On-board three-dimensional trajectory planning for reentry vehicle

Abstract

To design the flight trajectory on line for reentry vehicles, an on board trajectory planning method is proposed. Based the improved quasi-equilibrium glide condition (IQEGC), the concept of slope rate is presented, which indicates the flight path angle rate of the vehicle. Longitudinal trajectories with different flight range can be planned by changing slope rate. In order to increase the flight range variety scope, the bank angle is introduced in this new method. A much larger range covering area can be obtained by planning the slope rate and the bank angle. The maximum range has a fixed relationship with the slope rate, bank angle, initial heading error and the flight time. At the beginning, a data table was created by planning several trajectories under different conditions off line. Once a new target location is given, the corresponding range and line of sight (LOS) of the target can be calculated, and then the slope, bank angle, heading error, and flight time can be obtained by interpolating the data table using the range and LOS as inputs. A completed three dimensional trajectory can be quickly determined by the slope, bank angle, heading error and flight time. Simulation demonstrates that planning a trajectory with real flight time 2000s takes only 0.3s using this method. The flight trajectory planning efficiency is improved remarkably.