Method and apparatus for determining vehicle position using a satellite based navigation system

• US 5,359,521 A
• Filed: 12/01/1992
• Issued: 10/25/1994
• Est. Priority Date: 12/01/1992
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Gudat, Adam J., Kyrtsos, Christos T., Friedrich, Douglas W.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US07/983,697
• Time in Patent Office: 693 Days
• Field of Search: 364/449, 364/516, 364/439, 364/444, 364/424, 364/460, 342/352, 342/357, 342/457, 342/424, 340/988, 340/945
• US Class Current: 701/215
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/43 using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial

Abstract

An apparatus and method for determining the position of a vehicle relative to the center of the Earth uses navigation signals from a satellite based navigation system which includes a plurality of satellites orbiting the Earth. In one embodiment, a plurality of antennas are mounted on the vehicle. The distance between the antennas is precisely known. This distance is used to constrain the solution of a vehicle position estimate to improve the accuracy of the position estimate. In another embodiment, a plurality of receiver systems are used in place of the plurality of antennas. In yet another embodiment, a plurality of base stations with known positions are used to constrain the solution of the vehicle position estimate.

Claims

1. An apparatus for determining a position of a vehicle near the surface of the Earth using navigation signals from a satellite based navigation system which includes a plurality of satellites orbiting the Earth, the apparatus comprising:

first means, mounted on the vehicle at a first position, for receiving navigation signals from the plurality of satellites, for determining the position of each satellite from a respective first navigation signal, and for computing a first pseudorange for each satellite from said respective first navigation signal, each said first pseudorange representing a distance between said first means and a corresponding one of the plurality of satellites;

second means, mounted on the vehicle at a second position displaced a fixed distance δ

from said first position, for receiving navigation signals from the plurality of satellites, for determining the position of each satellite from a respective second navigation signal, and for computing a second pseudorange for each satellite from said respective second navigation signal, each said second pseudorange representing a distance between said second means and a corresponding one of the plurality of satellites; and

third means for computing the position of the vehicle based on said positions of said satellites, said first and second pseudoranges, and said fixed distance δ

.

2. An apparatus for determining a position of a vehicle near the surface of the Earth using navigation signals from a satellite based navigation system which includes a plurality of satellites orbiting the Earth, the apparatus comprising:

first means, mounted on the vehicle at a first position, for receiving navigation signals from the plurality of satellites;

second means, mounted on the vehicle at a second position displaced a fixed distance δ

from said first position, for receiving navigation signals from the plurality of satellites;

third means, electrically connected to said first and second means, for computing a first pseudorange and a first satellite position for each satellite based on the navigation signals received by said first means and a second pseudorange and a second satellite position for each satellite based on the navigation signals received by said second means; and

fourth means, electrically connected to said third means, for computing the position of the vehicle based on said first and second satellite positions, said first and second pseudoranges, and said distance δ

.

3. A method for determining a position of a vehicle near the surface of the Earth using navigation signals from a satellite based navigation system which includes a plurality of Earth-orbiting satellites, the method comprising the steps of:

(a) receiving a navigation signal from each of the plurality of satellites at a first antenna coupled to the vehicle;

(b) receiving a navigation signal from each of the plurality of satellites at a second antenna coupled to the vehicle, said second antenna being separated from said first antenna by a distance δ

;

(c) computing, for each antenna, a satellite position and a corresponding pseudorange for each satellite using the navigation signals; and

(d) computing a position of the vehicle relative to the Earth from said satellite positions, said pseudoranges, and said distance δ

between said first and second antennas.

4. The method of claim 3, wherein step (c) of computing is performed using a first receiver connected to said first antenna and a second receiver connected to said second antenna.

5. The method of claim 3, wherein step (c) of computing is performed using a single receiver connected to said first and second antennas.

6. A method for determining a position of a vehicle near the surface of the Earth using navigation signals from a satellite based navigation system which includes a plurality of Earth-orbiting satellites, the method comprising the steps of:

(a) receiving navigation signals from each of the plurality of satellites at an antenna coupled to the vehicle;

(b) computing an estimated position of the vehicle from said navigation signals received at the vehicle;

(c) receiving navigation signals from each of the plurality of satellites at a first base station having a known position;

(d) computing a satellite position and a pseudorange to said first base station for each satellite using said navigation signals received at said first base station;

(e) transmitting, to the vehicle from said first base station, said satellite positions and said pseudoranges;

(f) computing a first estimated distance between said first base station and the vehicle using said first estimated position of the vehicle and said satellite positions and pseudoranges received from said first base station;

(g) repeating steps (c)-(f) for a second base station to yield a second estimated distance between said second base station and the vehicle;

(h) repeating steps (c)-(f) for a third base station to yield a third estimated distance between said third base station and the vehicle; and

(i) computing, using a triangulation technique, a precise position estimate for the vehicle using said first distance and a known position for said first base station, said second distance and a known position for said second base station, and said third distance and a known position for said third base station.

7. A method for determining a position of a vehicle near the surface of the Earth using navigation signals from a satellite based navigation system which includes a plurality of Earth-orbiting satellites, the method comprising the steps of:

(a) receiving navigation signals from each of the plurality of satellites at an antenna coupled to the vehicle;

(b) computing a vehicle position estimate using said navigation signals received at the vehicle;

(c) refining the vehicle position estimate using a first base station and a double differencing technique to produce a first refined position estimate;

(d) computing a first distance between a known position of said first base station and said first refined position estimate;

(e) repeating steps (c) and (d) for a second base station to produce a second distance;

(f) repeating steps (c) and (d) for a third base station to produce a third distance; and

(g) computing a precise vehicle position estimate from said known positions of said first, second and third base stations and said first, second and third distances.