近地小推力转移轨道的加权组合制导策略

 研究了近地小推力转移轨道的制导问题，给出了一种基于局部最优控制律的自主制导算法。推导出了各改进春分点根数对应的局部最优控制律；通过最优推力分配和目标偏差两个策略，对各局部最优控制律进行动态加权组合，从而有效减少了制导律的设计参数。在此基础上，针对燃料最省转移轨道，定义了一种新的发动机开关函数。采用遗传/逐次二次规划混合优化算法计算了最优制导参数。与传统算法相比，该制导算法是一种闭环制导算法，能够实现飞行器的自主制导，并且制导过程中无需对制导参数进行更新。以地球低轨到高轨的小推力转移为例，采用该方法分别求解了时间和燃料最省转移问题，并与传统算法进行了比较分析。数值结果验证了该算法的有效性。

Guidance Scheme for Near-earth Low-thrust Orbit Transfers Using Blended Locally Optimal Laws

A simple autonomous guidance scheme is proposed for near-earth low-thrust orbit transfer problem, based on blending the locally optimal laws. First, the locally optimal control laws are derived for each modified equinoctial orbital element. Then, the locally optimal control laws are blended by taking considerations of the efficiency of any attempt to alter an orbital element and the deficits of each element from the final target value, so that only a few guidance parameters are required to be designed. Moreover, a new switch function is defined for solving the optimal fuel transfer problem. Finally, a hybrid optimization algorithm combining genetic algorithm with sequence quadratic programming is utilized to design the optimal guidance parameters. Different from classical methods, the proposed guidance algorithm is a closed-loop fashion, which can be easily implemented on board the spacecraft, and needs not to update the guidance parameters in the transfer process. Taking low-thrust transfer from LEO to HEO as an example, the minimum-time and fuel-optimal guidance problems are solved by the proposed algorithm, respectively. The effectiveness of the proposed algorithm is validated by comparing with the classical algorithms.