控制力矩陀螺群奇异角动量超曲面仿真分析

用角动量超曲面仿真分析了控制力矩陀螺构型奇异的产生机理。基于控制力矩陀螺群动力学总角动量和输出控制力矩,讨论了典型构型奇异存在的状况,并确定了奇异点存在的判断依据,对五棱锥构型的显奇异和隐奇异进行了角动量超曲面仿真,发现能通过零运动脱离奇异状态的隐奇异点,为控制力矩陀螺群的操纵律设计提供了重要依据。控制系统数学仿真结果表明该分析法有效。     

偶数重连续覆盖的Walker星座设计方法

针对期望覆盖重数为偶数重时连续覆盖Walker星座的构型设计问题,提出一种基于覆盖带理论的构型设计方法。首先分析同轨道卫星组成覆盖带时的构型设计特例,随后将结论推广,改进了传统Walker星座的构型表征形式并提出覆盖带构型参数。基于轨道参数的相平面映射,给出了异轨卫星组成覆盖带时特征宽度的计算方法。通过分析相平面上覆盖带的拼接情况,给出了轨道倾角的优化策略和偶数重覆盖任意纬度的Walker星座设计步骤。所提出方法能显著提高构型枚举效率,且能满足不同纬度范围的覆盖需求。仿真表明,该方法能减少约10%覆盖所需的卫星数量,并能通过调整构型参数进一步优化轨道面数量。     

Landing of the asteroid probe with three-legged cushioning: Planar asymmetric dynamics and safety margin

The probes landing on the surfaces of the asteroids can increase the scientific return of the exploration missions and also promote the development of deep space resources. Because of its excellent applicability to the uneven terrain and a lighter configuration than the four-legged mechanisms, the three-legged cushioning mechanisms are suitable for dissipating the impact energy and then quickly stabilizing the probe attitude when the probe lands on the micro-gravitational surfaces of the asteroids. Research on the landing dynamics of the probe facilitates to the design of the landing-cushioning mechanism and the optimization of its configuration, as well as the assessment of the landing safety. Comparing with the previous extensive related literature focusing on landing dynamics of the probes assisted by the four-legged cushioning mechanisms, this paper studies creatively the planar dynamics considering the asymmetric characteristic and the leg-leg coupling to understand the landing process of the asteroid probe with the three-legged cushioning mechanism and thereby to optimize the configuration of cushioning mechanism and assess safety margin of the landing. According to the touchdown status, the asymmetric landing modes are classified and the coupling issue in the construction of the landing models is explained. Consequently, two types of dynamics models describing the two-stages touchdown cushioning process of the probe are established. Then, five significant configuration factors of the cushioning mechanism are extracted, and their values combinations are designed according to the Taguchi orthogonal method. On this basis, the maximum safe landing attitude angles of the probe are solved by using these values combinations as the input conditions under the dangerous situations in different landing modes. The range analysis and nonlinear fitting methods are employed to discuss the influence of the configuration factors on the landing safety margin, and the favorable parameter values of the configuration factors are determined. Next, the influence of the ground obstacle on the landing safety margin and several methods to improve the margin are researched. Finally, the complete attitude changes of the probe in two representative landing cases are analyzed. The results studied in this paper can contribute to configuration optimization of the three-legged cushioning mechanisms and safety assessment of the legged probes landing on the asteroids, as well as to provide a reference for discussing the leg-leg coupling issue received less attention in landing dynamics of the probes with the four-legged cushioning mechanisms.     

航天器可展开薄膜遮光罩机械设计的发展与展望

从可展开薄膜遮光罩的几何构型、展开驱动技术、薄膜折痕设计和薄膜褶皱动力学分析四个方面论述了航天器可展开薄膜遮光罩机械设计的发展现状和特点，在分析比较的基础上对可展开薄膜遮光罩机械设计的发展趋势进行了展望，旨在为航天器可展开薄膜遮光罩的创新发展提供参考。