Abstract：The integrated navigation system composed of strapdown inertial navigation system/celestial navigation system/global navigation satellite system(SINS/CNS/GNSS) can effectively improve the positioning accuracy of missile and other aircraft, which often use the launch point inertial coordinate system of launch time as the datum. Firstly, we deduce and establish a simple integrated navigation mathematical model of SINS/CNS/GNSS under the launch inertial coordinate system, and take the attitude quaternion error of the model as an estimation to avoid the conversion between the attitude error angle and the misalignment angle of the mathematical platform. Then, we analyze and reasonably simplify the magnitude of gravity error caused by positioning error, and an accurate measurement noise model is derived. Finally, we realize the effective integration of SINS/CNS/GNSS by using extended Kalman filter(EKF). Simulation results show that the proposed method is effective and beneficial to engineering implementation.
