空天飞行器末端能量管理段自主轨迹制导方法研究

The terminal area energy management (TAEM) flight phase is critical for a reusable spaceplane during horizontal landing. While traditional TAEM guidance methods show low precision and poor robustness as a consequence of decoupling or offline strategy. The motivation and objective of this project are to construct a real-time trajectory-based TAEM guidance system, devoting to improve the guidance performance in terms of precision, robustness, and autonomy, simultaneously. The research starts from solving the online trajectory planning problem by convex optimization. Then a high-order sliding mode and backstepping based closed-loop guidance law is designed to ensure the robustness in the presence of system uncertainties. Moreover, by periodically regenerating the trajectory based on the current environment and flight situations, the robustness to external disturbances can be effectively handled. The terminal gliding capability of the unpowered spaceplane is predicted, based on which the terminal end position is reset in the emergency and fault situations. By this means, the self-adaptation and fault-tolerant guidance ability can be enhanced. At last, the proposed guidance strategy is validated in both numerical simulation and hardware-in-the-loop simulation environment. This project is devoted for enhancing the spaceplane autonomous ability on intelligent planning and decision. It is expected to make contributions to the cost reduction for flight test. The results can be regarded as theory and application foundation for spaceplane design.

末端能量管理段是可重复使用空天飞行器实现水平着陆的关键环节，传统末端能量管理段制导采用解耦或离线轨迹制导的策略，精度和鲁棒性均不足。本项目拟研究末端能量管理段实时轨迹闭环制导方法，旨在提高空天飞行器返回的精度、鲁棒性和自主能力。项目将从基于凸优化轨迹规划技术出发，解决强非线性、强约束的三维轨迹规划的最优解及实时性问题；然后，设计基于高阶滑模和反步法的闭环制导律，提高对内部扰动的鲁棒性，并通过周期性在线轨迹重构，提高对外部扰动的鲁棒性；进而，设计具备容错能力的自主制导策略，在任务不确定及故障情形下，通过快速预测滑翔能力重新设定末端到达位置，提高系统的自主飞行能力。通过数值和半物理仿真以验证方法的有效性及制导精度。该项研究有助于提高空天飞行器智能规划与自主决策能力，为飞行验证降低技术风险提供保障，成果可为空天飞行器的设计与开发奠定理论与应用基础。

空天飞行器作为一种新型天地往返可重复使用空间运载器，可极大地降低空间运载的成本、提高空间飞行的灵活性，对于满足我国未来大规模空间开发、形成廉价天地往返运输工具的战略需求具有重大意义。本项目针对空天飞行器末端返回任务，研究三维轨迹规划及先进制导，提出自主返回制导方法。主要贡献如下：（1）将现代控制理论思想用于解决轨迹规划问题，设计了基于高度域模型和高阶滑模的轨迹生成算法，并从理论证明了所生成的轨迹可满足终端条件和过程约束；提出了一种基于最优控制和伪谱法的末端返回三维轨迹规划方法，利用微分平坦特性重构规划问题，降低了规划问题维度，提高了求解效率。（2）提出了基于收缩规划区间的闭环校正制导策略，在制导周期内重新规划轨迹以补偿干扰的影响，而不是在不考虑 RLV 制导能力的情况下跟踪固定的参考轨迹，该校正制导策略能够抵抗较大的扰动，具有较好的鲁棒性。（3）设计末端返回制导与控制综合方案和仿真平台，包括任务管理、制导回路、控制回路、执行器、飞行器模型和传感器六部分，搭建闭环环境进行末端返回全包线制导与控制闭环仿真分析。