类星舰飞行器水平下降-垂直着陆轨迹实时优化问题研究

类星舰飞行器是一类新型完全可重复使用运载器，能够极大降低发射成本，是未来航天运输系统的重要发展方向。类星舰飞行器返回地球采用全新的水平下降-垂直着陆飞行方案。该飞行方案的大攻角气动减速、大角度姿态快速机动、气动力与推力“接力跑”式控制使得动力学出现强非线性、强耦合、多阶段特征，造成轨迹实时优化技术应用极大受限。为了解决该难题，本项目（1）提出一种面向轨迹实时优化的“N+M”自由度建模思想，建立N维水平下降和M维垂直着陆动力学模型，深度挖掘动力学的多阶段特征，揭示问题的最小阶描述规律；（2）提出一种处理强非线性、强耦合、多阶段动力学的邻近牛顿-康托维奇凸优化方法，建立邻近项自适应调节理论；（3）揭示动力学二阶信息对收敛稳定性与收敛速度的影响机理。通过本项目的研究，力争对水平下降-垂直着陆轨迹实时优化问题的数学建模、凸化求解、收敛机理建立全面认识，为类星舰飞行器的研制提供理论支撑。

Starship-type Vehicle (STV) is a new type of fully reusable launch vehicle, which can greatly reduce launch costs. The development of STV represents an important direction of space transportation system in the future. A unique Horizontal-Descent-Vertical-Landing (HDVL) flight scheme is adopted for STV to return to Earth. Due to the aerodynamic deceleration with a high angle-of-attack, rapid attitude maneuver, and ‘relay run’ sequential control of aerodynamic force and thrust, HDVL flight scheme is characterized by high nonlinearity, strong coupling, and multiphase dynamics, thus hindering the application of real-time trajectory optimization. To deal with this issue, this project (1) proposes a two-phase ‘N+M’ degree of freedom modeling methodology that establishes N and M dimensional dynamics models for the horizontal descent phase and the vertical landing phase respectively. By this way, the multiphase characteristics of dynamics are exploited, and as a result the minimum order description law of the HDVL flight scheme is obtained; (2) proposes a proximal-Newton-Kantorovich convex optimization approach to deal with the highly nonlinear, strongly coupled, and multiphase dynamics, and correspondingly developes the theory of adaptive adjustment for the proximal term; (3) demonstrates the effects of second-order dynamics information on both convergence stability and convergence speed. By virtue of this project, a comprehensive understanding of the mathematical modeling, convexification-based problem solving, and iteration convergence mechanism will be developed for the HDVL real-time trajectory optimization problem, which can provide theoretical support for the development of STV.