Calculation method for deflection of the vertical based on path gravity anomaly compensation

Abstract

To solve the inefficiency and complete autonomy issues for Deflection of the Vertical (DOV) determination in geomatics, navigation, and military weapon launching fields, a calculation method based on path compensation has been proposed. After conducting the discretization of the Vening-Meinesz formula in the spherical surface, a novel path gravity anomaly compensation based on the “remove-restore” algorithm was formulated to satisfy the requirement of regional high-precision gravity anomaly data. Meanwhile, utilizing the gravity field spherical harmonic model EIGEN-6c4, the deflection of the vertical was calculated using the Vening-Meinesz formula based on the “remove-restore” method, unlike the previous regional direct integral calculations. Finally, to verify the reliability and feasibility of the algorithm, the gravity measurement system, consisting of the high-precision gravimeter and Strapdown Inertial Navigation System, was constructed to conduct the simulation and shipborne experiments. The simulation and experiment results of the proposed method show that the root mean squares, relative to the real values, of DOV calculation components, are 0.89" and 1.67", while standard deviation values of the DOV components are the same within 2" in experiments, which satisfies the precision requirement of the DOV.

An autonomous and high-accuracy gravity disturbance compensation scheme for rotary inertial navigation system

“…The normal gravity derived from the model follows the normal direction of reference ellipsoid, and the magnitude of normal gravity can be solved analytically according to latitude and altitude [5,6]. However, in fact, due to the irregular topography and uneven mass distribution of the earth, there is inevitably a difference, also known as gravity disturbance, between the actual gravity and the normal gravity at any position [6][7][8]. Consequently, the gravity disturbance directly causes errors in the kinematic acceleration calculated by INS at each epoch and further generates cumulative navigation parameter errors such as the velocity, position and attitude.…”