Abstract
With the development of high-precision inertial navigation systems, the deflection of vertical (DOV), gravity disturbance, is still one of the main error sources that restrict navigation accuracy. For the DOV compensation of the Strapdown Inertial Navigation System (SINS) problem, the influences of the calculation degree of the spherical harmonic coefficient and the calculation error of the DOV on the compensation effect were studied. Based on the SINS error model, the error propagation characteristics of the DOV in SINS were analyzed. In addition, the high-precision global gravity field spherical harmonic model EIGEN-6C4 was established and the influence comparative analysis of the calculation degree of the spherical harmonic coefficient on the DOV compensation of SINS in different regions was carried out. Besides, the influence of the calculation error of the DOV on the compensation was emphatically analyzed. Finally, the vehicle experiment verified the feasibility of compensation in SINS based on the gravity field spherical harmonic model. The simulation and experiment results show that it is necessary to consider the influence of the calculation degree and the calculation error of the DOV on the compensation for long-time high-precision SINS with the position accuracy of 0.3 nm/h, while the SINS with general requirements for position accuracy can ignore the impact.
Highlights
Inertial navigation system (INS) is the position reckoning system that uses its inertial measurement units (IMU) to calculate the attitude, speed, and position information of the carrier [1]
In order to facilitate the navigation calculation, the normal gravity field defined in the reference ellipsoid is typically used instead of the global true gravity field for navigation calculation. at definitely ignores the difference between the normal gravity vector and the true gravity vector, which is the gravity disturbance vector [2, 3]
E deflection of vertical refers to the difference between the vertical line of the geoid and the normal line of the reference ellipsoid, that is, the deviation of the true gravity vector from the normal gravity vector [5]. e horizontal component of the deflection of vertical (DOV) directly determines the magnitude of the horizontal gravity disturbance
Summary
Inertial navigation system (INS) is the position reckoning system that uses its inertial measurement units (IMU) to calculate the attitude, speed, and position information of the carrier [1]. Starting from the SINS error model and combining the EIGEN-6C4 ultra-high-precision gravity field spherical harmonic model, this paper analyzes the compensation effect of the DOV calculated by the spherical harmonic model of different degrees.
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