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％）．     

利用压电和电流变功能材料构造的平面步进式驱动器

本文在国际上首次提出一种结合压电效应和电流变效应的新型平面步进式驱动器。研制的驱动器具有４个提供驱动力和产生位移的多层压电致动器,以及４个用来箝位的电流变箝位器。通过箝位器与压电致动器的不同组合,根据仿生运动模式,可实现沿ｘ向或ｙ向的蠕动式步进运动。实验结果显示,平面步进驱动器样机在ｘ向ｙ都能灵活的运动,并具有大行程和低于０．１μｍ的高分辨率。实验中以驱动器的最高步进速度为６ｍｍ／ｍｉｎ,最大承载     

MEMS变形镜用PZT厚膜致动器阵列的制备及性能表征

提出了一种基于锆钛酸铅(PZT)压电厚膜致动器阵列驱动的MEMS微变形镜,建立了该微变形镜的结构模型,分析了其结构中各层厚度对其性能的影响.PZT压电厚膜是通过基于PZT压电陶瓷体材料的湿法刻蚀技术制备的,刻蚀液为1BHF2HCl4NH4 Cl4H2O.以数字锁相方法测试了压电厚膜的介电性能,在100 kHz以下时,其介电常数和介质损耗分别优于2400和3%.利用悬臂梁方法测试了压电厚膜的也.横向压电系数,约为-250 pm/V.制备了4×4阵列的压电致动器阵列.采用激光多普勒测试压电致动器的电压位移曲线,在100 V的电压驱动下致动器的变形量大约为2.2/μm;测试了致动器的频率响应,其谐振频率高于100 kHz;致动器刚度大,带负载能力强.     

一维大行程高分辨率纳米定位平台的设计与性能测试

设计了一种大行程、高分辨率的一维纳米定位平台,并进行了性能测试．该平台采用差动杠杆原理和柔性铰链,运用两个压电陶瓷叠堆致动器驱动．对柔性铰链平台建模,通过材料力学及结构振动微分方程等相关知识,对柔性铰链微动平台的刚度、输入反作用力、放大倍数等参数进行了分析,得到平台结构参数对平台性能的影响,并结合有限元分析软件,确定了微动工作台参数;最后建立了实验系统,对微驱动定位系统的输出行程、分辨率性能进行了测试．实验结果表明,所设计的微驱动定位系统的行程达到240μm,分辨率达到10nm,外形尺寸80mm×60mm×20mm．可用于大行程高分辨率微动定位．     

北京大学工学院在压电材料领域取得突破性进展

正工学院力学与工程科学系李法新课题组在压电材料领域取得突破性进展,他们提出了一种周期正交的极化方法,将目前最常用的PZT压电陶瓷中的非线性畴变应变变得可逆,实现了约0.6%的超大致动应变,是传统PZT压电陶瓷的4倍。压电陶瓷致动器具有响应速度快、位移精度高、控制方便(电控)、体积小等优势,一直在致动器领域占据着主导地位。目前应用的压电致动器主要由锆钛酸铅(PZT)陶瓷制     

空间引力波望远镜超前瞄准机构致动器电荷驱动位移行为研究

超前瞄准机构(PAAM)是空间引力波探测望远镜的关键部件,其主要通过给压电致动器输入电压或电荷精确控制位移量,实现对望远镜高精度角度控制。因此,压电陶瓷致动器位移响应直接影响超前瞄准机构指向控制性能。本文提出等效电容量计算方法定量分析压电致动器在电荷驱动下的位移响应特性,并通过数值模拟仿真和实验验证等方式验证了计算方法的准确性和可行性。结果表明：在使用幅值5 V、频率0.05 Hz～5 Hz的正弦波信号控制的电荷放大器驱动某型号压电致动器时,采用本文方法分析结果与实验结果相比,二者位移响应最大偏差小于1.35%,为空间引力波探测望远镜超前瞄准机构的高精度指向控制提供了可能的分析方法和实现途径。     

微泵电磁致动器的研制与测试

本文阐述了微型机电系统领域中微泵的几种常见的致动方式及其特点。根据硅微泵的结构特点，制作出用于微型泵的电磁致动器，并对该电磁致动器进行了分析与振动测试。     

压电作动器对热变形层合板形状修复研究

基于一阶剪切效应Mindlin板理论,建立了在热载下含分布式压电作动器的复合材料层合板有限元分析模型和控制方程,分别研究了该板在内外表面存在温差的情况下的热变形,以及使用压电作动器对热变形区域进行形状修复的问题;在分析中考虑了压电作动器与复合材料层合板间含有胶接层的影响。由典型算例结果讨论,得到如下结论:1)使用压电作动器可以有效地对复合材料层合板的表面热变形形状进行修复;2)压电作动器的分布位置对修复效果影响很大;3)在电压达到一定数值后,继续增加电压值对修复效果贡献很小。     

压电叠堆位移放大致动器的动态特性

为了准确掌握压电叠堆位移放大致动器的动态特性,本文利用谐响应分析、阻抗测试法和动态投影栅线法对其进行分析研究。首先,使用ANSYS分析软件对放大机构的模态和位移随频率变化情况进行有限元分析。然后,运用压电陶瓷的阻抗测试法,对这一压电致动器的阻抗特性进行测量分析。最后通过动态投影栅线法对压电致动器的通放电位移状况进行测量分析。实验结果表明：位移放大机构的谐响应频率为1724Hz,能提供较大的输出力矩;压电致动器的谐振频率为8.3KHz左右,反谐振频率为8.75KHz左右,它的工作最快响应时间在0.3ms以内;它能在0.5ms内完成位移的突变,位移波动小于5um,且位移量随电压值呈线性变化;放电时的动态位移过程平稳。因此,这一压电致动器具有响应速度快,位移波动小、线性度好、精度高,输出力矩大等较好的动态响应特性,能被广泛应用于各种需要响应快、精度高、位移大的微位移控制驱动系统中,其应用前景值得期待。     

考虑作动器联接方式的结构形状控制优化

以压电材料梁式作动器控制复合材料层合板形状的设计问题为对象,研究有限个独立控制参数条件下的形状最优控制问题。研究了作动器与信号发生器(独立控制参数)联接关系的参数化描述方式,建立了作动器联接方式与控制参数协同设计的问题提法;针对优化问题中离散变量(联接方式描述参数)和连续变量(控制参数)共存的特点,建立了遗传算法和线性最小二乘(Linear Least Square,LLS)方法相结合的求解策略和方法;在响应分析所采用的有限元模型中,采用粘结层单元描述本体结构与作动器之间的连接。复合材料层合板形状控制设计的实例,验证了该文中建立的问题提法、优化模型和求解策略的有效性。     

复合作动器复合方式对平台主动隔振影响分析

为实现微隔振平台在较宽频带内的主动控制,将一弹性体和第三代压电致动器相串联,设计了一种复合式压电致动器。将复合致动器应用到微隔振平台,并对其整体建模、控制仿真时发现：弹性体相对于作动器位置不同时,在不同的外扰下对控制力的影响不同。为此,设计了一个针对不同外扰对控制力影响的评价函数,通过不同位置对评价函数影响的仿真,结果表明：当隔振平台系统受直接干扰时,弹性体位置对控制力的影响较大;当平台受地基扰动时,弹性体位置对控制力影响不显著。所以,复合作动器的布置形式取决于外扰的类型,且在实验室环境中,两种布置要达到相同的隔振效果,弹性体在上布置所耗费的能量小于其在下布置时的状态。     

新型惯性压电驱动机构的设计与初步实现

提出通过机械方式控制压电驱动机构和支撑面之间摩擦力的有序变化，形成有规律的新型惯性压电驱动机构．分析了机构的运动机理，建立了动力学模型，利用Matlab对机构进行了运动学仿真，设计并制作了驱动机构样机，对驱动机构动态特性进行了仿真分析和试验对比研究．两者结果吻合较好，表明采用简单的对称波形信号能驱动机构运动，直线驱动器最高速度可达1mm／s，最高步长分辨率为20nm，最大承载能力为1000g．     

Output Feedback Sliding Mode Control for a Linear Focusing Actuator in Digital Video Cameras

The output feedback sliding mode control offers an effective positioning method by robustness to parameter variation and disturbance rejection. This paper presents the output feedback sliding mode control based on a position estimation algorithm written in the microprocessor for use in the focusing control system of a digital video camera to achieve fast focusing response and accurate positioning despite vibration and friction of the movable part of the linear focusing actuator. The focusing performance by utilizing the output feedback sliding mode control includes a 60-ms setting time and 7-m steady-state error, respectively, which are only half and one-third of those in proportional-integral-derivative control when the movable part of the linear focusing actuator moves at a 5-mm stroke.     

Fabrication and experimental characterization of d31 telescopic piezoelectric actuators

A popular and useful piezoelectric actuator is the stack. Unfortunately with this type of actuation architecture the long lengths normally required to obtain necessary displacements can pose packaging and buckling problems. To overcome these limitations, a new architecture for piezoelectric actuators has been developed called telescopic. The basic design consists of concentric shells interconnected by end-caps which alternate in placement between the two axial ends of the shells. This leads to a linear displacement amplification at the cost of force; yet the force remains at the same magnitude as a stack and significantly higher than bender type architectures. This paper describes the fabrication and experimental characterization of three different telescopic prototypes. The actuator prototypes discussed in this paper mark a definitive step forward in fabrication techniques for complex piezoceramic structures. Materials Systems, Inc. has adapted injection molding for the fabrication of net shape piezoceramic actuators. Injection molding provides several advantages over conventional fabrication techniques, including: high production rate, uniform part dimensions, uniform piezoelectric properties, and reduced fabrication and assembly costs. Acrylate polymerization, developed at the University of Michigan, is similar to gelcasting, but uses a nonaqueous slurry which facilitates the production of large, tall, complex components such as the telescopic actuator, and is ideal for the rapid manufacture of unique or small batch structures. To demonstrate these fabrication processes a five tube telescopic actuator was injection molded along with a very tall three tube actuator that was cast using the acrylate polymerization method. As a benchmark, a third actuator was built from off-the-shelf tubes that were joined with aluminum end-caps. Each prototype's free deflection behavior was experimentally characterized and the results of the testing are presented within this paper.     

新型压电双晶片式惯性旋转驱动机构设计

提出了一种通过机械方式控制压电驱动机构和接触面间摩擦力矩的有序变化,形成以压电双晶片振子为驱动元件的新型压电惯性旋转驱动机构的研究方案．研究了该机构的运动机理,指出通过改变机构向不同方向运动时和支撑面之间的摩擦系数值,可以实现压电驱动机构的定向运动．对机构惯性冲击力矩的产生、摩擦阻力矩的改变形式进行了分析．设计了压电惯性旋转驱动机构,制作了试验样机,并对相关性能进行了测试试验结果证明该机构可以实现预期的运动.     

Zero-Power Magnetic Levitation Using Composite of Magnetostrictive/Piezoelectric Materials

We present a zero-power magnetic levitation technique using a composite of magnetostrictive and piezoelectric materials. The composite is bonded to iron yokes with an attached permanent magnet, by which the magnetic force exerted on movable yoke via air gap is controlled by the applied voltage on the piezoelectric material. The magnetic force control is based on the inverse magnetostrictive effect of the magnetostrictive material, i.e., the magnetization is varied with mechanical stress. The advantage of the composite is zero power consumption, because no current flows in static operation as a result of the capacitive property of the piezoelectric material. This feature will be useful in high-precision stage or conveyor systems using magnetic levitation where heat generation and power consumption should be avoided. The zero power characteristic of the composite is valid at any reference gap or load, whereas that of the conventional electromagnetic type is valid only at the equilibrium gap. We performed two levitation experiments: one using the composite to demonstrate the zero power advantage, and the other combining the composite to adjust the bias gap and electromagnet to stabilize the motion of the levitated yoke. The composite driven by a small dc-dc converter successfully varied the gap and maintained it constant with zero power consumption.     

摩擦系数变化式压电叠堆惯性直线驱动器

以压电叠堆和质量块组成的压电叠堆振子为动力元件,通过利用驱动器向左运动和向右运动时接触足与接触面摩擦系数的不同,设计并制作完成了一套摩擦系数变化式压电叠堆惯性直线驱动器．分析了该驱动器的工作原理并对驱动器的运动情况作了详细分析．搭建了专用测试系统,并采用该系统对摩擦系数变化式压电叠堆惯性直线驱动器进行了性能测试．试验结果表明：当频率为10Hz时,该试验装置最小稳定步长为0．19μm,最大移动速度为11．82μm／s,最大承载能力不低于900g．     

Field-Circuit Hybrid Method for Magnetic Actuator Using a Laminate Composite

The magnetic actuator using a laminate composite of piezoelectric (PZT) and magnetostrictive materials (MM) achieves active control of magnetic force without Joule heat loss. To study its characteristics, the field-circuit hybrid method is proposed based on the equivalent magnetic circuit and the finite element analysis (FEA) of piezoelectric and magnetic fields. The strain of laminate composite under different voltage is obtained through the piezoelectric FEA. On the basis of magnetostrictive equation, the MM branch in the magnetic circuit of the actuator is transformed equivalently, the work point of the actuator is determined, and the corresponding FEA model of magnetic analysis is then set up. The relationships between magnetic force, gap, and voltage are discussed by the hybrid method, which can be expanded into the design and analysis of the magnetostrictive actuator and sensor to improve simulation efficiency and precision.      

新型纳米分辨率位移定位平移台的研制

为克服已有压电驱动器存在的结构及控制系统复杂、定位行程小等缺陷,利用压电陶瓷的逆压电效应设计并制作了一种新型的压电纳米步进驱动器,建立光栅测试系统对这种压电驱动器的动态性能进行了测试.将压电纳米步进驱动器与电磁伺服马达耦合,设计新颖驱动结构,利用微机通过步进运动控制卡统一控制,实现大范围一维纳米分辨率位移定位.系统样机解决了所研制压电纳米步进驱动器双向运动、实用定位等问题.位移定位分辨率为50 nm,定位行程为100mm,纳米分辨率定位最大速度为0.6 mm/s.     

Analysis of a disk-type piezoelectric ultrasonic motor using impedance matrices

The dynamic behavior and the performance characteristics of the disk-type traveling wave piezoelectric ultrasonic motors (USM) are analyzed using impedance matrices. The stator is divided into three coupled subsystems: an inner metal disk, a piezoelectric annular actuator with segmented electrodes, and an outer metal disk with teeth. The effects of both shear deformation and rotary inertia are taken into account in deriving an impedance matrix for the piezoelectric actuator. The impedance matrices for each subsystem then are combined into a global impedance matrix using continuity conditions at the interfaces. A comparison is made between the impedance matrix model and the three-dimensional finite element model of the piezoelectric stator, obtaining the resonance and antiresonance frequencies and the effective electromechanical coupling factors versus circumferential mode numbers. Using the calculated resonance frequency and the vibration modes for the stator and a brush model with the Coulomb friction for the stator and rotor contact, stall torque, and no-load speed versus excitation frequencies are calculated at different preloads. Performance characteristics such as speed-torque curve and the output efficiency of the USM also are estimated using the current impedance matrix and the contact model. The present impedance model can be shown to be very effective in the design of the USM.