SYSTEM AND METHOD FOR VITALLY DETERMINING POSITION AND POSITION UNCERTAINTY OF A RAILROAD VEHICLE EMPLOYING DIVERSE SENSORS INCLUDING A GLOBAL POSITIONING SYSTEM SENSOR

• US 20100312461A1
• Filed: 06/08/2009
• Published: 12/09/2010
• Est. Priority Date: 06/08/2009
• Status: Active Grant

• Current Assignee: Ansaldo STS SPA
• Original Assignee: Ansaldo STS SPA
• Inventors: Laurune, William R., HAYNIE, MICHAEL B.
• Granted Patent: US 8,296,065 B2
• Time in Patent Office: Days
• US Class Current: 701/117
• CPC Class Codes: B61L 2205/04 Satellite based navigation systems, e.g. global positioning system [GPS]
• 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

A system vitally determines a position of a train. The system includes a plurality of diverse sensors, such as tachometers and accelerometers, structured to repetitively sense at least change in position and acceleration of the train, a global positioning system sensor, which is diverse from each of the diverse sensors, structured to repetitively sense position of the train, and a track map including a plurality of track segments which may be occupied by the train. A processor cooperates with the diverse sensors, the global positioning system sensor and the track map. The processor includes a routine structured to provide measurement uncertainty for each of the diverse sensors and the global positioning system sensor. The routine cross-checks measurements for the diverse sensors, and cross-checks the global positioning system sensor against the track map. The routine provides the vitally determined position of the train and the uncertainty of the vitally determined position.

Claims

1. A system for vitally determining position of a railroad vehicle, said system comprising:

a plurality of diverse sensors structured to repetitively sense at least change in position and acceleration of said railroad vehicle;

a global positioning system sensor, which is diverse from each of said diverse sensors, structured to repetitively sense position of said railroad vehicle;

a track map including a plurality of track segments which may be occupied by said railroad vehicle; and

a processor cooperating with said diverse sensors, said global positioning system sensor and said track map, said processor comprising a routine structured to provide measurement uncertainty for each of said diverse sensors and said global positioning system sensor, to cross-check measurements for each of said diverse sensors, to cross-check said global positioning system sensor against said track map, and to provide the vitally determined position of said railroad vehicle and the uncertainty of said vitally determined position.

2. The system of claim 1 wherein the vitally determined position of said railroad vehicle is structured to be used by an automatic train protection function or an automatic train operation function.

3. The system of claim 1 wherein said processor includes a display structured to display the vitally determined position of said railroad vehicle.

4. The system of claim 1 wherein the uncertainty of said vitally-determined position corresponds to the probability of a hazardous event resulting from a failure of said system being less than about 10⁻

9/hour.

5. The system of claim 1 wherein said global positioning system sensor includes a position coordinate and a position uncertainty value;

and wherein said routine is structured to cross-check said global positioning system sensor against said track map by projecting the position coordinate onto one of the track segments of said track map along a line perpendicular to said one of said track segments and determining if the distance from said position coordinate to said one of said track segments along said line is less than a predetermined value times said position uncertainty value.

6. The system of claim 1 wherein said cross-check for each of said diverse sensors includes a cross-check against an independent measurement of another one of said diverse sensors or a cross-check against an independent calculation based upon another one of said diverse sensors or said global positioning system sensor.

7. The system of claim 6 wherein said global positioning system sensor outputs a position;

wherein said independent calculation outputs a vitally determined velocity and a vitally determined acceleration;

wherein said routine includes a navigational state change calculation inputting the position from said global positioning system sensor, said vitally determined velocity and said vitally determined acceleration, and outputting a position; and

wherein one of said cross-checks is a cross-check of the position of said global positioning system sensor against the position of said navigational state change calculation.

8. The system of claim 7 wherein said cross-check of said global positioning system sensor against said navigational state change calculation provides a good quality value corresponding to the position of said global positioning system sensor when the position of said global positioning system sensor is consistent with the position output by said navigational state change calculation for at least three consecutive samples of the position of said global positioning system sensor.

9. The system of claim 6 wherein one of said diverse sensors is a tachometer including an output having a position;

wherein said independent calculation outputs a vitally determined velocity and a vitally determined acceleration;

wherein said routine includes a navigational state change calculation inputting the position from said tachometer, said vitally determined velocity and said vitally determined acceleration, and outputting a position; and

wherein one of said cross-checks is a cross-check of the position of the output of said tachometer against and the position output by said navigational state change calculation.

10. The system of claim 9 wherein said cross-check of said tachometer against said navigational state change calculation provides a good quality value when the position indicated by the output of said tachometer is consistent with the position output by said navigational state change calculation.

11. The system of claim 6 wherein two of said diverse sensors are tachometers each of which includes an output having a position;

wherein one of said diverse sensors is an accelerometer including an acceleration;

wherein said routine is structured to determine a velocity corresponding to the position of the output of each of said tachometers, and a velocity corresponding to the acceleration of said accelerometer; and

wherein one of said cross-checks is a cross-check of the velocity corresponding to the position of the output of each of said tachometers against the velocity corresponding to the acceleration of said accelerometer.

12. The system of claim 11 wherein said routine is further structured to determine one of a good quality value and a bad quality value corresponding to the velocity corresponding to the position of the output of each of said tachometers and the velocity corresponding to the acceleration of said accelerometer, and an average velocity as a function of the average of the velocities corresponding to the good quality value for a plurality of:

(a) said tachometers, and (b) said accelerometer.

13. The system of claim 12 wherein said diverse sensors are further structured to repetitively sense velocity of said railroad vehicle;

wherein said diverse sensors include a Doppler radar having a velocity; and

wherein one of said cross-checks is a cross-check of the velocity corresponding to the position of the output of each of said tachometers against the velocity of said Doppler radar.

14. The system of claim 12 wherein said routine is further structured to determine a standard deviation corresponding to the velocity for each of said tachometers, a standard deviation corresponding to the velocity corresponding to the acceleration of said accelerometer, and a standard deviation corresponding to said average velocity.

15. The system of claim 6 wherein said diverse sensors include a plurality of tachometers and an inertial sensor;

wherein said routine is structured to determine a position, the measurement uncertainty and a quality corresponding to each of said tachometers, said inertial sensor and said global positioning system sensor;

wherein said quality is one of a good quality value and a bad quality value; and

wherein said routine is further structured to vitally determine said position as a function of the average of the positions corresponding to the good quality value of said tachometers, said inertial sensor and said global positioning system sensor.

16. The system of claim 15 wherein said routine is further structured to determine the uncertainty of said vitally determined position as a function of the measurement uncertainties corresponding to the good quality value of said tachometers, said inertial sensor and said global positioning system sensor.

17. The system of claim 15 wherein said vitally determined position includes a track segment and a position along said track segment;

and wherein said routine is further structured to determine a good quality value corresponding to said vitally determined position when said track segment is not null and when a plurality of said tachometers, said inertial sensor and said global positioning system sensor have said good quality value.

18. The system of claim 15 wherein said routine is further structured to reset the position corresponding to each of said tachometers to said vitally determined position when there is said good quality value corresponding to said vitally determined position, and, otherwise, to not reset the position corresponding to each of said tachometers.

19. The system of claim 15 wherein said routine is structured to determine a position, the measurement uncertainty and a sensor quality corresponding to each of said diverse sensors and said global positioning system sensor;

wherein the vitally determined position of said railroad vehicle corresponds to a position quality;

wherein each of said sensor quality and said position quality is one of a good quality value and a bad quality value; and

wherein said routine is further structured to reset the uncertainty of said vitally determined position to the measurement uncertainty corresponding to said global positioning system sensor if both of said position quality and the quality of said global positioning system sensor have the good quality value, and, otherwise, to increase the uncertainty of said vitally determined position with movement of said railroad vehicle.

20. The system of claim 1 wherein said diverse sensors are further structured to repetitively sense velocity of said railroad vehicle;

and wherein said diverse sensors comprise at least three of;

two tachometers structured to measure position, a Doppler radar structured to measure velocity, and an accelerometer structured to measure acceleration.

21. The system of claim 1 wherein said vitally determined position of said railroad vehicle is structured to be used in a guide-way position system without sensors attached to said guide-way.

22. The system of claim 1 wherein said global positioning system sensor is the only direct measurement of location in the system.

23. A method of vitally determining a position of a railroad vehicle, said method comprising:

employing a plurality of diverse sensors to repetitively sense at least change in position and acceleration of said railroad vehicle;

employing a global positioning system sensor, which is diverse from each of said diverse sensors, to repetitively sense position of said railroad vehicle;

employing a track map including a plurality of track segments which may be occupied by said railroad vehicle;

providing measurement uncertainty for each of said diverse sensors and said global positioning system sensor;

cross-checking measurements for each of said diverse sensors;

cross-checking said global positioning system sensor against said track map; and

providing the vitally determined position of said railroad vehicle and the uncertainty of said vitally determined position from the sensed at least change in position and acceleration of said railroad vehicle from said diverse sensors and from the sensed position of said railroad vehicle from said global positioning system sensor.