Estimation and compensation for gravity disturbance based on Kalman filtering in inertial navigation

The gravity disturbance in inertial navigation system is the difference between the actual gravity and normal gravity on the same point, which includes two parts: deviation of plumb line and gravity anomaly. With the increase of inertial components' precision, the gravity disturbance becomes one of the major influence factors for the precision of long-time and high-precision inertial navigation system. To compensate this gravity disturbance, we derived and established the inertial navigation error equations by taking into account the gravity anomaly. The propagation of the errors was analyzed, and the state equation considering gravity anomaly is designed based on Kalman filtering. The gravity anomaly of inertial navigation system is compensated by using the velocity difference between GPS and inertial navigation system as view measurement. The simulation is carried out for 2 h, which shows that the gravity anomaly can be correctly calculated by Kalman filtering, and after the compensation, the accuracy of velocity, attitude and position can be improved by about 0.3 m/s and 0.3′ and 150 m, respectively.