Improving the performance of tightly-coupled GPS/INS navigation by using time-differenced GPS-carrier-phase measurements and low-cost MEMS IMU

Abstract

To avoid the difficulties in fixing the carrier phase ambiguities, the time difference carrier phase approach is applied to a GPS/IMU tightly-coupled navigation system to eliminate the ambiguity between two successive GPS epochs, which can provide high velocity estimation accuracy. The carrier phases are carefully corrected before use. A modified method is proposed by using the system matrix in each time update to calculate the integration of the velocity errors in the measurement update equation. A Cubature Kalman Filter (CKF) is applied to the integrated navigation system to improve the attitude estimation accuracy. The navigation result and comparison show the accuracy improvement after applying the carrier phase corrections, modified measurement update method and the CKF.