Variable structure based nonlinear missile guidance and autopilot design for a direct hit with thrust vector control

In this paper, we propose a variable structure based nonlinear missile guidance and autopilot systems for a direct hit with thrust vector control and divert control system inputs for the interception of a ballistic missile. The aim of the present work is to achieve the bounded target interception of the missile such that the distance between the missile and the target is close enough to trigger the missile's explosion. First, a 3 degree-of-freedom (DOF) sliding mode missile guidance law under considering external disturbances and zero-effort-miss (ZEM) are designed to minimize the distance between the missile and the target for the translation motion. Then, we proposed a quaternion-based sliding-mode attitude controller to track the attitude command and to cope with the effects from variations of missile's inertia, aerodynamic force and wind gusts. The exponentially stability of the overall system is analyzed thoroughly via Lyapunov stability theory before entering ZEM phase. Extensive simulation results are conducted to validate the effectiveness of the proposed integrated guidance law and autopilot system by use of the 5-DOF inputs.