火星着陆器动力下降段燃料最优制导律研究

发布时间：2018-02-12 11:15

本文关键词： 火星着陆器动力下降制导策略燃料最优路径点二阶滑模　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着人类对太空探索的不断深入,人造探测器探测任务已由早期对地球、月球探测发展到行星及彗星的探测,探测任务的类型经历了飞越、绕飞、硬着陆、软着陆、采样返回等几个阶段。着陆器的动力下降段主要用于实现行星的最终软着陆任务,是确保实现近距离研究行星的重要阶段之一。针对火星着陆器在任务可靠性、燃料消耗等多方面任务需求,本文以燃料最优为目标,对动力下降段的轨迹优化和最优跟踪制导策略开展了研究,主要包括以下几个方面:经过合理简化得到着陆器动力下降段运动模型,并将具有非凸特性的燃料最优问题转换为凸优化问题进行求解,通过轨迹优化得到了大量不同初始状态下的燃料最优着陆轨迹。针对得到的燃料最优轨迹,设计了一种基于二阶滑模的轨迹跟踪制导律。针对传统变结构控制使系统产生抖振,动态响应速率慢,以及存在大气等干扰时不具备较强鲁棒性等问题,设计一种二阶滑模到达条件,理论证明了其存在性和可达性,对存在干扰情况下的鲁棒性进行了分析;基于所设计的到达条件设计出跟踪制导律;通过数值仿真验证了所设计跟踪制导律的有效性。考虑最优轨迹存储将占据大量存储空间,本文在深入分析燃料最优解的基础上提出了一种新的路径点制导策略。通过其推力变化规律定义了新的路径点,选取线性制导律与之结合形成新的制导策略,该制导策略既具有燃料最优性,又较传统标称轨迹制导节省存储空间;分别采用线性插值和三次样条插值方法,获得了非典型初始位置对应的路径点,通过仿真验证所提出方法的有效性。
[Abstract]:With the deepening of human space exploration, the exploration mission of artificial probe has developed from the early exploration of the earth and the moon to the exploration of planets and comets. The types of missions have experienced overflight, orbit, hard landing, soft landing. The dynamic descent section of the lander is mainly used to realize the final soft landing mission of the planet, which is one of the important stages to ensure the close study of the planet. In this paper, the trajectory optimization and the optimal tracking guidance strategy of the power descent section are studied, which is aimed at the fuel optimization. The main contents are as follows: after reasonable simplification, the dynamic descent motion model of lander is obtained, and the fuel optimal problem with non-convex characteristics is converted to convex optimization problem. A large number of fuel optimal landing trajectories in different initial states are obtained by trajectory optimization. A trajectory tracking guidance law based on second-order sliding mode is designed for the fuel optimal trajectory. The system is buffeted by conventional variable structure control. The dynamic response rate is slow and there is no strong robustness in the presence of atmospheric disturbances. A second-order sliding mode arrival condition is designed and its existence and reachability are proved theoretically. The robustness in the presence of disturbances is analyzed. The tracking guidance law is designed based on the designed arrival conditions, and the effectiveness of the designed tracking guidance law is verified by numerical simulation. Considering that the optimal trajectory storage will occupy a large amount of storage space, Based on the analysis of the fuel optimal solution, a new path point guidance strategy is proposed in this paper. A new path point is defined by the law of its thrust variation, and the linear guidance law is selected to combine with it to form a new guidance strategy. The guidance strategy not only has fuel optimality, but also saves storage space compared with the traditional nominal trajectory guidance. The path points corresponding to the atypical initial position are obtained by using linear interpolation and cubic spline interpolation, respectively. The effectiveness of the proposed method is verified by simulation.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V448.2

【参考文献】