Patent ID: 8825396

Claim:
A quasi tightly coupled aided INS (QTC AINS) comprising: a. an inertial navigator ( 21 ) mechanization providing an a priori INS position and attitude solution of the antenna ( 24 ), b. a loosely-coupled AINS with an AINS Kalman filter ( 20 ) that computes an IG position measurement and measurement model and thereby constructs INS-GNSS position measurements and provides an a priori position VCV matrix ( 23 ), c. a GNSS position engine ( 26 ) that computes a GNSS position fix solution, the GNSS position fix solution having an uncorrected component of a GNSS position error due to an insufficient number of satellites, the GNSS position fix solution using observables from a plurality of satellites provided by a GNSS receiver ( 22 , 25 ) the externally provided a priori antenna position and the a priori position VCV matrix, the GNSS position engine providing a GNSS antenna position and position variance to the AINS Kalman filter, the AINS Kalman filter providing updated IG-GNSS position measurement and measurement model components, d. an INS position seeding process in which the externally provided a priori antenna position to the GNSS position engine ( 26 ) is an antenna position computed from the INS position and attitude solution, e. an observable subspace constraint (OSC) process that i. computes an OSC matrix, having rows and having columns, that suppresses the uncorrected component of the GNSS position error in the GNSS position fix solution in the IG-GNSS position measurement constructed by the AINS Kalman filter, and ii. multiplies the OSC matrix and the IG position measurement and measurement model to suppress the uncorrected component of the GNSS position error in the IG position measurement and measurement model.