基于协态估计的火箭动力下降邻近最优制导  

Neighboring Optimal Guidance for Rocket Powered Descent Based on Costate Estimation

作　　者：王远卓 张冉[1] 李惠峰[1] WANG Yuanzhuo;ZHANG Ran;LI Huifeng(School of Astronautics,Beihang University,Beijing 100191,China)

机构地区：[1]北京航空航天大学宇航学院,北京100191

出　　处：《宇航学报》2024年第5期741-752,共12页Journal of Astronautics

基　　金：国家自然科学基金(62103014)。

摘　　要：针对火箭动力下降需要满足精准软着陆的要求,提出一种基于协态估计的邻近最优制导方法。基于一阶最优必要条件,邻近最优制导方法通过在一条参考轨迹附近近似求解最优制导问题,得到闭环线性反馈制导方法。基于序列凸优化方法实现了参考轨迹的设计,由于箭载计算资源的限制以及信赖域约束的引入,在较少迭代次数下得到的参考轨迹协态并不满足一阶必要条件,导致邻近最优制导方法精度下降,因此提出了一种协态估计方法。首先,使用高斯伪谱方法对协态微分方程进行离散;然后,基于哈密尔顿函数为常数的特点,设计了新的、适应性强的性能指标;最后,基于极小值原理提出了协态估计算法。将上述方法应用到火箭动力下降仿真实例中,蒙特卡罗仿真结果表明,该方法在阻力系数偏差、推力加速度偏差和大气密度偏差下具有较好的制导精度与鲁棒性。Aiming at the requirement of accurate soft landing for rocket powered descent,a neighboring optimal guidance method is proposed based on costate estimation.According to the first order optimal necessary condition,a closed-loop linear feedback guidance method is obtained by solving the optimal guidance problem near the reference trajectory.The reference trajectory is designed using the sequential convex optimization method.Due to the limitation of computational resources and the introduction of trust region constraint,the costate obtained from the reference trajectory under fewer iterations does not satisfy the first order necessary condition,resulting in a decrease in the accuracy of the neighboring optimal guidance method.Therefore,a costate estimation method is proposed.At first,the costate differential equations are discretized by Gaussian pseudo-spectrum method.Then,based on the constant of Hamiltonian function,a new and well-adapted performance index is designed.Finally,a costate estimation algorithm is proposed based on minimum principle.The above method is applied to the simulation example of rocket powed descent,and the Monte Carlo simulation results show that the proposed method has good guidance accuracy and robustness under drag coefficient deviation,thrust acceleration deviation and atmospheric density deviation.

关 键 词：动力下降 邻近最优制导 参考轨迹 协态估计 蒙特卡罗 

分 类 号：V448.2[航空宇航科学与技术—飞行器设计]