红外地平仪姿态测量误差模型

分析得出地球扁率和红外辐射是扫描式红外地平仪测量误差的主要原因。针对地球扁率，基于方位角的确定，分别给出了滚动角和俯仰角的测量误差模型。在地球红外辐射方面，给出了确定地平仪扫人、扫出点位置的方法，进而给出地球红外辐射误差的计算方法。最后，通过算例，给出了有关仿真结果，对方法的有效性进行了验证。     

一种利用地球敏感器的星光导航方法

针对直接敏感地平的红外地平仪-星光导航系统精度低的问题,提出通过建立扁率误差补偿函数,研究扁率引起的姿态角测量误差;建立地心矢量的姿态角误差模型,通过修正地球扁率误差来补偿姿态角,对卫星施加姿态偏转指令调整地心矢量偏移。同时基于SODERN地球红外辐射模型,考虑红外辐射强度随纬度和季节的变化建立真实红外辐射曲线,通过滤波算法获得精确的地球切线边缘的量测信息,提高红外地平仪测量精度。仿真结果表明,该方法有效提高了基于红外地平仪的星光导航定位方法的可靠性和精度,导航位置误差能达到500m左右,较原有系统提高3倍以上。     

一种用于静态红外地球敏感器的高效算法

为提高微纳卫星的姿态检测效果，针对静态红外地球敏感器的全景鱼眼成像特点，以单张红外成像为研究对象建立成像模型，提出了间隔向量积与t Location-Scale分布置信区间均值结合的算法。将红外成像投影到空间球体上形成空间像点环；在像点环上间隔取点做向量积，得到当前目标姿态角的样本集合；通过t Location-Scale分布进行极大似然估计，得到目标姿态角样本均值和方差的估计量；再次计算1σ置信区间内样本均值，最终得到目标姿态角的估计值。相比于原算法，目标姿态角在±10°内的标准差由0.06°下降为0.03°，精度提高了50%。另外为避免迭代收敛的耗时问题，给出了应用于实际工程的查表法，使运算速度提高了87%，提升了静态红外地球敏感器的测量精度和效率。     

The deep space 1 extended mission

The primary mission of Deep Space 1 (DS1), the first flight of the New Millennium program, completed successfully in September 1999, having exceeded its objectives of testing new, high-risk technologies important for future space and Earth science missions. DS1 is now in its extended mission, with plans to take advantage of the advanced technologies, including solar electric propulsion, to conduct an encounter with comet 19P/Borrelly in September 2001. During the extended mission, the spacecraft's commercial star tracker failed; this critical loss prevented the spacecraft from achieving three-axis attitude control or knowledge. A two-phase approach to recovering the mission was undertaken. The first involved devising a new method of pointing the high-gain antenna to Earth using the radio signal received at the Deep Space Network as an indicator of spacecraft attitude. The second was the development of new flight software that allowed the spacecraft to return to three-axis operation without substantial ground assistance. The principal new feature of this software is the use of the science camera as an attitude sensor. The differences between the science camera and the star tracker have important implications not only for the design of the new software but also for the methods of operating the spacecraft and conducting the mission. The ambitious rescue was fully successful, and the extended mission is back on track.     

基于地月信息的奔月探测器自主光学导航

基于地月信息提出了一种奔月转移轨道的自主光学导航算法。该算法首先利用导航相机得到的地球和月球边缘图像与地、月几何形状模型，运用扩展源的空间获取算法导出地心和月心对应的像素，然后利用地心和月心像素、探测器的惯性姿态和该观测历元的地、月星历信息，通过基于UD分解的递推加权最小二乘算法确定了探测器轨道。还引入导航系统的可观度定义来分析了导航系统的可观性，数学仿真结果表明导航的位置误差小于30km，速度误差小于0．3m／s，证明该自主光学导航算法是有效的。     

基于OMNeT++的卫星姿态控制系统仿真

针对三轴稳定卫星的姿态控制系统,在离散事件仿真平台OMNeT 的基础上,建立了一个以星敏感器和陀螺为敏感器,反作用飞轮为执行机构的闭环控制仿真系统。采用双矢量定姿算法和PID控制算法,对该卫星在对地定向模式下的控制精度进行了仿真。仿真结果清晰地反映了星敏感器和反作用飞轮输出延时对控制精度的影响。整个仿真系统符合面向对象和模块化的程序设计理念,并实现了仿真程序的重用。     

A star scan/attitude determination experiment conducted on the geostationary meteorological satellite

The paper discusses the results of a star scan test performed on the spin stabilized Geostationary Meteorological Satellite (GMS) and used for the purpose of determining the vehicle's spin state. The test data shows that the payload camera, normally used for imaging the Earth and its cloud cover, sees a sufficient number of stars to provide for a rapid and accurate spin state update and that Earth and Sun blockage constraints have essentially no impact on the star detection process. Also presented are analytical results regarding how many stars constitute an observable set, the accuracy achievable using the five most easily detected stars, how star location affects state uncertainty, and why certain state components are more easily determined than others. The primary test conclusion is that star scan offers an attractive alternative to the presently used Earth horizon and landmark tracking attitude determination methods, as far as accuracy and computational complexity are concerned, provided the occasional star viewing intervals that are required do not interfere with the meteorological scheduling of the camera.     

超低轨卫星气动力辅助轨道控制研究

针对超低轨卫星所受气动力显著的特点,提出一种利用气动舵的气动力辅助轨道控制方法。通过分析大气旋转、卫星所处空间位置以及气动舵偏转角度对气动力的影响,对提出的轨道控制方法进行了优化。该方法通过调整气动舵产生连续微小的气动力对卫星轨道进行控制,使各轨道要素均保持在误差容限范围内。将其应用于太阳同步轨道上的对地观测卫星,仿真结果表明,该方法可以在卫星姿态保持三轴对地稳定的前提下,实现轨道保持控制,保证任意纬度下卫星实际位置与标称轨道位置偏差在给定范围内。     

Elimination of relative secular drift of orbits of two satellites caused by polar oblateness of the Earth

A method of elimination of relative secular drifts in satellite formations is suggested for the case of influence of a perturbation due to polar oblateness of the Earth. The method is applied to eliminate relative secular drifts in the case when a satellite is controlled using an engine mounted along its orientation axis (the satellite is supplied with a passive magnetic attitude control system) and with the help of a solar sail installed on one of the satellites. Analytical results are confirmed by numerical simulation.     

基于地轴矢量解算的SINS无纬度支持自对准方法

针对无纬度条件下SINS初始对准问题，提出了一种基于地轴矢量解算的对准方法。在静止基座下，利用陀螺仪敏感地轴矢量，直接建立导航系轴向矢量在载体系的正交投影，解析式确定姿态矩阵；晃动基座条件下，根据惯性系重力矢量观测，构建以地轴矢量为旋转轴的两组等角旋转矢量序列，利用QUEST算法求解旋转四元数实现对地轴矢量的优化解算，并以此建立导航系轴向矢量的载体惯性系投影，最后利用陀螺跟踪载体系相对惯性系的变化，确定载体系相对导航系的姿态关系。静止基座解算实验表明直接解析式对准与传统的解析式对准精度相当，但解算效率得到了提高；晃动基座仿真与船载实验均表明基于四元数的地轴矢量优化解算在精度上要优于三矢量几何解算方法，引入低通滤波环节后，对准精度进一步提高。     

天基照相跟踪空间碎片批处理轨道确定研究

随着国内外天基观测空间碎片研究的展开,文章提出了利用跟踪卫星的CCD(Charge
Coupled Device)相机对空间碎片进行轨道探测的方法,首先建立了CCD照相观测模型和基于 照相观测 的空间碎片批处理轨道确定模型。通过对CCD相机底片归算方法的分析可知,利用
CCD相机所获得的观测数据与跟踪卫星的姿态无关,且其精度只与测量和坐标转换计算的精 度有关,在测量和计算中可获得较高的精度。分别对分布密度较高的低轨道和地球同步 轨道区域的空间碎片进行了定轨分析。仿真结果表明,定轨时采用两个跟踪弧段的照相数据 定轨精度大大高于一个弧段照相数据的定轨精度;跟踪卫星距离空间碎片越近,定轨精度越 高;低轨道空间碎片的定轨精度高于地球同步轨道上的空间碎片定轨精度。
     

Inertially fixed pitch stabilization of satellites by solar radiation pressure

Utilization of solar radiation pressure to stabilize the pitch attitude of an unsymmetrical satellite along an inertially-fixed orientation is investigated. A controller employing two rotatable highly reflective control surfaces is proposed and a control strategy involving both nominal and feedback controls is synthesized. Accounting for the apparent annual motion of the Sun, the validity of the concept throughout the year is established through a stability analysis of the system. The influence of the Earth's shadow on the controller performance is also analyzed. The speed of response as well as the pointing accuracy capabilities of the system appear to be quite acceptable for long-life scientific missions.     

A fault-tolerant magnetic spin stabilizing controller for the JC2Sat-FF mission

This paper presents a spin-stabilization algorithm for the Japan Canada Joint Collaboration Satellite-Formation Flying (JC2Sat-FF) mission using magnetic actuation only. It is shown that under a reasonable assumption on the Earth’s magnetic field, the resulting control law is asymptotically stabilizing for an axisymmetric spacecraft, even under the failure of up to two magnetic torque rods and magnetic torque rod saturation. It is also stabilizing under quantization. The satellite motion remains stable under control outages, meaning that the error can be reduced by implementing the control intermittently. The effectiveness of the control law is demonstrated using a high fidelity attitude control system simulator for the JC2Sat-FF satellite.     

采用单框架控制力矩陀螺群的卫星侧摆机动控制研究

研究使用单框架控制力矩陀螺群 (SGCMGs)进行卫星姿态侧摆机动控制。研究频繁机动情况下由五棱锥构形和金字塔构形陀螺群进行侧摆机动控制的可行性 ,并探讨陀螺群构形奇异的避免问题。针对不同的陀螺群构形设计了不同的控制律 ,并比较两种构形的控制特性的异同。仿真结果验证了使用SGCMGs实现侧摆机动控制的有效性。     

Space flight visual simulation.

In this paper, based on the scenes of stars seen by astronauts in their orbital flights, we have studied the mathematical model which must be constructed for CGI system to realize the space flight visual simulation. Considering such factors as the revolution and rotation of the Earth, exact date, time and site of orbital injection of the spacecraft, as well as its orbital flight and attitude motion, etc., we first defined all the instantaneous lines of sight and visual fields of astronauts in space. Then, through a series of coordinate transforms, the pictures of the scenes of stars changing with time-space were photographed one by one mathematically. In the procedure, we have designed a method of three-times "mathematical cutting." Finally, we obtained each instantaneous picture of the scenes of stars observed by astronauts through the window of the cockpit. Also, the dynamic conditions shaded by the Earth in the varying pictures of scenes of stars could be displayed.     

上面级在发射轨道的辐射外热流分析

研究发射轨道的外热流是进行火箭上面级和卫星热控设计的基础。文章给出了基于一组轨道和姿态参数的太阳矢量与地球矢量的计算方法。针对圆柱外形的上面级,分析了其发射轨道外热流的变化规律,利用该计算方法计算了太阳矢量,而太阳矢量在长时间滑行段相对固定,太阳矢量和受晒因子随发射时间而发生大幅度的变化,使得外热流工况变得非常复杂。通过对太阳定姿且绕箭体纵轴慢旋,可改善火箭上面级的飞行热环境,简化卫星和上面级的热控系统设计。     

Behavior of tethered debris with flexible appendages

Active exploration of the space leads to growth of a near-Earth space pollution. The frequency of the registered collisions of space debris with functional satellites highly increased during last 10 years. As a rule a large space debris can be observed from the Earth and catalogued, then it is possible to avoid collision with the active spacecraft. However every large debris is a potential source of a numerous small debris particles. To reduce debris population in the near Earth space the large debris should be removed from working orbits. The active debris removal technique is considered that intend to use a tethered orbital transfer vehicle, or a space tug attached by a tether to the space debris. This paper focuses on the dynamics of the space debris with flexible appendages. Mathematical model of the system is derived using the Lagrange formalism. Several numerical examples are presented to illustrate the mutual influence of the oscillations of flexible appendages and the oscillations of a tether. It is shown that flexible appendages can have a significant influence on the attitude motion of the space debris and the safety of the transportation process.     

星载辐射计动平衡概述及在轨动平衡技术研究

作为卫星在轨对地探测的有效载荷,星载辐射计在轨扫描转动时的动平衡特性直接影响卫星在轨探测精度和姿态稳定度。文章介绍星载辐射计动平衡技术研究现状和发展趋势,并基于现有地面动平衡技术的局限和型号发展需求提出在轨动平衡技术的初步设想,阐述了在轨动平衡配平技术、测量技术和实时调整反馈控制技术,可为今后类似旋转式星载辐射计的动平衡设计和动平衡控制方法提供参考依据。     

An analysis of low-frequency component in microacceleration measurements made onboard the <Emphasis Type="Italic">Foton M-2</Emphasis> satellite

The low-frequency component is investigated in the data of measurements performed onboard the Foton M-2 satellite with the three-component accelerometer TAS-3. Investigations consisted in comparison of this component with its calculated analog found from a reconstruction of the satellite’s attitude motion. The influence of the Earth’s magnetic field on the accelerometer readings is discovered by way of spectral analysis of the functions representing the results of determining the low-frequency microacceleration by two methods. After making correction for this influence, the results obtained by these two methods coincided within a root-mean-square error of less than 10^?6 m/s².