Analytical Entry Guidance with Waypoint Constraints

In this paper, an entry guidance with waypoint constraints is proposed for a hypersonic glide vehicle based on approximate analytical trajectory solutions. The analytical solutions consist of zeroth- and first-order solutions, which can predict downrange, crossrange and generalized heading angle for a hypersonic glide trajectory. First, the desired mechanical energies of the vehicle at the waypoints are specified reasonably using the zeroth-order downrange solution. Then, the vehicle performs proper bank reversals to control lateral maneuvers in order to pass through all the waypoints. Thus, how to plan the bank reversal sequence is crucial. In order to pass through the next waypoint, the analytical downrange solution is used to plan the profile of the longitudinal lift-to-drag ratio, and the analytical crossrange solution is used to plan the sequence of bank reversals. When the vehicle is close enough to the waypoint, a proportional navigation method is utilized to ensure the arrival of the waypoint. The performance of the proposed guidance method is verified by conducting various trajectory simulations.