Abstract
In recent years, the significant improvement of inertial navigation, leaves the gravity disturbance as the important factor which affects the accuracy of inertial navigation. This paper focus on the compensation for gravity disturbance with gravity spherical harmonic model, especially the optimal degree of gravity spherical harmonic model with which to calculate the gravity disturbance. The effect of gravity disturbance on inertial navigation is analysed based on the amplitude-frequency response characteristics of inertial navigation error differential equation, then the dominantly influential frequency band of gravity disturbance can be found which is the target of compensation. Combination the dominantly influential frequency band with the spatial resolution of the Earth’s gravity spherical harmonic model EGM2008 which is used to calculate the gravity disturbance, the optimal degree can be determined based on an algorithm proposed in this paper. Finally, shipborne inertial navigation experiment confirms the correctness and effectiveness of the proposed algorithm.
Highlights
Inertial navigation system (INS) is currently the main means of navigation which measures the vehicle’s motion and constantly updates position
To reduce the computation complexity and maintain the compensation accuracy, the interest lies in this paper is to find an optimal degree used in the calculation of Earth Gravitational Model 2008 (EGM2008) instead of the maximum degree 2190
The shipborne experiment instruments consists of a highprecision strapdown inertial navigation system (SINS) as shown in figure 4 and a Novatel® GPS receiver contained in the electric system of SINS
Summary
Inertial navigation system (INS) is currently the main means of navigation which measures the vehicle’s motion and constantly updates position. EGM2008 is publicly released by the U.S National Geospatial Intelligence Agency (NGA) EGM Development Team This gravitational model is a spherical harmonic model (SHM) and is complete to spherical harmonic degree and order 2159, and contains additional coefficients extension to degree 2190 and order 2519 and the full access to this model’s coefficients is provided in [3]. It is because EGM2008 has degree and order up to 2190 that the gravity disturbance can be precisely calculated with this model.
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