Onboard Time-Coordination Entry Guidance Using Transformation of Frames

An onboard time-coordination entry guidance algorithm using transformation of frames is proposed for hypersonic glide vehicles. To deal with the contradiction between the flight time and range, the entry guidance scheme adopts the length of trajectories as the middle value between the longitudinal guidance and lateral guidance design. The longitudinal guidance algorithm is designed to satisfy the flight time constraint by solving the altitude-velocity profile, and the lateral trajectory design is represented by cubic curve smoothly. Since the lateral trajectories length changes with the altitude-velocity profile updates, the range is used to design the route as the constraint. The heading corridor is established by line-of-sight between the vehicle and the reference points on the lateral trajectory. To guarantee the uniqueness of the lateral trajectories, the transformation of frames between equatorial and planning frames is used to search the unique solution in lateral guidance. Numerical simulations are conducted to demonstrate the effectiveness of proposed scheme.