集成锁相环CD4046在电力参数测试仪中的应用

介绍了集成锁相环CD4046的工作原理及其内部结构,给出了CD4046在电力参数测试中的具体应用实例,并给出了实际测量的参数和锁相频率稳定范围。     

MEMS高量程微加速度计温度补偿的设计

目前基于压阻式MEMS加速度计的测量精度还不是很高,为了提高其精度,文中采用TI公司新一代的数字信号处理器TMS320F2812实时操作系统,通过对复合量程微加速度计的特性分析,找出加速度计温度漂移的变化规律;采取温度补偿措施消除温度变化带来的测量误差;系统依据数字温度传感器DS18B20提供温度参数,采用最小二乘法的软件算法对测量数据进行补偿处理;该系统处理时间短,可以满足其使用要求,算法简单有效,可以显著提高测量精度;实用表明使用高速DSP器件并采用有效的信号处理方法可以显著地改善MEMS加速度计的性能。     

基于FPGA的数字锁相环设计

介绍了一种应用VHDL语言设计数字锁相环的设计方法,阐明其基本工作原理和设计思想,给出了系统主要模块的设计过程和仿真结果;用可编程逻辑器件FPGA予以实现。该方案提高了DPLL的快速锁定性能,同时保证了锁定精度。     

软件锁相环环路滤波器和闭环幅频响应分析

为了解决软件锁相环设计时遇到的参数设置问题,通过导数逼近法给出了软件锁相环的Z域数学模型,并研究了参数变化对环路滤波器幅频响应及闭环幅频响应的影响,从而得到阻尼系数、系统增益、采样率与系统性能之间的关系,为实际设计软件锁相环时参数的设置提供了理论依据和参考.     

Linear and Nonlinear Tuning of Parametrically Excited MEMS Oscillators

Microelectromechanical oscillators utilizing noninterdigitated combdrive actuators have the ability to be parametrically excited, which leads to distinct advantages over harmonically driven oscillators. Theory predicts that this type of actuator, when dc voltage is applied, can also be used for tuning the effective linear and nonlinear stiffnesses of an oscillator. For instance, the parametric instability region can be rotated by using a previously developed linear tuning scheme. This can be accomplished by implementing two sets of noninterdigitated combdrives, choosing the correct geometry and alignment for each, and applying ac excitation voltages to one set and proportional dc tuning voltages to the other set. Such an oscillator can also be tuned to display a desired nonlinear behavior: softening, hardening, or mixed nonlinearity. Nonlinear tuning is attained by carefully designing combdrive geometry, flexure geometry, and applying the correct dc voltages to the second set of actuators. Here, two oscillators have been designed, fabricated, and tested to prove these tuning concepts experimentally     

光伏并网发电系统锁相环优化仿真研究

在光伏并网发电系统中,针对传统锁相环在电网电压不平衡的情况下存在的锁相精度不高的问题,提出了一种能快速、精确提取电网电压幅值和相位的双同步坐标系解耦锁相环(DDSRF-PLL)。通过采用双同步参考坐标系、标准的三相锁相环、去耦网络以及低通滤波器,有效地分离电压正、负序分量,滤除二次谐波,做到准确检测电网电压相位和幅值的目的,具有较好的动态响应特性。最后对电网电压单相跌落和两相跌落分别进行仿真,采用DSP样板进行验证。仿真结果验证了供电系统的精准性,提高了光伏并网发电系统并网的稳定性、有效性和可靠性。     

温度检测系统的非线性动态补偿研究

在温度测控系统中,对于温度传感器在测量时存在较大非线性动态偏移误差,提出基于参考模型的利用扩展卡尔曼滤波算法设计温度传感器的动态补偿的方法.用扩展卡尔曼滤波进行补偿器的参数辨识,从而得到比较精确的补偿器,因此温度传感器的动态偏移误差得到自动补偿.本文所设计的系统可以对温度进行有效的控制,且具有一定的鲁棒性和较好的响应速度.     

基于改进型二阶广义积分器的单相锁相环设计

针对传统基于二阶广义积分器的锁相环(SOGI-PLL)存在谐波抑制能力差、抗直流干扰能力不强的问题,提出了一种基于改进型SOGI的新型锁相环结构。该结构将两个SOGI模块串联,可以很好地消除电网存在的谐波分量以及直流干扰。针对传统的锁相环结构在面临电网频率波动时,无法对其进行自适应跟踪这一不足,采用了过零检测的方法来获得电网的实时频率,并将其直接馈送至改进的SOGI结构的谐振频率处,有效地提高了锁相环的频率自适应能力。仿真和试验结果均表明,所设计的改进型二阶广义积分器的锁相环具有锁相精度高、动态性能好的优点,对单相光伏并网技术的实现具有很好的参考价值。     

软件锁相环在超声电源中的应用研究

讨论了压电超声换能器的电学模型，从超声电源锁相控制的原理出发，建立了超声电源锁相控制系统的数学模型并进行了稳定性分析，得到了软件锁相环（Soft-ware Phase-Locked Loop，简称SPLL）算法的稳定条件。给出了基于高速混合信号处理器MSP430F2012实现SPLL算法的方法．实验结果验证了该SPLL的正确性和精确性。     

Scalarization Using Loop Alignment and Loop Skewing

Array syntax, which is supported in many technical programming languages, adds expressive power by allowing operations on and assignments to whole arrays and array sections. To compile an array assignment statement to a uniprocessor, the language processor must convert the statement into a loop that has the same meaning. This process is called scalarization.Scalarization presents a significant technical problem because an array assignment needs to be implemented as if all inputs are fetched before any outputs are stored. Since a loop intermixes loads and stores, the compiler typically allocates a temporary array to hold the intermediate result. Because these extra temporary arrays can cause performance problems in cache, many techniques have been developed to avoid their use or minimize their size.In this paper, we present a novel application of two compiler strategies—loop alignment and loop skewing—to address this problem. We show that these strategies can achieve the asymptotically minimal memory allocation for stencil computations. Our experiments with loop alignment and loop skewing demonstrate that it is extremely effective in improving memory hierarchy performance of Fortran 90 array code on standard uniprocessors. The result should be applicable to other array languages, such as MATLAB.     

Locomotion Control of a Biped Robot Using Nonlinear Oscillators

Recently, many experiments and analyses with biped robots have been carried out. Steady walking of a biped robot implies a stable limit cycle in the state space of the robot. In the design of a locomotion control system, there are primarily three problems associated with achieving such a stable limit cycle: the design of the motion of each limb, interlimb coordination, and posture control. In addition to these problems, when environmental conditions change or disturbances are added to the robot, there is the added problem of obtaining robust walking against them. In this paper we attempt to solve these problems and propose a locomotion control system for a biped robot to achieve robust walking by the robot using nonlinear oscillators, each of which has a stable limit cycle. The nominal trajectories of each limb's joints are designed by the phases of the oscillators, and the interlimb coordination is designed by the phase relation between the oscillators. The phases of the oscillators are reset and the nominal trajectories are modified using sensory feedbacks that depend on the posture and motion of the robot to achieve stable and robust walking. We verify the effectiveness of the proposed locomotion control system, analyzing the dynamic properties of the walking motion by numerical simulations and hardware experiments. Shinya Aoi received the B.E. and M.E. degrees from the Department of Aeronautics and Astronautics, Kyoto University, Kyoto, Japan in 2001 and 2003, respectively. He is a Ph.D. candidate in the Department of Aeronautics and Astronautics, Kyoto University. Since 2003, he has been a research fellow of the Japan Society for the Promotion of Science (JSPS). His research interests include dynamics and control of robotic systems, especially legged robots. He is a member of IEEE, SICE, and RSJ. Kazuo Tsuchiya received the B.S., M.S., and Ph.D. degrees in engineering from Kyoto University, Kyoto, Japan in 1966, 1968, and 1975, respectively. From 1968 to 1990, he was a research member of Central Research Laboratory in Mitsubishi Electric Corporation, Amagasaki, Japan. From 1990 to 1995, he was a professor at the Department of Computer Controlled Machinery, Osaka University, Osaka, Japan. Since 1995, he has been a professor at the Department of Aeronautics and Astronautics, Kyoto University. His fields of research include dynamic analysis, guidance, and control of space vehicles, and nonlinear system theory for distributed autonomous systems. He is currently the principal investigator of “Research and Education on Complex Functional Mechanical Systems” under the 21st Century Center of Excellence Program (COE program of the Ministry of Education, Culture, Sports, Science and Technology, Japan).     

基于DSP2812的全新数字锁相环

鉴于能量回馈控制系统要求回馈电流与电网电压严格同频同相,结合锁相环原理,提出了一种基于DSP TMS320F2812的高精度数字锁相控制方案.利用DSP内部的捕获单元、通用定时器和比较单元,方便地实现了对电网电压和回馈电流的信号捕获,从而达到调频调相的目的,达到并网条件.实验表明,此方法精度高,锁相速度快,保证了并网系...     

Real-Time Stabilization of an Eight-Rotor UAV Using Optical Flow

An original configuration of a small aerial vehicle having eight rotors is presented. Four rotors are devoted to the stabilization of the orientation of the helicopter, and the other four are used to drive the lateral displacements. A precompensation on the roll and pitch angles has been introduced so that the attitude dynamics is practically independent of the translational dynamics. This compensation is directly related to the velocity of the lateral motors. The dynamical model is obtained using the Euler–Lagrange approach. The proposed configuration is particularly useful for image processing since the the camera orientation is held constant. The eight-rotor rotorcraft is simpler to pilot than other rotorcrafts. A control strategy is proposed that uses the optical flow measurements to achieve a hover flight that is robust with respect to perturbations like wind. The new aerial configuration and control strategy have been tested in real-time experiments.      

Structure and Simulation Evaluation of an Integrated Real-Time Rescheduling System for Railway Networks

A critical problem faced by railways is how to increase capacity without investing heavily in infrastructure and impacting on schedule reliability. One way of increasing capacity is to reduce the buffer time added to timetables. Buffer time is used to reduce the impact of train delays on overall network reliability. While reducing buffer times can increase capacity, it also means that small delays to a single train can propagate quickly through the system causing knock-on delays to trains impacted by the delayed train. The Swiss Federal Railways (SBB) and Swiss Federal Institute of Technology (ETH) are researching a new approach for real-time train rescheduling that could enable buffer times to be reduced without impacting schedule reliability. This approach is based on the idea that if trains can be efficiently rescheduled to address delays, then less buffer time is needed to maintain the same level of system schedule reliability. The proposed approach combines a rescheduling algorithm with very accurate train operations (using a driver-machine interface). This paper describes the proposed approach, some system characteristics that improve its efficiency, and results of a microscopic simulation completed to help show the effectiveness of this new approach. The results demonstrate that the proposed integrated real-time rescheduling system enables capacity to be increased and may reduce knock-on delays. The results also clearly showed the importance of accurate train operations on the rescheduling system’s effectiveness.     

具有实时操作系统的嵌入式应用系统的设计

本文概述了嵌入式系统的核心,实时操作第及其特点,分析了在利用实时操作系统进行嵌入式系统设计时,经常要面对几个方面的问题。     

Solution Phase Synthesis and Workup Using an Integrated Approach

Traditional organic synthesis is often cumbersome and time consuming. Significant effort by manufacturers of automated systems has been directed at increasing the speed, efficiency, and consistency of performing chemical reactions. To date, the numbers of integrated systems that combine all the relevant steps of compound preparation are few. Using the five automated systems in tandem can successfully streamline research and development of potential drug candidates. The features of these workstations offer a unique approach for supporting the convenient synthesis and workup of diverse compounds without compromising reagent types or conditions used for synthesis. This poster details an example of the automated drug discovery approach to high throughput organic synthesis using the solution phase synthesis of a series of 1-indanones as building blocks and subsequent reductive amination reactions to generate a diverse group of amines. The purpose of each automated system is outlined along with its role in generating the small library as an illustration of the importance of time saving devices in laboratories.     

一个用Delphi实现的文件夹实时监控系统

本文介绍了一个实用的文件夹动态监控系统。该系统在多线程技术的基础上实现了文件夹监测和文件处理的同步进行。     

RTX技术在半实物仿真中的应用及开发

研究半实物仿真中的实时性的实现问题。针对以往采用的上下位机来实现半实物仿真的实时性说带来的复杂性问题,引入正在逐步应用的RTX（Real-Time Extension）实时技术,以达到降低系统复杂度和成本,提高实时系统的开发效率和灵活性的目的。探讨在半实物仿真中开发的要点,给出了一种通用的开发模式和流程,设计了共享内存及任务调度的编写算法。基于LabWindows/CVI开发半实物仿真的上位机,利用RTX技术实现非实时程序进程与实时程序进程之间的协同仿真。实验结果表明,该实时技术是可靠的、稳定的,提高了半实物仿真的控制精度,同时降低了半实物仿真测控系统的复杂度。     

Dynamic Friction and Wear in a Planar-Contact Encapsulated Microball Bearing Using an Integrated Microturbine

The demonstration and characterization of a novel planar-contact encapsulated microball bearing using a radial in-flow microturbine are presented. Stable operation of the air-driven silicon microturbine is shown for over 1 000 000 revolutions at speeds, pressure drops, and flow rates of up to 10 000 r/min, 0.45 lbf/in², and 3.5 slm, respectively. Incorporation of a gas thrust plenum using a novel packaging scheme has enabled comprehensive spin-down friction characterization of the encapsulated microball bearing. An empirical power-law model for dynamic friction has been developed for speeds of 250-5000 r/min and loads of 10-50 mN, corresponding to torques of 0.0625-2.5 muNldrm and friction torque constants of 2.25-5.25 x 10^-4 muNldrm/ r/min. The onset and effect of wear and wear debris have been studied, showing negligible wear in the load bearing surfaces for the operating conditions considered.     

Temperature Dependence of Quality Factor in MEMS Resonators

The temperature dependence of the quality factor of microelectromechanical system (MEMS) resonators is analyzed and measured. For silicon MEMS resonators, there are several energy loss mechanisms that determine the quality factor. These include air-damping, thermoelastic dissipation, and anchor and surface losses. For resonators operating at a low pressure in hermetic wafer-scale encapsulation, the effect of each energy loss mechanism is discussed. The temperature dependence of each mechanism and their contribution to the total quality factor is investigated. MEMS resonators can be designed to have either strong or weak dependence of on temperature, which is if the effects of the temperature on the dominant loss mechanisms are well understood. The sensitivity of up to 1% changes in quality factor per degree Celsius change of temperature was demonstrated by experiment. By using as the thermometer for temperature compensation, a preliminary experiment demonstrated less than 4-ppm resonant frequency variation over the 0 -70 temperature range. This indicates that the quality factor can be used as an absolute intrinsic thermometer for temperature compensation in the MEMS resonators.