Energy-based hybrid reentry guidance for hypersonic vehicles

An energy-based hybrid reentry methodology was developed for hypersonic vehicles. The three-degree-of-freedom reentry kinematic equations was conducted based on energy, and typical inequality constraints was converted to the constraints of bank-angle by using quasi-equilibrium glide condition (QEGC). Longitude guidance used a constant bank angle in initial descent, and segmented the standard trajectory in quasi-equilibrium glide phase since the range-to-go was monotonically decreased with energy, then used predictor-corrector online in every segment to reduce the calculating time. Lateral guidance designed a lateral reversal logic based on the crossrange corridor for crossrange varied almost linearly with energy between two bank reversals. The simulation results show that the proposed algorithm has the obvious decrease of calculating time, high guidance precision and is not sensitive to initial errors and disturbers.