EXTENDED DEAD RECKONING ACCURACY

Methods, systems, computer-readable media, and apparatuses for vehicular navigation are presented. Some configurations include computing a first attitude of a vehicle with respect to a reference frame at a first epoch; based on measurement data from an inertial navigation system (INS) of the vehicle, computing an attitude of the INS at a second epoch that is subsequent to the first epoch; based on the computed attitude of the INS and the computed first attitude of the vehicle, computing a second attitude of the vehicle at the second epoch; applying a constraint to the computed second attitude of the vehicle to produce an updated second attitude of the vehicle; and based on the updated second attitude of the vehicle, computing an updated attitude of the INS. Applications relating to road vehicular (e.g., automobile) use are described.