Nonlinear Gaussian filter algorithm enhancements for low-cost integrated navigation system

Attitude and heading reference system (AHRS) is a three dimensional measurement package including micro-inertial measurement units (MIMUs) and magnetic sensors. The parameter model for low cost tightly-coupled AHRS/INS is established due to the large drifts of micro inertial sensors, which are consist of micro gyros and micro accelerometers. Differing from the traditional extended Kalman filter (EKF) adopted in the integration system, the Gaussian Iterative EKF (IEKF) and Gaussian Quadratic EKF (QEKF) are introduced considering the achieved optimal estimates accuracy of nonlinear navigation system. In sequence, the measurement mode that fuses pseudorange-pseudorange rate-heading measurements is proposed and intensively illustrated. With these two improved filters being carried out under the same dynamic condition, the accuracy and kinematic performance are all enhanced as expected compared to the standard EKF, even if the accuracy of the micro sensors is modest.