil elements, a second pair of coil elements, and a third pair of coil elements, said coil elements being disposed so as to be substantially mutually coplanar within a major surface of a platform.
- 40. A correction system according to claim 39, wherein each of said pairs of coil elements includes a long coil and a short coil, and said pairs of coils are disposed at equal angles on a circle about an axis extending substantially perpendicular to said major surface, such that for each of said pairs of coils, a radius of said circle extends perpendicular to a direction of elongation of said pair, proceeding from said long coil to said short coil.
- 41. A correction system according to claim 40, wherein each of said pairs of coil elements further includes at least one compensation coil, constructed and arranged to modify at least one termination point of said coil elements, so as to provide relatively a high spatial field gradient along two orthogonal axes, and substantially zero field amplitude along a third orthogonal axis.
- 42. A correction system according to claim 23, wherein said processor further comprises:
(i) first sequencer for sequentially activating each of said three unidirectional coils and said six delta coils at said first frequency, and measuring said signal value corresponding to each of said unidirectional and delta coils at said first frequency; (ii) a data manipulating device for manipulating, for each of said unidirectional and delta coils, said storage means as a predetermined function of said shield device, so as to produce nine sets of manipulated magnetic field values, each corresponding to field energy from one of said unidirectional coils and delta coils.
- 43. A method of determining a substantially precise location of a field sensor within a navigational domain influenced by a field interfering object, the method comprising:
inducing within said field sensor a first signal value at a first waveform, the first signal value being influenced by said field interfering object; inducing within said field sensor a second signal value at a second waveform, the second signal value being influenced by said field interfering object; and, determining a correction to said first signal value for the effects of said field interfering object.
- 44. A method according to claim 43, wherein said determining a correction further including calculating an adjusted signal value as a predetermined function of said first signal value and said second signal value.
- 45. A method of determining a substantially precise location of a first field sensor within a navigational domain influenced by a field interfering object, the method comprising:
inducing within said first field sensor a first signal value, the first signal value being influenced by said field interfering object; inducing within a second field sensor a second signal value, the second signal value being influenced by said field interfering object; and, determining a correction to said first signal value for the effects of said field interfering object.
- 46. A method according to claim 45, wherein said determining a correction further including calculating an adjusted signal value as a predetermined function of said first signal value and said second signal value.
- 47. A method of determining a substantially precise location of a field sensor within a navigational domain influenced by a field influencing shield device, the method comprising:
inducing within said field sensor a first signal value, the first signal value being influenced by said field interfering object; accessing information from a storage device, said information including shield information incorporating the effect of said field influencing shield device at selected locations; and determining a correction to said first signal value for the effects of said field influencing shield device.
- 48. A method according to claim 47, wherein said determining a correction further including manipulating said storage device as a predetermined function of said shield information, so as to produce a set of manipulated magnetic field values corresponding to said effects of said field influencing shield device.
- 49. A method of determining a substantially precise location of a field sensor within a navigational domain influenced by a field interfering object, the method comprising:
sequentially projecting into said navigational domain, via three unidirectional coils and six delta coils, navigational energy at a first frequency, and measuring a-first signal value in said field sensor corresponding to each of said three unidirectional coils and said six delta coils, so as to produce nine of said first signal values; sequentially projecting into said navigational domain, via three unidirectional coils and six delta coils, said navigational energy at a second frequency, and measuring a second signal value in said field sensor corresponding to each of said three unidirectional coils and said six delta coils, so as to produce nine of said second signal values; calculating, for each of said unidirectional and delta coils, an adjusted signal value as a predetermined function of said first signal value and said second signal value, so as to produce nine adjusted signal values, each corresponding to navigational magnetic energy from one of said unidirectional coils and delta coils; forming three independent equations including (i) three adjusted signal values corresponding to said unidirectional coils, (ii) three predetermined field magnitude values due to each of said unidirectional coils and corresponding to said navigational energy at a last navigational point of said sensing coil, and (iii) unknown orientation variables, and simultaneously solving said independent equations to determine said orientation variables corresponding to said compensated orientation of said sensing coil; generating three lines and determining an intersection of said three lines, said intersection corresponding to said compensated position of said sensing coil, wherein each of said lines is generated from (i) adjusted signal values corresponding to a pair of said delta coils, and (ii) predetermined field magnitude values due to said pair of delta coils and corresponding to said navigational energy at said last navigational point of said sensing coil while oriented according to said compensated orientation.
- 50. A method of determining a substantially precise location of a first field sensor within a navigational domain influenced by a field interfering object, the method comprising:
sequentially projecting into said navigational domain, via three unidirectional coils and six delta coils, said navigational energy at a first frequency, measuring a first signal value in said field sensor corresponding to each of said three unidirectional coils and said six delta coils, so as to produce nine of said first signal values, and measuring a second signal value in a second field sensor corresponding to each of said three unidirectional coils and said six delta coils, so as to produce nine of said second signal values; calculating, for each of said unidirectional and delta coils, an adjusted signal value as a predetermined function of said first signal value and said second signal value, so as to produce nine adjusted signal values, each corresponding to navigational magnetic energy from one of said unidirectional coils and delta coils; forming three independent equations including (i) three adjusted signal values corresponding to said unidirectional coils, (ii) three predetermined field magnitude values due to each of said unidirectional coils and corresponding to said navigational energy at a last navigational point of said sensing coil, and (iii) unknown orientation variables, and simultaneously solving said independent equations to determine said orientation variables corresponding to said compensated orientation of said sensing coil; generating three lines and determining an intersection of said three lines, said intersection corresponding to said compensated position of said sensing coil, wherein each of said lines is generated from (i) adjusted signal values corresponding to a pair of said delta coils, and (ii) predetermined field magnitude values due to said pair of delta coils and corresponding to said navigational energy at said last navigational point of said sensing coil while oriented according to said compensated orientation.
- 51. A method of determining a substantially precise location of a field sensor within a navigational domain influenced by a field influencing shield device, the method comprising:
sequentially projecting into said navigational domain, via three unidirectional coils and six delta coils, said navigational energy at a first frequency, and measuring a first signal value in said field sensor corresponding to each of said three unidirectional coils and said six delta coils, so as to produce nine of said first signal values; forming three independent equations including (i) three adjusted signal values corresponding to said unidirectional coils, (ii) three predetermined field magnitude values due to fields from each of said unidirectional coils and corresponding to said navigational energy at a last navigational point of said field sensor, said predetermined field magnitude values being manipulated so as to account for said shield device, and (iii) unknown orientation variables, and simultaneously solving said independent equations to determine said orientation variables corresponding to said compensated orientation of said sensing coil; generating three lines and determining an intersection of said three lines, said intersection corresponding to said compensated position of said sensing coil, wherein each of said lines is generated from (i) adjusted signal values corresponding to a pair of said delta coils, and (ii) predetermined field magnitude values due to said pair of delta coils and corresponding to said navigational energy at said last navigational point of said sensing coil while oriented according to said compensated orientation, said predetermined field magnitude values being manipulated so as to account for said effect of the shield device.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of United States Provisional Application Number 60/161,991, filed Oct. 28, 1999, the contents of which are incorporated herein by reference in their entirety, and from which priority is claimed.
Provisional Applications (1)
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Number |
Date |
Country |
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60161991 |
Oct 1999 |
US |
Continuations (1)
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Number |
Date |
Country |
Parent |
09589779 |
Jun 2000 |
US |
Child |
10252258 |
Sep 2002 |
US |