基于混合优化的运载器大气层内闭环制导方法

Closed-loop endo-atmospheric guidance of launch vehicle based on hybrid optimization approach

针对运载器大气层内最优闭环制导问题,研究了一种将求解最优控制问题的间接法与直接法相结合求解最优上升轨迹的轨迹在线规划与闭环制导方法。该方法采用高斯伪谱法求解基于间接法推导的最优上升轨迹两点边值问题,能以较少的离散节点获得较高的求解精度,并具有较高的求解效率。为了进一步保证制导的实时性与飞行安全要求,提出了轨迹在线规划与闭环制导策略。最优上升轨迹求解结果表明,在同等的求解精度条件下,混合优化算法的离散节点个数仅为间接法的25%-40%,计算效率提高了50倍左右。建立导航模型进行闭环制导蒙特卡洛打靶仿真,制导算法满足实时性与过程约束要求,关机点高度、速度、弹道倾角及轨道倾角的最大偏差分别为-8.93 m、-3.35 m/s、0.015°、0.0018°,算法具有较高的制导精度。

In view of the optimal atmospheric ascent closed-loop guidance of launch vehicles, an online trajectory planning and closed-loop guidance approach is studied by combining the direct method with the indirect one for solving optimal atmospheric ascent trajectory. In this approach, Gauss pseudo-spectral method is applied to solve the Hamiltonian two-point boundary value problem of optimal ascent trajectory, which is derived from the indirect method. The hybrid method can obtain high solution accuracy and fast convergence rate with minor nodes. A strategy of on-line trajectory planning is introduced to further guarantee the real-time and safety requirements. The navigation models are established to conduct Monte Carlo targeting simulation with closed-loop guidance. The solution results of optimal ascent trajectory show that, for the same level of solution accuracy, the hybrid algorithm＇s node number is 25%-40% of the indirect method＇s node number, and the computational efficiency is improved about 50 times. The simulation results show that the guidance algorithm meets the real-time and flight path constraint requirements with high guidance precision. The maximum deviations of altitude, velocity, flight path angle, and orbit inclination at engine cut-off point are-8.93 m,-3.35 m/s, 0.015°, and 0.0018°, respectively.