Studying Of Gravity Compensation In Precision INS

Inertial Navigation System (INS) is a important navigation system with widely application in civil and military field. In INS, the acceleration sensed by the accelerometer include the carrier acceleration and the gravitational acceleration. So gravity compensation is necessary to separate the carrier acceleration and the gravitational acceleration. Historically, normal gravity was satisfactory for free inertial navigation for the poor inertial sensor. With the development of precise INS, Gravity error has become the main error in INS. To improve the accuracy of INS, a new gravity compensation method should be studied. It is significative to expand the application of INS.This paper introduces the theoretical foundation of INS and describes the navigation equations and error dynamics equations of INS in different frame (inertial frame, Earth-fixed-Earth-centered frame, local-level frame).Accordingly, the computer formulae of normal gravity in different frame are deduced. By using the EGM96 model and the simulated improved gravity model after GOCE mission for gravity compensation, the accuracy of INS is analysed respectively.At these base, the requirements to the resolution and the accuracy of gravity in the next precision INS with 5m/hr horizontal position error are analysed. Finally, a new gravity compensation method for precision INS is designed.