Distributed cooperative guidance for multiple missiles with fixed and switching communication topologies

This study investigates cooperative guidance problems for multiple missiles with fixed and switching directed communication topologies.A two-step guidance strategy is proposed to realize the simultaneous attack.In the first step,a distributed cooperative guidance law is designed using local neighboring information for multiple missiles to achieve consensus on range-to-go and leading angle.The second step begins when the consensus of multiple missiles is realized.During the second step,multiple missiles disconnect from each other and hit the target using the proportional navigation guidance law.First,based on the local neighboring communications,a sufficient condition for multiple missiles to realize simultaneous attack with a fixed communication topology is presented,where the topology is only required to have a directed spanning tree.Then,the results are extended to the case of switching communication topologies.Finally,numerical simulations are provided to validate the theoretical results.     

航天任务控制中心容灾模式研究

航天任务是一项高投入、高风险的活动,作为管理所有在轨飞行航天器及资源的航天任务控制中心,要求具备很高的可靠性与较强的容灾能力。国际航天大国对地面系统,特别是任务中心级的备份均非常重视,也开展了相关建设和系统运行。在对我国航天任务控制中心容灾模式进行探讨的基础上,提出容灾中心的技术要素、需求分析以及运行机制。     

信息物理融合系统及其在航空制造业应用展望

信息物理融合系统(Cyber-Physical System,CPS)是当前国内外研究的热点,是实施智能化制造的核心技术。阐述了CPS的定义、原理和特点,并就CPS在航空制造业的应用前景和发展路线进行了分析。     

Study on the system of night hours for decoding Korean astronomical records of 1625–1787

This paper presents a study of the dates and times of astrophysical phenomena seen in the night time hours in Korea between 1625 and 1787. This is a period when two different calendars were used and it is important to know which calendar was used to record events such as lunar eclipses. It is known that the Joseon court adopted Shixianli (a Chinese calendar of Adam Schall) in 1654, the fifth reign of King Hyojong. However, the year when the court introduced the calendar into the system of night hours has not yet been determined. To know the enforcement year is very important for studies on astronomical events that are presented in Korean historical documents. From Seungjeongwon Ilgi (Daily Records of the Royal Secretariat), we compile a total of 90 lunar eclipse records referring to the observation time of the eclipses and calculate the times of occurrence of the eclipses with respect to the calendrical methods: Chiljeongsan Naepyeon (a Korean calendar) and Shixianli. As a result, we find that the system of night hours by the former calendrical method was used in the Joseon dynasty until as late as 1710. We also verify that the times of sunrise and sunset were considered as the moments when the center of the Sun reached the horizon according to Chiljeongsan Naepyeon at least. Therefore, we think that this study will contribute to the studies on astronomical phenomena of the Joseon dynasty, particularly on the estimate of the observation time.     

Robust adaptive filtering method for SINS/SAR integrated navigation system

This paper presents a new robust adaptive filtering method for SINS/SAR (Strap-down Inertial Navigation System/Synthetic Aperture Radar) integrated navigation system. This method adopts the principle of robust estimation to adaptive filtering of observational data. A robust adaptive filter is developed to adaptively determine the covariance matrix of observation noise, and adaptively adjust the covariance matrix of system state noise according to the adaptive factor constructed based on predicted residuals. Experimental results and comparison analysis demonstrate that the proposed method cannot only effectively resist disturbances due to system state noise and observation noise, but it can also achieve higher accuracy than the adaptive Kalman filtering method.     

中继卫星星间天线指向误差传播率研究

基于中继卫星星间天线对用户航天器的跟踪规律,建立了准确的误差传递模型,并对分析结果进行了仿真验证。文中首先定义了误差传递模型所需的各类坐标系;然后使用微分方法分别建立了中继卫星轨道误差传递模型、中继卫星姿态误差传递模型,分析了滚动角、俯仰角和偏航角与指向精度之间的关系,以及位置保持控制对指向精度的影响;最后借助于STK软件的轨道计算功能,使用蒙特卡罗方法进行数学仿真,仿真结果验证了误差传递模型的准确性。     

IP over CCSDS/AOS空间通信QoS保证方法

首先分析空间通信体系发展趋势,提出基于IP over CCSDS/AOS的空间通信模型。在分析总结了地面网QoS(服务质量)机制和AOS(高级在轨系统)虚拟信道调度机制的基础上,提出一种IP(互联网协议)网络层区分服务与数据链路层AOS虚拟信道动态调度相结合的QoS保证方法。该方法将网络层的业务等级划分映射到AOS的虚拟信道分配算法中,并在此基础上实现AOS虚拟信道的动态调度,提高包括话音、视频在内的综合业务在空间链路传输的性能。     

A multiple-rendezvous,sample-return mission to two near-Earth asteroids

We propose a dual-rendezvous mission, targeting near-Earth asteroids, including sample-return. The mission, Asteroid Sampling Mission (ASM), consists of two parts: (i) flyby and remote sensing of a Q-type asteroid, and (ii) sampling of a V-type asteroid. The targeted undifferentiated Q-type are found mainly in the near-Earth space, and to this date have not been the target of a space mission. We have chosen, for our sampling target, an asteroid from the basaltic class (V-type), as asteroids in this class exhibit spectral signatures that resemble those of the well-studied Howardite–Eucrite–Diogenite (HED) meteorite suite. With this mission, we expect to answer specific questions about the links between differentiated meteorites and asteroids, as well as gain further insight into the broader issues of early Solar System (SS) evolution and the formation of terrestrial planets. To achieve the mission, we designed a spacecraft with a dry mass of less than 3 tonnes that uses electric propulsion with a solar-electric power supply of 15 kW at 1 Astronomical Unit (AU). The mission includes a series of remote sensing instruments, envisages landing of the whole spacecraft on the sampling target, and employs an innovative sampling mechanism. Launch is foreseen to occur in 2018, as the designed timetable, and the mission would last about 10 years, bringing back a 150 g subsurface sample within a small re-entry capsule. This paper is a work presented at the 2008 Summer School Alpbach,“Sample return from the Moon, asteroids and comets” organized by the Aeronautics and Space Agency of the Austrian Research Promotion Agency. It is co-sponsored by ESA and the national space authorities of its Member and Co-operating States, with the support of the International Space Science Institute and Austrospace.     

北斗导航系统在物联网中的应用展望

物联网是信息技术领域又一个重要发展,它使传统网络从人与人的联系扩展到物与物、物与人的联系。北斗导航系统是我国正在建设的全球卫星导航系统。分析北斗导航系统在物联网中应用的可行性,从物联网的组成结构出发,分析北斗导航系统相比于传统电信网络的优势,并对北斗导航系统在物联网中的应用模式进行展望。     

导弹敏捷转弯段的新型非奇异终端滑模控制

针对具有快时变性、不确定性、强非线性和系统初始状态远离平衡点等特点的敏捷导弹的直接力/气动力复合控制律设计问题,提出了一种新型非奇异终端滑模控制方法。为缩短到达平衡态的时间,设计了一种组合非奇异终端滑模面,提高了系统状态在滑模面上的收敛速度,设计了改进的变系数双幂次趋近律,提高了系统状态到达滑模面的速度,并利用扩张状态观测器实时估计系统内外扰动,消除了观测误差对系统造成的干扰,抑制了抖振。最后,证明了所提方法的有限时间收敛特性,通过仿真对比校验了所提方法的有效性。