US5202829A
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US
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Exploration system and method for high-accuracy and high-confidence level relative position and velocity determinations
Assignee: Trimble Inc
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Filing: 1991-06-10
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Granted: 1993-04-13
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Expires: 2011-06-10
Abstract
Abstract An embodiment of the present invention is a shipboard GPS positioning system having data links to outlying tailbuoys equipped with respective GPS receivers. On ship, an Intel 386-based microcomputer system collects data from various ship's equipment including the ship's GPS receiver and data from the several tailbuoy units. A computer-implemented process located in the microcomputer system controls the following processes. Periodically each GPS receiver produces updated pseudo ranges (PRs) and these are time-tagged. The time-tagged PRs for the ship are aligned according to their time tags with their counterpart PRs from the tailbuoys. The raw PRs are then passed through a Kalman mathematical filter to produce filtered pseudo-ranges (PRs). A position solution is then attempted for each GPS receiver using the PRs. The filters provide statistical data that is used to rate the quality of each PR in a weighted least squares solution process. Special measures are included to provide quality control/quality assurance, including the use of error ellipses on the display to present a graphic indication of expected solution accuracy, and the use of real time fault detection, isolation, and correction algorithms when redundant satellite information is available.
Inventors
- 👤 George J. Geier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:55
CPC Classifications
G; G01; G01S; G01S19/00; G01S19/01; G01S19/13; G01S19/14; G01S19/03; G01S19/04; G01S19/38; G01S19/39; G01S19/42; G01S19/43; G01S19/44
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
261 words
A mobile fleet exploration system for obtaining high accuracy relative earth position and velocity determinations amongst individual mobile units in the fleet from a plurality of GPS receiving stations distributed throughout the mobile fleet, the exploration system comprising: at least one outlying individual mobile unit including means for obtaining a first time-sequence of pseudo-ranges and pseudo-range-rates to a plurality of GPS satellites; a main mobile unit including means for obtaining a second time-sequence of pseudo-ranges and pseudo-range-rates to said plurality of GPS satellites; navigation computer means for calculating a plurality of relative earth positions and velocities from an input comprising a sequence of delta-pseudo-ranges and delta-pseudo-range-rates relative to said plurality of GPS satellites derived from the respective pseudo-ranges and pseudo-range-rates relative to said individual mobile fleet units and said main mobile unit and including a Kalman filter for filtering said delta-pseudo-ranges using information from said delta-pseudo-range-rates; associative means for pairing each pseudo-range in said first and second time-sequences of pseudo-ranges with a time-code indicating a time each respective pseudo-range was obtained; communication means for transferring said first and second time sequences of pseudo-ranges to the navigation computer means and associative means; and differencing means for time-aligning according to said time code and subtracting the corresponding pseudo-ranges and pseudo-range-rates of said first time-sequence of pseudo-ranges and pseudo-range-rates from said second time-sequence of pseudo-ranges and pseudo-range-rates to produce a sequence of delta-pseudo-ranges and delta-pseudo-range-rates and for communicating said delta-pseudo-ranges and delta-pseudo-range-rates to the navigational computer means wherein a difference in relative positions and velocities amongst the individual mobile fleet units can be determined.
Claim 2
Dependent Claim
261 words
A mobile fleet exploration system for obtaining high accuracy relative earth position and velocity determinations amongst individual mobile units in the fleet from a plurality of GPS receiving stations distributed throughout the mobile fleet, the exploration system comprising: at least one outlying individual mobile unit including means for obtaining a first time-sequence of pseudo-ranges and pseudo-range-rates to a plurality of GPS satellites; a main mobile unit including means for obtaining a second time-sequence of pseudo-ranges and pseudo-range-rates to said plurality of GPS satellites; navigation computer means for calculating a plurality of relative earth positions and velocities from an input comprising a sequence of delta-pseudo-ranges and delta-pseudo-range-rates relative to said plurality of GPS satellites derived from the respective pseudo-ranges and pseudo-range-rates relative to said individual mobile fleet units and said main mobile unit and including a Kalman filter for filtering said delta-pseudo-ranges using information from said delta-pseudo-range-rates; associative means for pairing each pseudo-range in said first and second time-sequences of pseudo-ranges with a time-code indicating a time each respective pseudo-range was obtained; communication means for transferring said first and second time sequences of pseudo-ranges to the navigation computer means and associative means; and differencing means for time-aligning according to said time code and subtracting the corresponding pseudo-ranges and pseudo-range-rates of said first time-sequence of pseudo-ranges and pseudo-range-rates from said second time-sequence of pseudo-ranges and pseudo-range-rates to produce a sequence of delta-pseudo-ranges and delta-pseudo-range-rates and for communicating said delta-pseudo-ranges and delta-pseudo-range-rates to the navigational computer means wherein a difference in relative positions and velocities amongst the individual mobile fleet units can be determined.
Claim 3
Dependent Claim
59 words
The system of claim 1, further comprising: pseudo-range quality testing means for determining whether particular pseudo-ranges within said first and second time-sequences of pseudo-ranges exceed a predetermined minimum reliability threshold and for preventing any pseudo-ranges that do not exceed said predetermined minimum reliability threshold from being used in determining a position or a velocity in the navigation computer means.
Claim 4
Dependent Claim
54 words
The system of claim 2, wherein: the pseudo-range quality testing means further comprises fault detection, isolation, and correction (FDIC) means for detecting whether a particular GPS satellite produces unreliable pseudo-ranges and for isolating any pseudo-ranges related to said particular GPS satellite from input to the navigation computer if said pseudo-ranges cannot otherwise be corrected.
Claim 5
Dependent Claim
48 words
The system of claim 1, further comprising: computational means for correcting said sequence of delta-pseudo-ranges from the differencing means to represent a set of line-of-sight vectors to said GPS satellites as being non-parallel and for outputting a sequence of corrected delta-pseudo-ranges for input to the navigational computer means.
Claim 6
Dependent Claim
45 words
The system of claim 1, wherein the navigational computer means further comprises an interacting weighted-least-squares means for accepting a plurality of uncertainty levels derived from said Kalman filter wherein a plurality of satellite measurements can be weighted to produce said relative earth positions and velocities.
Claim 7
Independent Claim
248 words
A method for obtaining high accuracy relative earth position and velocity determinations amongst individual mobile units in a fleet from a plurality of GPS signals received at stations distributed throughout the mobile fleet, the method comprising the steps of: obtaining a first time-sequence of pseudo-ranges and pseudo-range-rates to a plurality of GPS satellites from at least one outlying individual mobile unit; obtaining a second time-sequence of pseudo-ranges and pseudo-range-rates to said plurality of GPS satellites from a main mobile unit; calculating a plurality of relative earth positions and velocities with a navigation computer from an input comprising a sequence of delta-pseudo-ranges and delta-pseudo-range-rates relative to said plurality of GPS satellites derived from respective pseudo-ranges and pseudo-range-rates relative to said individual mobile fleet units and using a Kalman filter to filter said delta-pseudo-ranges with information from said delta-pseudo-range-rates; pairing each pseudo-range in said first and second time-sequences of pseudo-ranges in an associative means with a time-code indicating a time each respective pseudo-range was obtained; communicating said first and second time sequences of pseudo-ranges to said navigation computer and associative means; and time-aligning according to said time code and subtracting corresponding pseudo-ranges and pseudo-range-rates of said first time-sequence of pseudo-ranges and pseudo-range-rates from said second time-sequence of pseudo-ranges and pseudo-range-rates in a differencing means to produce a sequence of delta-pseudo-ranges and delta-pseudo-range-rates and for communicating said delta-pseudo-ranges and pseudo-range-rates to said navigational computer wherein a difference in relative positions and velocities amongst the individual mobile fleet units can be determined.
Claim 8
Independent Claim
248 words
A method for obtaining high accuracy relative earth position and velocity determinations amongst individual mobile units in a fleet from a plurality of GPS signals received at stations distributed throughout the mobile fleet, the method comprising the steps of: obtaining a first time-sequence of pseudo-ranges and pseudo-range-rates to a plurality of GPS satellites from at least one outlying individual mobile unit; obtaining a second time-sequence of pseudo-ranges and pseudo-range-rates to said plurality of GPS satellites from a main mobile unit; calculating a plurality of relative earth positions and velocities with a navigation computer from an input comprising a sequence of delta-pseudo-ranges and delta-pseudo-range-rates relative to said plurality of GPS satellites derived from respective pseudo-ranges and pseudo-range-rates relative to said individual mobile fleet units and using a Kalman filter to filter said delta-pseudo-ranges with information from said delta-pseudo-range-rates; pairing each pseudo-range in said first and second time-sequences of pseudo-ranges in an associative means with a time-code indicating a time each respective pseudo-range was obtained; communicating said first and second time sequences of pseudo-ranges to said navigation computer and associative means; and time-aligning according to said time code and subtracting corresponding pseudo-ranges and pseudo-range-rates of said first time-sequence of pseudo-ranges and pseudo-range-rates from said second time-sequence of pseudo-ranges and pseudo-range-rates in a differencing means to produce a sequence of delta-pseudo-ranges and delta-pseudo-range-rates and for communicating said delta-pseudo-ranges and pseudo-range-rates to said navigational computer wherein a difference in relative positions and velocities amongst the individual mobile fleet units can be determined.
Claim 9
Dependent Claim
59 words
The method of claim 6, further comprising the step of: determining whether particular pseudo-ranges within said first and second time-sequences of pseudo-ranges exceed a predetermined minimum reliability threshold with a pseudo-range quality testing means and preventing any pseudo-ranges that do not exceed said predetermined minimum reliability threshold from being used in determining a position in said navigation computer means.
Claim 10
Dependent Claim
44 words
The method of claim 7, wherein: the determining step further comprises detecting whether a particular GPS satellite is producing unreliable pseudo-ranges and isolating any pseudo-ranges related to said particular GPS satellite from input to the navigation computer if said pseudo-ranges cannot otherwise be corrected.
Claim 11
Dependent Claim
47 words
The method of claim 6, further comprising the step of: correcting said sequence of delta-pseudo-ranges from said differencing means to represent a set of line-of-sight vectors to said GPS satellites as being non-parallel and outputting a sequence of corrected delta-pseudo-ranges for input to said navigational computer means.
Claim 12
Dependent Claim
44 words
The method of claim 6, wherein: the calculating step further comprises an interacting weighted-least-squares method for accepting a plurality of uncertainty levels derived from said Kalman filter wherein a plurality of satellite measurements can be weighted to produce said relative earth positions and velocities.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1996-04-12 | 1996-10-12 | 1997-04-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-04-12 | 2000-10-12 | 2001-04-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-04-12 | 2004-10-12 | 2005-04-13 | $7700.00 | Window Closed / Lapsed |