Error analysis in gravity aided navigation

For underwater vehicles, because GPS signals are not always available, it is necessary to use inertial navigation system (INS) for navigation. In order to improve the navigation performance, the gravity value calculated by the gravity field model is introduced into the navigation system to reduce the influence of gravity on the navigation accuracy. However, due to the difference between the actual gravity field and the gravity field model, the navigation error caused by gravity field still exists. In this paper, this error is studied based on the theoretical analysis and simulation. The results show that the accuracy of gravity-aided navigation will decrease sharply when the position error of the underwater vehicles reach 9.6 n miles, because at this moment, the calculation error of vertical deflection is the largest. In the simulation experiment, the position error of the gravity-aided navigation system reach 9.6 n miles in 44 hours. Therefore, for the underwater vehicles navigation system, it is recommended that the vehicles should be corrected once every 44 hours.