Robust Attitude Control of a Flexible Launch Vehicle Subjected to Wind Disturbances

Abstract

The attitude control and robust performance problems are herein investigated for a coupled 3DOF launch vehicle system that includes flexible modes and nonlinear actuators. Although atmospheric conditions like wind and the transonic flight are extreme, the robust control design is efficient even for an asymmetric time-varying plant updated at each iteration during 50 seconds of simulation. A two-degree-of-freedom topology known as Kreisselmeier's structure, in which a TFL/LTR compensator is inserted, adding robustness to the control loop, satisfies the time domain requirements. The present work focuses on the time response and the low-frequency specifications of the Brazilian VLS rocket.