Abstract: The normal gravity model of a hypersonic boost-glide vehicle in near space is studied in this paper with the aim of alleviating the influence of the gravity model error on the precision of the inertial navigation system (INS) during flight. First, a spherical harmonic model of the Earth’s gravitational field is introduced and the normal gravity of the Earth is derived from it. Then, the coordinate transformation needed for the application of the gravity model to the near-space navigation algorithm is formulated. Subsequently, the gravity disturbance in near space and the impact of J₂ and J₄ gravity truncation errors are analyzed. Finally, different normal gravity models and different precisions of inertial measurement unit (IMU) are exploited to simulate the near-space navigation algorithm. Based on this, the influence of the independent and combined effects caused by the interference factors is analyzed, and the applicable conditions of the normal gravity model are discussed.

用于高超声速助推滑翔飞行器惯性导航的正常重力模型

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