Position and heading error-correction method and apparatus for vehicle navigation systems

A vehicular navigational system (2) is provided that compensates for temperature-dependent drift of bias in a vehicle heading sensor (6) associated with a dead reckoning vehicle positioning system (12). Specifically, a Kalman filter (38) generates a calibration curve for the rate of heading sensor bias drift with temperature change. The Kalman filter calculates coefficients for a model of heading sensor bias drift rate versus temperature at each point where the vehicle (4) is stationary. The bias drift rate calibration curve is then used to estimate a heading sensor bias periodically while the vehicle is moving. The navigational system further uses an aging time for temperature sensor bias drift rate to force convergence of the error variance matrix of the Kalman filter.