通信卫星模拟器通用基础平台设计研究

卫星模拟器主要是对地面测控系统遥测接收和遥控指令发送的工作状态进行检查和验证,验证地面测控系统设备正确性,提高地面测控系统对卫星故障的应急处理能力等。本文从软件系统架构高度对不同卫星各分系统模型共有属性进行抽象提炼和设计研究,提高软件架构及模块的复用性、扩展性和维护性,通信卫星模拟器通用基础平台可同时验证不同卫星对地面测试系统的任务要求,使不同卫星模拟器的建设和地面系统测试支持可以纳入一个规范化、通用化的系统框架中。     

The Dynamic Stability of a Dual-Spin Satellite

The attitude stability of a dual-spin satellite containing energy disipators on both bodies is investigated. Following Mingori, a symmetrical configuration of the satellite with a mass-spring-dashpot damper on each part is considered, and some new stability results are derived by the application of the Routh-Hurwitz criterion. lt is indicated that the Routh-Hurwitz criterion gives only sufficient conditions of stability for the dual-spin satellite considered. A criterion which is believed to represent both the necessary and sufficient condition of stability is presented here and this is used to check the stability of two specific designs of the dual-spin satellite.     

Global communication using a constellation of low Earth meridianorbits

The concept of meridian orbits is briefly reviewed. It is shown that, if a satellite in the meridian orbit makes an odd number (>1) of revolutions per day, then the satellite passes over the same set of meridians twice a day. Satellites in such orbits pass over the same portion of the sky twice a day and every day. This enables a user to adopt a programmed mode of tracking, thereby avoiding a computational facility for orbit prediction, look angle generation, and auto tracking. A constellation of 38 or more satellites placed in a 1200-km altitude circular orbit is favorable for global communications due to various factors. It is shown that appropriate phasing in right ascension of the ascending node and mean anomaly results in a constellation wherein each satellite appears over the user's horizon one satellite after another. Visibility and coverage plots are provided to verify the continuous coverage     

Analysis of reaction torque-based control of a redundant free-floating space robot

Owing to the dynamics coupling between a free-floating base and a manipulator,the non-stationary base of a space robot will face the issue of base disturbance due to a manipulator's motion.The reaction torque acted on the satellite base's centroid is an important index to measure the satellite base's disturbance.In this paper,a comprehensive analysis of the reaction torque is made,and a novel way to derive the analytical form of the reaction torque is proposed.In addition,the reaction torque null-space is derived,in which the manipulator's joint motion is dynamically decoupled from the motion of the satellite base,and its novel expression demonstrates the equivalence between the reaction torque null-space and the reaction null-space.Furthermore,the reaction torque acted as an optimization index can be utilized to achieve satellite base disturbance minimization in the generalized Jacobian-based end-effector Cartesian path tracking task.Besides,supposing that the redundant degrees of freedom are abundant to achieve reaction torque-based active control,the reaction torque can be used to realize satellite base attitude control,that is,base attitude adjustment or maintenance.Moreover,because reaction torque-based control is a second-order control scheme,joint torque minimization can be regarded as the optimization task in reaction torque-based active or in-active control.A real-time simulation system of a 7-DOF space robot under Linux/RTAI is developed to verify and test the feasibility and reliability of the proposed ideas.Our extensive empirical results demonstrate that the corresponding analysis about the reaction torque is correct and the proposed methods are feasible.     

Stability and Control of a Trap Mode in Synchronous Orbit

The possibility of the existence of a trap mode in synchronous orbit is investigated. It is shown that when such a mode exists, certain parameters of the satellite orbit may soon attain undesired equilibrium values, thus complicating the normal stationkeeping operation of the spacecraft. A state-dependent control force which eliminates any such trap mode in the satellite orbit is then investigated.     

Reliability of the Station-Keeping Activator Subsystem of a Geostationary Satellite

The reliability of the station-keeping activator subsystem of a geostationary satellite using electric thrusters is analyzed by modeling the probabilistic behavior of the system as a homogeneous Markov process. The method is applied to the particular case of a 400-kg satellite using 1.5-mN cesium contact electric thrusters. lt is shown that certain system configurations offer a mass improvement without loss of reliability.     

一种无塔校准方法研究

在地面卫星测控系统中,目前使用较多的有塔校准技术具有一定的局限性,为了克服这种局限性,本文针对已有的卫星测控系统设备提出一种无塔校准方法,给出了具体无塔校相和无塔校零的实现方法.     

一种单低轨星北斗备份与辅助方法及在轨验证

在低轨卫星上搭载导航载荷,为北斗系统提供有效的备份及辅助性能提升手段,是近年来卫星导航领域专家学者探讨的热点问题.针对全球卫星导航系统信号在恶劣电磁环境下的受扰问题,提出了一种利用单颗低轨卫星实现北斗备份和辅助的方法.北斗备份是指通过单颗低轨星独立为地面用户提供导航服务.北斗辅助是指利用单颗低轨星信号及信息,为地面用户...     

状态诊断知识描述语言的设计与实现

卫星状态诊断知识描述语言(SSDKDL)是针对卫星状态诊断专家系统(SSDES)的要求而设计的一种专用语言,该语言主要用于卫星状态诊断原始知识的描述,它的设计与实现为卫星管理领域专家提供一个知识规则表述的语言基础。本文就该语言的设计原理及实现方法进行系统阐述。     

卫星测控系统多通道地面测试平台设计

一般地面测试平台无法同时支持卫星对地测控测试和中继测控测试,需要开发多通道地面测试平台满足卫星测试需求.基于此,对卫星测控系统多通道地面测试平台设计进行讨论,采用彼此相对独立的2套地面测试设备,通过特定连接关系同时接入卫星对地测控链路和中继测控链路中,实现卫星多通道测控并行测试和地面测试设备的双机备份,在无须更改外部连接关系的基础上,通过模式选择、参数配置,可适用于不同模式下卫星测控通道地面测试需求.经过分析,该平台具有功能完善、适用性广、稳定性好等优点,已应用于某卫星的地面测试.测试结果表明,平台运行稳定,具有良好的使用效果.     

卫星通用测控模拟器设计与实现

介绍了一种适用于不同型号、不同环境的卫星通用测控模拟器的设计实现方法和应用现状及发展前景。该设备在70MHz以下完全采用了数字化处理，可通过连接某一频段内上／下变频器实现射频通用测控模拟器。     

Stabilization of a Satellite via Specific Optimum Control

The Optimum Stabilization of a tumbling satellite via Hamilton-Jacobi theory has been reported by one of the authors before in ?On the optimum stabilization of a satellite? [2]. This companion paper discusses the synthesis of a specific optimum control law for the same problem and compares the results with the optimum solution. It is shown that a specific optimum control law yields, acceptable performance while being much easier to instrument than the optimum control law.     

Tidal Models in a New Era of Satellite Gravimetry

The high precision gravity measurements to be made by recently launched (and recently approved) satellites place new demands on models of Earth, atmospheric, and oceanic tides. The latter is the most problematic. The ocean tides induce variations in the Earth's geoid by amounts that far exceed the new satellite sensitivities, and tidal models must be used to correct for this. Two methods are used here to determine the standard errors in current ocean tide models. At long wavelengths these errors exceed the sensitivity of the GRACE mission. Tidal errors will not prevent the new satellite missions from improving our knowledge of the geopotential by orders of magnitude, but the errors may well contaminate GRACE estimates of temporal variations in gravity. Solar tides are especially problematic because of their long alias periods. The satellite data may be used to improve tidal models once a sufficiently long time series is obtained. Improvements in the long-wavelength components of lunar tides are especially promising. This revised version was published online in August 2006 with corrections to the Cover Date.     

Attitude control of a bias momentum satellite using moment ofinertia

Analysis on the attitude controller based upon moment of inertia distribution for a bias momentum satellite is discussed. Spacecraft moment of inertia distribution is represented in the form of product of inertia terms in the system inertia matrix. The product of inertia between orthogonal body axes of the satellite is used to build a controller which controls the nutational motion caused by the angular momentum of the wheel. The attitude controller in the pitch axis controlling the pitch motion as well as nutational dynamics in the roll/yaw planes is analyzed in detail. Analytic expressions using linearized equations are derived providing further insight into the dynamic coupling effect among orthogonal body axes     

Comments on Stabilization of a Satellite

An expression is derived for the cost resultingfrom the stabilization of a satellite using aspecific optimal control (SOC). An exampleis given in which the optimal and SOC yieldvirtually identical costs.     

Satellite Librational Damping Using a Quasi-Feedback Solar Controller

The feasibility of developing a simple quasi-feedback solar attitude controller is explored. The case of arbitrarily-shaped satellites carrying two pairs of solar surfaces in circular orbits is considered. An approximate analytical approach is used to synthesize the suitable open-loop control relations enabling decay of the satellite librations. The quasi-feedback control scheme suggested here is found to be quite effective in damping the pitch motion. The proposed control approach appears to be particularly attractive as it requires knowledge of the librational angle and velocity only at a fixed satellite position in orbit.     

卫星状态智能诊断知识库设计方法

及时准确地发现并处理卫星出现的异常,对卫星运控管理非常重要,关系到卫星在轨使用寿命。设计卫星状态智能诊断知识库,基于该知识库构建的卫星在轨状态自动化报警诊断系统,能够辅助卫星管理人员进行运控管理,这对提高工作效率、降低管理成本、提高卫星安全性具有重要意义。     

Tethered dual spacecraft configuration: a solution to attitude control problems

A new dual spacecraft configuration comprising of two spacecraft halves judiciously connected through extremely short tethers is proposed. The simple tethered configuration induces stabilizing torques when subjected to attitude disturbances, thus ensuring 3-d pointing stability of both the satellite platforms. The enhanced system performance obtained using tethers enables a much greater flexibility in the choice of satellite mass distribution. Three particular TSS models involving parallel tethers, a `parachute-like' conical tether layout as well as a single tether connection have been considered. A detailed numerical response simulation shows that these modes of tether attachments bring about a radical change in the satellite attitude behavior from the nominal one involving relatively large librational amplitudes or instability to a virtually fixed desired orientation. Of these, the parachute configuration appears to be superior. The passive nature of the proposed mechanisms using tether lengths on the order of merely a couple of meters needed for small and medium size systems makes the concept particularly attractive for future space missions. Finally, it is felt that the proposed tethered dual satellite systems may offer a simple answer to three-axis attitude control problems.     

Precision Synchronization of Satellites in Inclined Orbits

Synchronization between an Earth station and a satellite in geostationary orbit can be accomplished by repeatedly transmitting sync burst signals and making small timing corrections. However, when a satellite is in an inclined nonsynchronous orbit, such as a navigation satellite, the problem is more complex due to the high relative velocity of the navigation satellite relative to the ground. One possible solution to the problem is examined by employing a satellite in geostationary orbit to communicate with the navigation satellite. It is shown that the uplink delay to the navigation satellite can be deduced to an accuracy of about 1 ns by making a single round trip transmission.     

基于多目标进化算法的卫星机动路径规划

建立了带挠性帆板卫星姿态控制问题的多目标优化模型,并基于一种多目标优化精英进化算法,规划卫星姿态机动的最优路径,以进一步提高卫星姿态控制系统的控制性能.仿真结果表明,所提方法只需运行一次,便能够有效地规划出一组多样性较好的非支配路径解,供决策者在不同的工作目标下选择,有效地缓解了卫星快速性、姿态稳定度、卫星机动所激发的帆板低振动强度之间的矛盾.