压电陶瓷微位移系统的变参数PID闭环控制方法

针对压电陶瓷器件在精密定位控制中存在的迟滞、蠕变和位移非线性等不足,本文采用压电陶瓷直接粘贴应变片组成测量电桥作为位置反馈环节,设计了带上下限位的变参数PID闭环控制微位移系统,达到了预期的控制精度和效果.     

基于双反馈模式的大范围自感应AFM测量系统

为了提高原子力显微镜（AFM）的测量范围,设计了一种基于双反馈测量模式的大范围自感应原子力显微镜系统,测量系统中有两条反馈回路:一条反馈回路由压电陶瓷与AFM测头组成,动态响应较快的压电陶瓷位移台的运动量可以表征被测样品表面的高频信息;另一条反馈回路由压电陶瓷位移台和纳米测量机（NMM）的反馈控制器组成,利用压电陶瓷位移台的位移信号控制NMM运动,NMM的mm级z向测量范围使得被测样品较大变化范围的低频轮廓信息很容易地被表征出来。使用本系统对平面样品和一维栅格进行了测量实验,实验结果表明采用双反馈的测量模式的AFM测量系统能够有效地表征被测样品的低频轮廓信息和表面高频信息,测量范围能够达到mm级,纵向分辨率达到nm级,具有良好测量重复性。     

一种新的外差干涉信号处理方法—相位及相位整数测量法

介绍了一种新的外差干涉信号处理方法－相位及相位整数测量法。用此方法不仅可使干涉测量的分辨率提高到λ／１０００－λ／２０００，而且扩大了测量范围，解决了大范围、动态测量位移的问题。文中还给出了用此方法进行信号处理的外差干涉仪测量压电陶瓷动态位移的实验结果。     

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。     

剪切压电陶瓷块微位移测量及非线性修正

通过搭建的剪切压电陶瓷块微位移测量系统,进行了5个不同目标电压的剪切压电陶瓷微位移测量实验,对实验数据分别进行二阶、三阶、四阶最小二乘拟合后进行非线性修正实验,其中采用三阶最小二乘拟合进行修正时效果最好,其位移1 050 nm行程时最大非线性误差为3 nm。对所得三阶最小二乘拟合多项式的系数进行样条插值拟合,从而实现对不同目标位移的非线性修正,其中位移900 nm行程时最大非线性误差为4 nm,仅为原始非线性误差的11%。     

压电陶瓷极化特性研究

使用DP-5型介电谱仪,测量由压电陶瓷材料制作的蜂鸣器的介电频率特性,验证理论猜测。实验测出压电陶瓷的极化方式与极化率与外场频率有关,随着频率的增加,压电陶瓷的离子位移极化率、电介质分子取向极化的极化率将减小,最终表现为相对介电常数减小。实验结果与理论猜测吻合。     

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。     

压电陶瓷应变的测量及应用

本文叙述压电陶瓷重要特性之一——应变(形变)的产生机理、分类、测量方法及应用。用迈克尔逊干涉法测量静态形变。采用贝塞尔函数法测量动态形变。贝塞尔函数法测量简便,精度高,用此法测出压电陶瓷在谐振状态下的动态形变后,可确定压电陶瓷的机械谐振频率f_r,机械Q_M值等参数,从而可评价压电陶瓷元件的质量。 叙述了利用压电陶瓷的形变研制成的一些高精度精密器件,如致动器,激光器谐振腔微调机构、微位移扫描器和压电千分尺等。     

高控位精度横向模压电微位移器的研究

介绍了d31横向伸缩模式压电徽位移驱动器的制作过程,应用高稳定的填满钨青铜型压电陶瓷作为该器件制备的基料,利用P-F干涉仪原理测量了电场-位移特性曲线,由此计算了压电常数d31并进行了讨论。该器件具有电控应变(位移)线性度高、滞后量小以及结构简单、制作工艺方便等特点,它在精密光学等技术领域有一定应用价值。     

一种高精度非接触式位移传感器及其应用

介绍了一种新型的基于改进傅科聚焦探测法且自带衍射光栅计量系统的非接触式位移传感器.因为没有采用音圈电机而是采用压电陶瓷驱动器,所以这种自带衍射光栅计量系统的传感器具有更高的精度.在测量工件表面形貌时,压电陶瓷驱动器驱动聚焦物镜进行垂直位移,从而确保在每一个采样间隔中焦点总是落在工件表面上,同时使得聚焦误差信号回零.该非接触式位移传感器的分辨力为10nm.     

BiAlO3掺杂PZT陶瓷的高压电性能和低电场应变滞后

铅基压电陶瓷因其优异的压电性能, 被广泛应用于压电器件。其中, 压电驱动器要求压电陶瓷具有较高压电性能并且在电场下具有较高的电致应变和较小的应变滞后。本研究通过施主-受主共掺, 得到高压电性能和低电场应变滞后的PZT陶瓷。采用传统固相反应法制备了(1-x)(Pb_0.95Sr_0.05)(Zr₅₃Ti₄₇)O₃-xBiAlO₃+0.2%MnO₂陶瓷(掺杂量为质量百分数), 并对其微观结构和压电性能进行了研究。结果表明：BiAlO₃掺杂量较少时, 陶瓷中缺陷偶极子的“钉扎”效应使得陶瓷畴壁转动困难, 陶瓷压电性能较弱, 应变滞后也较小。随BiAlO₃掺杂量增加, 缺陷偶极子“钉扎”效应减弱, 陶瓷的压电性能和应变滞后随之提高。本实验得到的性能最优组分为x=1.75%, 该组份陶瓷的压电系数d₃₃=504 pC/N, 机电耦合系数k_p=0.71, 机械品质因数Q_m=281, 居里温度T_C=312 ℃, 在10 kV/cm电场下的应变滞后仅为15%, 并且还具有较好的温度稳定性, 是一种具有应用价值的压电驱动器用压电陶瓷材料。     

Comparison between point and long‐gage FBG‐based strain sensors during a railway bridge load test

Strain is a key parameter in laboratory and bridge load testing. The selection of a strain sensor depends on several factors, including the aim of the test and the specimen material. The application of the right sensor is vital to obtain accurate readings, especially in the case of heterogeneous materials such as concrete. This paper focuses on long‐gage and point fiber Bragg grating‐based strain sensors and their possible applications on concrete elements. First, strain sensors are described, after which long‐gage and point fiber Bragg grating strain sensors are compared in a concrete specimen test, a concrete column test and static and dynamic load tests on a concrete railway bridge. Results show that although it is advisable to use long‐gage sensors when monitoring heterogeneous materials, there are some particular cases were both sensors type can provide accurate strain measurements.     

Ultrasonic Instrumentation for Measuring Applied Stress on Bridges

The measurement of applied stress on bridges can provide valuable information on the condition of the structure. The conventional technique for measuring applied stress is with a strain gage. However, strain gages can be time consuming to install because first the surface must usually be prepared. On a bridge, paint removal will most likely be necessary as part of this surface preparation. When dealing with lead-based paints, which are considered hazardous waste, many time consuming removal procedures are required. Because of these factors, a device that measures applied stress without requiring paint removal could be useful. While a “clamp-on” strain gage can also be used to measure applied stress without requiring paint removal, this type of strain gage can not be used on some bridge details, such as webs of I-beams and tops of box girders. An ultrasonic technique using non-contact electromagnetic transducers provides a possible method for applied stress measurement which is not limited by the same factors as those with conventional strain gages. The transducers operate through nonconductive and conductive (lead-based) paint and work on rusted, pitted surfaces. Our previous research developed a technique for measuring applied stresses on bridges with EMATs and included many laboratory tests. This paper describes field applications of the technique on actual bridge structures, as well as additional system testing and instrument calibration in the laboratory.     

柔性冗余度机器人残余振动主动控制

研究柔性冗余度机器人的残余振动主动控制问题，设计了具有压电作动器与应变传感器的机敏杆件，建立了受控系统的状态空间表达式，采用独立模态空间控制理论设计LQR状态反馈控制器，并基于对偶原理设计了具有指定收敛特性的Luenberger全维状态观测器，最后，以平面3R柔性冗余度机器人为例进行了计算机仿真，结果表明，采用这种主动控制方法可以显著改善柔性冗余度机器人的动力学品质。     

钛酸铋钠基无铅铁电陶瓷场致应变性能研究

钛酸铋钠(Bi_0.5Na_0.5)TiO₃(BNT)作为典型的钙钛矿型弛豫铁电体, 具有超高的场致应变, 是最有希望代替铅基体系的无铅压电体系之一。与铅基陶瓷相比, BNT基陶瓷具有驱动电压较高、迟滞较大以及温度稳定性差等劣势。为了优化无铅驱动器的应变性能, 本研究采用固相反应法制备(1-x){0.76(Bi_0.5Na_0.5)TiO₃-0.24SrTiO₃}-xNaNbO₃(BNT- ST-xNN, x=0~0.03)无铅铁电陶瓷。结果表明, 当x=0.01时, 该陶瓷在较低电场(E=4 kV/mm)下的应变值可达到0.278%, 等效压电系数d^*₃₃高达695 pm/V。此时, 陶瓷处于非遍历/遍历弛豫相界处, 电场诱导弛豫-铁电相变导致大场致应变。与x=0.01相比, x=0.02时应变值为0.249%, 略微下降, 但迟滞却降低至43%。此外, 该应变在25~100 ℃温度范围内维持稳定。本研究表明, 在BNT基陶瓷中固溶SrTiO₃和NaNbO₃组元可以提高场致应变值, 同时维持较低的驱动电场和良好的温度稳定性, 可用于压电驱动器研制。     

Method of temperature error compensation in strain transducers

A method of compensation for the temperature error of semiconductor bridge strain transducers is described. It is based on the use of a strain gage bridge as the temperature-sensitive element and controllable source of current for supply to the bridge. The supply current is regulated to compensate for variation in temperature sensitivity in relation to bridge resistance by means of positive feedback while a correcting voltage proportional to the temperature is formed for correcting zero drift. The method facilitates the temperature error of strain transducers to be reduced up to 0.5% at 70–80°C.Translated from Izmeritel'naya Tekhnika, No. 7, pp. 39–40, July, 1993.     

Comparison of strain gage and interferometric detection for measurement and control of piezoelectric actuators

The capability of controllable and repeatable positioning in the subnanometer range is fundamental not only for scanning probe microscope applications, but also for nanotechnology in general. Up to now, piezoceramic actuators have been used for this purpose. However, these actuators are far from being ideal transducers. For precise metrological applications, as well as for general use in scanning probe microscopy, some method has to be implemented to correct creep and nonlinearity of piezoceramic materials. In the present study, two different position measuring systems have been implemented—one based on strain gage detection and the other on interferometry. The corresponding results are presented and the performance of both setups compared.     

The effect of short range order on the thermal output and gage factor of Ni3FeCr strain gages

The ability of alloy 70Ni‐27.5Fe‐2.5Cr to form an ordered crystalline structure upon application of elevated temperature and the resulting effects on a variety of physical properties such as magnetism, strength, electrical resistance, and specific heat are well known. This paper demonstrates that strain gages made with 70Ni‐27.5Fe‐2.5Cr foil with an ordered crystalline structure have both high gage factors and high thermal outputs. The thermal output for strain gages made of 70Ni‐27.5Fe‐2.5Cr foil is demonstrated to be about 1,374 μΩ/Ω/K. The gage factor is nonlinear ranging in magnitude from about 5.0 to 3.6 for applied strains of 300 and 1,300 μE, respectively. The magnitude of gage factor and thermal output correspond with transformation of the crystalline structure from a state of disorder to a state of order. Comparisons to strain gages made with 36Ni‐57Fe‐7Cr foil are provided because of its use in the manufacturing of metal foil strain gages and their demonstrated high gage factors and high thermal outputs. Practical application for 70Ni‐27.5Fe‐2.5Cr strain gages is demonstrated by dead‐weight loading of shear‐beam load cells at low applied strain levels to minimise the effect of nonlinear gage factor; and Wheatstone bridge cancellation of high thermal output.     

考虑外部阻抗的压电叠层作动器机电耦合模型

压电叠层作动器在结构振动控制及其它场合表现出良好应用前景,建立能够反映其物理本质的数学模型非常重要。以压电材料的本构关系以及杆的纵向振动方程为基础,考虑外部阻抗的影响,推导了短路机械阻抗、电阻抗以及转换系数的表达式,并构造了转换方程,从而建立了能够描述压电叠层作动器与主体结构之间机电耦合特性的阻抗模型。理论分析和数值模拟结果表明外部阻抗对这些参数有重要影响：当两端的外部阻抗完全相同时,作动器的电阻抗和转换系数有最高的共振频率,作动器可看成两个具有固定-自由边界条件的作动器的串联。其它情况下则均有不同程度的降低。因此,为实现更好的控制效果需要考虑阻抗匹配问题。