单模态驱动双向运动的斜动子V形直线超声电机

针对双模态超声电机对模态频率一致性要求高以及单模态超声电机难以实现双向运动等问题,提出了一种单模态驱动双向运动的斜动子V形直线超声电机。电机由导轨和V形定子构成,导轨相对于V形定子倾斜安装,V形定子的工作模态为面内对称模态或面内反对称模态,通过切换工作模态改变定子驱动足运动轨迹相对导轨的倾斜方向,实现导轨正反向运动。在分析电机工作原理及设计原则的基础上,推导了电机运行的导轨倾角范围,并对设计制作的原理样机进行了模态实验和机械特性测试。实验表明:在导轨倾角为35°,激励峰峰值电压为600V,预压力为65 N条件下,当电机工作在面内对称模态,导轨正向运动,其最大空载速度为180mm/s,最大输出力为14N;当电机工作在面内反对称模态,导轨反向运动,其最大空载速度为125mm/s,最大输出力为24N。     

直线型驻波超声电机的定、动子间接触及摩擦分析

针对一种基于面内振动的直线型驻波超声电机的定、动子接触过程和摩擦机理进行了研究。在分析中将摩擦材料层简化为分布式线弹簧,利用对电机驱动过程中等速点和接触点的相对位置的分析,将接触区域进行了分区段的讨论,推导出电机速度和输出推力的关系并进行了计算机仿真。进而对不同间距下电机定、动子接触过程进行了分析和仿真。结果表明：电机的定、动子间距在建立摩擦模型中起关键作用,其变化对电机机械特性有显著的影响。     

Influence of Friction Interface Contact on Ultrasonic Motor Efficiency Under Static Conditions

The friction interface matching plays a deterministic role in the motor efficiency,and the microcosmic contact status of friction interface should be investigated to improve the ultrasonic motor performance.The main purpose is to improve the effective output power of ultrasonic motor.Hence,one studies the contact condition of the friction interface of the ultrasonic motor,analyzes the micro condition of contact interface through finite element analysis,optimizes unreasonable structures,and compares the two different-structure ultrasonic motors through experiments.The results reflect the necessity of optimization.After optimization,the stator and rotor deform after pre-pressure and the contact interface of them full contact theoretically.When reaching heat balance the effective output of the motor is 37%,and the average effective output efficiency is 2.384 times higher than that of the unoptimized.It can be seen that the total consumption of the ultrasonic motor system decreases significantly.Therefore,when using in certain system the consumption taken from the system will decreases largely,especially in the system with a strict consumption control.     

Stick-Slip Tower-Shaped Piezoelectric Actuator

Since stick-slip actuators present the advantage of allowing long displacements(several centimeters or even more)at a high speed with an ultra high resolution(5nm),a new type of stick-slip piezoelectric actuator is proposed to attain sub-nanometer positioning accuracy.The actuator is composed of a slider and a tower-shaped stator using forced bending vibration in y-z plane to generate tangential vibration on the top of the driving foot.When excited by the sawtooth input voltage,driving foot of the stator is able to generate a tangential asymmetrical vibration on the top,and the slider is thus pushed to move.A prototype and its testing equipment are fabricated and described.Following that,the testing of vibration mode and mechanical characteristics as well as stepping characteristics are conducted.Experimental results show that under the condition that the sawtooth input voltage is400VP-Pand the pre-pressure is 6N.Velocity of the actuator reaches its maximum 1.2mm/s at the frequency of 8000 Hz and drops to its minimum 35nm/s at the frequency of 1Hz.When the excitation signal is the single-phase sawtooth stepping signal,the tower-shaped actuator can directionally move forward or backward step by step.And when excited by the sawtooth stepping signal with 1Hz and 300VP-Pduring 1cycle(200ms),the actuator has a minimum stepping distance of 22 nm.     

一种利用纵振的直线超声电机(英文)

设计了一种利用变截面杆纵振模态工作的直线超声电机,该超声电机的特点是有两个变截面杆状并由一半圆环连接。位于圆环中间驱动足顶部质点以椭圆轨迹运动,当驱动足以一定预压力接触动子时,动子将输出直线运动。通过建立定子的有限元模型并对其进行谐响应分析验证了原理的可行性。提出了电机结构设计的要求,并通过有限元方法进行了结构参数灵敏度分析,为该类电机结构的设计提供了高效的方法。样机试验表明,该电机在100mm/s的运行速度下可以推动10N的负载。     

纵弯模态复合的两自由度直线超声电机

所研制的两自由度直线超声电机由一个圆柱形定子和一个滑板组成.通过三组压电陶瓷元件在定子上分别激励出两个互相垂直的弯振模态和一个纵振模态.任一弯振模态和纵振模态的组合,可以驱动滑板沿x或y方向作直线运动.本文从提高电机的输出性能和驱动效率出发,提出了电机设计的要点.这些要点包括工作模态的选择、模态频率的一致性、压电陶瓷元件和支承元件的位置、预压力的大小和干扰模态的影响等.     

Working Mechanism of a Kind of Non-resonant Linear Piezoelectric Motor with Flexible Driving End

A non-resonant piezoelectric linear motor with a flexible driving end,which has an extensive working frequency range and good operation stability,is studied theoretically and experimentally.Based on the microscopic vibration characteristics of the motor stator,the longitudinal vibration model is established for the whole motor system.According to the Coulomb friction model and the motor vibration model,the friction mechanism of the nonresonant piezoelectric linear motor is investigated by dynamical analysis of the whole motor system.Furthermore,the vibration characteristics and mechanical output characteristics of the stator are simulated and experimentally studied on the basis of the friction drive mechanism model.Finally,both the simulation and experimental results show that this kind of motor remain stable in the frequency domain from 2.2 kHz to 3.5 kHz and that when the pre-stress is 4 Nand the driving voltage is 90 V,the maximum velocity of the motor is above 4 mm/s and the maximum thrust is nearly 0.5 N.     

一种新型微型杆式超声电机及其驱动原理

提出了一种新型微型杆式超声电机,并对该杆式电机的驱动机理进行了仿真。该电机采用两段金属柱体压紧5片压电陶瓷片作为定子。该定子结构和压电陶瓷片的布局方式可以提高其机电转换效率。为尽量减小定、转子之间的径向滑移以提高摩擦传动效率,电机采用了柔性转子,对原理样机及其微型驱动器进行了性能实验。电机的外径为9mm,长度为15mm,重3.2g。当电机工作在杆式定子的一阶弯曲频率(72kHz)附近时,电机实测最大转速为520r/min,最大输出力矩为4.5mN·m。实验结果表明,该电机具有良好的稳定性,利用频率自动跟踪技术对电机转速进行闭环控制,可以将其转速波动稳定在3%之内。     

纵扭复合型压电超声电机的研究

概述了纵扭复合型超声电机研制过程中的几个关键技术问题。内容包括电机的工作原理 ,指出了压电陶瓷片的安放位置 ,确定了一种电机的结构形式 ,该结构形式能调节所需两共振频率趋于一致。用优化方法对该结构形式的定子进行动力学设计 ,提高了设计效率 ;驱动控制电路 ;电机加工中应注意的问题。最后装配了一台直径 45 m m的电机 ,实验表明电机具有一定的转速和扭矩。     

旋转行波超声电机非线性摩擦界面模型

分析了对行波超声电机定子和转子间接触状态，利用间距δ更准确地表征了定、转子间几种不同的接触情况；依据行波作用的特点，利用时空方程间的对应关系，提出了用接触变形角定量地表示定、转子间接触状态的变化情况，讨论了弹性滑动、弹性滞后，特别是stick-slip现象对摩擦界面的影响；改进了传统的线性纯滑动摩擦模型．建立了非线性摩擦界面输出特性仿真分析模型。     

基于弯振模态的螺纹杆式直线超声电机(英文)

介绍了基于弯振模态的螺纹杆式直线超声电机的运行机理.在梁弯曲振动模型的基础上,对螺纹杆式直线超声电机进行动力学分析,推导出电机定子驱动点的空间运动轨迹方程,并阐明了电机运行机理.本文应用有限元法分析了电机的振动模态和结构,设计并研制了样机.样机定子的尺寸为13 mm×13 mm×30 mm,最后对电机输出特性进行了测试,最大输出力为5.2 N.     

Dynamics Modeling and Numerical Analysis of Rotor with Elastic Support/Dry Friction Dampers

The elastic support/dry friction damper is a type of damper which is used for active vibration control in a rotor system.To establish the analytical model of this type of damper,a two-dimensional friction model-ball/plate model was proposed.By using this ball/plate model,a dynamics model of rotor with elastic support/dry friction dampers was established and experimentally verified.Moreover,the damping performance of the elastic support/dry friction damper was studied numerically with respect to some variable parameters.The numerical study shows that the damping performance of the elastic support/dry friction damper is closely related to the stiffness distribution of the rotor-support system,the damper location,the pressing force between the moving and stationary disk,the friction coefficient,the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk.In general,the damper should be located on an elastic support which has a large vibration amplitude in order to achieve a better damping performance,and the more vibration energy in this elastic support concentrates,the better performance of the damper will be.The larger the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk are,the better performance of the damper will be.There will be an optimal value of the friction force at which the damper performs best.     

超声椭圆振动化学机械抛光原理与实验系统

介绍了抛光工具超声椭圆振动产生的基本原理,并实际测试了抛光工具的椭圆运动特性。从理论上分析了在抛光工具上加入超声椭圆振动后,对改善和提高抛光效果的作用机理。在上述研究工作基础上,建立了超声椭圆振动辅助抛光实验系统并进行了实验研究。结果表明,该超声椭圆振动辅助抛光法对硅片抛光表面质量、材料去除率均有较显著的改善。     

三自由度超声电机定子的优化设计

研制了一种基于两个弯振模态和一个纵振模态 ,可分别绕 x,y,z轴转动的圆柱 -球体三自由度超声电机。从电机设计的角度讲 ,使电机的定子具有合适的工作模态是至关重要的。在通常情况下 ,人们往往采用试凑的办法来满足其工作模态的要求。但“试凑法”是经验性的 ,不仅耗时多 ,效率低 ,而且有可能得不到满意的结果。为此 ,本文建立了定子的优化设计数学模型 ,在 MATLAB环境下编写了相应的优化设计程序 ,并根据其优化设计结果 ,设计和制造了定子和电机的原型样机 ,其外径为 2 0 mm,长度为 67mm,重量为 1 5 7g。实验结果表明 :电机定子的模态频率和振型满足设计要求 ,并与优化结果相吻合。故本文提出的优化设计方法是可行和有效的 ,并可大大提高设计效率     

旋转型行波超声电机定子模态频率的一致性调节

从分析超声电机的工作机理出发,指出旋转型行波超声电机定子两相模态频率不一致影响超声电机旋转稳定性和输出效率。针对材料不均匀或加工误差引起的两相模态频率不一致的问题,利用结构摄动理论,通过求解定子的动力学方程,找到了调节两相模态频率一致性的方法。利用这一方法,以南京航空航天大学研制的某TRUM-60型超声电机为例,进行了AN SY S有限元计算,寻找合适的调节位置,并对两相模态频率不一致进行了调节,利用多普勒激光测振仪,对修改前后的定子的模态频率进行了测试,两相模态频率差从调节前的0.42kH z变为调节后的0.04 kH z。结果表明:这种方法对于调节定子两相模态频率的一致性是非常有效的。     

低温环境下超声电机定子特性

超声电机是一种新型的驱动器,由于其具有大力矩/重量比,控制性能好等优点,适合在航天器上使用,因此,在低温环境下对超声电机性能的变化进行研究就非常必要.分析了在低温环境下,超声电机定子弹性体和压电陶瓷元件性能变化,改进了不同环境下超声电机用压电陶瓷的压电方程,并通过该方程推出了压电陶瓷元件的d33随着温度的下降而降低.结合超声电机定子振动,归纳出低温环境下,超声电机定子对超声电机性能下降的影响.通过超声电机在低温环境下的性能测试,验证了低温环境下超声电机定子性能变化的理论分析.得到结论:压电陶瓷在低温环境下的性能下降是影响超声电机定子性能变化的主要原因.     

模态转换型超声电机中的椭圆运动

讨论了模态转换型超声电机表面质点椭圆运动的形成,研究了基于定、转子耦合和利用独立耦合器的模态转换型超声电机的原理。通过对具有斜槽的纵扭振动耦合器上观察到的表面质点椭圆运动进行的理论分析,提出了一种利用主结构中的子结构的局部振动获得模态转换的方法,可用于模态转换型超声电机的设计。     

液滴碰撞超声振动曲面的实验研究

通过实验研究了超声振动曲面上液滴碰撞的动力学行为。对边缘飞溅、表面飞溅以及毛细波、空化和子液滴回弹等复杂物理现象的产生机理和条件进行了分析,得到了超声振动曲面上发生边缘飞溅的临界曲线,并发现由于气动力的作用,超声振动曲面上发生边缘飞溅的临界超声振幅要小于平面情况。利用图像处理技术得到了不同条件下超声振动曲面对碰撞液滴的驱离效率以及飞溅液滴的尺寸分布。实验结果表明:碰撞液滴的驱离效率随振动曲面超声振幅的增大而增大,且呈线性增长;在高速碰撞中,碰撞速度几乎不影响超声振动曲面的液滴驱离效率;随着超声振幅的增加,飞溅液滴的平均尺寸增加。通过常温液滴与过冷液滴的碰撞实验对比,发现温度对超声振动曲面上液滴的动态碰撞过程影响较小。在过冷条件下,液滴驱离效率会略低于常温条件下,但仍能够持续有效地将液滴驱离表面,从而抑制冰层的增厚,说明超声振动曲面具有防水防冰的应用潜能。     

圆柱-球体三自由度超声电机及其控制

研制了一种一阶纵振和二阶弯振模态组合的圆柱-球体三自由度超声电机。研究了其中两个自由度的运动轨迹跟踪控制策略,并将其应用于电机样机的控制。其中,运转速度的控制采用激励电压幅值调节法,针对位置控制提出了两种运动轨迹控制策略一种是逐点比较控制,另一种是矢量分解控制。本文提出了调节激励电压幅值的3种脉冲宽度调制(PWM)方法,对这些方法作了比较,并通过一系列实验得到验证。结果表明当改变激励电压幅值时,保持3个振动模态的相位差不变和激励电压信号不失真,是简化控制过程、提高控制性能的关键;矢量控制法效果较好,并有轨迹跟踪误差小、运动平稳和噪声小等优点。     

Structural Design and Control of Variable Camber Wing Driven by Ultrasonic Motors

A novel variable camber wing driven by ultrasonic motors is proposed.Key techniques of distributed layout of drive mechanisms,coordination control of distributed ultrasonic motors as well as novel flexible skin undergoing one-dimensional morphing are studied.The system integration of small variable camber wing is achieved.Distributed layout of parallelogram linkages driven by geared ultrasonic motors is adopted for morphing,aimed at reducing the load for each motor and producing various aerodynamic configurations suitable for different flying states.Programmable system-on-chip(PSoC)is used to realize the coordination control of the distributed ultrasonic motors.All the morphing driving systems are assembled in the interior of the wing.The wing surface is covered with a novel smooth flexible skin in order to maintain wing shape and decrease the aerodynamic drag during morphing.Wind tunnel test shows that the variable camber wing can realize morphing under low speed flight condition.Lift and drag characteristics and aerodynamic efficiency of the wing are improved.Appropriate configurations can be selected to satisfy aerodynamic requirements of different flight conditions.The study provides a practical application of piezoelectric precision driving technology in flow control.