Adaptive attitude controller of a reentry vehicles based on Back-stepping Dynamic inversion method

This paper presents an attitude control algorithm for a Reusable Launch Vehicle (RLV) with a low lift/drag ratio (L/D < 0.5), in the presence of external disturbances, model uncertainties, control output constraints and the thruster model. The main novelty of proposed control strategy is a new combination of the attitude control methods included backstepping, dynamic inversion and adaptive control methods which will be called Backstepping-Dynamic inversion-Adaptive (B.D.A) method. In the proposed method, a single control variable is considered as the bank angle, while the angle of the attack and the side slip angle will be stabilized in the inherent value. The purpose of this control is the attitude control of the vehicle to track the commanded bank angle and keep the vehicle in the desired trajectory. Lyapunove stability analysis of the closed loop system will be performed to guaranty the stability of the vehicle in the presence of the considered constraint. The control performance will be evaluated based on six degrees of Freedom (6DOF) model of the reentry capsule. Also the results of the proposed control algorithm will be compared with the Backstepping-Dynamic inversion (B.D) control method.