Research on Gravity Compensation Method based on Interpolated Gravity Grid Region

With the increase in the accuracy of inertial measurement unit (IMU), the error caused by gravity disturbance has become a key factor restricting the positioning accuracy of strapdown inertial navigation system (SINS). The paper analyses the equation of the gravity disturbance affecting the position accuracy under the static base, which illustrates the necessity of gravity compensation. The gravity grid area with high resolution is calculated by the Eigen-6C4 gravity model and it is refined to compensate by interpolation. Through simulation experiments of six cases, it is proved that the distribution of position error is periodic. Compared with the uncompensated case, the compensation method can greatly improve the positioning accuracy. Compared with the case without interpolation, the interpolation method can further improve the positioning accuracy by refining the gravity field. Among the four interpolation methods, the near-point interpolation method can achieve a smaller positioning error and a more stable error distribution, which provides a reference for the interpolation of the measured gravity field.