绳系卫星系统中的周期运动

在椭圆轨道上飞行的绳系卫星系统的重要特征是系绳的方向角具有周期性运动，称为驻环。不稳定的驻环导致全系统的不稳定性。本文给出系统运动的数学模型、距离速率控制方法、求解驻环的数值迭代算法、驻环的稳定性和吸引域以及控制参数平面上驻环存在的区界和计算机仿真结果     

卫星液体晃动气浮台仿真试验系统的运动分析

本文通过边界元数值法求解了部分充液自旋球腔内的液体晃动问题。以流体运动的基本方程和系统运动的Ｅｕｌｅｒ动力学方程为基础，考虑了贮箱偏置、涡旋、重力及Ｃｏｒｉｏｌｉｓ力等因素对流体晃动和系统运动状态的影响，求解出液体的速度场，并在此基础上估算液体的能量耗散率和系统的章动时间常数     

卫星定位导航算法研究中卫星运动参数及导航星选取的仿真

在卫星定位导航系统的定位算法研究过程中，导航卫星星座中各卫星的运动参数，包括位置和速度参数，是进行研究的基础。因此在这一过程中，必须根据需要生成仿真卫星运动参数。针对定位卫星星座的特点，推导了适用于进行算法研究的导航卫星运动参数的仿真公式。在此基础上，依据卫星定位用户工作的方式特点，给出了一种判断用户机可视卫星的公式。作为算例，最后给出了以ＧＰＳ参数为基础的导航卫星星座运动参数的仿真结果     

基于遗传算法的空间自由漂浮机械臂系统运动规划

为了研究空间自由漂浮机械臂系统的运动规划问题,本文将其动力学模型转化为以关节角速度为控制输入变量的非线性控制系统状态方程,确定了以能耗最小为主要目标,同时满足一定约束条件的多种目标函数,提出了运用遗传算法求解最优控制变量的运动规划方法。同时,以机械臂从初始位形运动至指定终端位形的过程为仿真算例,对上述规划算法及其应用进行了分析和验证。仿真结果表明该算法有效可行,能够为机械臂系统的空间操作提供理论参考。     

绳系卫星系统二维平面运动和常规动力学

在假设了无质量的系绳和地球中心引力场后，绳系卫星系统在同一轨道平面内运动由子星－母星之间相对位置向量描述，亦即由该向量的长度（两星间距）变化和方位角的变化而决定。在引入距离速率控制算法之后，系统的动力学主要由方位角运动而定。当母星轨道为圆形时，系统运动状态具有极限点，而在椭圆轨道下则有极限环。采用了非线性动态系统的方法和技术来计算极限状态和分析它们的稳定特性以及运动的分形问题。用本文中方法对ＴＳＳ     

绳系卫星系统复杂模型研究

对绳系卫星系统提出一种仿真度更高的动力学模型，着重研究状态保持阶段的子星的振荡与姿态运动。主星设为质点，与系统质心相合，作圆轨道运动；子星取为三维刚体，系绳采用株式模型。除绳系统动能、引力位能及系绳弹性势能外，还考虑了系绳的结构阻尼，以及由系绳外皮包引起的弯曲力矩与扭转力矩。计算机辅助推导参与模拟计算程序设计。     

分布式卫星构形调整的协同规划研究

为降低分布式卫星系统构形调整规划的求解复杂性,提出一种协同规划策略,将构形最优调整问题划分为两层规划问题,包括整体协同的星位分配与首星位相位优化的顶层规划,以及各卫星自身调整策略优化的底层规划.通过响应面模型表达两层规划的耦合,以顶层规划驱动响应面的更新,顶层规划和底层规划交替迭代执行,重点探索有价值的区域,逐步接近最优解和达到高的求解精度.以多星多冲量构形调整问题验证协同规划策略的有效性,建立了相关模型,以低计算代价获得了示例问题的满意构形调整策略.提出的协同规划策略明显降低了问题求解的复杂度,大大减少了计算开销,且易于并行执行,为充分利用各卫星的计算资源实现自主规划提供了有价值的思路.     

用于微小卫星的微型双稳态电磁阀

为满足微小卫星对推进系统小质量、小体积、低功耗、低成本的要求，设计了一种微型双稳态电磁阀。采用尽量缩短阀门衔铁运动行程、合理设定衔铁两端间隙、用两个线圈实现开／关控制等措施，以及新的工艺和制造技术．实现了阀门的轻质、低功耗、快响应和长寿命。试验和实际应用结果表明，该阀门完全可满足微小卫星的应用要求。     

2005年世界军用卫星发展综述

2005年,世界军用卫星领域取得了很大发展。侦察卫星继续受到各国和地区的重视,特别是天基雷达卫星和导弹预警卫星。美国稳步推进军用通信卫星系统的升级换代,法国发射了新一代军用通信卫星。以欧洲伽利略系统为代表,美俄欧三大导航定位卫星系统都取得了重要进展。     

1999年世界卫星技术及应用发展动态

1999年,世界卫星技术及应用领域发展平稳。以铱星系统为代表的移动通信卫星系统受到资金问题的困扰,静止轨道通信卫星平台进一步向大型化方向发展;很多国家和地区在1999年发射了高分辨率遥感卫星或出台了高分辨率遥感卫星计划,体现出对高分辨率遥感的重视;欧洲出台了伽利...     

Tether-platform coupled control

From the control point of view, tethered systems pose several challenges, the major one pertaining to the regulation of the unstable system dynamics during the retrieval phase. On the other hand, the system configuration permits design of controllers using length rate, tension and offset schemes, which are not feasible with other satellites. Here “offset” refers to the time dependent variation of the tether attachment point at the platform end. The present paper studies several applications of the offset scheme in controlling the tethered systems. To that end, planar equations of motion of a space platform based Tethered Satellite System (TSS) are derived by the Lagrangian procedure. This is followed by representative results aimed at the offset control of platform pitch, tether attitude and vibration motions. The offset scheme is used for simultaneous control of platform and tether pitch motion. Finally the attention is directed towards simultaneous regulation of the platform pitch and longitudinal tether vibration. The numerical results clearly show considerable promise for the offset control scheme in regulating tether, platform and combined tether-platform dynamics.     

TETHERED SATELLITE SYSTEM ANALYSIS (1) — TWO-DIMENSIONAL CASE AND REGULAR DYNAMICS

The study on tethered satellite system (TSS) in two-dimensional in-planar motion is restricted in that the tether is assumed to be massless. The equations of motion are given in a spherical coordinate system to describe the magnitude (tether length) and direction angle of the position vector between the satellites. A length rate control algorithm is adopted, and the controlled motion of the directional angle by the algorithm will have a stable equilibrium state. The equilibrium state is a fixed point if the orbit of the base-satellite is circular, and a limit cycle if the orbit is elliptic. The value and stability of the equilibrium state are determined by the parameters of the control algorithm, and the bifurcation analysis is also given. Two typical TSS missions have been simulated.     

空间绳系机器人抓捕非合作目标的质量特性参数辨识

针对空间绳系机器人抓捕非合作目标/空间垃圾后需要对其进行回收/拖曳的精确控制问题,提出了一种利用抓捕后保持阶段的振动特性辨识目标参数的方法。首先,根据质量特性参数辨识的需要,推导了系统的动力学模型。不同于以往将本体卫星和被抓捕目标简化为质点的动力学模型,本文针对任意的目标抓捕位置,在考虑重力梯度影响的基础上,利用拉格朗日法获得系统各广义坐标的动力学公式。然后,分析非合作目标和系绳在后抓捕保持阶段的姿态运动。最后,在非合作目标与本体卫星没有任何信息交互的情况下,利用后抓捕阶段目标卫星和系绳特有的振动,并使用具有鲁棒性可遗忘因子的递推最小二乘法,提出了包括转动惯量和质心到任意抓捕点距离在内的质量特性参数辨识算法。     

Optimal control of a spinning double-pyramid Earth-pointing tethered formation

The dynamics and control of a tethered satellite formation for Earth-pointing observation missions is considered. For most practical applications in Earth orbit, a tether formation must be spinning in order to maintain tension in the tethers. It is possible to obtain periodic spinning solutions for a triangular formation whose initial conditions are close to the orbit normal. However, these solutions contain significant deviations of the satellites on a sphere relative to the desired Earth-pointing configuration. To maintain a plane of satellites spinning normal to the orbit plane, it is necessary to utilize “anchors”. Such a configuration resembles a double-pyramid. In this paper, control of a double-pyramid tethered formation is studied. The equations of motion are derived in a floating orbital coordinate system for the general case of an elliptic reference orbit. The motion of the satellites is derived assuming inelastic tethers that can vary in length in a controlled manner. Cartesian coordinates in a rotating reference frame attached to the desired spin frame provide a simple means of expressing the equations of motion, together with a set of constraint equations for the tether tensions. Periodic optimal control theory is applied to the system to determine sets of controlled periodic trajectories by varying the lengths of all interconnecting tethers (nine in total), as well as retrieval and simple reconfiguration trajectories. A modal analysis of the system is also performed using a lumped mass representation of the tethers.     

Stability of a ring of connected satellites

The motion of a large number of artificial satellites connected in a ring one after another by tethers of variable length is considered. Every satellite is supposed to have a control system programmed according to some tether tension law as a function of the distance between tethered satellites. The effect of the tension control law on the stability of stationary rotation of this ring is investigated. The final stability condition includes two requirements: 1) the nominal tether tension should be less than a definite limit equal, up to numerical coefficient, to one satellite weight divided by the number of satellites; 2) tether tension should decrease (or remain constant) with the increase of the distance between tethered satellites. In dynamics the artificial rings of this kind are much like their natural prototype—meteor rings. On the other hand, the investigation of the artificial rings contributes to developing an unexpected view upon meteor rings, suggesting a model of an imaginary equivalent string.     

一种用于空间系绳卷取的自适应机构

针对空间绳网系统的缆绳收口要求,介绍了一种由双转子电机、双卷筒和自由导绳套筒组成的自适应缆绳卷取机构,给出了机构的设计思路。通过建立其系统动力学方程,据此得到系统各状态变量的稳态解,理论和实验分析缆绳卷取过程的特性,证实此卷取机构的有效性和一定的适应性,为类似空间绳系的卷取机构设计提供参考。     

绳系卫星系统的运动与控制

绳系卫星系统的运动与控制分析,是绳系卫星应用的基础。本文的数学模型考虑了作用在子星、主星及系绳上的空气阻力以及在伸展与收回阶段主星与系绳之间的质量传递,给出了相应的具体的计算式。应用该数学模型,本文对现有的几种主要控制法,进行了模拟计算,作出评审意见。     

Ground assisted rendezvous with geosynchronous satellites for the disposal of space debris by means of Earth-oriented tethers

Previous studies have shown that extended length Earth-oriented tethers in the geosynchronous (GEO) region can be used to re-orbit satellites to disposal orbits. One such approach involves the extension of a GEO based tether, collection of a debris object, and retraction of the tether, which transfers the retracted configuration to a higher energy orbit for debris disposal. The re-extension of the tether after debris disposal returns the configuration to the near-GEO altitude. The practical feasibility of such a system depends on the ability to collect GEO debris objects, attach them to a deployed tether system, and retract the tethers for transfer to the disposal orbits.This study addresses the collection and delivery of debris objects to the deployed tether system in GEO. The investigation considers the number, type and the characteristics of the debris objects as well as the collection tug that can be ground controlled to detect, rendezvous and dock with the debris objects for their delivery to the tethers system.A total of more than 400 objects are in drift orbits crossing all longitudes either below or above the geostationary radius. More than 130 objects are also known to librate around the stable points in GEO with periods of libration up to five or more years. A characterization of the position and velocity of the debris objects relative to the collection tug is investigated. Typical rendezvous performance requirements for uncooperative GEO satellites are examined, and the similarities with other approaches such as the ESA's CX-OLEV commercial mission proposal to extend the life of geostationary telecommunication satellites are noted.     

Results of the parabolic flight tests of the rapunzel deployer

The tether assisted re-entry of small payloads is a highly interesting tool for space transportation especially for the return of small payloads from Space Station ISSA. The small tether mission Rapunzel was initiated in 1991 by the Institute of Astronautics, TU München and the Kayser-Threde Company, to design a low cost and feasible tether experiment for the verification of the tether assisted re-entry. Together with the Samara State Aerospace University, Russia, a mission concept on a Russian Resurs or Photon capsule was developed. Based on this mission a deployer has been designed, mainly based on technology of the textile industry, which insures high reliability at low cost. Recently a similar configuration is being discussed for the ESA-TSE mission.The main work during the recent time was the development and test of the breadboard model of the deployer system. After successfully completing initial ground tests with the deployer, further tests during the ESA Parabolic Flight campaign in November 1995 were conducted. After a short introduction of the overall mission scenario, the planned configuration in orbit, this paper will present the results of the microgravity test campaign onboard the KC-135 aircraft and compare them with the ground test. The deployer showed a good performance during all tests, including ejection of the end-mass, deployment, and braking. Problems that occurred during the tests will be discussed, and solutions for the detected flaws and the results of the redesign now in progress will be presented. These verifications have shown the feasibility of the concept and will lay the base for the planned development of the flight model of the deployer.