小天体柔性附着状态协同估计方法

针对小天体附着过程易发生倾覆、反弹导致任务失败问题,提出“柔性附着”概念,替代传统小天体探测的刚性附着模式,为提高小天体附着任务可靠性提供新的解决思路和技术途径。在此基础上,针对柔性着陆器的状态估计问题展开研究。首先建立了柔性着陆器近似模型,提出了柔性着陆器“等效面”概念及柔性着陆器姿态的近似表征方式,进而提出了柔性附着状态协同估计方法,并通过数值仿真检验了柔性着陆器状态协同估计的可行性。     

机动再入体的带落角约束扩展比例导引律设计

传统的各种制导律都是以获得最小脱靶量为最终目标,没有考虑到导弹击中目标时刻的末端落角.为了保证非自旋再入体完成精确打击目标的任务,针对非自旋再入体垂直打击目标的制导问题,设计了一种带落角约束的扩展比例导引律.仿真研究表明,所设计的末制导律能够保证非自旋再入体命中目标时的脱靶量和末端落角都能满足要求,可以为开展近空间非自旋再入体制导问题的研究提供测试平台.     

Small satellite survey mission to the second Earth moon

This paper presents an innovative space mission devoted to the survey of the small Earth companion asteroid by means of nano platforms. Also known as the second Earth moon, Cruithne, is the target identified for the mission. Both the trajectory to reach the target and a preliminary spacecraft budget are here detailed. The idea is to exploit high efficient ion thrusters to reduce the propellant mass fraction in such a high total impulse mission (of the order of 1e6 Ns). This approach allows for a 100 kg class spacecraft with a very small Earth escape energy (5 km²/s²) to reach the destination in about 320 days. The 31% propellant mass fraction allows for a payload mass fraction of the order of 8% and this is sufficient to embark on such a small spacecraft a couple of nano-satellites deployed once at the target to carry out a complete survey of the asteroid. Two 2U Cubesats are here considered as representative payload, but also other scientific payloads or different platforms might be considered according with the specific mission needs. The small spacecraft used to transfer these to the target guarantees the manoeuvre capabilities during the interplanetary journey, the protection against radiations along the path and the telecommunication relay functions for the data transmission with Earth stations. The approach outlined in the paper offers reliable solutions to the main issues associated with a deep space nano-satellite mission thus allowing the exploitation of distant targets by means of these tiny spacecraft. The study presents an innovative general strategy for the NEO observation and Cruithne is chosen as test bench. This target, however, mainly for its relevant inclination, requires a relatively large propellant mass fraction that can be reduced if low inclination asteroids are of interest. This might increase the payload mass fraction (e.g. additional Cubesats and/or additional scientific payloads on the main bus) for the same 100 kg class mission.     

从月球逃逸探测小行星的发射机会搜索

从月球逃逸探测小行星的发射机会搜索因需考虑日、地、月引力的影响而使问题变得复杂。针对该多体系统的发射机会搜索问题,提出了一种分层渐近的搜索方法。该方法首先通过分析地月系质心与小行星的几何关系,搜索从地月系质心到小行星的发射机会,进而以地月运动为研究对象,推导出了从月球轨道切向逃逸机会的判别条件,并基于此判别条件及等高线图法对逃逸机会进行了搜索。同时,为提高所得发射机会在多体模型下的轨道修正收敛性,给出了基于月心逃逸轨道参数为终端约束的日-地与日-地-月动力学模型的轨道渐近修正方法。最后,以近地小行星(3908)Nyx和(190491)2000 FJ20为例,搜索其从月球逃逸的发射机会,仿真计算表明了该方法的有效性。     

人体变形中局部坐标系旋转失真问题

分析了人体变形中选取3个基轴构建坐标系所存在的缺陷,提出了一种位置-四元数的方法,解决了曲线骨架驱动的旋转失真现象.采用四元数球面线形插值和B样条四元数插值的方法构建人体变形中曲线骨架的局部坐标系,采用位置-四元数-缩放的方式代替传统的转化矩阵,通过人体表面顶点在该坐标系下的绑定,实现人体皮肤、肌肉的变形.试验结果显示:该方法有效地消除了局部坐标系的旋转失真现象,适用限制少,易于实现.     

滚转弹两框架导引头的前馈补偿技术

针对弹体滚转情况下两框架平台式导引头的伺服控制问题,基于导引头运动学和动力学,建立了导引头稳定回路模型。结合弹体滚转条件下的导引头输入指令和输出视线角速率关系,构建了视线闭环回路。针对偏航、俯仰通道间的解耦控制问题,推导出解耦条件,要求两通道由失调角到光轴转动角速度的传递函数相同。仿真分析了该模型在视线角输入以及弹体姿态扰动输入时,弹体滚转对导引头跟踪精度产生的影响,并由此提出了滚转角速度前馈补偿控制方案。结果表明,采用结合滚转角前馈补偿控制的两框架平台式导引头方案可以满足滚转弹的制导精度要求。     

行星着陆自主导航与制导控制研究现状与趋势

行星着陆自主导航与制导控制技术是行星着陆过程的核心技术之一,关系到行星着陆任务的成败。本文基于未来火星和小天体着陆对自主导航与制导控制技术的发展需求,阐述了进一步开展自主导航与制导控制研究的必要性,围绕行星着陆过程环境特点,分析了自主导航与制导控制技术所遇到的挑战,随后概括了行星着陆自主导航与制导控制所涉及的关键技术,并综述了关键技术的研究现状。最后对我国未来行星着陆探测自主导航与制导控制技术的发展方向进行了展望。     

Aerodynamic Design Methodology for Blended Wing Body Transport

This paper puts forward a design idea for blended wing body(BWB).The idea is described as that cruise point,maximum lift to drag point and pitch trim point are in the same flight attitude.According to this design idea,design objectives and constraints are defined.By applying low and high fidelity aerodynamic analysis tools,BWB aerodynamic design methodology is established by the combination of optimization design and inverse design methods.High lift to drag ratio,pitch trim and acceptable buffet margin can be achieved by this design methodology.For 300-passenger BWB configuration based on static stability design,as compared with initial configuration,the maximum lift to drag ratio and pitch trim are achieved at cruise condition,zero lift pitching moment is positive,and buffet characteristics is well.Fuel burn of 300-passenger BWB configuration is also significantly reduced as compared with conventional civil transports.Because aerodynamic design is carried out under the constraints of BWB design requirements,the design configuration fulfills the demands for interior layout and provides a solid foundation for continuous work.     

小天体软着陆自主光学导航与制导方法研究

针对小天体软着陆任务自主性、实时性的需求,对软着陆小天体自主导航与制导问题 进行了研究。提出了一种利用激光测距仪和光学导航相机跟踪目标着陆点的自主导航方案, 利用测距矢量以及目标点之间的几何关系,确定着陆平面法向方向和目标点位置。分析期望 的探测器下降轨迹特点,给出了一种基于制导变量的脉冲控制制导律,通过对目标点视线与 着陆平面法向矢量之间夹角的控制,将软着陆小天体控制分解为切向控制与法向控制两部分 。最后,通过数学仿真对自主导航制导系统的性能进行了验证,结果表明该方法能够满足垂 直软着陆的任务需要,实现高精度软着陆。     

“北京一号”小卫星图像分析

20世纪80年代中期开始,世界航天界兴起了发展小卫星的热潮,特别是小卫星星群或星座的发展,将取代部分现代大型应用卫星的功能。文章提出并总结了图像综合品质评价技术指标,对中国的“北京一号”（DMC＋4灾难监测星座）小卫星图像进行评价,从图像的空间分辨率、光谱分辨率和时间分辨率几个方面对中国“北京一号”小卫星图像进行分析。