Thrust Vector Control of an Upper-Stage Rocket with Multiple Propellant Slosh Modes

The thrust vector control problem for an upper-stage rocket with propellant slosh dynamics is considered. The control inputs are defined by the gimbal deflection angle of a main engine and a pitchingmoment about the center of mass of the spacecraft. The rocket acceleration due to themain engine thrust is assumed to be large enough so that surface tension forces do not significantly affect the propellant motion duringmain engine burns. Amulti-mass-springmodel of the sloshing fuel is introduced to represent the prominent sloshingmodes. A nonlinear feedback controller is designed to control the translational velocity vector and the attitude of the spacecraft, while suppressing the sloshing modes. The effectiveness of the controller is illustrated through a simulation example.