考虑负载均衡的过驱动航天器推力器分配方法

以过驱动航天器的推力器控制分配误差最小、推力器负载均衡等为设计目标,构建航天器推力分配混合优化模型,并将其转化为线性规划模型进行求解,提出了一种考虑负载均衡的航天器推力器动态分配算法。该算法在确保分配误差最小前提下,能够降低各推力器的最大分配推力之差,有效均衡各推力器总工作时长和开关次数,进而延长推进系统的整体工作寿命。进一步定义了表征负载均衡性能的推力平衡度和干扰敏感度性能指标,并在此基础上给出了一种分配算法负载均能能力的定量化评价方法。在仿真验证中,采用平衡度和敏感度对算法性能进行定量评估,结果表明该方法在保证控制性能和控制分配误差的前提下,能够有效均衡各推力器最大推力,提高了系统的平衡度和对扰动力矩的鲁棒性。     

Review of in-space assembly technologies

With the rapid development of space technology and the increasing demand for space missions, the traditional spacecraft manufacturing, deployment and launch methods have been unable to meet existing needs. In-space assembly (ISA) technologies can effectively adapt to the assembly of large space structures, improve spacecraft performance, and reduce operating costs. In this paper, the development and technologies for ISA are reviewed. ISA is classified from multiple angles, and the research status of ISA is shown clearly through the visual mapping knowledge domain. Then the development status of autonomous robot assembly in the United States, Europe, Japan, Canada and China is reviewed. Furthermore, the key technologies of ISA are analyzed from three aspects: assembly structure design, robot technologies and integrated management technologies. ISA technologies are still facing major challenges and need to be further explored to promote future development. Finally, future development trends and potential applications of ISA are given, which show that ISA will play a vital role in human space exploration in the future.     

Anti-disturbance attitude control of combined spacecraft with enhanced control allocation scheme

In this paper, we propose a novel anti-disturbance attitude control law for combined spacecraft with an improved closed-loop control allocation scheme. More specifically, a saturated approach is adopted to guarantee the global asymptotic stability under control input saturation. To enhance the robustness of the system, a nonlinear disturbance observer is constructed to compensate the disturbances caused by inertial parameter uncertainty and unmodeled dynamics. Next, the quadratic programming algorithm is used to obtain an optimal open-loop control allocation scheme, where both energy consumption and actuator saturation have been considered in the allocation of the virtual control command. Then, a modified closed-loop control allocation scheme is proposed to reduce the allocation error under the actuator uncertainty. Finally, stability analysis of the closed-loop system with the proposed allocation scheme is provided. Simulation results confirm the effectiveness of the proposed control scheme.     

一种低信噪比条件下的深空探测载波捕获算法

针对深空测控通信系统中,接收端收到的载波信号信噪比极低的特点,提出了一种时分复用的二维FFT载波捕获方法。该方法在降低资源消耗的情况下,能够有效实现低信噪比条件下的载波捕获。仿真实验表明,使用此种方法,能够在载噪比为17 dBHz的条件下,完成对载波频偏最大为100 kHz、载波频率变化率最大为100 Hz/s的载波信号的快速捕获,是一种兼顾性能和工程应用的捕获方法。     

Effective control allocation using hierarchical multi-objective optimization for multi-phase flight

For different flight phases in an overall flight mission, different control and allocation preferences should be pursued considering lift, drag or maneuverability characteristics. The multi-objective flight control allocation problem for a multi-phase flight mission is studied. For an overall flight mission, different flight phases namely climbing, cruise, maneuver and gliding phases are defined. Firstly, a multi-objective control allocation problem considering drag, lift or control energy preference is constructed. Secondly, considering different control preferences at different flight phases, the analytic hierarchical process method is used to construct a comprehensive performance index from different objectives such as lift or drag preferences. The active set based dynamic programming optimization method is used to solve the real-time optimization problem. For the validation, the Innovative Control Effector (ICE) tailless aircraft nonlinear model and the angular acceleration measurements based adaptive Incremental Backstepping (IBKS) are used to construct the validation platform. Finally, an overall flight mission is simulated to demonstrate the efficiency of the proposed multi-phase and multi-objective flight control allocation method. The results show that the comprehensive performance index for different phases, which are determined from the Analytic Hierarchy Process (AHP) method, can suitably satisfy the preference requirements for different flight phases.     

民用飞机综合模块化航电系统资源状态监控技术研究

随着处理器和机载嵌入式实时分区操作系统等相关技术的不断升级换代,IMA系统功能的集成度也越来越高,高集成度增加了系统资源分配的难度,需要通过对系统资源状态进行实时监控和分析进而不断优化系统配置。首先对IMA系统的分区特性进行了深入研究,基于探针插桩监控数据采集技术,提出了一种系统行为和时间资源状态监控的策略。研究了数据监控采集系统的软件架构,在此基础上设计和实现了系统行为监视器和时间资源监视器,并在某民机重点预研课题中进行了应用验证。结果表明,能够有效帮助应用开发者和系统综合者直观分析系统时间性能瓶颈,优化资源配置方案,实现计算资源的负载均衡。对IMA系统资源状态监控及资源配置优化具有一定的指导意义和实用价值。     

等效带宽在无线ATM网络的MAC协议中的应用

在ＶＢＲ图像的动态时隙分配算法的判决条件中引入了等效带宽的概念。利用等效带宽将终端输出缓冲区内信元个数和终端当前所占用的时隙数之间联系起来，从而得出了动态时隙分配精确的判断条件。结果表明，这种方法提高了图像业务动态时隙分配算法的有效性及无线ＡＴＭ网络的信道利用率。     

Reducing mission operations costs through spacecraft autonomy: the near earth asteroid rendezvous (near) experience

With a maximum time of 12 days out of ground contact and a round-trip light time as high as 56 minutes, The Near Earth Asteroid Rendezvous (NEAR) spacecraft requires a moderate degree of onboard autonomy to react to faults and safe the spacecraft. Beyond the basic safing requirements, additional functions are carried out onboard. For example, on-board calculation of the Sun, Earth, asteroid, and spacecraft positions allow the spacecraft to autonomously orient itself for science and downlink operations. On-board autonomous momentum management during cruise relieves Mission Operations from planning, scheduling, and carrying out many manual momentum dumps. During development, additional operations, such as center-of-mass management during propulsive maneuvers and optical navigation were also considered for onboard autonomy on the NEAR spacecraft, but were not selected. The allocation of functions to onboard software or to ground operations involved tradeoffs such as development time for onboard software versus ground software, resource management, life cycle costs, and spacecraft safety.After two years of cruise operations, considerable experience with the NEAR autonomy system has accrued. The utility of some autonomous capabilities is greater than expected, others less so. Software uploads increased spacecraft autonomy in some cases, and the impact on Mission Operations can be assessed. Allocation of functions between spacecraft autonomy and ground operation during development of future missions can be improved by applying the lessons learned from the NEAR experience.     

一个基于多重推理的遥感图片解译专家系统

本文研究了在图象模式识别过程中引入人工智能的知识学习、知识表达和知识推理的理论和技术,设计并实现了一个应用于遥感图片解译的计算机视觉专家系统。 为使系统具有较高的智能化程度,本文提出了一种新的推理方法——多重推理法,它具有处理某些不完全知识和错误知识的能力,并且推理过程所运用的部分知识(规则)是从已知样本中自动归纳学习生成的。     

HT-1微小卫星及其在国土资源调查中的应用

文章简要介绍了航天清华一号 (HT - 1)微小卫星及其图像质量状况 ,并以HT - 1扬州景图像为例 ,用ENVI软件对图像进行噪声消除、波段间错位纠正与假彩色合成、地面分辨率求算 ,探讨了其在国土资源调查中的应用。结果表明 :HT - 1图像信息量丰富 ,但噪声明显 ,可通过中值滤波基本消除 ;各波段图像间像元错位较大 ,仍可以通过波段配准来消除 ;地面分辨率为 :4 1 6 989m ,基本达到了设计的要求 ;能满足中比例尺的国土资源调查领域的应用要求