Locomotive location system and method

• US 20050065726A1
• Filed: 11/04/2004
• Published: 03/24/2005
• Est. Priority Date: 01/10/2002
• Status: Active Grant

• Current Assignee: Australian Rail Track Corp. Ltd. (Government of Australia)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Meyer, Thomas J., Metzger, Thomas R.
• Granted Patent: US 7,209,810 B2
• Time in Patent Office: Days
• 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 25/021 Measuring and recording of train speed
• 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: B61L 25/028 Determination of vehicle position and orientation within a train consist, e.g. serialisation

Abstract

A locomotive location system and method utilizes inertial measurement inputs, including orthogonal acceleration inputs and turn rate information, in combination with wheel-mounted tachometer information and GPS/DGPS position fixes to provide processed outputs indicative of track occupancy, position, direction of travel, velocity, etc. Various navigation solutions are combined together to provide the desired information outputs using an optimal estimator designed specifically for rail applications and subjected to motion constraints reflecting the physical motion limitations of a locomotive. The system utilizes geo-reconciliation to minimize errors and solutions that identify track occupancy when traveling through a turnout.

Claims

1. A location system for locating the position of a locomotive on a trackway comprising:

an inertial sensor system for sensing linear and rotary acceleration associated with the movement of a locomotive over a trackway, said intertial sensor system having a first plurality of rate-of-turn rotary acceleration sensors having respective first sensitive axes and a second plurality of rate-of-turn acceleration sensors having respective second sensitive axes, the first and second sensitive axes oppositely aligned;

a sensor for determining, either directly or indirectly, distanced traveled over the trackway;

a radio-frequency based geo-positional receiver for at least periodically determining a geo-positional value for the locomotive;

an optimal estimator for accepting information on a continuous or periodic basis from the inertial sensor system, the distanced traveled sensor, and the geo-positional receiver and establishing a first computational instance for determining locomotive location as a function of information from the inertial sensor system, the distanced traveled sensor, and the geo-positional receiver.

2. The locomotive location system of claim 1, further including a method of determining track occupancy upon passage by the locomotive through a turnout having a first and at least a second track leading therefrom, comprising the steps of:

establishing within said optimal estimator a first computational instance for the first track and a second computational instance for the second track using predetermined track parameters, each of the first and second computational instances computing location and corresponding estimated error states until one of the first and second computational instances exhibits pre-determined features in its estimated error states to indicate that the track for that instance is not the track occupied by the locomotive.

3. The locomotive location system of claim 2, further comprising the step of:

ceasing the computational instance that exhibit pre-determined features in its estimated error states indicating that track for that instance is not the track occupied by the locomotive.

4. The locomotive location system of claim 1, wherein said inertial sensor system provides X and Y acceleration values and a Z turn rate value.

5. The locomotive location system of claim 4, wherein said output of the inertial sensor system is subject to gravity model and/or sphereoid constraint correction.

6. The locomotive location system of claim 1, wherein said distance traveled sensor comprises a wheel tachometer.

7. A method of determining track occupancy of a locomotive after the locomotive has passed through a turnout onto either of a first or at least a second track, comprising the steps of:

inertially sensing linear acceleration and turn rate associated with the movement of a locomotive over a trackway, the sensing step including combining turn rate information from a first plurality of turn rate sensors having respective first sensitive axis and a second plurality of turn rate sensors having respective second sensitive axis aligned in opposite directions;

determining, either directly or indirectly, distanced traveled over the trackway;

establishing, in an optimal estimator, a first computational instance for the first track and a second computational instance for the second track using predetermine track parameters,

effecting the continued processing of each of the first and second computational instances computing at least the location of the locomotive and/or values related thereto by derivation or integration and the corresponding estimated error states until one of the first and second computational instances exhibits pre-determined features in its estimated error states indicating that the track for that instance is not the track occupied by the locomotive.

8. The method of claim 7, further comprising the step of:

ceasing the computational instance that exhibit pre-determined features in its estimated error states indicating that track for that instance is not the track occupied by the locomotive.

9. A locomotive location system for locating the position of a locomotive on a trackway comprising:

a strapdown inertial navigation system for providing at least linear and rotary acceleration associated with the movement of a locomotive over a trackway and at least a first integral thereof, said intertial sensor system having a first plurality of rate-of-turn rotary acceleration sensors having respective first sensitive axes and a second plurality of rate-of-turn acceleration sensors having respective second sensitive axes, the first and second sensitive axes oppositely aligned;

a sensor for determining, either directly or indirectly, distanced traveled along the trackway;

an optimal estimator for accepting information on a continuous or periodic basis from the strapdown inertial navigation system, the distanced traveled along the trackway sensor and establishing a first computational instance for determining locomotive location as a function of information from the strapdown inertial navigation system and the distanced traveled along the track sensor; and

a radio-frequency based geo-positional receiver for at least periodically determining a geo-positional value for the locomotive.

10. The locomotive location system of claim 9, further including a method of determining track occupancy upon passage by the locomotive through a turnout having at least a first and a second track leading therefrom, comprising the steps of:

determining a first computational instance for the first track and a second computational instance for the second track using predetermined track parameters, each of the first and second computational instances successively computing location and corresponding estimated error states until one of the first and second computational instances exhibits pre-determined features in its estimated error states indicating that track for that instance is not the track occupied by the locomotive.

11. The locomotive location system of claim 9, further comprising the step of:

halting the computational instance that exhibit pre-determined features in its estimated error states indicating that track for that instance is not the track occupied by the locomotive.