Design of Nonlinear Terminal Guidance/autopilot Controller for Missiles with Pulse Type Input Devices

This investigation addresses a nonlinear terminal guidance/autopilot controller with pulse-type control inputs for intercepting a theater ballistic missile in the exoatmospheric region. Appropriate initial conditions on the terminal phase are assumed to apply after the end of the midcourse operation. Accordingly, the terminal controller seeks to minimize the distance between the commanded missile and the target missile to ensure a hit-to-kill interception. In particular, a 3D terminal guidance law is initially developed to eliminate the so-called “sliding velocity,” thus, constraining the relative motion between the missile and the target along the line of sight. Sliding mode control is adopted to design stable pulse-type control systems. Then, a quaternion-based attitude controller is used to orient appropriately the commanded missile, taking into account the fact that the missile is a rigid body, to realize interceptability. The stability of the overall integrated terminal guidance/autopilot system is then analyzed thoroughly, based on Lyapunov stability theory. Finally, extensive simulations are conducted to verify the validity and effectiveness of the integrated controller with the pulse type inputs developed herein.