一种卫星延时遥测分类处理和下传方法

延时遥测是掌握卫星在测控站不可观测弧段工作状态的重要手段,在深入分析卫星遥测参数特征的基础上,对卫星遥测参数按类型进行分类处理,提出了对各类延时遥测参数不同的处理、存储和下传方法;实现了下行遥测码速率受限情况下优化利用卫星存储资源和下行信道资源,使地面可准确掌握卫星在不可观测弧段的工作状态,尤其为不可观测弧段异常问题的判断和定位提供有效的遥测数据支持;实现了延时遥测数据的自主存储和下传,大大减轻了地面测控站的控制工作量.该延时遥测方法已成功应用于某卫星,取得了良好的应用效果.     

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。     

低轨卫星可控式冗余分包遥测技术

随着卫星功能日趋复杂,遥测参数越来越多,处理要求越来越快,遥测设计面临越来越大的压力,必须拓展新的设计思路.本文讨论了一种低轨卫星可控式冗余分包遥测技术,更好地缓解遥测信道“瓶颈”,满足用户多样化的遥测需求,提高卫星遥测能力.该设计采用PCM（Pulse Code Modulation,脉冲编码调制）遥测和分包遥测相结合的方案,在信道资源有限,遥测参数庞大、用户需求多样的约束条件下,通过星载软件模式控制的方法实现了动态可编程遥测处理和遥测数传通道的冗余处理,提高了遥测信道的资源利用率、遥测设计的灵活性和系统的可靠性,该技术已成功应用于某在轨卫星,并被多颗在研卫星所采用.     

同步轨道通信卫星天线覆盖图在轨测试方法

同步轨道通信卫星天线覆盖图在轨测试的目的是检验卫星入轨后上下行覆盖图与设计覆盖区域的一致性,以及太阳照射产生的天线热变形等因素对覆盖特性的影响。针对卫星上常用的固定赋形波束天线、区域波束天线和可移动点波束天线等类型的星载天线在轨测试问题,分析了几种在轨测试方法的原理,包括偏置卫星姿态法、转动天线平台法以及使用移动测量站的方法,提出了偏置卫星姿态法中融合转发器遥测参数判决和多站联合在轨测试的解决方案,有效解决了既要节省宝贵的燃料又要尽可能测量多条切线方向图的工程难题。对真星的固定赋形波束天线和可移动点波束天线进行了在轨测试,测试结果与实际特性吻合很好,验证了方法的可行性。最后,针对融合遥测参数判决的多站联合偏置卫星姿态法的测量不确定度进行了分析。     

AOS标准在海洋动力环境探测卫星中的应用

以我国在轨成功运行的首发海洋动力环境探测卫星为例,描述了在我国遥感卫星中首次全面采用AOS(高级在轨系统)标准实现整星数据流统一动态管理的数据管理方案。该方案采用AOS标准的源包多路复用机制实现对卫星遥测数据的动态调度传输,提高了信道利用率;采用虚拟信道的动态调度机制在数传信道和激光通信信道实现将卫星的低速平台数据和高速有效载荷业务数据进行动态合路传输,从而实现整星信息的综合利用,增强了卫星自主管理能力。针对卫星在轨应用情况,对该方案的优点进行了总结。     

动量轮在轨状态可靠性贝叶斯网络建模与评估

卫星动量轮在轨运行环境复杂,并且无失效数据,难以利用传统方法进行可靠性建模与评估。为此,提出一种利用贝叶斯网络融合动量轮各种试验信息及轴温和电流等遥测数据的可靠性建模与评估方法。基于失效分析建立贝叶斯网络拓扑结构,根据试验数据估计网络参数,而后,通过贝叶斯网络的推理得到动量轮可靠度的点估计和区间估计,并利用在轨遥测数据实时评估动量轮可靠性,获得动量轮可靠性变化趋势比较明显的遥测数据取值区间。该方法对动量轮实时状态监控具有一定的理论和实践意义。     

小波变换在遥测数据处理中的应用

采用离散小波变换方法对在轨卫星遥测数据进行处理,利用噪声和信号在不同小波尺度上的性质不同．基于极大极小化思想选取去噪处理中的阈值,达到分离噪声和信号的目的。结果表明：利用小波变换可有效消除卫星遥测数据的噪声。     

基于新陈代谢GM（1,1）模型的导弹遥测故障预测算法

在人工监视遥测关键参数是否超出阈值范围以判断导弹故障的传统模式基础上,对GM（1,1）预测模型进行了改进,研究了基于新陈代谢的GM（1,1）预测算法对遥测参数实时预测效果.该算法能不断去掉最老的信息,充分利用最新的信息,避免了预测模型老化的现象;由于用于预测的数列维度较少,便于计算,能够保证算法的实时性.用MATLAB编程实现算法,比对实测数据的预测值与实际值,并进行误差分析.结果表明,该算法对遥测参数的预测精度较高,可为及时发现导弹故障提供科学的依据.     

S波段活动测控设备自动化程度提高研究

针对日益繁重的在轨卫星长期管理工作,从实现中心透明测控模式的角度出发,就如何提高S波段活动测控设备自动化程度和操作可靠性,解决人员精力与卫星长期管理质量之间的矛盾提出解决思路,并重点讨论了提高RMCS、监控分系统、测距测速分系统、遥测分系统自动化程度的方法。     

航天器动作状态的可视化遥测方法研究

遥测是航天器在轨状态监控的重要手段,随着任务形式逐渐复杂,航天器在轨动作也越来越多,常规的信息遥测手段难以满足要求。针对该问题,本文提出一种可视化遥测方法,使用相机在轨拍摄图像对航天器动作过程进行直观监测,并通过分析计算,获得航天器动作的速度、位移等关键信息,通过月地高速再入返回飞行器在轨验证,证明了该方法的有效性。     

一种基于投影寻踪的航天器健康评估方法

针对常用健康评估方法在航天器测控管理领域应用过程中出现的通用性、易用性和适用性方面的不足,提出了一种基于投影寻踪评估模型的航天器健康评估方法.该方法首先计算得出分系统运行状态的可信度;然后利用卫星故障预案和故障实例构建投影寻踪评估模型,自动获取运行状态指数评价权重;最后通过构建等级评价标准对航天器健康状态进行评估.以某在轨卫星为例进行仿真测试,验证结果显示该方法所构建模型简便且易于升级维护,评估结果与实际情况吻合,对解决实际的工程问题具有实用价值.     

卫星热控涂层地面模拟试验与在轨验证比对分析

卫星在轨运行期间,热控涂层要经受空间复杂环境效应的影响,其光学和热控性能逐渐下降,影响卫星可靠性和寿命。本文利用卫星搭载技术,完成热控涂层5年的在轨试验,验证空间多因素环境对热控涂层的影响。同时,利用地面模拟试验装置,模拟空间质子、电子、紫外等5年的辐照剂量对热控涂层的作用。对在轨试验结果进行解读和分析,并与地面模拟试验结果进行比对。结果显示,在搭载试验和地面试验前,热控涂层太阳吸收比（α_s）为0.12,经5年在轨搭载试验后,α_s退化为0.23。经地面模拟试验后,α_s退化为0.22。搭载试验和地面试验的热控涂层性能均呈现线性退化规律,表明在确定的轨道环境和固定的剂量率条件下,热控涂层的退化与环境作用时间正相关,同时验证了地面试验的有效性。     

Strategies for in-orbit calibration of drag-free control systems

Drag-Free Satellites (DFS) are a class of scientific satellite missions designed for research on fundamental physics as well as geodesy. They consist, basically, of a small inner satellite (test mass) located in a cavity inside a larger satellite, the normal one. The Drag-Free Attitude Control System (DFACS) is the most complex technology on-board these satellites. This key technology allows the residual accelerations on experiments on board the satellites to be significantly reduced. In order to achieve this very low disturbance environment (for some missions <10⁻¹⁴ g) the drag-free control system has to be optimized. This optimization process is required because of uncertainties in system parameters that demand a robustness of the control system. This paper will present approaches for in-orbit calibration of drag-free control systems. The discussion includes modeling, with scale factors and cross couplings, possible excitation signals, comparison of different parameter identification/estimation methods as well as simulation results.     

空间在轨装配技术综述

代表国家科技实力的空间站、空间望远镜、大型通信天线、空间太阳能电站、在轨燃料补给站、深空探测中转站及地外基地等空间大型平台和基础设施的建设需求日益迫切,如何对此进行智能自主建造是当前的巨大技术挑战。鉴于大型平台与基础设施在未来空间探索中的重要性,国内外航天研究机构均提出并发展了在轨装配的系列技术方案。本文主要对在轨装配研究现状和技术发展情况进行系统地综述。首先分析了有人与无人在轨装配的国内外技术进展,总结了在轨装配技术的发展路线、装配层次与方法;然后在此基础上,详细梳理了在轨装配的技术需求和应用前景,并得出在轨装配的使能关键技术——模块化技术、机器人技术和地面模拟装配技术,预期为中国未来的空间在轨装配研究提供有益的参考。     

Digital twin model of gas turbine and its application in warning of performance fault

The digital twin-driven performance model provides an attractive option for the warn gas-path faults of the gas turbines. However, three technical difficulties need to be solved: (1) low modeling precision caused by individual differences between gas turbines, (2) poor solution efficiency due to excessive iterations, and (3) the false alarm and missing alarm brought by the traditional fixed threshold method. This paper proposes a digital twin model-based early warning method for gas-path faults that breaks through the above obstacles from three aspects. Firstly, a novel performance modeling strategy is proposed to make the simulation effect close to the actual gas turbine by fusing the mechanism model and measurement data. Secondly, the idea of controlling the relative accuracy of model parameters is developed. The introduction of an error module to the existing model can greatly shorten the modeling cycle. The third solution focuses on the early warning based on the digital twin model, which self-learns the alarm threshold of the warning feature of gas-path parameters using the kernel density estimation. The proposed method is utilized to analyze actual measured data of LM2500 +, and the results verify that the new-built digital model has higher accuracy and better efficiency. The comparisons show that the proposed method shows evident superiority in early warning of performance faults for gas turbines over other methods.     

Magnetometer Compensation Scheme and Experimental Results on ZDPS-1A Pico-satellite

In a pico-satellite with small volume, measurements from on-board three-axis magnetometer (TAM) are not accurate, as it can be easily disturbed by other electronic systems. To improve its accuracy, a scheme of compensation methods is introduced in this article. The scheme is based on an improved measurement model of pico-satellite TAM, and it mainly consists of three steps. First, in satellite design stage, several techniques are recommended to simplify the afterwards compensations. Then after satellite assembly, TAM ground tests and pre-launch calibration with least-square batch filter are introduced to improve magnetometer performance. At the end, a post-launch calibration with unscented Kalman filter (UKF) is implemented with in-orbit data. The compensation scheme is used in the development of Chinese pico-satellite ZDPS-1A made by Zhejiang University. Results show that with the introduced compensation scheme, the maximum error of ZDPS-1A TAM can be reduced from 80 mG to 6 mG (1 G=10-4 T).     

A view of the commercial launch services market

The commercial launch market is as dynamic and evolutive as ever. Following a period of relatively steady growth, we have, however, witnessed a rather more turbulent phase in the past two years. This is partly due to the various economic and financial crises experienced in 1998 and partly to a significant increase in the number of in-orbit and on-ground problems experienced by satellite manufacturers and operators. What is the Arianespace's view of the current market and of the short and medium-term trends?     

航天器在轨故障特征数据生成方法

针对故障特征数据模拟生成算法与航天器的原理、模型关联度高,航天器状态描述模型不成熟、难以应用于工程实践的现状,根据反映航天器在轨故障的遥测数据表现形式和变化时间长短,将航天器故障进行分类。从遥测数据变化的角度,针对每类故障遥测数据的变化特点,研究了符合每类故障数据变化规律的故障特征数据生成算法及基于WEB服务的故障特征数据生成原型系统实现方式。生成的故障特征数据在故障检测、诊断与预警等方面得到成功应用,使航天器对象、状态演化规则和测控信息产生等故障输入数据更接近真实的动态特征。     

A novel two-stage extended Kalman filter algorithm for reaction flywheels fault estimation

This paper investigates the problem of two-stage extended Kalman filter(TSEKF)-based fault estimation for reaction flywheels in satellite attitude control systems(ACSs). Firstly, based on the separate-bias principle, a satellite ACSs with actuator fault is transformed into an augmented nonlinear discrete stochastic model; then, a novel TSEKF is suggested such that it can simultaneously estimate satellite attitude information and actuator faults no matter they are additive or multiplicative; finally, the proposed approach is respectively applied to estimating bias faults and loss of effectiveness for reaction flywheels in satellite ACSs, and simulation results demonstrate the effectiveness of the proposed fault estimation approach.     

A Diagnostic Tree Approach for Fault Cause Identification in the Attitude Control Subsystem of Satellites

Space and Earth observation programs demand stringent guarantees ensuring smooth and reliable operations of space vehicles and satellites. Due to unforeseen circumstances and naturally occurring faults, it is desired that a fault-diagnosis system be capable of detecting, isolating, identifying, or classifying faults in the system. Unfortunately, none of the existing fault-diagnosis methodologies alone can meet all the requirements of an ideal fault- diagnosis system due to the variety of fault types, their severity, and handling mechanisms. However, it is possible to overcome these shortcomings through the integration of different existing fault-diagnosis methodologies. In this paper, a novel learning-based, diagnostic-tree approach is proposed which complements and strengthens existing efficient fault detection mechanisms with an additional ability to classify different types of faults to effectively determine potential fault causes in a subsystem of a satellite. This extra capability serves as a semiautomatic diagnostic decision support aid to expert human operators at ground stations and enables them to determine fault causes and to take quick and efficient recovery/reconfiguration actions. The developed diagnosis/analysis procedure exploits a qualitative technique denoted as diagnostic tree (DX-tree) analysis as a diagnostic tool for fault cause analysis in the attitude control subsystem (ACS) of a satellite. DX-trees constructed by our proposed machine-learning-based automatic tree synthesis algorithm are demonstrated to be able to determine both known and unforeseen combinations of events leading to different fault scenarios generated through synthetic attitude control subsystem data of a satellite. Though the immediate application of our proposed approach would be at ground stations, the proposed technique has potential for being integrated with causal model-based diagnosis and recovery techniques for future autonomous space vehicle missions.