Research On Reentry Stage Control For Reusable Boost Vehicle

Reusable boost vehicle (RBV) is a type of new launch vehicle, which can effectively reduce space transportation costs and improve transport efficiency. Flight control system is an important part of a reusable booster vehicle, its performance will directly affect flight safety,determine the success of recovery. Flight segment of RBV includes: launch, flip attitude adjustment, reignite, unpowered reentry, sail flying and landing. During the unpowered reentry process, large maneuver of attack angle will generate to greater induced drag and lead to severe aerodynamic heating. How to design the vehicle, which meets the mission requirements without aggravating the burden of the aircraft thermal protection, becomes the difficulty of RBV research.In this paper, the scheme of vertical turnaround maneuver with the capability of the rocket engines re-ignition is chosed, focus on the research of reentry attitude control for RBV.During reentry process, the engines are shutting down. Firstly, nonlinear mathematical model of RBV is buildt based on the correlation theory. Then, the gain scheduling method based on the stable radius is proposed, and the principle of determining flight point is given. Afterwards,the two-stage control allocation scheme is designed on RBV with heterogeneous redundancy implementing agencies. In the first control allocation stages, the desired torques of rneumatic rudders and reaction control system (RCS) are calculated. In the second control allocation stages, manipulation torque for each actuator is got based on the outer point penalty function algorithm. Finally, the proposed gain scheduling method is used to choose the filght points and design the control law. Optimize the control parameters of PID controller at the filght points based on the genetic algorithms. Mach number and attack angle are chosen as the scheduling variables to design the gain scheduling nonlinear controller. Last, evaluate the control system by joint simulation of nonlinear mathematical model, control allocation module and gain scheduling module.