US6230100B1
Expired / Lapsed
US
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Method and apparatus for differential scale factor calibration in differential odometry systems integrated with GPS
Assignee: Aumovio Systems Inc
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Filing: 1997-01-31
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Granted: 2001-05-08
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Expires: 2017-01-31
Abstract
Abstract Calibration of a differential scale factor associated with left and right wheels of a vehicle having a terrestrial navigation system. The terrestrial navigation system includes a GPS receiver integrated with a dead reckoning system. The dead reckoning system has wheel sensors coupled to the left and right wheels. The calibration of the differential scale factor includes: determining a heading change with the dead reckoning system, using the determined heading change to determine an open loop heading, determining an error in the differential scale factor based on the open loop heading and an alternate heading, and using the error in the differential scale factor to adjust an initial value of the differential scale factor.
Inventors
- 👤 George Jeffrey Geier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:31
CPC Classifications
G; G01; G01C; G01C22/00; G01C22/02; G01C22/025
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
187 words
A method for calibrating a differential scale factor associated with left and right wheels of a movable vehicle in which a terrestrial navigation system is installed, said terrestrial navigation system comprised of a GPS receiver integrated with a dead reckoning system, said dead reckoning system utilizing wheel sensors coupled to said left and right wheels, said method comprising the steps of: determining a heading change based upon said dead reckoning system, said differential scale factor of said dead reckoning system having an initial value wherein said differential scale factor is indicative of a difference in size of tires attached to the left and right wheels; using said determined heading change derived from said dead reckoning system to determine an open loop heading; summing successive determined values of said open loop headings over a time period based upon said movable vehicles traveling a predetermined distance; determining an error in said differential scale factor based upon said summed successive open loop headings and a heading computed by said GPS receiver; and using said error in said differential scale factor to adjust said initial value of said differential scale factor.
Claim 2
Independent Claim
187 words
A method for calibrating a differential scale factor associated with left and right wheels of a movable vehicle in which a terrestrial navigation system is installed, said terrestrial navigation system comprised of a GPS receiver integrated with a dead reckoning system, said dead reckoning system utilizing wheel sensors coupled to said left and right wheels, said method comprising the steps of: determining a heading change based upon said dead reckoning system, said differential scale factor of said dead reckoning system having an initial value wherein said differential scale factor is indicative of a difference in size of tires attached to the left and right wheels; using said determined heading change derived from said dead reckoning system to determine an open loop heading; summing successive determined values of said open loop headings over a time period based upon said movable vehicles traveling a predetermined distance; determining an error in said differential scale factor based upon said summed successive open loop headings and a heading computed by said GPS receiver; and using said error in said differential scale factor to adjust said initial value of said differential scale factor.
Claim 3
Dependent Claim
36 words
The method of claim 1 wherein said steps of determining a heading change, using said determined heading change and determining an error in said differential scale factor are repeated to further adjust said differential scale factor.
Claim 4
Dependent Claim
12 words
The method of claim 1 wherein said predetermined distance is one kilometer.
Claim 5
Dependent Claim
26 words
The method of claim 1 wherein said error in said differential scale factor is tested for reasonableness before being used to adjust said differential scale factor.
Claim 6
Dependent Claim
24 words
The method of claim 1 wherein said open loop heading is initialized to a value based upon a GPS heading from said GPS receiver.
Claim 7
Dependent Claim
16 words
The method of claim 1 wherein said initial value of said differential scale factor is one.
Claim 8
Dependent Claim
23 words
The method of claim 1 wherein said alternate heading is determined at a time when said movable vehicle has traveled a predetermined distance.
Claim 9
Dependent Claim
18 words
The method of claim 1 wherein said error in said differential scale factor is adjusted in real time.
Claim 10
Dependent Claim
21 words
The method of claim 1 wherein said dead reckoning system includes wheel sensors installed on front wheels of said movable vehicle.
Claim 11
Dependent Claim
21 words
The method of claim 1 wherein said dead reckoning system includes wheel sensors installed on rear wheels of said movable vehicle.
Claim 12
Dependent Claim
24 words
The method of claim 1 wherein said dead reckoning system includes wheel sensors installed on both front and rear wheels of said movable vehicle.
Claim 13
Independent Claim
202 words
A method for calibrating a differential scale factor associated with left and right wheels of a movable vehicle in which a terrestrial navigation system is installed, said terrestrial navigation system comprised of a GPS receiver integrated with a dead reckoning system, said dead reckoning system utilizing wheel sensors coupled to said left and right wheels, said method comprising the steps of: determining a heading change based upon said dead reckoning system, said differential scale factor of said dead reckoning system having an initial value wherein said differential scale factor is indicative of a difference in size of tires attached to the left and right wheels; using said determined heading change derived from said dead reckoning system to determine an open loop heading; determining an error in said differential scale factor based upon said summed successive open loop headings and a heading computed by said GPS receiver, wherein said error in said differential scale factor is tested for reasonableness before being used to adjust said differential scale factor by comparing the square of said error in said differential scale factor with a residual variance; and using said error in said differential scale factor to adjust said initial value of said differential scale factor.
Claim 14
Independent Claim
202 words
A method for calibrating a differential scale factor associated with left and right wheels of a movable vehicle in which a terrestrial navigation system is installed, said terrestrial navigation system comprised of a GPS receiver integrated with a dead reckoning system, said dead reckoning system utilizing wheel sensors coupled to said left and right wheels, said method comprising the steps of: determining a heading change based upon said dead reckoning system, said differential scale factor of said dead reckoning system having an initial value wherein said differential scale factor is indicative of a difference in size of tires attached to the left and right wheels; using said determined heading change derived from said dead reckoning system to determine an open loop heading; determining an error in said differential scale factor based upon said summed successive open loop headings and a heading computed by said GPS receiver, wherein said error in said differential scale factor is tested for reasonableness before being used to adjust said differential scale factor by comparing the square of said error in said differential scale factor with a residual variance; and using said error in said differential scale factor to adjust said initial value of said differential scale factor.
Claim 15
Independent Claim
201 words
An apparatus for calibrating a differential scale factor associated with left and right wheels of a movable vehicle, said apparatus comprising: wheels sensors, coupled to said left and right wheels of said movable vehicle, for determining distance traveled by said left and right wheels; means for determining a heading change of said movable vehicle based upon said distance traveled by said left and right wheels, said differential scale factor having an initial value wherein said differential scale factor is indicative of a difference in size of tires attached to the left and right wheels; means, responsive to said means for determining said heading change, for determining an open loop heading; means, responsive to said means for determining said open loop heading, for summing successive determined values of said open loop headings over a time period based upon said movable vehicle traveling a predetermined distance; a GPS receiver for computing a heading of said movable vehicle; means for determining an error in said differential scale factor based upon said summed successive open loop headings and said heading of said GPS receiver; and means, responsive to said error in said differential scale factor, for adjusting said initial value of said differential scale factor.
Claim 16
Independent Claim
201 words
An apparatus for calibrating a differential scale factor associated with left and right wheels of a movable vehicle, said apparatus comprising: wheels sensors, coupled to said left and right wheels of said movable vehicle, for determining distance traveled by said left and right wheels; means for determining a heading change of said movable vehicle based upon said distance traveled by said left and right wheels, said differential scale factor having an initial value wherein said differential scale factor is indicative of a difference in size of tires attached to the left and right wheels; means, responsive to said means for determining said heading change, for determining an open loop heading; means, responsive to said means for determining said open loop heading, for summing successive determined values of said open loop headings over a time period based upon said movable vehicle traveling a predetermined distance; a GPS receiver for computing a heading of said movable vehicle; means for determining an error in said differential scale factor based upon said summed successive open loop headings and said heading of said GPS receiver; and means, responsive to said error in said differential scale factor, for adjusting said initial value of said differential scale factor.
Claim 17
Dependent Claim
25 words
The apparatus of claim 13 further including means for repeatedly adjusting said differential scale factor based upon additional determined errors in said differential scale factor.
Claim 18
Dependent Claim
12 words
The apparatus of claim 13 wherein said predetermined distance is one kilometer.
Claim 19
Dependent Claim
28 words
The apparatus of claim 13 further including means for testing said error in said differential scale factor for reasonableness before being used to adjust said differential scale factor.
Claim 20
Dependent Claim
28 words
The apparatus of claim 16 wherein said means for testing includes means for comparing the square of said error in said differential scale factor with a residual variance.
Claim 21
Dependent Claim
24 words
The apparatus of claim 13 wherein said open loop heading is initialized to a value based upon a GPS heading from said GPS receiver.
Claim 22
Dependent Claim
16 words
The apparatus of claim 13 wherein said initial value of said differential scale factor is one.
Claim 23
Dependent Claim
26 words
The apparatus of claim 13 wherein said heading of said alternate means is determined at a time when said movable vehicle has traveled a predetermined distance.
Claim 24
Dependent Claim
18 words
The apparatus of claim 13 wherein said error in said differential scale factor is adjusted in real time.
Claim 25
Dependent Claim
18 words
The apparatus of claim 13 wherein said wheel sensors are installed on front wheels of said movable vehicle.
Claim 26
Dependent Claim
18 words
The apparatus of claim 13 wherein said wheel sensors are installed on rear wheels of said movable vehicle.
Claim 27
Dependent Claim
21 words
The apparatus of claim 13 wherein said wheel sensors are installed on both front and rear wheels of said movable vehicle.
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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) | 2004-05-07 | 2004-11-06 | 2005-05-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-05-07 | 2008-11-06 | 2009-05-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-05-07 | 2012-11-06 | 2013-05-08 | $7700.00 | Window Closed / Lapsed |