In this paper, the attitude control problem of reusable launch vehicles (RLVs) during reentry phase is investigated by using compound adaptive fuzzy H-infinity control (CAFHC) strategy in the presence of parameter uncertainties and external disturbances. Firstly, the control-oriented attitude model is established by a model transformation based on the six-degree-of-freedom(6-DoF) dynamic model of the RLV. Secondly, a novel attitude control scheme is developed and the control strategy consists of two parts to achieve a stable and accurate attitude tracking during reentry flight process. An attitude tracking controller is designed utilizing adaptive fuzzy H-infinity control approach combined with an identification model to improve the attitude tracking performance in the interior of fuzzy approximation region of attitude angle. Next, an attitude stabilization controller based on boundary adaptive technique is employed to assure the robustness of the closed-loop system in the exterior of fuzzy approximation region of attitude angle. Furthermore, the stability of the closed-loop system is guaranteed within the framework of Lyapunov theory and the attitude tracking error converges to a small neighborhood around origin. Finally, the simulation results are presented to demonstrate that the effectiveness of the proposed control scheme for reentry RLV, and its tracking performance performs better than the other control method.

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Summary Using a type‐2 adaptive fuzzy sliding mode control approach, a nonlinear reentry attitude control scheme is presented in this paper for a reusable launch vehicle (RLV) with aeroservoelastic model that assures reliable tracking of guidance commands. The mutual interactions between aerodynamics, structural dynamics, and the flight control system may lead to the aeroservoelasticity problem. Thus, based on the six‐degree‐of‐freedom geometry model of a RLV, the aeroservoelastic model is firstly established via hypothetical modal method and Galerkin method. Then, the overall attitude control strategy is carried out in two‐loop subsystem controller by using backstepping method. For each loop subsystem, a sliding mode controller is developed to assure tracking of guidance commands, and the interval type‐2 fuzzy logic systems combined with adaptive technique are employed to approximate the nonlinear parts to improve the reentry attitude tracking performance. Furthermore, the virtual control is introduced to the control strategy to attenuate the effect of control saltation. Theoretical analysis based on Lyapunov approach illustrates that the closed‐loop system under the designed control method is uniformly stable, and the attitude tracking error converges to a small neighborhood around origin. Finally, the six‐degree‐of‐freedom flight simulation results are provided to demonstrate the effectiveness of the proposed control scheme and aeroservoelastic characteristic of reentry RLV.

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