对有扰情况下欠驱动航天器三轴姿态保持控制问题进行了研究,提出一种基于俯仰偏置动量轮和滚动轴推力器的姿态保持控制方法。该方法基于偏置动量航天器滚动-俯仰轴耦合的原理实现,避免了欠驱动零动量航天器平衡点附近欠驱动轴耦合弱的问题;将航天器的姿态运动分为长周期运动和短周期运动,用极点配置方法进行控制律设计,给出保证系统稳定的参数选取范围,求出了系统稳态误差。最后,通过数值仿真验证了所设计的控制器不但能快速消除初始姿态偏差,而且能抵抗外干扰将航天器姿态保持在平衡点附近。

To maintain the three-axis attitude of the underactuated nadir-pointing spacecraft,an attitude hold control method based on the pitch-axis bias momentum wheel and roll-axis thruster was proposed.The method was based on coupling between the roll and yaw axes of biased-momentum spacecraft, and could avoid the problem that zero momentum spacecraft′s underactuated axis and actuated axis were almost decoupled. Spacecraft attitude dynamics was divided into long-period dynamics and short-period dynamics, and the control laws were designed by the pole-assignment method. The scale of control parameters was confirmed, and the stable state error of the control system was obtained. The simulation results show that the designed controller can eliminate initial attitude error of the spacecraft and resist the external disturbance,and the spacecraft attitude is maintained at the equilibrium point.

月球车工作前自身初始位置和姿态的确定对提高其导航能力具有重要作用,这一过程也称为初始化,初始化精度将严重影响其后续导航性能。针对月面特殊环境,现有的应用于地面环境的初始化方法不再适用这一问题,提出了一种静止条件下的月球车INS/CNS自主初始化方法。该方法分为粗初始化和精初始化两个阶段,粗初始化主要为精初始化提供初始参数。精初始化则综合利用惯性导航解算得到的水平速度、星光方位矢量和天体高度量测信息,并在考虑加速度计偏置引起的天体高度误差的基础上建立了精确的天体高度量测方程,精确估计月球车的初始位置和姿态。半物理仿真实验表明当陀螺漂移为0.1(°)/h、加速度计偏置为10?g、星敏感器精度为3″时,采用所提方法的初始位置估计精度优于30 m,初始姿态估计精度优于10″,是一种非常有效的月球车自主初始化方法。

The determination of initial position and attitude of lunar rover has great influence on its naviga-tion performance. The initialization accuracy has significant impact on the overall navigation accuracy. Since the traditional initial alignment method is not suitable for the lunar special environment, this paper presents a new autonomous initialization method for lunar rover based on INS/CNS integration. The method is divided into two stages: coarse initialization stage and fine initialization stage. The coarse initialization stage is mainly used to provide the initial parameters for the fine initialization stage. In the fine initialization stage, the horizontal velocity errors of INS, starlight vectors and star altitudes are used as measurements. The star altitude error caused by the biases of accelerometers is taken into account and its corresponding measurement equation is accurately established. Based on this, the position and attitude of the rover is estimated accurately. Semi-phy

从轨道、天线和指向控制角度,对小倾角轨道GEO卫星多波束天线对地覆盖特性进行建模仿真和优化研究。首先对小倾角轨道、天线波束安装与排布、倾斜轨道控制以及波束动态指向等问题进行了理论分析与建模,得到了基于姿态偏置控制的天线动态覆盖计算模型;接着构造了天线覆盖性能的评估指标,并从指向角度建立了覆盖特性优化模型;最后,工程算例仿真表明,通过天线指向优化既可以解决覆盖问题,又能改善对服务区的覆盖特性。研究结果表明,文中建立用于覆盖计算、评估和优化的模型合理正确,可用于天线覆盖仿真。

Simulation and optimization for antenna coverage characteristics of inclined GEO satellite with multi-beam antenna were presented from the view of satellite orbit,antenna and pointing.Firstly,the problems of inclined orbit,sub-beam installation,inclined orbit control and beam dynamic pointing were analyzed and formulated for dynamic coverage calculation. Secondly,the evaluation indexes of antenna coverage were constructed and optimization model was built for antenna coverage.Finally,the simulation results show that the uncover problems can be solved and the coverage characteristics can be improved by optimizing the antenna pointing.