Guidance Law Design Of Terminal Area Energy Management For Reusable Launch Vehicle

With the increasing demand for space launch,reusable aircraft came into being.Reusable aircraft is favored by the world’s aerospace powers for its low launch cost,excellent reliability and safety.Throughout the whole flight process of reusable aircraft,the reentry stage is an important stage to ensure the safe return of aircraft from outer space,and the end area energy management stage in this stage is of unparalleled importance.It undertakes the important task of initial reentry and automatic landing of aircraft,and is the key to ensure the safe and accurate landing of aircraft.Therefore,the research on the energy management section of the terminal area has become a hot direction in the field of aerospace research.The research object of this paper is the trajectory design and guidance technology of the end area energy management section of reusable aircraft.Firstly,the aircraft model that needs to be studied is modeled,the required coordinate system and its transformation are given,the force of the aircraft is analyzed,and the kinematics and dynamics model of reusable aircraft is established;Secondly,the two-dimensional particle dynamic equation based on height is deduced,the trajectory of the energy management section at the end of the reusable aircraft is designed to maximize the flying range,and the simulation analysis is carried out to obtain the maximum lift drag ratio sliding trajectory and the changes of relevant parameters when the flying range is maximized,so as to provide support for the follow-up research;Then,two kinds of flight conditions that may be close to the maximum range control profile during quasi equilibrium gliding are studied: constant velocity quasi equilibrium gliding and constant dynamic pressure quasi equilibrium gliding;Finally,a guidance law based on linear quadratic regulator(LQR)to maintain the quasi balanced gliding state is given.The simulation verification and analysis of the given guidance law are carried out through the open-loop and closed-loop simulation of three trajectories,which shows that the LQR guidance law of constant dynamic pressure quasi balanced gliding has better effectiveness and rapidity.