低功耗宽调谐范围锁相环设计

针对传统锁相环输出频率范围有限、功耗大的缺陷,通过对压控振荡器震荡机理进行理论分析,设计了一款用于时钟发生器的低功耗、宽调谐范围、低相位噪声锁相环。该锁相环采用了新型可编程、低调谐增益、低功耗的环形振荡器,达到了宽频率输出范围、低相位噪声、低功耗的目的,采用SMIC公司0.18um混合信号工艺,用Cadenced的Hspice仿真工具进行仿真,在1.8V电源电压供电情况下获得了50MHz~1.7GHz的频率锁定范围和1.8mW~2.3mW的较低功耗。单边带相位噪声在10KHz频偏处为-104dBc/Hz.。     

Robust observer–controller compensator design using the loop shaping design procedure and the algebraic method

This paper investigates robust observer‐controller compensator design using Vidyasagar's structure (VS). VS has a unit matrix parameter H similar to the Q parameter for the Youla–Kucera parameterization. VS can be designed based on the left coprimeness of the central controller in the H_∞‐loop shaping design procedure (H_∞‐LSDP) and therefore can preserve the intrinsic properties of the H_∞‐LSDP. This paper introduces algebraic methods to simplify the design of H in the VS controller by solving specific algebraic equations. In particular, the algebraic design of H can achieve two things. First, a dynamic H adjusts the tracking performance and yields the integral action. Second, a dynamic H rejects the input and output sinusoidal disturbances with known frequencies. These attributes are indications of the flexibility of the proposed method since the output‐feedback controller design of the H_∞‐LSDP cannot easily deal with such conditions. This paper discusses the achieved loop and the closed‐loop behavior of the system with VS, and also gives two numerical examples. The first example shows that the proposed method results in a better design in many aspects than the resulting from H_∞‐LSDP. The second example shows the application of the proposed method to rejecting input and output step disturbances, and input and output multiple sinusoidal disturbances, for which the H_∞‐LSDP can hardly be used. Copyright © 2009 John Wiley & Sons, Ltd.     

船载光电成像三轴自主稳定平台控制回路设计

船载光电成像稳定平台为舰船在高速及恶劣海况下进行光电成像侦察提供了基础条件,近年来光电平台结构越来越复杂,要求的稳定精度越来越高,为了提高平台稳定精度,必须选择合适的结构方案并进行合理的控制回路设计;文中介绍了稳定平台的几种框架形式,从稳定原理方面分析了各自的特点,指出三轴稳定平台系统是最佳的选择方案,在此基础上对三轴自主稳定平台伺服稳定控制回路进行了设计,仿真结果表明在选择合适的超前-滞后网络后,系统的隔离度达56db,稳定性能满足使用要求。     

PDE Toolbox和最小二乘法在导热问题中的应用

设计金属加热的控制策略,首先要获得金属导热体的开环系统模型.针对一个带有矩形孔的金属薄板上的热传导问题,采用PDE Toolbox进行求解和仿真,并用最小二乘方法进行热传导系统的建模与仿真,以获得模型中的参数.将此参数与求解微分方程方法所得到的数据进行对比,结果表明,采用最小二乘法可以更清楚地了解金属板的外部特性,并获得输入输出信号的差分方程,而求解微分方程的方法则显示了金属板的内部特性,两种方法是等效的.     

基于PID反馈的高Q值加速度计闭环检测电路

高Q值加速度计由于能够很好地降低热机械布朗噪声,被广泛应用于高精度低噪声检测领域,相应的闭环接口电路却成为其应用的困难之一.通过分析传感器的器件结构和动态响应,提出了一种基于PID反馈的闭环检测电路来克服传感器因高Q值造成的不利影响,改善系统的频率特性和动态响应.根据设计原理设计和测试了基于PCB板级的闭环检测电路.电...     

基于四阶段人工优化的软件流水技术

代码体积是优化存储资源有限的嵌入式系统的重要因素之一。针对该特点,使用oprofile性能分析工具,以EEMBC基准程序集作为工作负载,提出四阶段人工优化软件流水方法(FPMO)。电信类的自相关程序实验结果表明,FPMO以2.04%的代码增量为代价换来40.678%的性能提升,而单纯的编译器自动优化则以33.35%的体积膨胀换来38.33%的性能提升。     

基于JTAG仿真的ARM Linux设备Bootkit检测技术研究*

ARM Linux嵌入式设备正遭受着日益严重的Bootkit威胁。针对传统检测技术对Bootkit检测的局限性,提出了一种基于JTAG的固件底层检测方法。该方法以基本块级跟踪和循环识别构成的系统跟踪优化算法为基础,利用跟踪系统的启动过程中记录到的信息,对Bootloader引导阶段和内核启动阶段进行监控,从而实现对ARM Linux嵌入式设备Bootkit的分阶段检测。实验结果表明,以跟踪优化算法为基础的Bootkit分段检测技术不仅极大提高了跟踪效率,亦有效检测出了Bootkit的存在,达到了预期效果。     

Optimal back-off point determination and controller weight selection for multivariate systems under finite-horizon control

Plant economic performance is most often related to the operating point, specifically the mean values of the process variables; meanwhile, most existing performance assessment techniques involve examining the variances or covariances of the controlled variables. A combined approach is to determine the appropriate trade-off between variances of different process variables in order to operate the plant at the point that provides maximum economic benefit while satisfying the operating constraints. This problem is referred to as the minimum backed-off operating point selection, and previous works have formulated it as a non-convex constrained optimization problem. In the current work, a new technique is introduced that can provide the optimal plant operating point. Additionally, this method provides the weights for a finite horizon controller that results in the optimal trade-off in process variable variances that will allow satisfaction of the operating constraints at the optimal operating point. In this method, the plant and disturbance models for the given process are used to generate data representing possible trade-offs between process variable standard deviations. Employing a piecewise linear regression to describe the sample points of this standard deviations data allows for the operating point selection problem to be solved as a small number of linear programs. The advantages of this approach are demonstrated through the use of mathematical and simulation case studies.     

基于三端口双向DC/DC 储能变流器的电流内环控制策略研究

多端口双向DC/DC储能变流器是一种进行能量控制变换的电力电子装置,是一种新型前沿技术,在以风力发电、光伏发电、燃料电池发电多能互补的智能微电网系统以及电动汽车能量管理控制系统中有着良好发展前景。系统主拓扑结构是以三端口双向DC/DC变换器作为储能装置,分别连接负载端、超级电容器和蓄电池,所组成的电动汽车充放电能量管理系统。通过对三端口双向DC/DC 储能变流器的控制策略的深入研究,采用状态空间法和波特图的形式来研究电流内环控制策略,实现储能装置在发电系统及电动汽车能量管理系统中的稳定应用,改善电能的利用效率。     

10万吨聚丙烯装置仿真应用与环管反应器的模拟

聚丙烯是当今世界5大通用树脂之一,因其优秀的热塑性能使之在工业生产中的应用逐年增加。因此,生产装置和设计公司对各牌号聚丙烯在生产加工中的指标控制也日趋严格,对其工艺的优化也在不断地探讨和实践。本文以中国石油庆阳石化公司10万吨/年聚丙烯装置为基础,结合Honeywell公司的UniSim Design为基础建模平台建立操作工仿真培训系统(OperatorTraining System)。对Basell公司的Spheripol工艺进行全流程模拟与分析,确定与验证合理的操作参数与控制条件。并且还针对Spheripol的环管反应器进行专门的模拟与讨论,应用Honeywell机理优化差值矩阵模块,并进行适当的改进,通过快速迭代和实时收敛大大减轻了各个硬件节点的计算负荷,运用软硬件相结合的双层法在内层建立稳定的机理模型,在外层建立优化的控制模型。同时在计算结果的基础上分析了反应物与产物在环管反应器中的动态特性,以及主要操作条件的变化对浆液密度、反应温度等重要指标的影响,指出了环管反应器在70℃～80℃范围会出现控制临界点,建立了符合其性能的操作指标和优化目标。为实际反应器的生产操作提供了理论依据,并且对今后探讨DCS与...