可重复使用运载器自动着陆纵向制导律设计

Design of Longitudinal Guidance Law for Reusable Launch Vehicle Autolanding

在可复用运载器准确着陆控制问题的研究中,为实现可重复使用运载器(RLV)跟踪基准着陆轨迹以便安全地自动着陆,建立了以待飞航程为独立变量的无动力运动方程,利用线性二次调节器(LQR)方法设计了纵向制导律。纵向制导律以速度偏差、高度偏差和航迹倾斜角偏差作为输入,给出迎角指令和减速板偏角指令。针对基准情况、存在初始条件和气动参数不确定性的情况进行了仿真。仿真结果表明,设计的纵向制导律可行,能很好地消除初始条件和气动参数不确定性的影响,准确地跟踪基准着陆轨迹,具有很好的鲁棒性,并且着陆速度、着陆动压和下沉速率均满足着陆要求。

In order to make the reusable launch vehicle track the reference trajectory to land automatically safely, equations of motion using the range - to - go as the independent variable were derived. With the derived equations of motion, a longitudinal guidance law based on linear quadratic regulator（LQR） theory was then developed. Based on the developed guidance law, we used the deviations of velocity, height and flight - path angle as inputs and gives out the command of the angle of attack and the deflection of speed brake. Simulations were done in both reference condi- tion and conditions with initial deviations and aerodynamic uncertainties. The simulation results show that the longitu- dinal guidance law developed in this paper is effective and it can eliminate the impacts of initial deviations and aero- dynamic uncertainties. The reference trajectory is well tracked with good robustness and the requirements for landing velocity, landing dynamic pressure and sinking rate are met.