Methods and apparatus for determining that a train has changed paths

• US 6,374,184 B1
• Filed: 06/01/2000
• Issued: 04/16/2002
• Est. Priority Date: 09/10/1999
• Status: Expired due to Fees

• Current Assignee: Ge-Harris Raliway Electronics LLC
• Original Assignee: Ge-Harris Raliway Electronics LLC
• Inventors: Zahm, Charles L., Matheson, William L.
• Primary Examiner(s): Zanelli, Michael J.
• Assistant Examiner(s): Gibson, Eric M
• Application Number:
  US09/585,184
• Time in Patent Office: 684 Days
• Field of Search: 701/213, 701/200, 701/205, 701/207, 701/216, 701/217, 701/208, 701/214
• US Class Current: 701/213
• CPC Class Codes: B61L 2205/04 Satellite based navigation systems, e.g. global positioning system [GPS]
• CPC Class Codes: B61L 25/023 Determination of driving direction of vehicle or train
• 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
• CPC Class Codes: G01S 19/45 by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement

Abstract

A path determination device is configured to receive measured heading and distance information; determine heading corrections, distance corrections, and residuals utilizing a Kalman filter assuming a selected, known path was taken; and to determine a probability that the selected, known path actually was taken utilizing the determined residuals. The additional information utilized by the Kalman filters provides a more robust measurement indication of whether a particular path is taken than mere measurements and correlations of path curvature.

Claims

1. A path determination device configured to:

receive measured heading and distance information;

determine heading corrections, distance corrections, and residuals utilizing a signal assuming a selected, known path was taken; and

determine a probability that the selected, known path actually was taken utilizing the determined residuals.

2. A device in accordance with claim 1 further configured to receive measured satellite positions and pseudorange information, determine satellite position and pseudorange corrections utilizing a processor, and utilize the satellite position and pseudorange measurements in conjunction with the measured heading and distance information to determine the residuals.

3. A device in accordance with claim 1 configured to determine heading corrections, distance corrections, and residuals for at least two different selected known paths from the same heading and distance information.

4. A device in accordance with claim 1 configured to determine heading corrections, distance corrections, and residuals utilizing a filter assuming a selected, known path was taken.

5. A device in accordance with claim 4 wherein said filter is a Kalman filter.

6. A device in accordance with claim 1 configured to determine a most probable path using p₁(t)=prob{path 1 is true|z(t_i)=z_i} where z_i is the measurement vector, i.e., z_i=[Δ

ψ

](t_i), and Δ

ψ

is the heading error.

7. A device in accordance with claim 6 further configured to use a global position satellite receiver to determine a path most probable to have been taken, where $p_j$

(ti)=p

(zi|path

 



1,zi-1)

pj

(ti-1)p

(zi|path

 



1,zi-1)

p1

(ti-1)+p

(zi|path

 



2,zi-1)

p2

(ti-1),j=1,2$\mathrm{and}$$p<br><br>\left(z_i|\mathrm{path}<br><br>\text{\hspace{1em}<br><br>}<br><br>1<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{is}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{true},z_{i-1}\right)=\frac{1}{{{\left(2<br><br>\mathrm{\pi <br><br>}\right)}^{n/2}<br><br>\left[\det <br><br>\left(S_1<br><br>\left(t_i\right)\right)\right]}^{1/2}}<br><br>\exp <br><br>\left[-\frac{1}{2}<br><br>r_1^T<br><br>S_1^{-1}<br><br>\left(t_i\right)<br><br>r_1<br><br>\left(t_i\right)\right]$

where r₁ is a residual associated with a first path Kalman filter and

8. A device in accordance with claim 7 further configured so that p₁(t₀)=p₂(t₀)=½

at initialization.

9. A device in accordance with claim 1 further configured to determine probabilities p₁(t_i) and p₂(t_i) recursively as a vehicle moves down the path.

10. A device in accordance with claim 9 wherein said vehicle is at least one of a locomotive, automobile, boat, and airplane.

11. A method for determining a path taken after a turnout, said method comprising the steps of:

receiving measured heading and distance information;

determining heading corrections, distance corrections, and residuals; and

determining a probability that the selected, known path actually was taken utilizing the determined residuals.

12. A method in accordance with claim 11 wherein said step of determining heading corrections, distance corrections, and residuals further comprises the step of utilizing a filter assuming a selected, known path was taken.

13. A method in accordance with claim 12 further comprising the steps of:

receiving measured satellite positions and pseudorange information;

determining satellite position and pseudorange corrections utilizing the filter; and

utilizing the satellite position and pseudorange measurements in conjunction with the measured heading and distance information to determine the residuals.

14. A method in accordance with claim 11 further comprising the step of determining heading corrections, distance corrections, and residuals for two different selected known paths from the same heading and distance information.

15. A method in accordance with claim 11 further comprising the step of determining a most probable path using p₁(t)=prob{path 1 is true|z(t_i)=z_i} where z_i is the measurement vector, i.e., z_i=[Δ

ψ

](t_i), and Δ

ψ

is the heading error.

16. A method in accordance with claim 15 further comprising the step of using a GPS receiver to determine a most probable path, where $p_j$

(ti)=p

(zi|path

 



1,zi-1)

pj

(ti-1)p

(zi|path

 



1,zi-1)

p1

(ti-1)+p

(zi|path

 



2,zi-1)

p2

(ti-1),j=1,2$\mathrm{and}$$p<br><br>\left(z_i|\mathrm{path}<br><br>\text{\hspace{1em}<br><br>}<br><br>1<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{is}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{true},z_{i-1}\right)=\frac{1}{{{\left(2<br><br>\mathrm{\pi <br><br>}\right)}^{n/2}<br><br>\left[\det <br><br>\left(S_1<br><br>\left(t_i\right)\right)\right]}^{1/2}}<br><br>\exp <br><br>\left[-\frac{1}{2}<br><br>r_1^T<br><br>S_1^{-1}<br><br>\left(t_i\right)<br><br>r_1<br><br>\left(t_i\right)\right]$

where r₁ is a residual associated with a first path Kalman filter and

17. A method in accordance with claim 16 wherein said step of using a GPS receiver to determine a most probable path further comprises the step of configuring the GPS receiver such that p₁(t₀)=p₂(t₀)=½

at initialization.

18. A method in accordance with claim 11 further comprising the step of determining probabilities p₁(t_i) and p₂(t_i) recursively as the vehicle moves down the path.

19. A system for determining a path taken after a turnout, said system comprising:

a distance measuring device;

a heading measuring device;

a path database; and

a processor configured to access said path database, said processor further configured to determine a probability that a selected, known path actually was taken utilizing determined residuals.

20. A system according to claim 19 wherein said processor further configured to:

receive measured heading information from said heading measuring device;

receive measured distance information from a distance measuring device;

determine heading corrections, distance corrections, and residuals; and

determine a probability that a selected, known path actually was taken utilizing said determined residuals.

21. A system in accordance with claim 20 wherein said processor is further configured to assume a selected, known path was taken when determining heading corrections, distance corrections, and residuals.

22. A system in accordance with claim 21 wherein said processor further configured to:

receive measured satellite position and pseudorange information;

determine satellite position and pseudorange corrections utilizing a filter; and

utilize the measured satellite position and pseudorange measurements in conjunction with the measured heading and distance information to determine the residuals.

23. A system in accordance with claim 20 wherein said processor further configured to determine heading corrections, distance corrections, and residuals for two different selected known paths from the same heading and distance information.

24. A system in accordance with claim 20 wherein said processor further configured to determine a most probable path using p₁(t)=prob{path 1 is true|z(t_i)=z_i} where z_i is the measurement vector, i.e., z_i=[Δ

ψ

](t_i), and Δ

ψ

is the heading error.

25. A system in accordance with claim 24 further comprising a GPS receiver and wherein said processor further configured to use information from said GPS receiver to determine which path is most probable, where $p_j$

(ti)=p

(zi|path

 



1,zi-1)

pj

(ti-1)p

(zi|path

 



1,zi-1)

p1

(ti-1)+p

(zi|path

 



2,zi-1)

p2

(ti-1),j=1,2$\mathrm{and}$$p<br><br>\left(z_i|\mathrm{path}<br><br>\text{\hspace{1em}<br><br>}<br><br>1<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{is}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{true},z_{i-1}\right)=\frac{1}{{{\left(2<br><br>\mathrm{\pi <br><br>}\right)}^{n/2}<br><br>\left[\det <br><br>\left(S_1<br><br>\left(t_i\right)\right)\right]}^{1/2}}<br><br>\exp <br><br>\left[-\frac{1}{2}<br><br>r_1^T<br><br>S_1^{-1}<br><br>\left(t_i\right)<br><br>r_1<br><br>\left(t_i\right)\right]$

where r₁ is a residual associated with a first path Kalman filter and

26. A system in accordance with claim 25 wherein said GPS receiver further configured such that p₁(t₀)=p₂(t₀)=½

at initialization to determine which path is most probable.

27. A system in accordance with claim 19 wherein said processor further configured to determine probabilities p₁(t_i) and p₂(t_i) recursively as a vehicle moves down the path.