Patent ID: 7610152

Claim:
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 a database having at least a geometric track model contained therein, the navigation system also including inertial components for measuring heading and variations thereof and acceleration and variations thereof and a satellite responsive GPS for providing geopositional 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 for correcting the geometric track model contained in the database for subsequent use for navigation upon the railway track.