Entry Guidance with Terminal Time Constraint Based on Reduced-Order Dynamics

An entry guidance method that considers the terminal time constraint has been developed for hypersonic glide vehicles. A key insight underpinning this method is that the flight time becomes fixed once the vehicle's longitudinal motion is established. Based on this, an altitude versus velocity profile that satisfies the time-To-go requirement is first generated in the longitudinal guidance. Then, the lateral guidance algorithm formulates a bank reversal logic based on the flight trajectory obtained by integrating reduced-order dynamics. With this logic, the vehicle can reach the desired terminal interface while implementing terminal time control by tracking the longitudinal profile. Simulations results reveal the effectiveness of the proposed scheme in managing the terminal time constraint while satisfying conventional entry requirements.