关键词: 可重复使用运载火箭, 垂直起飞垂直着陆, 动力减速段制导, 重力转弯解析解, 自适应启动

Abstract:

One of the key technologies of rocket vertical recovery is the guidance technology in the powered deceleration phase. The requirements and constraints in the powered deceleration phase for the guidance system in the return process are analyzed， and a powered deceleration guidance method based on the gravity-turn analytical solution with variable axial apparent acceleration is studied. Considering the existence of propellent consumption in the powered deceleration phase， the mass lost in the flight process of the rocket is expanded by the first-order Taylor expansion at the initial mass， and then the first-order gravity-turn analytical solution of the variable axial apparent acceleration is obtained， and the superiority of the analytical solution is verified by simulation. Using this analytical solution， an adaptive handover method based on the range to be flown is designed， which can better correct the range deviation of the landing point. Based on the analytical prediction， the angle of attack and sideslip angle are corrected by the deviation between the landing point prediction and the virtual target point feedback， so as to meet the constraints of range， shutdown point speed and shutdown point attitude at the same time. The simulation results show that the adaptive handover method has the advantages of reducing the angle of attack and improving the position correction capability during dynamic deceleration flight. The guidance method proposed can meet the terminal position and specific mechanical energy constraints as well as the constraint of the terminal angle of attack， causing only slight change in the heat flow in the aerodynamic deceleration section of different trajectories.

Key words: reusable launch vehicle, vertical takeoff vertical landing, guidance for powered deceleration phase, gravity-turn analytical solution, adaptive handover