After the analysis of each frequency space disturbing gravity vector results computed with point-mass model,building the subsection polynomial function fitting model to substitute point-mass model to compute trajectory disturbing gravity.

As the flying long-range ballistic missile can be affected by the earth s gravity field, and the space disturbing gravity can affect it s guidance and control accuracy, the trajectory disturbing gravity need to be real-time calculated to correct the inertia guidance system and actual trajectory.

Approximation of the Disturbing Gravity of the Active Phase of Ballistic Missile;

A study on polynomial fitting of computing space disturbing gravity with point-mass model;

Simulation experiment of quickly determination of disturbing gravity using wide-area polynomial approximation

So it is necessary to calculate gravity anomaly real-time on the missile.

The characters of several current calculation methods of disturbing gravitation are compared and the spherical harmonics function to calculate the disturbing gravitation is adopted.

Since the iterative calculation of the traditional spherical harmonic model for solution of the disturbing gravitation problem cannot be avoided,an increase in orders of model will result on a decrease in the speed of calculation.

With the improvement of ballistic missile system technology,the tool error affecting missile hitting accuracy has been reduced and disturbing gravitation has been a main factor.