Design and experimental validation of a linear piezoelectric micromotor for dual-slider positioning

In this paper, a linear piezoelectric micromotor for dual-slider positioning by a single piezoelectric element (PZT) is proposed. A slider 1 and a permanent magnet are connected by the PZT, and a slider 2 is placed on the permanent magnet by the magnetic force. The slider 1 is a small steel cuboid and can be clamped and released by an electromagnet base. When it is released, it can be driven by impact friction force generated by the PZT. When it is clamped, it keeps stationary, and the slider 2 can be positioned based on the smooth impact friction drive of the micromotor. Both the sliders can be positioned independently with a long motion range as well as a high positioning resolution. Due to a single PZT used in the micromotor and miniaturized design of the mechanism, the proposed micromotor has been constructed with a compact size as well as a relatively high loading capacity.

     

Experimental Measurements of the Strain Energy Release Rate for Stiction-Failed Microcantilevers Using a Single-Cantilever Beam Peel Test

In this paper, we present experimental measurements of the strain energy release rate for stiction-failed polysilicon microcantilevers using a newly developed single cantilever beam peel test. Our experiments show that dry-contacting microcantilevers adhere exclusively as tip-stuck, "arc-shaped" stiction failures, while adhesion under "wet" conditions generate exclusively "s-shaped" stiction failures. Microcantilevers were "peeled" from the substrate under displacement control using a piezoelectric actuator attached to one end of an array of microcantilever beams. The crack length was monitored using interferometric imaging, and related to the applied displacement using established equations from linear elastic fracture mechanics. The pull-off forces associated with "arc-shaped" stiction failures were an average value of 89.7 nN, for 1000 mum long beams, and an average value of 123 nN for 1500 mum long beams. Adhesion energies for s-shaped failures were measured as 13.7 mJ/m² for IPA released beams and 15.4 mJ/m² for deionized water released beams. These values are in good agreement with previous measurements. The proposed experimental method enables application of a simple fracture mechanics model using a standard specimen geometry. These experiments, using both wet and dry adhesion failure conditions, show that the quality of the adhesive failure depends upon the magnitude of the forces pulling the microcantilever into contact with the underlying substrate     

基于BP神经网络的矩形压电振子振动模态区分*

采用BP神经网络,把矩形压电振子的各阶振型位移输入到神经网络中进行训练,提取各阶模态的振型特征,可实现矩形压电振子的共振振幅分布和振动模态阶次的非线性映射,以此区分各个模态。仿真实验结果显示,建立的神经网络模型可以从ANSYS输出的各模态中准确识别出矩形压电振子的B(3,1)模态,对训练样本外的尺寸也有一定的识别效果,表明所建立的BP神经网络可以有效地用于该矩形压电振子的振动模态区分。     

Adaptive Kalman filter and dynamic recurrent neural networks-based control design of macro-micro manipulator

In this paper,a composite control scheme for macro-micro dual-drive positioning stage with high acceleration and high precision is proposed.The objective of control is to improve the precision by reducing the influence of system vibration and external noise.The positioning stage is composed of voice coil motor(VCM) as macro driver and piezoelectric actuator(PEA) as micro driver.The precision of the macro drive positioning stage is improved by the combined PID control with adaptive Kalman filter(AKF).AKF is used to compensate VCM vibration(as the virtual noise) and the external noise.The control scheme of the micro drive positioning stage is presented as the integrated one with PID and intelligent adaptive inverse control approach to compensate the positioning error caused by macro drive positioning stage.A dynamic recurrent neural networks(DRNN) based inverse control approach is proposed to offset the hysteresis nonlinearity of PEA.Simulations show the positioning precision of macro-micro dual-drive stage is clearly improved via the proposed control scheme.     

Analysis of a 0.1-μm stepping bi-axis piezoelectric stage using a 2-DOF lumped model

Piezoelectric stages are widely used for parts manipulation, including micro-component assembly and bio-cell manipulation. This paper proposes a bi-axis piezoelectric stage based on a friction driven mechanism. The carrier slides on a supporting frame and slider constructed in the same plane as a low-profile stage. The dynamic model of the friction driven is based on a 2-DOF lumped model considering the impact and separation behavior. The first mass is the bulk piezoelectric actuator (slab)—as a vibrator—and the second is the driven slider. The stiffness ratio of the piezoelectric slab-to-the driven slider affects the output force of the slider because of the contact time ratio. Moreover, the stepping size is adjusted according to the duty ratio of the pulse width of the driving signal. The stepping size of 0.1 μm is achieved in the X and Y axes corresponding to 3% and 5% of the duty ratio, respectively, of 512-Hz carrier frequency in 20-Vpp driving signal. When the duty ratio is 100%, the full speed of 18 and 16 mm/s are achieved in the X- and Y-axes, respectively. The dimensions of the piezoelectric stage are 61 × 58 × 21.3 (high) mm³.

     

Four-leg independent mechanism for MEMS microrobot

In this paper, the development of a quadruped micro-electro mechanical system (MEMS) microrobot with a four-leg independent mechanism is described. As the actuator mechanism inside small robot bodies is difficult to realize, many microrobots use external field forces such as magnetism and vibration. In this paper, artificial muscle wires that are family of shape memory alloy are used for the force of the actuator. The artificial muscle wire shows the large displacement by passing the electrical current through the material itself. The double four-link mechanism is adopted for the leg system. The link mechanism transforms the linear motion of the artificial muscle wire to the foot step-like pedaling motion. The location of the backward swing motion is lower than that of forward swing motion. This motion generates the locomotion force. As a result, the total length of the constructed quadruped MEMS microrobot was 6 mm. The microrobot could perform similar gait pattern changes as the quadruped animal.     

高速受电弓非定常气动特性分析

为保证高速列车受电弓与接触网之间具有良好的接触特性,针对强烈气流干扰会引起受电弓振荡的问题,用脱体涡模拟(Detached Eddy Simulation,DES)方法研究高速列车受电弓在开、闭口运行条件下的非定常抬升、阻力特性.结果表明,开、闭口运行对受电弓气动特性的影响有较大不同,尤其对受电弓及其滑板的抬升力波动影响明显.开口运行时整弓和滑板的抬升力波动幅度明显大于闭口运行;而开、闭口运行对整弓和滑板气动阻力的大小与波动幅度的影响很小。     

基于滚压的压电叠堆压电转换特性仿真分析

本文提出一种基于滚压的压电俘能器结构,结合Cymbal压电换能器和压电振子叠堆,利用滚珠作为激励源,可以把机构的往复振动转换为对压电振子的单向压迫.使用仿真软件对俘能器结构中滚珠压迫压电单元的力,以及该俘能器结构在并联和串联模式下输出的电压和俘获的电能进行仿真分析,得到该结构的压电转换特性.仿真结果表明,滚珠对压电叠堆的压迫力与压电陶瓷层数并不是单向递减,1-5层时递增,5层以后压迫力逐渐减小.在压电陶瓷的总层数不变的情况下,并联和串联时压电叠堆所俘获的总电能是不变的.两种联接模式下总电能随层数的变化关系为5层以内时随层数的增加而减小,超过5层后逐渐增加.     

基于ANSYS的压电圆片振子径向振动模式分析

压电陶瓷问世不过几十年,然而发展非常迅速,压电陶瓷振子的应用日趋广泛.为了更深入研究压电振子的特性,在ANSYS的软件平台上,对压电圆陶瓷片振子进行建模仿真;利用有限元分析方法,得到压电圆陶瓷片的多阶振动模式.再根据谐振理论,对其输入导纳-频率关系进行分析.结合模态分析结果文件进行筛选,得到了压电陶瓷圆片径向振动频率,最后通过理论分析和实验测试,验证了仿真值比理论值更接近测试值.相对传统的振动模式分析方法,此方法更为简单、准确、直观.     

A single-magnet nonlinear piezoelectric converter for enhanced energy harvesting from random vibrations

Power harvesters from mechanical vibrations are commonly linear mechanical resonators that are most effective when excited at resonance. Differently, under wideband vibrations, linear converters are suboptimal. A nonlinear converter is here proposed that implements nonlinearity and bistability by employing a single external magnet, in order to improve conversion effectiveness while simplifying device fabrication. The converter is composed of a piezoelectric bimorph on a ferromagnetic cantilever. The fabrication technology is based on the screen printing of a PZT low-curing-temperature paste on harmonic steel substrate. The ferromagnetic cantilever converter, under proper coupling with the external magnet, bounces between two stable states when excited by random vibrations and generates an electric output via the piezoelectric effect. According to theoretical predictions, when bistable behaviour is present, experimental results demonstrate an improvement of about 400% of the rms voltage generated by the converter with respect to the linear case.     

Polysilicon angular microvibromotors

Two types of LPCVD polysilicon angular microvibromotors were designed, fabricated, and successfully operated in air and in vacuum. Each utilizes an electrostatically driven lateral resonant structure (the converter) to actuate a circular microrotor by means of oblique mechanical impact. Oscillatory linear motion is consequently converted into continuous angular motion. The microrotors are fabricated both 60 and 100 μm in diameter and are restrained at the center by a polysilicon hub. The converter tips are retracted by electrostatic comb drives and are propelled forward toward the rotor by elastic forces generated by folded beam flexures at frequencies ranging from 10 to 20 kHz. A preliminary measurement has shown the rotor to be driven at speeds as high as 60000 r/min. The rotors were operated both in low vacuum and in air. One operated continuously for as long as 4 h with no significant wear or degradation of performance. These polysilicon vibromotors have applications as high-response micromanipulators or positioners     

压电式双振子微型发电机功率调节电路设计

为克服压电式单振子微型发电机通过一般整流、滤波和储能控制电路不能连续为瞬时发射功率较大的无线传感器网络发射模块供电的问题,提出了一种双振子振动发电的结构思想,介绍了双振子振动发电原理;提出了一种双振子微型发电机输出功率调节控制电路技术方案,它由主一辅整流电路、主储能器、滤波器、辅助补充能量控制电路、稳压电路、滞回比较器、开关控制电路和电子开关等组成.经实验证明:封装了该功率调节电路的压电式双振子微型发电机平均输出功率为250～950 μw,瞬时输出功率可以达到680 mw,而自身的功耗只有40微瓦以下,能满足连续振动环境中微功耗电子器件、传感器或间歇式较大功耗遥测电路供电的要求.     

窄带随机激励下三稳态压电俘能器的动力学特性与实验研究

本文研究了窄带随机激励下三稳态压电俘能器的动力学输出特性.首先,建立了非线性三稳态压电俘能器的分布参数型机电耦合运动方程,并基于多尺度法推导得到系统运动方程响应的解析解以及一阶、二阶稳态矩的表达式.其次,分析了磁铁间距、噪声强度和激励幅值等参数对系统稳态响应的影响.研究结果表明,在一定参数范围内,随着噪声强度的增加,压电振动俘能器会经历阱内振动、阱间振动甚至大轨道周期运动,以表现出单稳态、双稳态和三稳态特性;改变磁铁水平间距和竖直间距构造三稳态压电俘能器,其振动幅值和采集电压相较于双稳态明显提高.最后,通过实验比较了压电俘能器在不同位形时的采集性能,结果表明了三稳态压电俘能器的优越性,为窄带随机激励下的非线性振动俘能器的设计提供一定的理论依据.     

Insect-model based microrobot with elastic hinges

This paper describes the new concept of making a microrobot based upon insects and its implementation using rigid plates and elastic hinges. One unique feature of an insect's structure is its deformable external skeleton, to which wings and legs are attached, forming a closed-loop mechanism. Frictionless deformation of elastic elements, instead of conventional rotational joints, allows for efficient actuation in the microscale. We propose three-dimensional micromechanisms based on an external skeleton and have fabricated several examples using polysilicon plates and polyimide hinges. By folding the polysilicon plates along the polyimide hinges just like paper, 3D structures can be constructed on silicon wafers. These structures can be easily actuated by electrostatic force. Closed-loop flapping mechanisms have been fabricated and electrostatically actuated to demonstrate the motion of the external skeleton system. Resonant vibration was observed in a frequency range of around 10 kHz. Actuation using electrostatic induction is also considered     

采煤机无线监测装置压电换能元件参数匹配分析

考虑到压电自供电装置中压电振子的几何参数直接影响其共振频率,从而影响压电自供电装置的发电量,因此需要根据环境激励频率设定最佳的压电振子的几何参数,对基于压电自供电的采煤机状态无线监测装置进行研究,通过理论分析、仿真以及实验方法对对不同悬臂梁结构在不同外界激励作用下的发电量进行研究.研究结果表明:悬臂梁自由端的质量块质量以及悬臂梁长度越大,悬臂梁压电结构的固有频率越低;随着悬臂梁厚度的增加,悬臂梁压电结构的固有频率逐渐增大.以此为依据对采煤机不同监测位置的装置选取最佳匹配的压电结构几何参数,并通过采煤机工作状态监测实验验证了本文研究的压电自供电无线监测装置的可行性.     

一种基于粘滑运动原理的微小型机器人建模与实验

为实现微小型机器人的精密运动定位,提出一种基于粘滑运动原理的足式微小型机器人.机器人足由双压电膜驱动,本身为空间不等截面的弹性梁结构.首先建立了柔性足的有限自由度模型和机器人系统的动力学模型.然后根据粘滑驱动中的粘滞和滑移过程的不同特点,分别对粘滞过程的静力学与滑移过程的瞬态动力学进行了分析,得到了机器人运动位移、分辨力与驱动电压之间的关系,并分析了粘滞-滑移过程中摩擦力的变化以及足尖的状态切换过程.分析结果表明,在粘滞阶段,基体的静态位移与驱动电压近似呈线性关系,且随驱动电压的增高而增大;在滑移阶段,由于柔性足的振动及振动与摩擦力的耦合关系,足端的滑移距离及基体位移与驱动电压之间存在非线性关系.建立了机器人样机,对机器人的运动分辨力和位移响应进行了测试,实验数据显示,基于粘滑运动原理,机器人可以实现0.88μm的高运动分辨力.     

汽车车内噪声主动控制系统仿真

降低汽车空腔的振动,是抑制汽车车内噪声的有效途径之一;以激振器、作动器和控制器等为主要部件,搭建了简化的汽车车内噪声主动控制系统,该系统通过将汽车空腔模型简化为板件,以减弱板件振动为目标,实现了汽车车内噪声主动控制;采用简谐正弦及余弦信号作为激振器发出的激励,用于模拟板件的初始振动,控制器通过采用模糊控制算法直接控制压电陶瓷作动器的振动,压电陶瓷作动器的振动用于抑制板件的振动,完成了汽车车内噪声主动控制系统仿真;仿真结果表明,研究采用的汽车车内噪声主动控制系统,使汽车空腔振动降低23%,为解决由汽车发动机和动力总成的振动所引发的汽车车内噪声问题提供了一个有效途径。     

Resonant-Type Smooth Impact Drive Mechanism Actuator with Two Langevin Transducers

A smooth impact drive mechanism (SIDM) is a unique piezoelectric actuator that is widely used as a camera focusing mechanism, cell phone lens movement mechanism, etc. This principle enables a compact driving mechanism; however, it cannot generate high-speed movement because a soft-type multilayered piezoelectric transducer (PZT) is utilized at off-resonant movement. This paper proposes a resonant-type SIDM actuator driven with hard-type PZTs to realize high-speed and powerful operation. The fundamental principle is also based on the conventional SIDM; therefore, a saw-shaped movement is required. To generate a high-power ultrasonic output, two Langevin transducers are adopted instead of a soft-type multilayered PZT. One Langevin transducer was a stator and the other was slider whose tip was adhered to a carbon fiber reinforced plastic (CFRP) rod. The CFRP rod was connected to the stator transducer with the frictional force. To obtain quasi-saw-shaped vibration, the longitudinal vibration for each Langevin transducer was excited and these movements were added at the connection point at the CFRP rod. In order to combine these vibration modes, the lengths of the stator and slider Langevin transducers were designed to make the resonant frequencies ratio to be 1:2. By using the proposed principle, the slider Langevin transducer was successfully driven with the speed of 0.11 m/s and the output force was 1.8 N with no load.     

Novel piezoelectric actuator control slider using transverse-mode deformation

This work proposes a novel structure design of active slider with a piezoelectric actuator at the top of the slider body and a soft layer between the substrate and head elements, to efficiently control the flying height of slider. A parametric simulation was performed to obtain an optimize dimension of PZT actuator and the most efficient soft material. Then three types of slider structures were designed and investigated with considering air bearing effects to achieve large actuation efficiency.     

Voltage-induction type electrostatic film motor driven by two- to four-phase ac voltage and electrostatic induction

This paper describes a voltage-induction type electrostatic film motor that operates by feeding electric power to the slider by electrostatic induction. In the electrostatic motor, applying voltages to both of its stator and slider contributes to its fine positioning resolution and better controllability. However, in some cases such as relatively small motors, the electric wires connected to the slider could cause mechanical disturbances to the motor motion. In the new electrostatic motor, electric wires are connected only to the stator, thus the slider motion is not disturbed. The power to the slider is transferred by electrostatic induction between induction electrodes fabricated in both of the stator and the slider. The proposed motor has a two- to four-phase driving-electrode configuration, which consists of a two-phase driving electrode in the slider and a four-phase driving electrode in the stator. The paper first analyzes the thrust force characteristics of the driving-electrode configuration, and then analyzes the characteristics of voltage-induction configuration, both based on capacitance-network analysis. Experimental results showed good agreements with the analyses, confirming the feasibility of the voltage-induction type electrostatic motor.