Abstract: Aiming at the problem that a reusable launch vehicle (RLV) may have airbrake failure during the terminal area energy management phase and cannot accurately control the speed, which may lead to a failure to reach the landing window steadily, an on-line RLV terminal area energy management algorithm considering the failure of the airbrake is proposed. Firstly, the motion model of the vehicle under the condition that the airbrake is stuck is established, and the influence on the vehicle motion is also analyzed. Secondly, the longitudinal nominal trajectory of the vehicle is designed based on the energy corridor method. In combination with the flight capability, a finite-time convergence trajectory tracking controller is designed to track the ground geometric trajectory. Then, the relationship between the dynamic pressure profile and the flight distance is deduced. The traditional four-parameter solution of the dynamic pressure profile is simplified to a single parameter update problem. An on-line modified dynamic pressure profile algorithm under the condition that the airbrake is stuck is proposed to avoid the iteration of the dynamic pressure profile. Finally, the simulation verification shows that the RLV can reach the autonomous landing window smoothly when the airbrake is faulty and with aerodynamic uncertainty, which is robust.

Key words: Airbrake failure, Energy corridor, Trajectory tracking controller, On-line dynamic pressure profile correction algorithm