Sliding-mode-based contour-following controller for guidance and autopilot systems of launch vehicles

Abstract

This study addresses a sliding-mode-based contour-following controller design for guidance and autopilot systems of launch vehicles with highly maneuverable actuators, mainly consisting of the thrust vector control and side jet systems, to perform the trajectory-tracking task given a predetermined trajectory. In particular, the trajectory is pre-designed by the method of calculus of variations with focus on maximizing the final velocity transferring to the orbit to obtain the optimal trajectory for a launch vehicle throughout the whole course. Chiefly, an integrated guidance/autopilot controller is designed to achieve the main goal of robust tracking issues for launch vehicles in real time such that the relative motion between a vehicle and the predetermined trajectory is minimized. As for the attitude control, an autopilot system is designed not only to stabilize the attitude of the launch vehicle but also to realize the guidance law of the translational motion control. In order to establish a complete system model, besides the motion dynamics of launch vehicles, we also take into account several influential factors such as the propellant effort of a movable nozzle thrust vector control and side jet systems, aerodynamic influence, the Earth’s gravitational field, and wind gusts/shears. The overall stability of the integrated guidance/autopilot system is assured via rigorous analysis by Lyapunov stability theory, and its corresponding performance is verified by numerical simulations.