考虑边缘效应的平行平板式静电微执行器Pull-in模型

在MEMS执行器的设计中,求出准确的Pull-in参数是至关重要的。在过去的研究中,对于漏电场不能忽略的平行平板式静电微执行器,通常只能采用有限元法数值求解。但是,有限元法繁琐、费时而且不直观。平行平板电容器的漏电容解析模型通常有两种：一种简单的;一种详细的。基于这两种漏电容解析模型,分别导出了漏电场不能忽略的平行平板...     

Pull-In Analysis of Torsional Scanners Actuated by Electrostatic Vertical Combdrives

This paper presents pull-in analysis of torsional MEMS scanners actuated by electrostatic vertical combdrives with general comb gap arrangements and cross sections. The analysis is based on a 2-DOF actuator with a single voltage control. Three failure modes of the scanners are identified as in-plane twist, transversal motion, and out-of-plane twist. For each failure mode, analytical expressions of pull-in deflection are obtained by applying 2D analytical capacitance models to the derived pull-in equations. From these, the dominant pull-in mechanism is shown to be in-plane twist for scanners with high-aspect-ratio torsional springs. The analytical calculations for both symmetric and asymmetric capacitances are shown to be in good agreement with simulation results. The optimum scanner design is achieved when the pull-in deflection matches the capacitance maximum angle. The condition can be expressed in terms of the ratio of the comb thickness to the comb gap, which is smaller than the typical aspect ratio of deep reactive ion etching. The optimum tradeoff between the maximum deflection angle and the number of movable combs is achieved by adjusting the overlap of the movable and fixed combs and the distance of the comb sets from the axis of the rotation.     

Snap-Through and Pull-In Instabilities of an Arch-Shaped Beam Under an Electrostatic Loading

The snap-through and pull-in instabilities of the micromachined arch-shaped beams under an electrostatic loading are studied both theoretically and experimentally. The pull-in instability that results in a system collision with an electrode substrate may lead to a system failure and, thus, limits the system maximum displacement. The beam/plate structure with a flat initial configuration under an electrostatic loading can only experience the pull-in instability. With the different arch configurations, the structure may experience either only the pull-in instability or the snap-through and pull-in instabilities together. As shown in our computation and experiment, those arch-shaped beams with the snap-through instability have the larger maximum displacement compared with the arch-shaped beams with only the pull-in stability and those with the flat initial configuration. The snap-through occurs by exerting a fixed load, and the structure experiences a discontinuous displacement jump without consuming power. Furthermore, after the snap-through jump, the structures are demonstrated to have the capacity to withstand further electrostatic loading without pull-in. Those properties of consuming no power and increasing the structure deflection range without pull-in is very useful in microelectromechanical systems design, which can offer better sensitivity and tuning range.     

Nonlinear Control of an Electrostatic Micromirror Beyond Pull-In With Experimental Validation

This paper is aimed at demonstrating the potential benefits of applying nonlinear control techniques to a type of microelectromechanical system, namely, electrostatic micromirrors, in order to extend their stable operation range, enhance the system's performance, and allow controller tuning and system operation to be performed in a systematic manner. A nonlinear tracking control based on feedback linearization and trajectory planning has been developed. Aspects essential to the implementation, such as the prevention of devices from destruction due to contact, modeling and sensing schemes, the influence of the dynamics of the driving circuit on performance, and the device characterization, have been thoroughly addressed, and practical solutions have been proposed. The experimentation is performed on a setup built with low-cost commercial off-the-shelf instruments and components in a laboratory environment. The experimental results show that the developed control system can achieve stable operation beyond the pull-in position for both set-point and scanning controls.$hfill$ [2008-0268]      

静电驱动MEMS谐振式压力传感器闭环拓扑研究

谐振式压力传感器闭环拓扑结构对保持机械谐振器振荡的稳定性和可靠性起着重要作用.针对一种典型结构的静电驱动电容检测MEMS谐振式压力传感器,在分析工作原理的基础上,构建了其混合信号模型.基于该模型搭建了自激振荡、自动增益控制、锁相环和带AGC的自激振荡四种闭环拓扑结构.在混合信号仿真平台下,对四种拓扑结构在起振状况、自动...     

电除尘高频电源串并联混合谐振变换器的应用

介绍电除尘用高频电源的组成原理,分析串并联混合谐振变换器并给出实验结果,说明了采用该变换器的技术优越性。     

陶瓷驱动器应用中的滞环特性及研究进展

陶瓷驱动器作为高精度定位系统设计的关键器件，其滞环特性一直是影响被控系统性能的重要因素，因此滞环特性的建模与控制是目前亟待解决的核心技术问题。本文首先介绍了陶瓷启动器的滞环特性及其对高精度定位的不利影响，然后重点论述了国内外在陶瓷驱动器应用于非线性系统控制中的主要建模与控制方法。     

基于观测器的机械臂执行器故障诊断方法研究

为了提高机器人系统的可靠性,针对机器人的机械臂控制系统,提出一种基于观测器的执行器故障诊断方法。在考虑系统存在外部干扰的情况下,通过设计干扰观测器抵消外部干扰对故障诊断结果的影响。为了进一步诊断系统执行器故障,提出一种基于二阶滑模观测器的故障诊断方法,通过等效输出注入项对系统执行器故障信号进行故障估计,以完成机械臂执行器的故障诊断任务。最后,建立了双关节机械臂控制系统仿真模型并通过数值仿真分析说明了该故障诊断方法的有效性和应用前景。因此,本研究有助于提高工业机器人系统的可靠性和安全性。     

电动执行机构中光电编码器脉冲波形问题的研究

介绍电动执行机构中光电编码器的结构、工作原理,以及如何实现光电编码器输出脉冲方波信号,论述光电编码器对电动执行机构产生的影响。     

Bistable Thin-Film Shape Memory Actuators for Applications in Tactile Displays

Bistable shape memory actuators were fabricated by microsystem technology processes and characterized with regard to their use in tactile graphic displays. The actuators were realized as sputter-deposited buckled metallic thin-film carriers, having structured Ti–Ni–Cu and Ti–Ni–Hf shape memory alloys on the top and at the bottom, respectively. They were sputtered on wavy-structured substrate and had lateral dimensions ranging from 2.2 to 3.5 mm in width and from 1 to 3 mm in length. The actuators were switched with voltages in the range of 0.2 to 0.8 V and with currents in the range of 0.2 to 0.8 A. A force of 2.2 mN with a displacement of 0.7 mm was reached. To improve the performance further, a special test setup was developed. The bistable actuators in it were sputtered on a planar substrate with lateral dimensions ranging from 6 to 8 mm in width and from 3 to 6 mm in length. These actuators were switched with actuation voltages in the range of 0.6 to 1.6 V and with currents in the range of 0.6 to 1.8 A. Thus, a force of 16 mN with a displacement of 1.2 mm was reached. $hfill$[2007-0261]      

步进驱动方式在电动执行器控制中的应用

通过分析电动执行器产生振荡现象的原因,提出采用步进驱动方式消除振荡现象的方法,给出了选择进参数的原则和进步参数随负载变化的自适应调整方法。     

Root Locus for Random Reference Tracking in Systems With Saturating Actuators

This paper develops a root locus technique for random reference tracking in systems with saturating actuators. This is accomplished by introducing the notion of S-poles, which are the poles of the quasilinear system obtained by applying the method of stochastic linearization to the original system with saturation. The path traced by the S-poles on the complex plane when the gain of the controller changes from 0 to infin is the S-root locus. We show that the S-root locus is a subset of the standard root locus, which may terminate prematurely in the so-called termination points. A method for calculating these points is presented and a number of other, more subtle, differences between the usual and the S-root loci are described. In addition, the issue of amplitude truncation in terms of the S-root locus is investigated. Finally, an application of the S-root locus to hard disk drive controller design is presented.     

Resonant silicon accelerometers in bulk micromachiningtechnology-an approach

The fabrication and characterization of resonant silicon accelerometers, made in bulk micromachining technology, is presented. The devices consist of a silicon mass, coupled axially to a strain-sensitive vibrating silicon beam. The beam is driven electrothermally and sensed piezoresistively by means of implanted piezoresistors. Two different accelerometer types are shown, differing in the complexity of the respective fabrication processes and in performances. Closed-loop operation of the devices is demonstrated. Also in the closed loop, static and dynamic measurements of prototypes have been performed. The sensor types presented are compared, and the resonant acceleration sensor concept is discussed     

锁相技术在谐振变换器中的应用

为了提高移相控制方式的谐振变换器在轻载条件下的效率。本文提出了一种基于电流跟踪的移相控制方式。由于此控制方式能使滞后桥臂的电压与电流始终保持一定的相位,使得变换器即使在轻载条件下仍能实现软开关。文中给出了由锁相芯片CD4046实现电流跟踪移相控制的设计和参数选择方法。     

串联弹性驱动器设计、建模及在机器人上的应用

相比于传统的刚性驱动器, 串联弹性驱动器(Series elastic actuator, SEA)具有被动柔顺性、阻抗低、抗冲击、力感知等诸多优点, 因而已被广泛应用于各种机器人系统中. 首先根据弹性和阻尼特性将串联弹性驱动器分为弹性型、阻尼型和弹性−阻尼型串联弹性驱动器, 介绍不同类型串联弹性驱动器的优缺点, 并详细概述弹性和阻尼特性的机械实现方式; 然后对各类串联弹性驱动器作为力传感器的建模方法进行介绍; 接着叙述串联弹性驱动器在机器人系统中的主要应用, 如力传感器、安全保护、降低能耗; 最后展望串联弹性驱动器未来的发展方向.     

MEMS Electrostatic Actuation in Conducting Biological Media

We present design and experimental implementation of electrostatic comb-drive actuators in solutions of high conductivity relevant for biological cells. The actuators are operated in the frequency range 1-10 MHz in ionic and biological cell culture media, with ionic strengths up to 150 mmol/L. Typical displacement is 3.5 mum at an applied peak-to-peak signal of 5 V. Two different actuation schemes are presented and tested for performance at high frequency. A differential drive design is demonstrated to overcome the attenuation due to losses in parasitic impedances. The frequency dependence of the electrostatic force has been characterized in media of different ionic strengths. Circuit models for the electric double layer phenomena are used to understand and predict the actuator behavior. The actuator is integrated into a planar force sensing system to measure the stiffness of cells cultured on suspended structures.     

控制工程静电危害和防护

为了减小静电干扰,消除静电危害,研究了静电的产生及释放过程的特点及其电磁辐射的危害,并提出了避免静电干扰的一些方法以及应采取的防护措施,建立了静电防护系统,从而减少静电时设备的损坏。由于产生静电的方式多种多样,因此在采取防护措施方面也要考虑多方面因素,必须进行综合考虑,采取不同的防护措施,并不定期进行测量。经证明,提出的方法对于静电防护是有效的。     

A Model for Electrostatic Actuation in Conducting Liquids

This paper presents a generalized model that describes the behavior of micromachined electrostatic actuators in conducting liquids and provides a guideline for designing electrostatic actuators to operate in aqueous electrolytes such as biological media. The model predicts static actuator displacement as a function of device parameters and applied frequency and potential for the typical case of negligible double-layer impedance and dynamic response. Model results are compared to the experimentally measured displacement of electrostatic comb-drive and parallel-plate actuators and exhibit good qualitative agreement with experimental observations. The model is applied to show that the pull-in instability of a parallel-plate actuator is frequency dependent near the critical frequency for actuation and can be eliminated for any actuator design by tuning the applied frequency. In addition, the model is applied to establish a frequency-dependent theoretical upper bound on the voltage that can be applied across passivated electrodes without electrolysis.