Network Control in ATM-Based LEO Satellite Networks

Low Earth Orbiting (LEO) satellite networks with on-board asynchronous transfer mode (ATM) switches hold the promise of offering an economically viable extension of terrestrial ATM systems by providing connectivity to areas where existing terrestrial networks are either infeasible or impractical. Network management in ATM LEO satellite networks is typically performed by the Network Control Center (NCC). The main contribution of this paper is to propose a network management system configuration with a stand-by solution and to describe an experimental Satellite Management Information Base (SMIB) that we have developed for implementation in ATM LEO satellite networks.     

天基激光器的排热方案研究

天基激光器运行过程中产生的大量废热需要排散,采用传统的热泵、单相或两相流体排热回路以及消耗性冷却剂等热控技术会使整个热管理系统质量、体积或功耗过大。以系统的轻量化和紧凑性为指标,对辐射冷却-冰蓄冷组合排热方案用于天基激光器的可行性进行了研究,结果表明,该方案能满足激光器废热排放要求,可大大减轻热控系统的质量和体积,说明它在未来天基激光器热管理中具有相当的应用潜力。     

航天器太阳能电池用硅橡胶粘结剂的低温性能

研究了航天器太阳能电池用盖片胶KH－S－A和底片胶KH－S－B在低温条件下的力学性能规律，发现在77－298K，随温度降低，两种胶的弹性模量呈线性增加，拉伸剪切强度明显提高，分别在113K和143K处出现最大值，为室温下的12．8倍和7．9倍。断口分析表明，拉伸剪切破坏在室温下表现为混合破坏，低温下表现为界面破坏。     

A Safe and Reliable Routing Mechanism of LEO Satellite Based on SDN

Satellite networks have high requirements for security and data processing speed. In order to improve the reliability of the network, software-defined network (SDN) technology is introduced and a central controller is set in the network. Due to the characteristics of global perspective, control data separation, and centralized control of SDN, the idea of SDN is introduced to the design of the satellite network model. As a result, satellite nodes are only responsible for data transmission, while the maintenance of the links and the calculation of routes are implemented by the controller. For the massive LEO satellite network based on SDN, a state evaluation decision routing mechanism is proposed. The designed mechanism monitors the status of the entire network effectively and reduces the on-board load on the satellite network. The best routing decision is made under the comprehensive consideration of the current and historical status of each intersatellite link between Low Earth Orbit (LEO) satellite network nodes. The calculation and storage requirements are controlled within a reasonable range. Based on the curve parameter transmission fuzzy encryption algorithm, a safe and reliable condition assessment decision routing mechanism (CADRM) is designed. It ensures that the personal information of the LEO satellite network can be transmitted safely and effectively. The experimental simulation results show the improvement of network throughput, the reduction of packet loss rate and the enhancing of network reliability.     

航天器诊断系统的多观测模糊融合技术研究

为解决航天器诊断系统中冗余多观测信息存在不确定性时的数据融合与冲突处理问题，给出了一种基于模糊理论的多观测融合算法，对算法进行了数学描述．该算法以模糊测度理论为背景，首先将冗余观测数据进行模糊化表示，然后按照模糊融合理论进行结果融合，最后进行模糊融合结果的可靠性评估．该算法解决了冗余观测存在不准确信息时的诊断问题．通过航天器诊断系统中的实测数据实例，说明了算法的实用性．     

Control of flexible spacecraft using nonlinear approximation of input shape dependence on reorientation maneuver parameters

This paper presents a design of a novel advanced feedforward controller for a large-angle reorientation maneuver of a spacecraft with flexible appendages, such as a telecommunication satellite. The controller is capable of fast computation of an optimal feedforward input shape for a nonlinear flexible system. This is achieved through radial basis function (RBF) network approximation of the feedforward dependence on the maneuver parameters. The paper describes a flexible spacecraft testbed and studies, the application of the controller to the testbed control. It presents a few insights into the design, and performance analysis of the RBF network approximation. The designed controller is demonstrated to combine excellent performance in the compensation of residual flexible vibrations for the nonlinear system under consideration, as well as computational simplicity.     

椭圆形悬挂轨道控制策略研究

为了实现椭圆形悬挂轨道,文中以航天器相对运动动力学模型为基础,对椭圆形悬挂轨道的控制策略进行了分析研究.根据悬挂轨道的定义,通过理论分析和推导,得到了悬挂星在椭圆悬挂轨道上运行时所需要的控制加速度,并对其进行了数值仿真.仿真结果表明:控制加速度曲线平滑,易于实现和控制,且仿真结果与泛开普勒轨道所需的控制加速度一致,椭圆形悬挂轨道实现方法正确可行.     

航天器近距离相对轨道的滑模控制

基于滑模控制原理,研究了近距离追踪航天器与目标航天器交会对接时,相对运动轨道的控制问题.首先,建立非线性航天器相对运动模型;其次,利用滑模控制原理和分数阶导数的相关性质,设计了整数阶PD控制器和分数阶PD~α控制器;最后,分别运用整数阶和分数阶控制器对未扰和受扰系统实施控制.数值仿真结果表明,整数阶与分数阶控制器均能实现对未扰和受扰系统的控制,验证了方法的有效性.同时发现,在时效性上,分数阶控制器明显优于整数阶控制器;在能效性上,达到相同控制目标时,分数阶控制器的能量消耗大于整数阶控制器.     

Study on the Technology of Spacecraft Dynamic Simulation and Emulation

To meet the requirements and functions of spacecraft dynamic simulation and emulation according to different flight periods, the realization of real time system with different configurations, control of the development cycle and examples of application are presented in detail. On the basis of the satellite dynamic simulation technology, distributed network integrated with the component testing platforms is used to construct a multi-level bus network system. The system takes into full consideration the confi...     

信息融合与多Agent技术在航天器能源管理系统在轨故障诊断中的应用

航天器能源系统的可靠运行对于航天器在轨安全有重要意义,其中能源管理是决定能源系统可靠性的关键因素;目前我国在航天器能源系统在轨故障诊断方面研究较少,绍了国内外故障诊断技术的现状以及相关技术在国外航天器中的实际应用,介绍了航天器能源管理系统的故障种类、检测原理以及解决方法,提出了一种引入信息融合和多Agent技术的新型航天器能源管理系统故障诊断方法;结合实际工程需求,探讨了该方法在航天器能源管理系统中应用的可行性,最后简要介绍了该技术在能源管理系统故障处理中的实现方案。