Abstract: Aiming at the attitude control problem of non affine hypersonic flight vehicles, a nonlinear control method based on backstepping is proposed. Firstly, the disturbance in the dynamics of angle of attack is estimated via a disturbance observer and the virtual control command of pitch rate is designed based on it. Then for the function describing the dynamics of pitch rate including non affine terms and uncertain parameters, consider it as an extended state and estimate it via a state observer. Next, the control laws of the elevons are designed based on the dynamic inversion method and the stability of the closed loop system is proved via the Lyapunov theory. A command filter is introduced to avoid the “explosion of complexity” problem in backstepping method and obtain the first and second derivatives of the virtual command. The proposed method is applicable when the flight vehicle flies at variable speed and height. Finally, the effectiveness of the proposed method is verified via comparative simulation experiments.

Key words: Hypersonic flight vehicle, Non affine; Attitude control, Backstepping, Extended state observer, Disturbance observer