Abstract: The ballistic missiles are easily intercepted by the missile defense systems due to the absence of maneuverability in exo-atomosphere. It is important to design an effective guidance law to improve the success penetration rate of ballistic missile. An active defense nonsingular terminal sliding mode cooperative guidance law is presented. In ballistic missile active defense scenarios, one or more defending missiles, named defenders, accompany the ballistic missile to intercept the incoming interceptor missiles launched from the missile defense systems. The guidance process for the defenders is divided into two phases: Phase 1 and Phase 2. For Phase 1, a line of sight (LOS) based guidance law is designed, by which the defending missile positions itself on LOS between the ballistic missile and the interceptor missile. In this phase, the proposed guidance law can notably reduce the needed maneuverability of defending missile. To simplity the designing, the guidance law uses an approximate relative motion model, of which accuracy is acceptable in Phase 1. For Phase 2, a guidance law based on LOS angular velocity nullifying strategy is proposed. In this phase, the proposed guidance law uses more accurate relative motion models and avoids the increased errors induced by the approximate relative motion model in Phase 2. Simulation results show the high performance of the guidance laws.

Key words: control science and technology, guidance law, finite time convergence, nonsingular terminal sliding mode control, pulse width modulation