Abstract: The integrated navigation system model of missile system is often established under the launch inertial coordinate system, and the strapdown inertia/celestial navigation/satellite navigation (SINS/CNS/GNSS) is one of the most studied integrated modes. The state equation of the integrated navigation system is strongly nonlinear, and the common filtering method is extended Kalman filtering (EKF). In order to improve the precision and reliability of integrated navigation system, the UKF filter model of the integrated navigation system was designed, directly using the attitude, position and velocity parameters as part of the state, and the attitude and position provided by CNS and GNSS to form the measurement equation.The generation process of attitude sample points, mean value and variance was given. Simulation results show that, compared with EKF algorithm, UKF algorithm can improve the accuracy of navigation parameters by about 20%~30%, and that the realtime performance of the system can be guaranteed.

Key words: integrated navigation, launch inertial coordinate system, UKF algorithm, attitude estimation, sampling point calculation