Robust approximate optimal control for air-breathing hypersonic vehicle

This paper investigates the robust approximate optimal control problem for air-breathing hypersonic vehicle (AHV). By input-output linearzation and introducing auxiliary variables, the high-order nonlinear AHV dynamics are transformed to a second-order feedback decoupling model. Then a virtual command is designed by back-stepping strategy to guarantee the practical finite-time convergence of tracking error. In order to drive the AHV with uncertainties to follow the virtual command, a robust approximate optimal controller based on adaptive dynamic programming (ADP) is proposed. Different from the conventional robust method, both the robustness and the input cost are taken into consideration in the proposed controller, which can optimize the control actions and hence avoid the chattering. Besides, the proposed controller adopts a single critic network design instead of actor-critic structure, which ensures the stability of the system autonomously and simplifies the implementation procedure. The simulation results show the effectiveness of the proposed scheme.