中国的三种非同步轨道卫星移动通信系统星座方案

本文介绍基于我国的三种非同步轨道卫星移动通信系统星座方案：低、中轨系统各有２４和１８颗星，轨道高度分别为１３２６和８０３５ｋｍ，两系统各以５°和３０°的仰角对我国的覆盖率为９９．７８％和９９．９６％；椭圆轨道系统１２颗星，近、远地点分别为４２７和２９０６ｋｍ，以７°和１５°仰角对我国北纬２０°以上地区覆盖率分别为９７．９０％和８９．６１％，若增加４颗中轨卫星，以１５°仰角对我国的覆盖率为９９．９９％。     

星间激光通信技术进展与趋势

较详细地评述了目前国外卫星间光通信技术研究的现状．根据关键单元技术的进展情况，总结了未来星间光通信系统的发展趋势。     

A New Derivation of the Cubature Kalman Filters

This paper investigates the cubature Kalman filtering (CKF) for nonlinear dynamic systems. This third‐degree rule based filter employs a spherical‐radial cubature rule to numerically compute the integrals encountered in nonlinear filtering problems, thereby removing the requirements of explicitly computing the Jacobians. The cubature rule, however, requires computing the intractable integrals over a high‐dimensional spherical region for multidimensional applications. Moreover, the cubature formula that has been used to construct the spherical cubature formula has some demerits, most notably its inconvenient properties in computation and low estimation accuracy. Aimed at these issues, a general class of CKFs that uses only cubature rules is derived in this paper. It can be shown that the conventional CKF is a special case of the proposed algorithm. The paper also includes higher‐degree CKFs, especially two representative types of the fifth‐degree CKFs. Performance of the proposed algorithms is demonstrated via two target tracking problems. The experimental results, presented herein, illustrate the superior performance of higher‐degree CKFs to conventional nonlinear filters.     

基于NSGA-Ⅱ算法的轨道转移优化方法研究

在普适变量法求解Lambert转移问题基础上,提出基于NSGA-Ⅱ（non-dominated sorting genetic algorithm-Ⅱ）算法的轨道转移时间-能量优化问题解决方法：通过修改非优超排序方法和采用空间扩张策略对NSGA-Ⅱ算法进行了改进,运用约束支配的概念解决了约束条件下Pareto最优集分层困难的问题。仿真实验表明：改进的NSGA-Ⅱ算法能有效求解轨道转移时间-能量优化问题,且比原算法提高了Pareto前沿散布性能。     

基于磁强计和陀螺测量的卫星轨道姿态一体化确定算法

突破卫星轨道和姿态参数分别确定分而治之的传统模式,提出了利用磁强计和陀螺测量信息同时确定卫星轨道和姿态参数的新方法。利用磁强计提供的地磁场测量值与地磁场模型计算值之间的差值,以及陀螺提供的角速度信息,推导了轨道姿态一体化确定扩展卡尔曼滤波算法。利用局部可观测性理论定量地计算系统局部可观测矩阵的条件数,进而利用该条件数对系统的可观测性进行深入分析。最后对本文算法进行了数学仿真,结果表明该算法的可行性和有效性。     

Spacecraft formation control strategy on Sun-Earth Lissajous orbit

To carry out the deep space exploration tasks near Sun-Earth Libration point L2, the CRTBP dynamic model was built up and the numerical conditional quasi-periodic orbit (Lissajous orbit) was computed near L2. Then, a formation controller was designed with linear matrix inequality to overcome the difficulty of parameter tuning. To meet the demands of formation accuracy and present thruster’s capability, a threshold scheme was adopted for formation control. Finally, some numerical simulations and analysis were completed to demonstrate the feasibility of the proposed control strategy.     

空间智能操控装备在轨服务建模与仿真研究

为了保证空间智能操控装备在轨服务任务的顺利实施,研究了与其相关的规划、建模与仿真等关键技术。在此基础上,研制开发了一套空间智能操控装备在轨服务仿真系统;该系统采用HLA/RTI仿真框架,实现了空间态势监控、任务规划、轨道机动规划、测控资源计算、轨道机动仿真、在轨操作仿真、控制指令生成与发送等功能。基于该仿真系统,进行了空间智能操控装备在轨服务任务的仿真分析,对关键任务节点进行了反复验证。     

螺纹电极的制作方法

介绍了用电火花成形方法加工螺纹时的电极制作方法，尤其是换电极加工螺纹时电极的制作方法。     

Continuous-time orbit problems are decidable in polynomial-time

We place the continuous-time orbit problem in P$\mathsf{P}$, sharpening the decidability result shown by Hainry [7].     

空间光通信中轨道短时预报

瞄准、捕获和跟踪(PAT)技术是星间光通信的关键技术之一,高精度卫星轨道短时预报能有效实现PAT.首先在EGM96地球引力场模型下建立了卫星状态动力方程和预报方程,然后改进基于数值算法的扩展卡尔曼滤波算法对卫星轨道短时预报,最后以champ卫星星载GPS实时定轨数据为卡尔曼滤波器观测数据进行仿真实验:预报卫星位置误差约亚米级,速度误差约0.05m/s;卫星位置和速度的均方差估计趋于稳定,在一定程度上能很好地克服离散误差和模型误差对轨道估计精度的影响.PAT瞄准精度约1.6 μrad.预报轨道精度能满足空间光通信PAT技术要求.