Vehicle position determination system and method

• US 5,390,125 A
• Filed: 02/18/1993
• Issued: 02/14/1995
• Est. Priority Date: 02/05/1990
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Gudat, Adam J., Kyrtsos, Christos T., Stafford, Darrell E., Christensen, Dana A., Sennott, James W., Friedrich, Douglas W.
• Primary Examiner(s): Chin, Gary
• Application Number:
  US08/019,540
• Time in Patent Office: 726 Days
• Field of Search: 364/443, 364/449, 364/455, 364/459, 364/474.37, 342/357, 342/450, 342/451, 342/192, 342/457, 73/178 R
• US Class Current: 701/214
• CPC Class Codes: B60K 31/0008 including means for detecting potential obstacles in vehicle path
• CPC Class Codes: B60K 31/04 and means for comparing one electrical quantity, e.g. voltage, pulse, waveform, flux, or the like, with another quantity of a like kind, which comparison means is involved in the development of an electrical signal which is fed into the controlling means
• CPC Class Codes: B62D 1/28 non-mechanical , e.g. following a line or other known markers
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/27 creating, predicting or correcting ephemeris or almanac data within the receiver
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• CPC Class Codes: G01S 19/52 Determining velocity
• CPC Class Codes: G01S 5/009 Transmission of differential positioning data to mobile
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G08G 1/20 Monitoring the location of vehicles belonging to a group, e.g. fleet of vehicles, countable or determined number of vehicles

Abstract

Systems and methods allow for the accurate determination of the terrestrial position of an autonomous vehicle in real time. A first position estimate of the vehicle 102 is derived from satellites of a global positioning system and/or a pseudolite(s). The pseudolite(s) may be used exclusively when the satellites are not in the view of the vehicle. A second position estimate is derived from an inertial reference unit and/or a vehicle odometer. The first and second position estimates are combined and filtered using novel techniques to derive a more accurate third position estimate of the vehicle'"'"'s position. Accordingly, accurate autonomous navigation of the vehicle can be effectuated using the third position estimate.

Claims

1. A system for determining an estimate of the position of a vehicle based on pseudoranges derived from a vehicle positioning system and prior position estimates, the system comprising:

(a) first means for receiving signals from a plurality of satellites, responsively determining respective pseudoranges from said satellites to the vehicle, and deriving a first position estimate of the vehicle'"'"'s position as a function of said pseudoranges;

(b) second means responsive to said first means for receiving the prior position estimates and responsively determining a vehicle path model using a best fit algorithm;

(c) third means responsive to said second means, said third means for extrapolating a second position estimate from said vehicle path model; and

(d) fourth means responsive to said third means, said fourth means for setting said first position estimate equal to said second position estimate if said second position estimate is more accurate.

2. A method for determining an estimate of the position of a vehicle based on a vehicle position system and prior position estimates via a best fit algorithm, the method comprising the steps of:

(1) receiving signals from a plurality of satellites, responsively determining respective pseudoranges from said satellites to said vehicle, and computing a first position estimate using the vehicle positioning system as a function of said pseudoranges;

(2) determining a vehicle path model using the best fit algorithm as a function of the prior position estimates;

(3) extrapolating a second position estimate from said vehicle path model; and

(4) setting said first position estimate equal to said second position estimate if said second position estimate is more accurate.