SURROGATE-ASSISTED HIERARCHICAL OPTIMIZATION METHOD FOR VARIABLE SWEEP FLIGHT VEHICLE TRAJECTORY

Morphing flight vehicles can adaptively change the configuration to achieve favorable aerodynamic performance for different flight conditions, which has attracted much attention in recent years. As the most crucial procedure, the trajectory design generally determines the morphing flight vehicle performance. To sufficiently improve the flight range, a surrogate-assisted hierarchical optimization method is developed for the variable sweep flight vehicle trajectory, which consists of inner and external optimization processes. In the inner optimization process, the trajectory is optimized by the pseudospectral method to maximize the flight range, where the angle of attack and sweep angle change rates are selected as the control variables. Compared with the fixed wing, the variable sweep wing can extend the total range by 6.79%. In the external optimization process, the boundary states of different trajectory phases (i.e., initial trajectory angle of each phase, terminal trajectory angle and velocity) are optimized to further increase the flight range. Considering the time-consuming inner optimization process, a Kriging surrogate-assisted differential evolution method is adopted to execute the external optimization efficiently and effectively. After the external optimization, the total range can be further increased by 15.86% compared with the initial morphing flight vehicle trajectory.