Study on a new algorithm for tracking ballistic missile in free flight phase

This paper presents an application of a new adaptive filtering algorithm based on a standard earth ellipsoid model in tracking ballistic missile in free flight phase. The traditional Extended Kalman Filtering algorithm (EKF) has defect in two aspects: 1) observation values applied in observation equation mainly include azimuth, pitch angle and radial distance (or radial velocity), without Doppler frequency; 2) Jacobi matrix of the system needs to be calculated, and high nonlinearization could result in degradation of calculation precision. In this paper, an algorithm used for tracking ballistic missile in free flight phase which is based on UKF observation equation with Doppler frequency is presented. The algorithm has been applied in hybrid coordinate system of the standard earth ellipsoid model (the earth is assumed as an ellipsoid planet). It has higher tracking precision compared with EKF algorithm. Monte Carlo simulation conducted to model ballistic missile in free flight phase by using MATLAB software justified the efficacy and the reasonableness of the new algorithm.