应变反馈式压电陶瓷微位移驱动器的研制

介绍了采用应变片测量压电陶瓷微位移驱动器位移的原理和设计思想,介绍了实验装置的结构,给出了实验结果,证明将应变片直接粘贴在压电陶瓷基体表面测量其位移的方法是可行性的;通过对压电陶瓷滞回特性的测定,提出了建立压电陶瓷的控制模型的基本思路。     

大位移压电陶瓷驱动器的设计与试验

针对大位移压电陶瓷驱动器,研究了压电陶瓷双晶片的驱动效能。基于压电陶瓷材料的逆压电效应,应用压电陶瓷双晶片在机械自由、电学短路状态下,一片加正向电压缩短另一片加反向电压伸长共同作用产生弯曲变形,通过组合设计将压电陶瓷双晶片的弯曲变形位移叠加起来,实现了压电陶瓷驱动器的大位移输出。在相同电压的条件下,此压电陶瓷驱动器的输出位移量比叠层驱动器有较大的增加,达200μm,结构尺寸也大大减小。该驱动器不需要位移放大机构,可直接应用于有大位移要求的机构驱动。     

基于电流控制的压电陶瓷驱动器

为了解决电压控制型压电陶瓷驱动器驱动压电陶瓷时存在的迟滞、蠕变和带宽窄的问题,设计了基于电流控制的压电陶瓷驱动器,利用压电陶瓷致动器位移与其所带电荷量间的线性关系,该驱动器通过控制压电陶瓷的充电电流和时间控制其位移量．在此基础上,提出了以分辨率换取稳定性的动态保持控制方法,采用该电流型驱动器,实现了开环下对压电陶瓷致动器的稳定、快速、高精度定位．实验结果表明,该驱动器驱动行程为10μm的压电陶瓷时,满行程带宽大于1．5kHz,重复定位精度小于4nm（0．4％）．     

高线性度的二维无耦合纳米压电位移系统设计

设计了一套具有高线性度的二维无耦合纳米压电位移系统。提出了一种多个压电陶瓷同步线性操作的电荷控制方案,设计采用基于非线性反馈控制和相似控制相结合的具有接地配置功能的压电控制器。控制器中引入了T型电阻网络,使电容较小的压电致动器能够进行低频线性操作。并对压电陶瓷驱动的位移平台进行了机械结构设计,平台采用嵌套式串联结构来避免耦合位移。通过解析法和ANSYS Workbench有限元仿真两方面对位移平台进行了刚度及位移分析。搭建了一套干涉位移测量系统,对压电位移台的位移、耦合误差及线性度进行了验证测试。实验结果表明:系统满行程内二维位移台的耦合误差最大仅为0.098%,可以将迟滞不对称引起的剩余轨迹偏差减小到0.79%,两个压电陶瓷间的最大轨迹偏差仅为行程范围的0.23%,理论分析和实验验证了所设计多压电电荷控制器的可行性,且系统可有效抑制耦合位移并使定位精度得到明显提高。     

压电陶瓷振动传感器的迟滞非线性误差补偿研究

针对振动测试中压电陶瓷传感器的迟滞非线性会影响检测精度的问题,分析了压电陶瓷的微观极化机理,解释了压电陶瓷传感器产生迟滞非线性的原因。为了有效补偿压电陶瓷的迟滞非线性,提高检测精度,提出了一种可以反映压电陶瓷传感器非对称迟滞特性的改进Bouc-Wen模型,研究并给出了模型参数对迟滞曲线的大小、形状及平稳性影响关系和逆模型的求取方法。利用改进Bouc-Wen逆模型作为补偿器来补偿压电陶瓷传感器的迟滞非线性,实验验证结果表明:采用逆补偿后,校正位移总是能够很好跟踪传感器的实际输入位移,有效保证了检测精度。     

基于三段PI模型的压电驱动器迟滞补偿方法

迟滞非线性降低了压电陶瓷驱动器对期望位移的跟踪精度,为解决该问题,本文通过二次规划寻优算法,基于最小均方误差准则,以压电陶瓷驱动器的运动速度规律为依据,对压电陶瓷运动速度规律不同的迟滞段分别进行PI建模.建模结果表明,相较于传统PI模型,本文提出的三段PI模型能精确地描述压电陶瓷迟滞曲线的非奇对称性.在对压电陶瓷三段PI建模的基础上,计算出压电陶瓷三段PI逆模型的阈值向量与权系数向量.通过建立的三段PI逆模型对压电陶瓷进行迟滞补偿控制,实验结果表明,与传统PI逆模型迟滞补偿控制相比,三段PI逆模型迟滞补偿控制方法将压电陶瓷对期望位移的跟踪精度提高了81.3%.     

压电陶瓷微位移器特性测试实验研究

运用光学干涉原理,结合微系统测试分析仪器,分别对压电陶瓷管和压电陶瓷位移器的非线性特性进行测试研究,主要对升压及降压时PZT位移进行测试和电源驱动器闭环状态下的性能测试。     

压电陶瓷驱动器菱形位移放大机构的动态应变测量

为监测压电陶瓷驱动器并联驱动时各自的动态输出状态,利用压电陶瓷驱动器中位移放大机构的菱形对称结构建立全桥应变测量方法,通过位移放大机构菱边在振动过程中的动态应变变化来反映压电陶瓷驱动器的工作状态。对不同状态下位移放大机构菱边的动态应变进行实验研究,结果表明:利用位移放大机构对称菱边建立的全桥应变测量方法能够有效获取位移放大机构在振动过程中的动态应变变化,且能够对位移放大机构的运行状态进行实时监测,在带负载和不带负载情况下,设计的位移放大机构菱边在振动过程中的应变量级都在几个微应变,该测量结果也反映出设计的位移放大机构刚度较好,能够保证压电陶瓷驱动器有较好的输出性能。     

新型程控压电陶瓷驱动电源

压电陶瓷驱动电源是压电陶瓷微位移和精密定位系统中的核心控制装置,本文设计了新型双路程控压电陶瓷驱动电源,提出了锁相环调节时钟基准、计数起始时刻控制、E2PROM在线编程和幅度调节等技术,实现了驱动信号的调频、调幅、调相,并且可输出周期或单次任意波形.该电源突破了传统驱动电源固定驱动波形及相位的限制,可根据压电陶瓷的动作要求在线设计驱动波形和参数,预置驱动次数,使压电陶瓷产生各种需要的动作,拓展了压电陶瓷的应用领域.     

晶体结构对压电陶瓷微位移驱动器特性的影响

对钙钛矿结构的ＰＺＴ－５和钨青铜结构的ＰＢＮＮ二种压电陶瓷制成的压电微位移器进行了电压－位移特性的比较和分析，发现我们所研制的ＰＢＮＮ压电微位移器具有线性好、回零好、等优点。     

SAW Sensor Network Fabricated on a Polyvinylidine Difluoride (PVDF) Substrate for Dynamic Surface Profile Sensing

A combination of two 2-D sensor networks is proposed as a dynamic surface profile sensor network for biomimicing applications. A surface acoustic wave device fabricated on a polyvinylidine difluoride substrate has been investigated as the elementary 1-D bending curvature sensor used in the network. The device was tested under an injected signal and it shows the variation in amplitude and phase angle of output signal with respect to the injected signal in response to the bending curvature. These dual outputs provide opportunity to make an intelligent sensor with self error limit determination capability. Finally, a network of such sensors is proposed as a dynamic surface profile sensor     

Electrochemical detection of biomolecule with mixed self-assembled monolayers of ferrocene-undecanethiol

Thiol self-assembled monolayers (SAMs) have been widely used as a modification method to immobilize biomolecules to gold surfaces. However, the additional layers of SAM and biomolecules make electron transfer difficult, leading to a large overpotential in electrical signal. Electron transfer mediation is the most popular solution to overcome the problem of the overpotential for an electrochemical biosensor. We introduced mixed SAMs of mercapto-dodecanoic acid (MDA) and ferrocene-undecanthiol. Ferrocene-undecanthiol acts as an electron transfer mediator and MDA is used for immobilization of biomolecule. The electron transferability of mixed SAMs is affected by pH, kinds of electrolytes, and the composition of the thiol molecule. We optimized the carboxyl acid and ferrocene molecule ratio which is a crucial factor in the performance of mixed SAMs and electrochemically detected the avidin. The detection limit was 2.0 microg/mL of avidin concentration.     

大坝有限元分析应力取值的研究

提出了基于误差控制下的自适应网格的有限元应力取值标准:即给定一全局误差限作为自适应有限元网格剖分的准则,以此网格计算所得应力即为有限元应力取值。应用适用于工程计算的Z2后验误差估计方法以及h-型自适应策略,对一个典型的重力坝剖面进行了线弹性自适应有限元计算。计算结果表明:给定一个全局误差限,网格剖分调整若干次后即可满足误差要求,不会出现因角缘应力集中出现剖分不收敛的情况;存在一个全局误差限,使得当继续降低误差限时,坝踵和坝趾的角缘应力趋于稳定值。     

基于双耦合混沌振子变尺度微弱信号检测方法研究

以双耦合Duffing混沌振子为研究对象,提出了一种基于双耦合Duffing混沌振子与变尺度相结合的微弱信号检测新方法。分析了双耦合Duffing混沌振子检测微弱周期信号的原理。利用变尺度方法,克服了Duffing振子检测微弱周期信号受频率限制的缺陷。通过双耦合Duffing混沌振子系统与单Duffing混沌振子系统进行比较,表明双耦合Duffing混沌振子系统具有明显的优越性。该方法用于检测任意多频微弱信号具有明显优势。     

Technical limitations to homodyne detection at audio frequencies

Homodyne detection relies on the beat between a relatively strong local oscillator (LO) field at the carrier frequency and a signal beam with sidebands centered around the carrier frequency. This type of signal detection, or signal readout, is widely used in quantum optics applications and is expected to be used in advanced interferometric gravitational wave detectors. We investigate experimentally the limitations to making such measurements in a laboratory environment at audio frequencies. We find that beam jitter noise, electronic noise of the photodetectors, and the LO intensity noise can limit the homodyne detection in this frequency band, and we discuss potential solutions.     

频谱带宽和功率可变多普勒信号的计算机模拟

计算机模拟的多普勒信号，可以为各种多普勒信号处理方法的研究提供信号源，从而了解各种不同处理方法的性能。本文提出的方法，运用白噪声通过一时变滤波器的原理，模拟产生平均频率，带宽和功能均随时间变化的多普勒信号。     

Super‐Resolution Nonlinear Photothermal Microscopy

Super‐resolution fluorescence microscopy enables imaging of fluorescent structures beyond the diffraction limit. However, this technique cannot be applied to weakly fluorescent cellular components or labels. As an alternative, photothermal microscopy based on nonradiative transformation of absorbed energy into heat has demonstrated imaging of nonfluorescent structures including single molecules and ~1‐nm gold nanoparticles. However, previously photothermal imaging has been performed with a diffraction‐limited resolution only. Herein, super‐resolution, far‐field photothermal microscopy based on nonlinear signal dependence on the laser energy is introduced. Among various nonlinear phenomena, including absorption saturation, multiphoton absorption, and signal temperature dependence, signal amplification by laser‐induced nanobubbles around overheated nano‐objects is explored. A Gaussian laser beam profile is used to demonstrate the image spatial sharpening for calibrated 260‐nm metal strips, resolving of a plasmonic nanoassembly, visualization of 10‐nm gold nanoparticles in graphene, and hemoglobin nanoclusters in live erythrocytes with resolution down to 50 nm. These nonlinear phenomena can be used for 3D imaging with improved lateral and axial resolution in most photothermal methods, including photoacoustic microscopy.     

Interconnect characteristics of fiber image guides

We investigated various factors that influence the transmission of high-density and high-bandwidth signals propagated through fiber image guides. The effects of signal power uniformity, optical cross talk, mode dispersion, and modal noise were considered. A model for power uniformity and optical cross talk is provided that we used to evaluate the channel density of several coupling modes. Also, modal noise was experimentally measured for several conditions of coupling to the fiber image guide. A commercially available fiber image guide was evaluated in the context of these performance considerations and was experimentally tested. The resultant minimum signal channel based on these criteria was found to consist of three fiber elements. The limit on transmission length that is due to modal dispersion was estimated at 1.65 m at 2.5-Gbits/s and at 42 cm at 10-Gbits/s data rates. Optical cross talk and modal noise were found to place a lower limit on the signal channel density. These characteristics compare favorably with electrical interconnect densities that are projected for tape automated bonding and flip-chip bonding techniques used at the chip-to-module and chip-to-board packaging levels.     

基于SYSTEM Ⅱ的新型微波中功率计量系统

SYSTEMⅡ功率传递系统是微波小功率计量领域内应用比较广泛的测试系统之一,通过对传统中功率计量方法的分析研究,提出了利用SYSTEMⅡ功率传递系统实现中功率计量的构建方案。采用低反射系数等效信号源结构,构成反射系数小、输出稳定、输出电平可调的中功率等效信号源;采用中功率衰减器和SYSTEMⅡ功率传递系统中含有的高精度终端式小功率座构成中功率传递标准,通过交替比较法,实现微波中功率计的高精度自动校准。     

一种基于聚丙烯孔洞型铁电驻极体薄膜的新型传感器

采用聚丙烯孔洞型铁电驻极体薄膜作为机电转换材料,将其层叠封装制成压力传感元件,并设计电荷放大器将其输出信号放大,用无线发射模块/无线信号接收模块连以信号处理模块,做成无线传感器。这种无线传感器可用于报警、运动监测。