An optimization approach to optimal placement of collocated piezoelectric actuators and sensors on a thin plate

The purpose of this paper is to suggest a criterion for the optimal placement of collocated piezoelectric actuator–sensor pairs on a thin flexible plate using modal and spatial controllability measures. Consideration is given to the reduction of control spillover effect by adding an extra spatial controllability constraint in the optimization procedure. The spatial controllability is used to find the optimal placement of collocated actuator–sensor pairs for effective average vibration reduction over the entire structure, while maintaining modal controllability and observability of selected vibration modes. It is found that the methodology for optimal actuator placement can be used for a collocated system without damaging the observability performance of the collocated sensors. Experimental validation of our optimal placement is done on a simply supported thin plate with a collocated piezoelectric actuator–sensor pair.     

Pressure measurement by GaAs piezoelectric sensors

A new pressure sensor for pressures up to 100 bar and temperatures of about 200 degrees C is presented. It uses the piezoelectric effect of 111 oriented semi-insulating GaAs. This material allows the monolithic integration of sensor and electronic circuit.<>     

Plate with piezoelectric actuators/sensors

This paper investigates the robust control of low-frequency modes of a thin all-clamped plate with piezoelectric actuators and sensors. Locations of the actuators and sensors are important in reducing the spillover effects of uncontrolled modes. Locations good for controlling the low-frequency modes are evaluated by using the modal shapes. The uncertainties at the high-frequency region and the low-frequency region around the frequency zero should be considered for the stability of the control system. These two uncertainties can limit the gain of the vibration controller. Low-pass filters and high-pass filters are introduced to alleviate the high-frequency and the low-frequency uncertainty, respectively. The linear quadratic Gaussian (LQG) control with the low-pass filters and high-pass filters is demonstrated to suppress the first three modes of an all-clamped plate and gives 10~20-dB reduction of vibration in the experiment. Also, the highest gains of the controller for the plant, which consists of the nominal model and several uncontrolled modes, are evaluated to vindicate the usefulness of high-pass filters     

基于压电薄膜和片上可编程系统的可穿戴体征监测系统

随着社会经济的发展,人口与建筑密度日益增大,火灾发生的概率越来越大,扑救难度也越来越高。传统的消防防护服属功能服装只能实现防火,隔热和阻燃等基本功能。而消防战斗员的生命体征无法被消防指挥员及时获知,这对保障消防战斗员的生命安全,和消防现场的应急指挥非常重要。正是在这种形势下,可穿戴体征监测系统的研究才具有重要的实用意义。研究的可穿戴体征监测系统,是可装配于救援防护服本体上,基于压电薄膜技术和片上可编程系统技术搭建的,具有生命体征监测和告警功能的电子系统。装配了该系统的救援防护服,不仅能够实现传统防护服对救援队员的保护作用,还可以实时监测救援队员的生命体征,通过声光告警电路将现场信息反馈给救援队员,提高了消防救援和指挥效率。     

Algorithms for optimal scheduling and management of hidden Markovmodel sensors

The author considers a hidden Markov model (HMM) where a single Markov chain is observed by a number of noisy sensors. Due to computational or communication constraints, at each time instant, one can select only one of the noisy sensors. The sensor scheduling problem involves designing algorithms for choosing dynamically at each time instant which sensor to select to provide the next measurement. Each measurement has an associated measurement cost. The problem is to select an optimal measurement scheduling policy to minimize a cost function of estimation errors and measurement costs. The optimal measurement policy is solved via stochastic dynamic programming. Sensor management issues and suboptimal scheduling algorithms are also presented. A numerical example that deals with the aircraft identification problem is presented     

A local approach for the LPV identification of an actuated beam using piezoelectric actuators and sensors

This paper considers the identification of structural dynamics by identifying its frequency response functions (FRFs) – a mathematical representation of the relationship between the vibration response at one location and excitation at the same or another location. The spatially-varying characteristics of the FRFs at various input and output locations are explored, and lead to a spatial linear parameter varying (LPV) representation. A local LPV identification technique for lumped systems is adapted here to spatially-interconnected systems. The identification of a spatial LPV model facilitates the experimental work, and also simplifies the controller synthesis. The proposed approach is applied to identify an actuated beam equipped with an array of collocated piezoelectric actuators and sensors for performance illustration.     

最优闭环发送分集

发送分集 (TransmitDiversity)是在第三代移动通信系统中应用的一个关键技术。本文对TD -SCDMA系统的MISO(Multiple -InputSingle -Output)信道 ,推导出闭环发送分集 (ClosedLoopTransmitDiversity)中的最优权值 (即调整发送权值使移动台接收信号的功率达到最大值 ) ,表明发送权值的计算实际上就是估计上行信道增益的平均值。经过计算得到 ,与空时分组编码 (Space -TimeBlockCoding)相比 ,使用最优权值的闭环发送分集 (CLTD)技术可使移动台的接收信噪比提高 3dB ,并通过仿真加以验证     

双闭环控制的生物芯片点样仪

在高定位精度的运动系统中,光栅尺做为位置反馈元件大量使用。本点样仪选用Galil公司的DMC1800控制卡、松下交流伺服电机、雷尼绍光栅尺和贝塞德运动单元,定位精度可以满足设计要求。控制软件采用VB编写。     

MEMS传感器和智能传感器的发展

MEMS传感器和智能传感器可以被称为新时代传感器的典型代表,在智能化以及集成化方面体现出独特的优势。随着我国科学技术发展水平的提高,MEMS传感器和智能传感器也处于不断发展的过程中,同时应用的范围不断拓宽,为各行各业带来了极大的便利。文章对此展开分析。     

Precoder Partitioning in Closed-loop MIMO Systems

We study unitary precoding for multistream MIMO systems with partial channel state information at the transmitter. We introduce a quantization scheme in which the full space of non-equivalent precoding matrices is partitioned into Grassmannian and orthogonalization parts. The Grassmannian part is used for maximizing the power after precoding and the orthogonalization part is used for removing cross talk between the data streams. We show that orthogonalization improves the attainable capacity when the receiver is linear. We give a parametrization for the non-equivalent orhogonalization matrices and a metric which measures the orthogonality of the transmission. Optimal orthogonalization codebooks for two-stream transmission are presented. When feedback is limited, the optimal partitioning of feedback bits between Grassmannian and orthogonalization parts becomes an issue. In correlated scenarios, the number of feedback bits may be significantly reduced by investing bits into the orthogonalization part.     

Closed-loop stability analysis of microwave amplifiers

A stability analysis technique of microwave amplifiers, valid for large- or small-signal regimes, is presented. The technique calculates the system poles and zeroes from a closed-loop frequency response of the circuit linearised around its steady state. The method has been applied to an S-band monolithic amplifier, detecting spurious oscillations for certain specific bias conditions and input power levels, in good agreement with measurements     

Closed-loop feedback systems using reduced-order models

Theorems are given to demonstrate that the tracking properties of reduced-order models obtained by Padé-type approximation methods are unchanged under constant (and dynamic) state or output feedback. Hence it follows that an optimal feedback law for the reduced-order model may be used for suboptimal control of the high-order system, with similar tracking of the output as for the open-loop case.     

焊线机超声波闭环控制

超声波是焊线机焊接过程中的重要参与元素,超声波控制效果决定着焊接的品质和速度。在分析超声换能器频率特性和电流响应的基础上,给出了频率自动跟踪和电流受控输出的闭环控制方案,提高了超声波效率,缩短了响应时间,增强了超声波输出的稳定性。实验结果表明,此方法实现了受控的上升时间和较小的超调     

开关电容式闭环微加速度计的稳定性研究

该文对开关电容式闭环微加速度计的系统稳定性进行了深入研究。提出了可通用于该类微传感系统的动态特性分析方法,并具体研究了传感器品质因子、力反馈延迟、电路补偿单元的参数多种因素对系统稳定性的影响。基于 CMOS工艺实现了一款接口电路芯片实例,实验结果表明,充分的电路补偿设计对于保证系统稳定性十分关键,实际的系统稳定边界与理论分析结果也较为吻合,从而证明了理论分析方法的正确性。     

Micropotentiometric sensors

This paper covers recent developments in microfabricated potentiometric liquid chemical sensors. It includes a discussion of the various types of solid-state potentiometric sensors, including the inherent and practical challenges involved in implementing and commercializing the devices. The paper also presents recent advances that overcome some of these difficulties, including progress toward compatible microreference electrodes.     

可编程传感器

混合信号CMOS集成可编程传感器与系统的问世,促进了汽车产品在减少有害物质排放、改进安全系统、实现无缺陷质量标准与提高可靠性等方面的改进——当然也有效地促进了成本的降低。早先的传感器系统都是由无源元件和简单的IC组装而成的。进入九十年代以后,可编程的、嵌入有敏感元件的单片系统IC,逐步取代了上述由许多元器件组装而成的传感器模块。这些先进的集成系统,遵守Moors定律,虽然复杂得多,但是由于芯片内信号处理能力的增强,成本却反而降低了。本文将介绍两种当今常用的集成传感器和敏感器件接D线路的构造。传感器需要进行…     

Spin-dependent sensors

The discovery and development of structures using the spin dependence of conduction electrons has led to products and product developments in recording heads and nonvolatile memory. It has also led to the introduction of several new products which sense magnetic fields using these new structures. This article describes giant magnetoresistance and magnetic tunnel junction structures and how they are used in several applications.     

基因传感器

21世纪是生物学发展的时代,特别是生物科学与计算机科学经融合产生的生物信息学将得到蓬勃的发展。事实上,从20世纪叨年代初随着人类基因组计划的实施,生物信息学就已开始形成。一般地讲,生物信息学指的是利用数理和信息科学的观点、理论和方法去研究生命现象,获取生物学的数据,分析和提取生物信息的科学。对于人类基因组计划,生物信息学就是研究遗传基因信息的科学。传感技术是信息科学的三大技术之一,是信息获取的手段。利用传感技术获取生物的信息是生物信息学发展的要求和必然。因此,随着生物信息学的发展,获取基因信息的基因…     

Closed-loop measurement of equipment efficiency and equipmentcapacity

Formal definitions for the components of efficiency and capacity, mathematical formulas for computing overall efficiency, and data collection strategies are proposed for rigorous measurement of equipment efficiency and equipment capacity. Measurement of overall equipment efficiency (OEE) under the TPM paradigm is extended to support the maintenance of capacity parameters for production planning. The weaknesses or equipment analyzes based on utilization and aggregate UPH (units per hour) figures are contrasted against the robustness of the proposed approach. Applications in semiconductor factories are discussed