Reentry glide analytical guidance considering time constraints

A time controllable entry guidance method is proposed based on analytical design of drag-energy profile, online adaptive analytical update, and robust tracking algorithm. Firstly, a multi-segment smooth drag-energy standard profile based on corridor boundary dual parameter interpolation is designed, and multiple constraints including terminal flight path angle are applied. Then, the analytical predictive formulas for time and range to-go considering the influence of earth rotation are derived, and high-precision analytical design of the standard profile is completed by correcting the double parameters of the profile. Subsequently, a drag-energy profile online adaptive update strategy based on dual/single parameter sequential solution mode is designed, which can adaptively switch between two profile update algorithms based on real-time situation, and complete analytical update of the remaining profile adaptively, satisfying the constraints of terminal energy, flight path angle, range and flight time. On this basis, a standard profile tracking algorithm and time controllable entry analytical guidance algorithm framework are designed, achieving online rapid generation of guidance commands. Finally, using CAV-H entry glide as an example, simulation is conducted to verify the effectiveness, computational efficiency, and multi-task applicability of the proposed method. Compared with current methods based on analytical predictor-corrector guidance, the proposed method has higher time, range and terminal states control accuracy. Compared with existing methods based on standard profile, the proposed method has higher computational efficiency and larger adjustable time range.