Full-stage Reentry Trajectory Optimization for Reusable Launch Vehicle

In this paper, full-stage reentry trajectory optimization for the reusable launch vehicle from 120km to ground is investigated. The full-stage trajectory is optimized stage by stage with the sufficient consideration of properties in different phases. The proposed trajectory optimization strategy solves the problem of state discontinuous at multi-segment trajectory switching points. For the initial reentry phase, a sequential convex programming with variable trust region method is developed to improve the convergence efficiency of the algorithm. For the terminal area energy management phase, a reference dynamic pressure profile is designed to solve the attack angle, while the bank angle is determined by tracking the ground trajectory. For the approach and landing phase, we proposed a method which can generate reference geometry based on quasi-equilibrium glide and exponential descent subphase, respectively. The secant line method is used to determine the height of the contact points and ensure the smooth transition between the two subphases. Finally, numerical simulations are provided to show the efficiency of the proposed method.