Rapid generation of multi-target entry trajectory for hypersonic glide vehicles

An entry trajectory planning algorithm that generates multi-target trajectories satisfying path and terminal constraints is investigated in this paper. The entry trajectory is divided into the initial and glide phase, and a switch condition is used to ensure a smooth connection of these two phases. A nominal angle of attack is used in the whole trajectory and then the bank angle is the main control variable which is under design. In the initial phase, a constant bank angle is used to generate the trajectory to match a fix terminal height of transition condition. In the glide phase, a planner consists of the longitudinal and lateral sub-planner is developed based on the drag acceleration guidance logic. The drag acceleration profile is designed as a second order curve of velocity, its initial and terminal points are fixed and the middle value of the drag acceleration is calculated onboard according to the distance to go. The magnitude of the bank angle is solved from the longitudinal sub-planner, whereas the sign of the bank angle is determines by the lateral sub-planner. Then, a tracker is employed to follow the reference drag acceleration profile. The algorithm converts the highly constrained multi-target entry trajectory planning problem into a two parameters searching problem. Finally, the approach is tested using Common Aero Vehicle-H model, and the results demonstrate that the algorithm can generate multi-target entry trajectories rapidly while satisfying all the path and terminal constraints.