Method and system for determining the position of an object moving along a course

• US 7,769,538 B2
• Filed: 03/03/2005
• Issued: 08/03/2010
• Est. Priority Date: 03/05/2004
• Status: Expired due to Fees

• Current Assignee: Alstom Belgium SA (Alstom SA)
• Original Assignee: Alstom Belgium SA (Alstom SA)
• Inventors: Rousseau, Michel
• Primary Examiner(s): Beaulieu; Yonel
• Application Number:
  US10/591,851
• Publication Number:
  US 20070203640A1
• Time in Patent Office: 1,979 Days
• Field of Search: 701200-202, 701/207, 701213-215, 340/988, 342/357.06
• US Class Current: 701/207
• 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: B61L 25/026 Relative localisation, e.g. using odometer

Abstract

The position of an object moving along a course is determined by a relative measured position while its associated second confidence interval is smaller than a first confidence interval associated with an absolute measured position and is determined by the absolute position when the second confidence interval exceeds the first confidence interval.

Claims

1. A method for securely determining a position of an object moving along a known course, with respect to a distance run by the moving object, comprising steps of:

determining an absolute position of the object with a first confidence interval;

determining a relative position of the object with a second confidence interval;

selecting a smaller confidence interval among the first and second confidence intervals when the object is moving along the course, with respect to the distance run by the moving object;

determining the location and/or positioning of the object using the relative position while the second confidence interval is the smaller interval; and

determining the location and/or position of the object using the absolute position while the first confidence interval is the smaller confidence interval.

2. The method as recited in claim 1 wherein the object is a vehicle.

3. The method as recited in claim 2 wherein the vehicle is a train.

4. The method as recited in claim 1 wherein the step of determining the absolute position includes a railway-safe positioning method involving a digital mapping of possible trajectories and at least one satellite communication receiver.

5. The method as recited in claim 4 wherein the at least one satellite communication receiver is a GNSS receiver.

6. The method as recited in claim 1 wherein the step of determining a relative position includes detecting the presence of a beacon and integrating a speed of the object with reference to a location of the beacon.

7. The method as recited in claim 6 wherein the speed is calculated via a GNSS Doppler signal.

8. The method as recited in claim 1 wherein the first and second confidence intervals determine the position of the object with an error probability less than 10⁻

9.

9. The method as recited in claim 8 wherein the error probability is in the order of 10⁻

12.

10. The method as recited in claim 1 wherein the first confidence interval for the absolute position is in the order of 50 m.