As a common integrated navigation system, the strapdown inertial navigation system (SINS)/global positioning system (GPS) can estimate velocity and position errors well. Many auxiliary attitude measurement systems can be used to improve the accuracy of attitude angle errors. In this paper, the in-flight alignment problem of the integrated SINS/GPS/Polarization/Geomagnetic navigation system is discussed. Firstly, the SINS/Geomagnetic subsystem is constructed to improve the estimation accuracy of horizontal attitude angles. Secondly, the polarization sensor is used to improve the estimation accuracy of heading angle. Then, a federal unscented Kalman filter (FUKF) with non-reset structure is applied to fuse the navigation data. Finally, simulation results for the integrated navigation system are provided based on experimental data. It can be shown that the proposed approach can improve not only the speed and position, but also the attitude error effectively.
SINS (Strap-down Inertial Navigation System) and GPS (Global positioning system) integrated navigation system has been extensively applied in many areas. In-flight alignment (IFA) is one of the key technologies. In this paper, an iterative unscented Kalman filter (IUKF) for SINS/GPS integrated navigation system is proposed to achieve IFA approach. Firstly, the nonlinear error equation of SINS is established, and the difference between the position and velocity of the two navigation systems is taken as the observation variables. Then, an IUKF is proposed to minimize the truncation error caused by Taylor expansion and reduce the influence of initial state value on the system state. Finally, simulation results can prove that the IUKF improves the navigation precision and robustness of system compared with the counterpart of UKF.
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