Attitude optimization control of hypersonic flight vehicle considering partially unknown control direction

In this paper, a control method based on periodic sliding mode technology and adaptive dynamic programming algorithm is proposed for the attitude dynamics of hypersonic flight vehicle. The method takes into account a case that there is unknown control direction in a single channel. First, under the premise that the disturbance observers estimate the coupling and other disturbances, the attitude dynamics are decomposed into mathematical models of pitch channel and yaw-roll channel, respectively. Then, a periodic sliding mode control law with both stability and rapidity is designed for the unknown control direction in pitch channel. In the yaw-roll channel, an optimal attitude control law satisfying cost function is designed based on adaptive dynamic programming algorithm. What’s more, the closed-loop system is proved to be stable by Lyapunov stability theorem. Finally, the simulation results show that the attitude angle can track the command stably, which proves the effectiveness of the control scheme. Compared with the backstepping control scheme, the simulation results show that the proposed scheme can effectively avoid the divergence of the system because of the control direction switch, and the system have better dynamic performance and robustness.