Position and velocity estimation system for adaptive weighting of GPS and dead-reckoning information

A terrestrial vehicle position and velocity estimation system, comprising:

• input interface means for accepting raw global position system (GPS) pseudo range (PR) and pseudo range rate (PRR) measurement data, GPS position estimate data, and GPS velocity estimate data from a GPS navigation receiver mounted to a terrestrial vehicle;
• first computational means for mathematically modeling an error effect on said raw measurement data, position estimate data, and velocity estimate data due to periods of selective availability (SA) wherein range errors are deliberately introduced into GPS satellite transmission data to reduce the position accuracy of unauthorized GPS users;
• second computational means for mathematically modeling a heading scale factor error effect on an accumulated heading error of a dead-reckoning turning rate sensor connected to said terrestrial vehicle;
• third computational means for mathematically modeling an odometer scale factor error effect of a dead-reckoning odometer sensor connected to said terrestrial vehicle;
• Kalman filter means connected to a respective output of each of the first through third computational means for blending data output from each of the first through third computational means and to produce and output an estimate of a heading error and the odometer scale factor error from at least one of said raw GPS PRR measurements and said GPS velocity estimate data;
• and
• computer means connected to the Kalman filter means for computing a position and a velocity of said terrestrial vehicle from data obtained from said dead-reckoning turning-rate sensor and said dead-reckoning odometer sensor as individually corrected and weighted in the Kalman filter means for respective scale factor errors by partial PR and PRR measurement data periodically obtained from said GPS navigation receiver.