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1.
Yi Wei Qingjun Li Fangnuan Xu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(1):393-400
A new orbit-attitude-vibration coupled dynamic model of the tethered solar power satellite (Tethered SPS) is established based on absolute nodal coordinate formulation. The Hamilton’s equation of the system is derived by introducing generalized momentum through Legendre transformation. The correctness of the proposed model is verified by an example. The dynamic characteristics of the Tethered SPS are studied using the symplectic Runge-Kutta method. Simulation results show that the orbital radius and the total energy of the system are well preserved. The attitude of the system is unstable when the mass of the bus system is small. However, the attitude stability is dependent on some other parameters of the system, which requires further studies. It is also found that the average tether force/deformation can be roughly estimated by simplifying the solar panel as a particle. The proposed model can be used to study the orbit-attitude-vibration coupled dynamics and control problems. 相似文献
2.
Michael A. Earl Philip W. Somers Konstantin Kabin Donald Bédard Gregg A. Wade 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(8):2135-2146
For the first time, the spin axis orientation of an inactive box-wing geosynchronous satellite has been estimated from ground-based optical photometric observations of Echostar-2’s specular reflections. Recent photometric light curves obtained of Echostar-2 over four years suggest that unusually bright and brief specular reflections were occurring twice within an observed spin period. These bright and brief specular reflections suggested two satellite surfaces with surface normals separated by approximately 180°. The geometry between the satellite, the Sun, and the observing location at the time of each of the brightest observed reflections, was used to estimate Echostar-2’s equatorial spin axis orientation coordinates. When considering prograde and retrograde rotation, Echostar-2’s spin axis orientation was estimated to have been located within 30° of either equatorial coordinate pole. Echostar-2’s spin axis was observed to have moved approximately 180° in right ascension, within a time span of six months, suggesting a roughly one year spin axis precession period about the satellite’s angular momentum vector. 相似文献
3.
《中国航空学报》2020,33(1):255-270
This study creates and combines the general maneuver libraries for fixed-wing aircraft to implement tactical maneuvers. First, the generalized maneuver libraries are established by analyzing the characteristics of tactical maneuvers required in battlefields. The 7th order polynomial is applied to both the creation of the maneuver libraries and the generation of the trajectories or flight paths for modal inputs. To track the desired trajectory, we design the Attitude Command Attitude Hold (ACAH) system and the Rate Command Rate Hold (RCRH) system using Model Following Controller (MFC). Moreover, the Line-of-Sight (LOS) guidance law is designed. In particular, the CONDUIT® is employed to optimize the gains so that the control systems meet the aircraft Handling Qualities (HQ) criteria. Finally, flight simulations are performed for the longitudinal loop, immelmann-turn, and climb-slalom-descent maneuvers to verify that tactical aggressive maneuvers are realizable via the combination of maneuver libraries. This study can contribute to the development of flight techniques for aircraft tactical maneuvers and to the revision of air force operational manuals. 相似文献
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5.
三轴稳定遥感卫星姿控系统故障情况下的系统重构 总被引:1,自引:0,他引:1
论述三轴对地稳定遥感卫星姿控系统中部分轮子或部分陀螺故障情况下的姿控系统重构。文中论述了只在俯仰通道有一偏置动量轮正常工作,而滚动和偏航通道轮子故障条件下的系统重构。另外还论述了偏航陀螺故障,姿控系统其它部件正常情况下,控制系统采用Whecon原理与PIM控制相结合的设计。以上两种系统重构拟用于实际系统中,经过数学仿真验证,姿控系统在故障情况下能够完成基本任务。 相似文献
6.
Large amplitude MHD waves are commonly found in the solar wind. Nonlinear interactions between the MHD waves are likely to
produce finite correlation among the wave phases. For discussions of various transport processes of energetic particles, it
is fundamentally important to determine whether the wave phases are randomly distributed (as assumed in quasi-linear theories)
or they have a finite coherence. Using a method based on a surrogate data technique and a fractal analysis, we analyzed Geotail
magnetic field data (provided by S. Kokubun and T. Nagai through DARTS at the Institute of Space and Astronautical Science)
to evaluate the phase coherence among the MHD waves in the earth's foreshock region. The correlation of wave phases does exist,
indicating that the nonlinear interactions between the waves is in progress.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
8.
李伟红 《华北航天工业学院学报》2002,12(4):17-19
本文介绍了多线程网络编程的实现。并给出了用Visual C 6.0实现的一个多线程端口扫描程序的关键代码。 相似文献
9.
基于神经网络的导弹姿态控制系统故障诊断 总被引:1,自引:0,他引:1
本文提出了一种多层前向神经网络快速误差向后传播学习算法FBP(FasterrorBackPropagationLearningAlgorithm),通过某导弹姿态控制系统故障诊断的仿真研究,验证了BP(误差后向传播学习算法)和FBP用于导弹姿态控制系统故障诊断的有效性,FBP学习算法较之BP学习算法学习速度的快速性 相似文献
10.
一种基于误差四元数的战术导弹垂直发射姿态调转控制器 总被引:3,自引:0,他引:3
针对战术导弹垂直发射姿态调转时的快速性要求,研究了垂直发射快速姿态调转的控制问题。首先基于误差四元数并结合垂直发射的具体特点,建立了战术导弹垂直发射的非线性数学模型;然后通过李亚普诺夫第二方法进行控制系统设计,得出了基于误差四元数反馈控制器。分析了系统的稳定性和鲁棒性。该控制器实现了绕欧拉特征轴的旋转,缩短了姿态调转的时间,最后通过仿真验证其有效性。 相似文献