Method for secure determination of an object location, preferably a vehicle moving along a known course

• US 6,768,447 B2
• Filed: 12/20/2002
• Issued: 07/27/2004
• Est. Priority Date: 06/30/2000
• Status: Expired due to Term

• Current Assignee: Alstom Belgium SA (Alstom SA)
• Original Assignee: Alstom Belgium SA (Alstom SA)
• Inventors: Franckart, Jean-Pierre
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): MULL, FRED H
• Application Number:
  US10/327,583
• Publication Number:
  US 20030169203A1
• Time in Patent Office: 585 Days
• Field of Search: 342/357, 342/357.02, 342/357.08, 342/357.09, 342/357.12, 342/457, 342/455, 701/301, 701/213, 701/214
• US Class Current: 342/357.31
• CPC Class Codes: B61L 2205/04 Satellite based navigation systems, e.g. global positioning system [GPS]
• CPC Class Codes: B61L 25/021 Measuring and recording of train speed
• CPC Class Codes: B61L 25/025 Absolute localisation, e.g. providing geodetic coordinates
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks
• CPC Class Codes: G01S 5/02695 Constraining the position to lie on a curve or surface

Abstract

A device for determining the location or the position of an object moving along a known course includes equipment associated with the object. The equipment includes at least one central computer, at least one receiver/decoder of signals originating from one or more satellites, a radio interface and a database having a mapping of the course of the object. The device includes further central equipment including a central computer, one or more radio interfaces, a bus system, a database including the mapping of the course, an application for managing modifications of the mapping and at least one console, and moving-object/central-equipment and man/moving-object interface elements.

Claims

1. A method of determining the location or the position of an object moving along a known course comprising:

securely mapping said known course; and

performing an elementary measurement involving at least one satellite, wherein the elementary measurement comprises determining an individual domain along said course between two mileage points, said domain depending on a standard deviation of timing measurement errors of said elementary measurement, the speed of light, a coefficient linked with coordinates of said satellite and said course, and a weighting factor defining an error distribution for any measurement recording, so that a probability of non-presence of the object in said individual domain is predefined.

2. Method according to claim 1, wherein said secure mapping obtains two relationships with three unknown variables representing coordinates of said object whose location or position is to be ascertained, and wherein at least one other relationship between the three unknown variables is obtained with the aid of information transmitted by at least one satellite whose position is known.

3. Method according to claim 1, wherein the elementary measurement recording is redundant.

4. Method according to claim 3, wherein a plurality of individual domains are determined by a plurality of elementary measurement recordings carried out simultaneously, which are based on different satellites or on pairs of different satellites.

5. Method according to claim 4, further comprising increasing a number of satellites in order to record a plurality of elementary measurements simultaneously.

6. Method according to claim 5, further comprising determining an existence of a common domain, which is defined as an intersection of the various individual domains.

7. Method according to claim 6, further comprising rejecting individual domains which have no point in common with the common domain.

8. Method according to claim 7, further comprising, if there is a non-null common domain, determining a domain which is a union of non-rejected individual domains as the domain of possible presence.

9. Method according to claim 8, further comprising defining a probability of non-presence in the union domain as a product of the probabilities of non-presence in the known individual domains.

10. Method according to claim 9, wherein the individual domains defining the union domain depend on a parameter defining an error distribution which is greater than or equal to a parameter selected for determining the individual domains defining the common domain.

11. Method according to claim 1, wherein an elementary measurement is carried out with the aid of at least one pair of satellites using the same reference time.

12. Method according to claim 11, wherein the pair of satellites used for an elementary measurement belong to the same constellation.

13. Method according to claim 1, wherein an elementary measurement is carried out with the aid of at least one satellite belonging to a constellation and a receiver linked with the object moving along the known course, said receiver having a clock synchronized with a reference time of the constellation to which the satellite belongs.