Research on time interval of gravity compensation for airborne INS

Determination of time interval when gravity compensation implements in inertial navigation system (INS) will improve the efficiency of compensation theory and avoid overshoot of navigation results. As an error corresponding to position, gravity disturbance propagation in INS is associated with regional gravity field, velocity and altitude of vehicle. In this contribution, position error function of INS combined with gravity disturbance is established and the critical magnitude causing position error more than 0.1nm/h is found for difference velocity of airborne vehicle. Further, gravity covariance models are used to conclude critical frequency that will cause higher error noise power introduced in navigation. The expression for time intervals of gravity compensation is then established considering velocity of vehicle and frequency of gravity disturbance. It is proved by simulations that the higher velocity need a shorter time interval of compensation, and for rugged gravity disturbance time interval of compensation is shorter than less active field.