Heading and position error-correction method and apparatus for vehicle navigation systems

Claim 1

A vehicle navigational system having built-in error correction comprising: (a) a distance traveled sensor; (b) a heading sensor having a bias that drifts over time; (c) a dead reckoning system having a distance traveled sensor interface and a heading sensor interface, wherein the dead reckoning component receives distance-traveled data from the distance-traveled sensor and heading data from the heading sensor and generates a first set of vehicle position data and a first set of vehicle heading data; (d) a reference vehicle position system in direct communication with the dead reckoning component, wherein the reference vehicle position system generates a second set of vehicle heading data and a second set of vehicle position data to the dead reckoning system; (e) a first computational means for determining if the vehicle is stationary; (f) a second computational means for generating an updated heading sensor bias; (g) a third computational means for generating a heading sensor bias drift rate; (h) a fourth computational means for integrating the first set of vehicle heading data and the second set of vehicle heading data into an integrated vehicle heading; (i) a fifth computational means for integrating the first set of vehicle position data and the second set of vehicle position into an integrated vehicle heading; (j) a sixth computational means for calculating an integrated vehicle heading correction using the estimated bias drift rate to compensate for integrated vehicle heading errors induced by heading sensor bias drift and an integrated vehicle position correction using the first integrated vehicle heading correction to compensate for integrated vehicle position errors induced by heading sensor bias drift; and (k) a seventh computational means for calculating a corrected vehicle heading and position.

Claim 22

A method for correcting heading and position error induced by a sensor drift in a vehicle navigational system, comprising the steps of: (a) transmitting heading data from a heading sensor to a dead reckoning system having a memory and storing the heading data in a memory of the dead reckoning system; (b) transmitting distance traveled data from a distance-traveled sensor to the dead reckoning system and storing the distance traveled data in the memory of the dead reckoning system; (c) transmitting heading sensor bias data from the heading sensor to the dead reckoning system and storing the heading sensor bias data in the memory of the dead reckoning component; (d) transmitting reference position data from a satellite to the reference vehicle position system; (e) calculating a heading sensor bias drift rate using the data transmitted to the dead reckoning system and stored in the memory of the dead reckoning system; (f) estimating a vehicle heading using the heading data transmitted to the dead reckoning system and stored in the memory of the dead reckoning system; (g) estimating a vehicle position using the distance traveled data transmitted to the dead reckoning system and stored in the memory of the dead reckoning system and the estimated vehicle heading; (h) calculating an integrated vehicle heading using the estimated vehicle heading and the reference position data transmitted to the reference vehicle position system; (i) determining whether the integrated vehicle heading requires correction; (j) calculating an integrated vehicle position using the estimated vehicle position and the position data transmitted to the reference vehicle position system; (k) determining whether the integrated vehicle position requires correction; (l) calculating a heading correction using the calculated heading sensor bias drift rate; (m) calculating a position correction using the calculated heading correction; (n) correcting the vehicle heading using the calculated heading correction; and (o) correcting the vehicle position using the calculated position correction.

Claim 23

A method for correcting heading and position error induced by a sensor drift in a vehicle navigational system, comprising the steps of: (a) transmitting heading data from a heading sensor to a dead reckoning system having a memory and storing the heading data in a memory of the dead reckoning system; (b) transmitting distance traveled data from a distance-traveled sensor to the dead reckoning system and storing the distance traveled data in the memory of the dead reckoning system; (c) transmitting heading sensor bias data from the heading sensor to the dead reckoning system and storing the heading sensor bias data in the memory of the dead reckoning component; (d) transmitting reference position data from a satellite to the reference vehicle position system; (e) calculating a heading sensor bias drift rate using the data transmitted to the dead reckoning system and stored in the memory of the dead reckoning system; (f) estimating a vehicle heading using the heading data transmitted to the dead reckoning system and stored in the memory of the dead reckoning system; (g) estimating a vehicle position using the distance traveled data transmitted to the dead reckoning system and stored in the memory of the dead reckoning system and the estimated vehicle heading; (h) calculating an integrated vehicle heading using the estimated vehicle heading and the reference position data transmitted to the reference vehicle position system; (i) determining whether the integrated vehicle heading requires correction; (j) calculating an integrated vehicle position using the estimated vehicle position and the position data transmitted to the reference vehicle position system; (k) determining whether the integrated vehicle position requires correction; (l) calculating a heading correction using the calculated heading sensor bias drift rate; (m) calculating a position correction using the calculated heading correction; (n) correcting the vehicle heading using the calculated heading correction; and (o) correcting the vehicle position using the calculated position correction.