Research on SINS in application of reentry navigation for lifting reentry vehicles

Because of the black-out phenomenon and limited available navigation means in reentry phase for lifting reentry vehicles, the strapdown inertial navigation system (SINS) based on geocentric inertial coordinate system is employed and analyzed. Various Error sources of SINS are modeled to analyze the influence on navigation accuracy by means of covariance analysis. Then the importance degree of each error sources obtained is used to improve navigation accuracy. A second-order damping scheme is designed to restrain the SINS divergence in three channels by using the assisted altitude from outside during reentry phase. For the SINS with given specifications applied on a typical reentry trajectory, the simulation results via covariance analysis show that the initial attitude error has the greatest influence on navigation accuracy among certain typical error resources. The designed damping loop alleviates the divergence of SINS effectively. The effect depends on the designed damping coefficients.