Basic performance of BeiDou-2 navigation satellite system used in LEO satellites precise orbit determination

The visibility for low earth orbit（LEO） satellites provided by the BeiDou-2 system is analyzed and compared with the global positioning system（GPS）. In addition, the spaceborne receivers＇ observations are simulated by the BeiDou satellites broadcast ephemeris and LEO satellites orbits. The precise orbit determination（POD） results show that the along-track component accuracy is much better over the service area than the non-service area, while the accuracy of the other two directions keeps at the same level over different areas. However, the 3-dimensional（3D） accuracy over the two areas shows almost no difference. Only taking into consideration the observation noise and navigation satellite ephemeris errors, the 3D accuracy of the POD is about30 cm. As for the precise relative orbit determination（PROD）, the 3D accuracy is much better over the eastern hemisphere than that of the western hemisphere. The baseline length accuracy is 3.4 mm over the service area, and it is still better than 1 cm over the non-service area. This paper demonstrates that the BeiDou regional constellation could provide global service to LEO satellites for the POD and the PROD. Finally, the benefit of geostationary earth orbit（GEO） satellites is illustrated for POD.     

基于变权重变异鸽群优化的无人机空中加油自抗扰控制器设计

针对空中加油过程中的受油机模型建模误差和强扰动以及自抗扰控制器（ADRC）人工参数整定难的问题，提出了一种基于变权重变异鸽群优化（VWMPIO）算法的无人机自抗扰控制器优化算法。首先，给出了六自由度无人机（UAV）模型，基于自抗扰控制结构设计了一种受油机的姿态控制器，在此基础上用所提出的变权重变异鸽群优化算法整定了自抗扰控制器参数。随后，将变权重变异鸽群优化与其他基本鸽群优化算法、粒子群优化算法进行了实验对比，并从控制性能和抗噪声性能的角度对自抗扰控制器和传统的比例-微分-积分（PID）控制器进行了仿真对比。实验结果表明所提算法能提高复杂态势环境下无人机空中加油的控制精度和扰动抑制性能。     

Properties of the high area-to-mass ratio space debris population at high altitudes

In the framework of its space debris research activities ESA established an optical survey program to study the space debris environment at high altitudes, in particular in the geostationary ring and in the geostationary transfer orbit region. The Astronomical Institute of the University of Bern (AIUB) performs these surveys on behalf of ESA using ESA’s 1-m telescope in Tenerife. Regular observations were started in 1999 and are continued during about 120–140 nights per year. Results from these surveys revealed a substantial amount of space debris at high altitudes in the size range from 0.1 to 1 m. Several space debris populations with different dynamical properties were identified in the geostationary ring. During the searches for debris in the geostationary transfer orbit region a new population of objects in unexpected orbits, where no potential progenitors exist, was found. The orbital periods of these objects are clustered around one revolution per day; the eccentricities, however, are scattered between 0 and 0.6. By following-up some of these objects using the ESA telescope and AIUB’s 1-m telescope in Zimmerwald, Switzerland, it was possible to study the properties of this new population. One spectacular finding from monitoring the orbits over time spans of days to months is the fact that these objects must have extreme area-to-mass ratios, which are by several orders of magnitudes higher than for ‘normal-type’ debris. This in turn supports the hypothesis that the new population actually is debris generated in or near the geostationary ring and which is in orbits with periodically varying eccentricity and inclination due to perturbations by solar radiation pressure. In order to further study the nature of these debris, multi-color and temporal photometry (light curves) were acquired with the Zimmerwald telescope. The light curves show strong variations over short time intervals, including signals typical for specular reflections. Some objects exhibit distinct periodic variations with periods ranging from 10 to several 100 s. All this is indicative for objects with complicated shapes and some highly reflective surfaces.     

一种确定自旋卫星姿态的新方法

提出了一种在自旋稳定卫星自旋轴与几何体轴重合或几乎重合时只利用太阳角计算自旋卫星姿态的方法。给出了方法的原理及适用范围。研究表明：定姿精度仅与太敏测量精度有关,减小了传统方法中太敏与地敏两项测量误差产生的误差,方法原理简单、精度高。由实际卫星数据的长期验证可知：方法能在卫星自旋轴与实际几何轴偏差较小时实现快速定姿,定姿结果满足要求。     

航天多光谱扫描仪物方摆镜尺寸的确定

本文讨论多光谱扫描仪中扫描摆镜尺寸的计算方法,给出摆镜参数和望远镜参擞之间的尺寸关系。     

北斗星座仿真的单天线姿态确定技术研究

载体姿态测量的实际需要和多天线姿态测量的局限性决定了单天线姿态测量系统拥有广泛的发展前景。分析了单天线测姿的应用价值和基本原理,从我国的具体国情出发,提出了基于北斗卫星星座仿真的单天线姿态确定技术研究的方法。利用STK平台对目前组网运行的北斗卫星星座和理想的北斗满卫星星座进行了仿真,利用Matlab平台进行了实验,仿真实验结果和误差分析表明,北斗卫星星座仿真的单天线姿态确定技术在适用条件和测姿准确性等方面效果理想,在一定精度要求下满足应用需要,对建立实用可靠的单天线测姿具有积极的推动作用。     

基于先验信息的多光纤惯组快速检测方案研究

针对含多惯组制导弹箭的长期整弹贮存期检测问题,提出了基于先验信息比对的快速检测方案。该方案建立了光纤惯组检测适用误差模型,在弹箭内各惯组相对姿态不变的前提下,以历史检测姿态角作为先验信息,通过惯性器件输出直接计算当前惯组相对姿态角,并结合姿态矩阵正交化特性进行比对。通过该方法可检测出弹箭内各惯组器件性能是否达标,缩短了检测时间,简化了检测流程。理论分析和仿真结果验证了该方案的可行性。     

极低频超大型航天器姿态机动与物理试验验证

针对具有0.01 Hz极低频主模态的超大型航天器的姿态机动问题,给出利用经典的Bang-Bang轨迹规划方法、滤波轨迹规划方法和传统的相平面控制方法进行姿态机动的方案,构建了极低频超大型航天器姿态机动地面物理试验系统,对不同的姿态机动控制方法进行了试验验证.针对不同的姿态机动轨迹规划方法,采用喷气发动机或控制力矩陀螺作...     

我国中继卫星系统在交会对接任务中的应用

我国中继卫星系统在交会对接任务中得到了成功应用,显著提升了测控通信覆盖率,充分体现了中继卫星系统在交会对接任务测控通信中发挥的重要作用.结合中继卫星系统特点,分析交会对接任务对中继卫星系统的任务需求;探讨了中继卫星捕获跟踪用户目标、对用户目标测定轨、着陆场直升机缝隙通信等关键技术;最后总结了中继卫星系统抗雨衰影响、多目标支持能力、应急支持能力等方面的经验做法,并提出了后续改进和完善的建议.