Modeling and input-output decoupling of hypersonic vehicles

This paper studies the problems of modeling and input-output decoupling of generic hypersonic vehicles. Dynamical equations of hypersonic vehicles are derived using Lagrangian approach, which capture the dominating characteristics and primary interactions. Then, based on the simplified model, the original decoupling problem is reformulated as an asymptotical stability problem of the corresponding error system. The popular dynamic inversion is employed to design the decoupling controller, which can achieve steady-state decoupling. However, external disturbance will greatly destroy the effect of decoupling before the system reaches steady state. To this end, based on the error system, robust H_∞ theorem can be easily used to address this issue by reducing the impact of disturbance on error system outputs, which ultimately results in approximate decoupling. Moreover, the degree of approximate decoupling can be enhanced by choosing a small performance index γ. Simulations verify the effectiveness of proposed controllers.