Entry Trajectory Generation Using Reference Drag Acceleration and Range-based Parameter Design Method

This paper describes a new methodology for determining design parameters based on drag acceleration profile equations used in space shuttles during reentry. The original equations of reentry guidance include many unknown parameters, making trajectory design very complex. Thus, it is necessary to simplify design processes for successful practical implementation. Considering the shapes of feasible entry corridors, design parameters are distinguished from given parameters, and new design parameters are introduced to reduce their overall number. To determine new design parameters, we adopted the sensitivity of predicted ranges to design parameter changes, which can be used to sequentially update parameters, thereby reducing range error. The proposed algorithm is structured to prevent specific design parameters from violating trajectory constraints and deviating from feasible entry corridors. The proposed method could determine the design parameters that can satisfy a feasible entry corridor while minimizing range error. Moreover, numerical simulations were conducted for various target flight ranges to validate the performance of the proposed algorithm.