基于显著性检测的星载嵌入式跟踪系统

随着航天科技的不断发展,计算机视觉算法在卫星上的应用方兴未艾,为了实现更多的功能需求和应对可能的威胁,视觉目标跟踪作为其中基础但具有挑战性的任务更是至关重要。然而,目前已有的目标跟踪算法大多数算法只限于对图像序列进行跟踪。另一方面,受到硬件条件制约,很多优秀的算法因为复杂度较高很少被应用到星载嵌入式系统中。这些目标跟踪算法运行时,通常需要人为地给出目标的边界框。为了自动得到边界框,需要目标检测算法对输入图像进行运动目标检测。本文提出了一种基于显著性检测和相关滤波的单目标检测与跟踪一体化算法,并与嵌入式系统相结合,在搭载的TMS320C6678芯片上达到了2 048 pixel×2 048 pixel分辨率下24 fps的帧率。具体地,检测算法负责对图像进行预处理并获得边界框,然后目标跟踪算法给出目标在后续帧中的位置。为了验证算法在实际跟踪中的有效性,本研究搭建了一个由相机、DSP和云台组成的光学平台并进行了实验验证。在该系统中,DSP自动完成检测、跟踪、驱动云台和再检测任务,达到了很好的检测跟踪效果。     

Secure communication in CloudIoT through design of a lightweight authentication and session key agreement scheme

Internet of Things (IoT) is a newly emerged paradigm where multiple embedded devices, known as things, are connected via the Internet to collect, share, and analyze data from the environment. In order to overcome the limited storage and processing capacity constraint of IoT devices, it is now possible to integrate them with cloud servers as large resource pools. Such integration, though bringing applicability of IoT in many domains, raises concerns regarding the authentication of these devices while establishing secure communications to cloud servers. Recently, Kumari et al proposed an authentication scheme based on elliptic curve cryptography (ECC) for IoT and cloud servers and claimed that it satisfies all security requirements and is secure against various attacks. In this paper, we first prove that the scheme of Kumari et al is susceptible to various attacks, including the replay attack and stolen-verifier attack. We then propose a lightweight authentication protocol for secure communication of IoT embedded devices and cloud servers. The proposed scheme is proved to provide essential security requirements such as mutual authentication, device anonymity, and perfect forward secrecy and is robust against security attacks. We also formally verify the security of the proposed protocol using BAN logic and also the Scyther tool. We also evaluate the computation and communication costs of the proposed scheme and demonstrate that the proposed scheme incurs minimum computation and communication overhead, compared to related schemes, making it suitable for IoT environments with low processing and storage capacity.     

A Family of Fifth-Order Runge-Kutta Pairs

The construction of a Runge-Kutta pair of order with the minimal number of stages requires the solution of a nonlinear system of order conditions in unknowns. We define a new family of pairs which includes pairs using function evaluations per integration step as well as pairs which additionally use the first function evaluation from the next step. This is achieved by making use of Kutta's simplifying assumption on the original system of the order conditions, i.e., that all the internal nodes of a method contributing to the estimation of the endpoint solution provide, at these nodes, cost-free second-order approximations to the true solution of any differential equation. In both cases the solution of the resulting system of nonlinear equations is completely classified and described in terms of five free parameters. Optimal Runge-Kutta pairs with respect to minimized truncation error coefficients, maximal phase-lag order and various stability characteristics are presented. These pairs were selected under the assumption that they are used in Local Extrapolation Mode (the propagated solution of a problem is the one provided by the fifth-order formula of the pair). Numerical results obtained by testing the new pairs over a standard set of test problems suggest a significant improvement in efficiency when using a specific pair of the new family with minimized truncation error coefficients, instead of some other existing pairs.

     

嵌入式操作系统VxWorks下PPPoE的实现

PPPoE是一种很常用的拨号协议,介绍PPPoE Discovery阶段的基本流程和帧封装格式,同时介绍PPP的连接控制协议(LCP)、认证协议(CHAP、PAP)、IP控制协议I(PCP)各协议子层之间的关系和PPP的数据包封装格式.讨论PPPoE、PPP协议在嵌入式操作系统VxWorks的TCP/IP协议栈体系中的具体位置和PPP、PPPoE数据包收发二个方向的处理流程,同时给出VxWorks下PPPoE实现的具体的软件模块设计,具有一定的工程应用价值.     

基于单片机的嵌入式SNMP代理器设计与实现

将SNMP(简单网络管理协议)用于控制,使监控现场的信号通过SNMP传输。给出了在51单片机上实现SNMP代理器的方案。阐述了网络接口、A/D采集以及串口的设计,软件采用实时多任务操作系统M icro-C/OS,用人机交互任务、数据采集任务、SNMP处理任务实现所需要的功能。     

基于uClinux的嵌入式系统在通信用高频开关组合电源监控中的应用

uClinux操作系统和ARM微处理器的结合是工业控制领域的有效方案,该方案实现了对通信高频开关组合电源的监控,不仅使嵌入式电源监控系统具有丰富的网络功能、灵活的软硬件扩展性能,而且使通信电源具有良好通用性、稳定性和可靠性。     

基于LPC2378的天调匹配性能检测仪的设计及实现

为了解决生产中短波天调配谐过程存在的劳动强度大,统计不够准确等问题,设计了一种检测仪。该检测仪以嵌入式技术为基础,利用短波电台所提供的遥控命令,实现短波天调自动配谐功能,并根据统计得到的配谐数据判断天调匹配性能是否合格。经生产验证,该测试仪在提高劳动效率的同时,还能减少人工统计数据可能带来的误差。     

多层PCB中内埋电阻的特性分析及应用

计算、分析了多层PCB内埋平面电阻的特性，并将其应用于一种多层射频板威尔金森功分器的设计，研究并分析了平面电阻尺寸对该功分器射频性能的影响。     

“高频电子线路”理论课内嵌实验的探讨

国内大学的工程实践性课程通常理论课和实验课分开讲授，时间跨度大，内容不匹配，难以达到互相推动、互相促进的理想效果。在理论课讲授过程中同步内嵌实验课是一种无需变动复杂的课程体系，而能显著改善教学效果的方法。本文以“高频电子线路”课程的教学实践为例，探讨了此类改革面临的挑战和应对方法。     

Self-reconfiguration of real-time communication in cyber-physical systems

Today, in domains like automation and robotics systems consist of various sensors and computation nodes. Due to the temporal dependency in quality of measured data, such Cyber-Physical Systems (CPS) commonly have real-time requirements on communication. In addition, these systems shall become more flexible and scalable, e.g., by adding new components to the CPS. This would be most suitable if a CPS could react to the presence of a new component and reconfigure itself to run afterward with the new component integrated to the CPS. This capability is covered by the term Plug-and-Produce. In this paper, we propose a concept to enable Plug-and-Produce within a CPS whose network uses different communication media, e.g., Ethernet and CAN. To enable real-time communication provided by different communication protocols, their different synchronization mechanisms have to be combined to get a common time base within the entire system. For this purpose, we consider Ethernet as well as CAN-based real-time communication protocols and their synchronization mechanisms. The proposed concept for self-reconfiguration aims to be integrated into our three layered software architecture that is presented as well.