针对扰动环境下火星精确着陆动力下降段自主轨迹规划问题，在终端时间自由条件下，研究了基于序列凸优化方法的自主轨迹规划方法。首先，在终端自由情况下，建立初始状态无扰动轨迹预规划问题。其次，结合鲁棒Tube-MPC思想，针对线性反馈控制律，建立扰动环境下着陆轨迹重规划问题，分析重规划问题的可行性，给出了预规划问题可行的必要性条件，为控制参数的选取提供参考，提出扰动环境下火星精确着陆自主轨迹规划框架。然后，针对终端自由问题，将飞行时域映射到单位时间，建立序列凸优化子问题，对子问题进行线性近似，使用序列凸优化方法进行求解并分析了收敛解的最优性。最后，进行数值仿真，验证扰动环境下火星精确着陆自主轨迹规划方法的有效性。
An autonomous trajectory planning method of Mars landing powered-descent in the disturbed environment is proposed based on the sequential convex programming method with the consideration of free terminal time. Firstly, considering the free terminal time, a trajectory planning problem without disturbance is established. Secondly, based on the robust Tube-MPC and the linear feedback control law, we establish a series of replanning problems of landing trajectory under the disturbed environment. The feasibility of the replanning problems is analyzed, and the necessary conditions for the feasibility of the preplanning problem are given to provide a reference for selection of control parameters. The autonomous trajectory planning framework for Mars precise landing under the disturbed environment is then proposed. Thirdly, considering the free terminal time, the flight time domain is mapped to the unit time, and a sub-problem of sequence optimization is established. The sub-problem is linearly approximated, and the sequential convex programming is employed to solve it. It is proved that the convergent solution of the approximation problem is a KKT solution of the original problem. Finally, numerical simulation is carried out to verify the effectiveness of the method.
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