US3744312A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Navigation apparatus
Assignee: Smiths Group PLC
•
Filing: 1971-06-02
•
Granted: 1973-07-10
•
Expires: 1991-06-02
Abstract
Abstract Navigation apparatus for a military tank includes three fluxvalve detector-pairs that each sense fore-aft and athwartships components of the earth''s magnetic field at different distances from the craft along a non-ferromagnetic boom. Fractionallyweighted values of the components sensed by the detector-pair nearest the tank are subtracted from their corresponding component-values sensed by the detector-pair furthest from the tank. To the results of the subtractions there are added fractionally-weighted values of the components sensed by the intermediately-located detector-pair so as thereby to derive component-values corrected for the craft-produced magneticdeviation and also for changes in location of the effective magnetic-center of the tank arising from changes in orientation of the tank''s gun. These values, before they are used to indicate tank-heading and compute northing and easting of the craft, are corrected for local magnetic-variation by combining with a fraction of each, a preselected fraction of the other.
Inventors
- 👤 E Anderson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 05:11
CPC Classifications
G; G01; G01C; G01C17/00; G01C17/02; G01C17/28; G01C17/30
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
256 words
Navigation apparatus for use with a craft, comprising magnetic-detector devices spaced apart from one anOther for sensing the earth''s magnetic field as subjected to deviation by the craft, the magnetic-detector devices sensing the magnitudes at more than two spaced locations of the component of deviated field acting parallel to a first of two mutually-inclined craftaxes, and the magnitudes at more than two spaced locations of the component of the deviated field acting parallel to a second of the two axes, means for deriving from the magnetic detector devices first signals in accordance with the respective said magnitudes of the component of deviated field acting parallel to the said first axis, means for deriving from the magneticdetector devices second signals in accordance with the respective said magnitudes of the component of deviated field acting parallel to the said second axis, first circuit means responsive to the set of said first signals to provide an output representation in accordance with the component of undeviated field acting parallel to the said first axis, and second circuit means responsive to the set of said second signals to provide an output representation in accordance with the component of undeviated field acting parallel to the said second axis, said first and second circuit means each comprising means for modifying more than one of the respective set of signals to modify the ratio to one another of those signals, and means responsive to the ratio-modified signals to derive the output representation of the respective said circuit means in accordance with difference between them.
Claim 2
Dependent Claim
256 words
Navigation apparatus for use with a craft, comprising magnetic-detector devices spaced apart from one anOther for sensing the earth''s magnetic field as subjected to deviation by the craft, the magnetic-detector devices sensing the magnitudes at more than two spaced locations of the component of deviated field acting parallel to a first of two mutually-inclined craftaxes, and the magnitudes at more than two spaced locations of the component of the deviated field acting parallel to a second of the two axes, means for deriving from the magnetic detector devices first signals in accordance with the respective said magnitudes of the component of deviated field acting parallel to the said first axis, means for deriving from the magneticdetector devices second signals in accordance with the respective said magnitudes of the component of deviated field acting parallel to the said second axis, first circuit means responsive to the set of said first signals to provide an output representation in accordance with the component of undeviated field acting parallel to the said first axis, and second circuit means responsive to the set of said second signals to provide an output representation in accordance with the component of undeviated field acting parallel to the said second axis, said first and second circuit means each comprising means for modifying more than one of the respective set of signals to modify the ratio to one another of those signals, and means responsive to the ratio-modified signals to derive the output representation of the respective said circuit means in accordance with difference between them.
Claim 3
Dependent Claim
74 words
Navigation apparatus according to claim 1, wherein the magnetic-detector devices comprise a first group of magnetic-detector devices for sensing the magnitudes of the component of deviated field acting parallel to the first axis at individual ones of the respective said spaced locations, and a second group of magnetic-detector devices for sensing the magnitudes of the component of deviated field acting parallel to the second axis at individual ones of the respective said spaced locations.
Claim 4
Dependent Claim
26 words
Navigation apparatus according to claim 2, including a non-ferromagnetic member, the magnetic-detector devices of each group thereof being carried by the member at spaced positions thereon.
Claim 5
Dependent Claim
32 words
Navigation apparatus according to claim 1, including means for providing a representation of magnetic heading of the craft in accordance with the output representations provided by said first and second circuit means.
Claim 6
Dependent Claim
49 words
Navigation apparatus according to claim 1, including speed-sensing means for providing a signal dependent upon velocity of the craft, and computing means responsive to this signal and the output representations provided by the first and second circuit means, to compute the distances travelled by the craft along earth-defined axes.
Claim 7
Dependent Claim
41 words
Navigation apparatus according to claim 1, including variation-correction means for deriving in accordance with the output representations provided by said first and second circuit means two signals dependent respectively upon said components of undeviated field corrected for local magnetic-variation or grid-variation.
Claim 8
Dependent Claim
28 words
Navigation apparatus according to claim 6, wherein said variation-correction means includes means for combining the output representations provided by said first and second circuit means in predetermined proportions.
Claim 9
Dependent Claim
93 words
Navigation apparatus according to claim 5, including variation-correction means responsive to said representations provided by said first and second circuit means for deriving two signals dependent respectively upon said components of undeviated magnetic field corrected for local magnetic-variation, and wherein said computing means comprises two integrators, two switches associated with the two integrators respectively, each said switch being selectively operable for supplying said signal dependent upon craft-velocity to its respectively-associated integrator, and timing means for operating the two switches for periods of time dependent respectively upon said signals derived by said variation-correctiOn means.
Claim 10
Dependent Claim
15 words
Navigation apparatus according to claim 1, wherein said first and second axes are mutually-perpendicular axes.
Claim 11
Dependent Claim
20 words
Navigation apparatus according to claim 9, wherein said first and second axes are fore-aft and athwartships axes of the craft.
Claim 12
Dependent Claim
230 words
Navigation apparatus for use in a craft, comprising magnetic-detector devices spaced apart from one another for sensing the earth''s magnetic field as subjected to deviation by the craft, the magnetic-detector devices sensing the magnitudes at at least two spaced locations of the component of deviated field acting parallel to a first of two mutually-inclined craft-axes, and the magnitudes at at least two spaced locations of the component of deviated field acting parallel to a second of the two craft-axes, means for deriving from the magnetic-detector devices first signals in accordance with the respective said magnitudes of the component of deviated field acting parallel to the said first axis, means for deriving from the magnetic-detector devices second signals in accordance with the respective said magnitudes of the component of deviated field acting parallel to the said second axis, means for sensing the earth''s magnetic field as subjected to deviation by the craft to derive a representation in accordance with the position of the effective magnetic-centre of the craft, means for responding to the said first signals and said representation to provide an output signal in accordance with the component of undeviated field acting parallel to the said first axis, and means for responding to the said second signals and said representation to provide an output signal in accordance with the component of undeviated field acting parallel to the said second axis.
Claim 13
Dependent Claim
230 words
Navigation apparatus for use in a craft, comprising magnetic-detector devices spaced apart from one another for sensing the earth''s magnetic field as subjected to deviation by the craft, the magnetic-detector devices sensing the magnitudes at at least two spaced locations of the component of deviated field acting parallel to a first of two mutually-inclined craft-axes, and the magnitudes at at least two spaced locations of the component of deviated field acting parallel to a second of the two craft-axes, means for deriving from the magnetic-detector devices first signals in accordance with the respective said magnitudes of the component of deviated field acting parallel to the said first axis, means for deriving from the magnetic-detector devices second signals in accordance with the respective said magnitudes of the component of deviated field acting parallel to the said second axis, means for sensing the earth''s magnetic field as subjected to deviation by the craft to derive a representation in accordance with the position of the effective magnetic-centre of the craft, means for responding to the said first signals and said representation to provide an output signal in accordance with the component of undeviated field acting parallel to the said first axis, and means for responding to the said second signals and said representation to provide an output signal in accordance with the component of undeviated field acting parallel to the said second axis.
Claim 14
Dependent Claim
33 words
Navigation apparatus according to claim 11, wherein the said means for providing the output signals each comprise means for modifying one of the respective first and second signals in accordance with said representation.
Claim 15
Dependent Claim
49 words
Navigation apparatus according to claim 12, wherein the said means for providing the output signals each include means for modifying the ratio to one another of the respective first and second signals, and means for deriving the respective output signal in accordance with difference between the respective ratio-modified signals.
Claim 16
Dependent Claim
34 words
Navigation apparatus according to claim 12, wherein the said representation comprises one signal for modifying the respective one of said first signals, and another signal for modifying the respective one of said second signals.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-09 | 1977-01-08 | 1977-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-09 | 1981-01-08 | 1981-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-09 | 1985-01-08 | 1985-07-10 | $7700.00 | Window Closed / Lapsed |