Train navigator with integral constrained GPS solution and track database compensation

• US 20060271291A1
• Filed: 05/03/2006
• Published: 11/30/2006
• Est. Priority Date: 05/04/2005
• 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.
• Granted Patent: US 7,610,152 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 25/025 Absolute localisation, e.g. providing geodetic coordinates

Abstract

The present invention provides a new set of algorithmic solutions to accommodate track inaccuracy information in track databases. Navigation and measurement aiding processes are defined by a stochastic mode relative to a moving rail frame defined so that it is aligned with the heading of the compensated track database at the current along track-position. Filtering generates long and short wavelength track alignment disturbances commensurate with track grade to compensate for track database errors; a stochastic error model is defined as the difference between the deterministic implementation and the actual stochastic processes Bayesian estimation of the error variables is implemented via a digital Kalman filter with the navigation, database, and measurement errors removed by subtracting the filter estimates.

Claims

1. A method for navigation in a system including railway track having a plurality of track irregularity classes with a quantitative value associated with each class and a railway vehicle for movement along the railway track having a navigation system for determining railway vehicle position along the railway track, the navigation system including inertial components for measuring heading and variations thereof and acceleration and variations thereof and a satellite responsive GPS for providing geo-positional data, comprising the steps of:

establishing an a-priori stochastic model of actual navigation errors and an a-priori stochastic model of a measurement aiding process;

effecting a Kalman type filtering of error variables to create estimated track database errors constrained by the track irregularity class; and

implementing substantially real-time feedback of estimated track database errors subsequently used for navigation upon the railway track.

2. The method of claim 1, wherein said second-mentioned step includes providing, as an input thereto, a satellite-based GPS measurement related to a current position of the railway vehicle on the railway track.

3. A method for rail track database compensation in a system including railway track having a plurality of track irregularity classes with a quantitative value associated with each class and a railway vehicle for movement along the railway track having a navigation system for determining railway vehicle position along the railway track, the navigation system including inertial components for measuring heading and variations thereof and acceleration and variations thereof and a satellite responsive GPS for providing geo-positional data, comprising the steps of:

establishing an a-priori stochastic model of actual navigation errors and an a-priori stochastic model of a measurement aiding process;

effecting a Kalman type filtering of error variables to create estimated track database errors constrained by the track irregularity class; and

implementing substantially real-time feedback of estimated track database errors subsequently used for navigation upon the railway track.

4. The method of claim 3, wherein said second-mentioned step includes providing, as an input thereto, a satellite-based GPS measurement related to a current position of the railway vehicle on the railway track.

6. The method of claim 4, wherein said second-mentioned step includes providing, as an input thereto, a satellite-based GPS measurement related to a current position of the railway vehicle on the railway track.

5. A method of simultaneous navigation and rail track database in a system including railway track having a plurality of track irregularity classes with a quantitative value associated with each class and a railway vehicle for movement along the railway track having a navigation system for determining railway vehicle position along the railway track, the navigation system including inertial components for measuring heading and variations thereof and acceleration and variations thereof and a satellite responsive GPS for providing geo-positional data, comprising the steps of:

establishing an a-priori stochastic model of actual navigation errors and an a-priori stochastic model of a measurement aiding process;

effecting a Kalman type filtering of error variables to create estimated track database errors constrained by the track irregularity class; and

implementing substantially real-time feedback of estimated track database errors subsequently used for navigation upon the railway track.