Method and system for high-integrity vehicle localization and speed determination

1. A system for determining the location of a vehicle comprises:

an on-board computer;

a ground penetrating radar mounted on the vehicle and communicably connected to the on-board computer; and

a reflective landmark located at a known location along the path of the vehicle wherein the reflective landmark includes reflective elements arranged to encode data;

wherein at least one of the reflective elements is semi-transparent to the signal energy of the ground penetrating radar;

wherein the ground penetrating radar transmits signal energy and detects reflected signal energy reflected by the reflective landmark and communicates encoded data representative of the reflected signal energy to the on-board computer; and

wherein the on-board computer decodes the encoded data and thereby determines the location of the vehicle.

2. The system of claim 1 , wherein a sequence of reflective landmarks are located at known locations along the path of the vehicle.

3. The system of claim 1 , wherein the vehicle is a rail vehicle.

4. The system of claim 1 , wherein the ground penetrating radar is mounted on an underside of the vehicle.

5. The system of claim 1 , wherein the reflective landmark encodes a single bit of data.

6. The system of claim 1 , wherein the reflective landmark encodes multiple bits of data.

7. The system of claim 6 , wherein the reflective landmark is comprised of an array of reflective elements.

8. The system of claim 7 wherein the array of reflective elements is a two-dimensional array.

9. The system of claim 7 wherein the array of reflective elements is a three-dimensional array.

10. A method for determining the location of a vehicle, comprising:

placing reflective landmarks including an array of reflective elements in known locations along a vehicle's path, where the reflective elements are layered vertically and where the reflective elements of upper layers are made from a material that is semi-transparent to signal energy of a ground penetrating radar;

transmitting signal energy into ground along vehicle's path with a ground penetrating radar;

detecting reflected signal energy reflected by the reflective elements of the reflective landmarks using a ground penetrating radar;

communicating encoded data representative of the reflected signal energy to an on-board computer;

decoding the encoded data; and

processing the decoded data to determine the vehicle's location.

11. The method of claim 10 , further comprising placing a sequence of reflective landmarks at known locations along the path of the vehicle.

12. The method of claim 11 , further comprising processing a sequence of encoded data representative of the reflected energy from the sequence of reflective landmarks to determine the vehicle's location.

13. The method of claim 10 , further comprising processing encoding data from the signal energy reflected from the vertically layered reflective elements to determine the vehicle's location.

14. The method of claim 10 , wherein the ground penetrating radar detects signal energy reflected by layers of reflective elements.

15. The method of claim 10 , further processing the decoded data to determine vehicle speed.

16. The method of claim 10 , wherein the reflective landmark is comprised of a linear array of reflective elements.

17. The method of claim 10 wherein the array of reflective elements is a two-dimensional array.

18. The method of claim 10 wherein the array of reflective elements is a three-dimensional array.

19. The system of claim 1 where the reflective elements encode information in vertical columns of reflective elements.

20. The method of claim 10 wherein the reflective elements encode information in vertical columns of reflective elements.