Reentry attitude control for a reusable launch vehicle with aeroservoelastic model using type‐2 adaptive fuzzy sliding mode control

Abstract

SummaryUsing 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.