Systematic experimental based modeling of a rotary piezoelectric ultrasonic motor

In this paper, a new method for equivalent circuit modeling of a traveling wave ultrasonic motor is presented. The free stator of the motor is modeled by an equivalent circuit containing complex circuit elements. A systematic approach for identifying the elements of the equivalent circuit is suggested. The Levenberg-Marquardt parameter estimation algorithm is used to model the alteration of the admittance after placing the rotor on the stator. Thereafter, theoretical assessments and experimental measurements are used to account for the speed reduction that is caused by placing the rotor on the stator and applying the load torque. Finally, the effects of temperature changes and the resultant response of the motor are computed. Results of the experiments and measurements are used to verify and validate the precision of the new modeling method.     

新型惯性式直线超声压电电机的运动机理及实验研究

提出了一种新型惯性式直线超声压电电机.该电机利用压电晶体的逆压电效应和惯性位移原理,由定子的轴向变形,通过摩擦力的作用,以惯性位移的形式传递运动.它由两部分组成,定子由具有位移放大功能的压电复合换能器和轴组成,动子为一带有缺口和环形凹槽的环.分析了该电机的工作原理,并通过仿真和实验相结合的方法分析了两种激励方式对电机性能的影响.实验结果表明:样机采用方波驱动比采用锯齿波驱动的效果好;在采用方波驱动信号驱动时,样机的最大空载速度可达到11 mm/s,最大输出力达到0.5 N.     

非共振型压电电机驱动的大行程精密定位旋转平台的建模和实验

针对目前光波导封装使用的精密定位平台行程小,结构与控制系统复杂的问题,提出了非共振型压电电机驱动的大行程精密旋转定位平台。该平台通过压电电机的连续作动和步进作动两种工作模式来满足大行程和高精度要求。首先对该精密旋转定位平台进行动力学建模,确定了系统运动方程。然后,分析其作动机理,研究影响旋转平台转速的不同因素。最后,实验研究该精密旋转定位平台的速度、步距、分辨率与负载特性,确定平台连续作动与步进作动的驱动方式。实验结果表明,在直流偏置为60V,峰峰电压为120V,频率为180 Hz的正弦波电压激励下,该精密旋转定位平台最大转速可达47 963.2μrad/s,分辨率和最大负载分别为3μrad和60g。与现有的大行程精密定位旋转平台相比,设计的平台具有行程大,精度高,结构简单,稳定可控,且装配调试方便,易于批量化生产等优势。     

叶片式气动马达转速响应特性分析

以一种典型的气动执行元件叶片式气动马达为研究对象,建立了马达的运动学模型,对马达在不同气源压力下的输出转速进行了仿真,通过其输出速度曲线的动态特性参数,分析了马达转速响应特性,为该类马达的结构优化设计奠定了基础。     

Principle and experimental verification of novel dual driving face rotary ultrasonic motor

Existing rotary ultrasonic motors operating in extreme environments cannot meet the requirements of good environmental adaptability and compact structure at same time,and existing ultrasonic motors with Langevin transducers show better environmental adaptability,but size of these motors are usually big due to the radial arrangement of the Langevin transducers.A novel dual driving face rotary ultrasonic motor is proposed,and its working principle is experimentally verified.The working principle of the novel ultrasonic motor is firstly proposed.The 5th in-plane flexural vibration travelling wave,excited by the Langevin transducers around the stator ring,is used to drive the rotors.Then the finite element method is used in the determination of dimensions of the prototype motor,and the confirmation of its working principle.After that,a laser Doppler vibrometer system is used for measuring the resonance frequency and vibration amplitude of the stator.At last,output characteristics of the prototype motor are measured,environmental adaptability is tested and performance for driving a metal ball is also investigated.At room temperature and 200 V(zero to peak) driving voltage,the motor’s no-load speed is 80 r/min,the stalling torque is 0.35 N·m and the maximum output power is 0.85 W.The response time of this motor is 0.96 ms at the room temperature,and it decreases or increases little in cold environment.A metal ball driven by the motor can rotate at 210 r/min with the driving voltage 300 V(zero to peak).Results indicate that the prototype motor has a large output torque and good environmental adaptability.A rotary ultrasonic motor owning compact structure and good environmental adaptability is proposed,and lays the foundations of ultrasonic motors’ applications in extreme environments.     

Analysis and experiments of a novel synchronous PM planar motor with minimized cogging force

We deal with analysis and experiments of a novel moving-coil-type synchronous permanent magnet planar motor (SPMPM) with reduced cogging force. Our previous study assumed that the equation of magnetic flux existing between a permanent magnet (PM) and core was a second-order polynomial, and the minimum cogging force was theoretically and geometrically calculated without FE analysis. In this paper, the cogging force of SPMPM with an iron core is calculated exactly using geometrical factors, which are desired for determining the magnetic flux density. The analytical results of the cogging force using the factors agree well with those obtained by FE analysis and experiment. Several methods for reducing the cogging force of the SPMPM, such as separation and arrangement of the iron core, addition of an extra core, and addition of auxiliary core teeth, are introduced in this paper. Velocity control experiments of the SPMPM with modified and unmodified cores are carried out and the results are compared with each other. The velocity ripple of SPMPM with a modified core is much smaller than that of SPMPM with an unmodified core.     

压电旋转驱动器制作及性能测试

提出了通过控制正压力来改变摩擦力的方案,进而研制了一种以压电叠堆为动力转换元件的新型压电旋转驱动器。采用两个驱动用压电叠堆对称布置的方式设计了该旋转驱动器结构,探讨了旋转驱动器运动机理,制作了压电旋转驱动器试验样机并对其进行了试验测试。试验结果表明,该驱动器输出步长线性度较好,当驱动电压为10 V、频率为2 Hz时,驱动器旋转步长为20 μrad。分析了驱动器输出稳定性,针对存在的问题提出通过施加控制系统来有效提高不同起始位置驱动器的运动稳定性。对试验结果进行误差分析,找出了产生误差的原因,为驱动器的进一步优化设计提供了参考。研究证明了该压电旋转驱动器设计方法的可行性,利用该方法可以制作出结构简单,体积小,适合在微驱动领域中应用的驱动器。     

一种压电步进微动转台的研究

介绍了一种基于尺蠖原理的回转式步进压电微动转台。借助柔性机械结构,将压电陶瓷的微位移以角度方式输送出来。在结构设计方面,采用柔性铰链放大结构,夹紧器和驱动器均采用双驱动器结构,实现推-拉接力运动。配以适当的四路驱动信号,实现了压电微动转台的单步、多步连续匀速转动。最后对样机进行了实验测试。实验结果表明,所设计的压电步进微动转台结构紧凑、分辨力高且运动稳定。同时,动体没有缠绕,使得驱动器可以在任意位置启动,并可在360°范围内连续匀速转动。在频率为5Hz、幅值为30V驱动电压下测得最小步距小于3″,在频率为40Hz幅值为160V的驱动电压下速度达到430.4″/s。     

气体耦合式宽带/低频压电振动俘能器

为实现低频/宽频带/高强度振动能量回收及基于能量回收的主动振动控制,提出了一种气体耦合式振动俘能器。介绍了俘能器的系统构成原理,对其能量回收特性进行了理论与试验研究。理论分析结果表明,俘能器的发电能力及特性是由环境振动强度、气缸/压电振子的结构与性能参数、系统质量/背压等多种要素共同决定的;其它条件确定时,存在使电压最大的最佳频率以及使俘能器工作与否的最低临界频率;增加背压/质量可不同程度地提高俘能器的输出电压和有效带宽、降低临界频率,但对最佳频率无明显影响。采用Ф60×0.9mm3双晶压电振子及Ф16×100mm3气缸制作了样机,测试了不同背压及质量时俘能器的电压-频率特性。结果表明,俘能器最佳/临界频率、最大输出电压及有效带宽等与背压/质量关系均与理论分析结果相吻合。不同条件下所测得的最佳频率均为55Hz左右;背压0.4 MPa、质量10kg时所获得临界频率/最大输出电压/对应25V输出电压有效带宽为9Hz/88V/72Hz,分别为质量2.5kg时的0.36倍、2倍和2.2倍。     

多振子压电发电机的输出特性

为提高多振子压电发电机的输出能力及有效频带宽度,从理论及试验两方面研究了各压电振子直接串/并联及经整流桥串/并联时的输出电压特性.结果表明,压电振子结构及数量相同时,经整流桥串/并联输出的电压及频带宽度均优于直接串/并联输出的电压及频带宽度,且压电振子经整流桥串联输出方式优于并联输出方式,其电压波动也较小.最后,制作了...     

纳米精度压电马达的动力学模拟及试验

设计并制作完成了一种基于压电陶瓷逆压电效应的纳米精度压电步进马达.根据其结构简化模型,推导出该压电纳米马达在脉冲电源作用下的运动特性表达式.编写软件,设定参数对压电马达的运动性能进行模拟,结果表明了马达的线性步进运动特点.设计光栅测试系统,对压电马达样机进行运动测试,试验结果证实了模拟结构的正确性.该类压电纳米马达具有可以实现连续步进位移,步进速度快,单步分辨率小,行程长和便于利用微机实现智能控制等特点.纳米马达的位移分辨率可以达到10nm,最快速度为0.6mm/s,最长行程为5cm.     

Output feedback integral control of piezoelectric actuators considering hysteresis

In this paper, output feedback integral control of piezoelectric actuators is considered with respect to the hysteresis effect. The linear dynamics of the piezoelectric actuator is modeled as a linear state space system with an input nonlinearity that considers the hysteresis effect. A proof of the Lyapunov stability of the system with integral control is presented, and a method for deriving the upper bound for the regulating gain is shown. A simple example is used to illustrate the approach, and then the approach is applied for tracking a step signal with an experimental single-axis piezoelectric actuator to verify that the system is stable.     

Static characteristics of gas bearings with a rotary bush

The static characteristics of a gas bearing with a rotary bush are investigated on the basis of an analytical method developed by Sheinberg for a specific bearing structure.     

Design and analysis of a new high frequency double-servo direct drive rotary valve

Researchers have investigated direct drive valve for many years to solve problems, such as fluid force imbalance and switching frequency. The structure of the rotary valve has received considerable research interest because of its favorable dynamic properties and simple structure. This paper studied the high frequency double-servo direct drive rotary valve (DDRV), and proposed a novel structure and drive method satisfying high reversing frequency and adequate quantity of flow. Servo motors are integrated into the valve by the innovative structure, which is designed to equilibrate the unbalanced radial fluid force with the symmetric distributed oil ports. Aside from the fast reversing function of the valve, the DDRV presented high performance in linearity of the flow quantity and valve opening as a result of the fan-shaped flow ports. In addition, a computational fluid dynamics (CFD) method based on Fluent was conducted to verify the flux regulation effect of the height change of the adjustable boss.     

基于压电陶瓷的微进给平台的实验研究

超精密加工技术是机械制造业中最重要的部分,基于压电陶瓷的微位移机构是近年来发展起来的一种新型微位移机构,设计了基于压电陶瓷为驱动的,以弹性铰链为支撑的微进给平台.并进行了大量的试验,从中得出适于应用的线性电压一位移曲线.采用不同的升降压步长对平台进行驱动,改善了电压一位移的迟滞度.     

经济型变频器的研究

本文采用了单片机PIC16F877和SPWM(Slne Pulse WidthModulation)的技术。提出了一种基于PIC16F877产生的智能控制信号用软件程序去控制SPWM的新方法,设计了一种高效、低成本、功能齐备的小型变频器。     

Concepts for a class of novel piezoelectric self-locking long-stroke actuators

The friction-type motor is the most common type in the field of piezoelectric motors. One limitation of friction-type motors is their inability to achieve high output push force or torque. Based on the theory of self-lock, a novel mechanism for the linear piezoelectric motor is proposed. On the basis of the proposed mechanism, three prototype models have been developed. The new motors transfer the force and displacement generated by a piezoelectric actuator to the output directly, whereas the friction-type motor transfers via the induced friction between the stator and the rotor. The achieved positioning precision is within 10 nm, while the push force is up to 1,176 N. The new motors can be applied in cases where both high positioning precision and heavy load are essential.     

单晶压电悬臂梁等效黏性阻尼建模与实验

为了完善压电悬臂梁非耦合集总参数模型,进而优化设计压电振子,本文根据机械振动理论以及阻尼理论,建立了单晶压电振子等效阻尼系数的理论模型。理论分析并实验验证了基板材料性能,结构尺寸以及截面形状等不同因素对等效机械阻尼及电阻尼的影响规律。最后,制备了3组不同形状尺寸的压电振子样品,并进行了冲击振动试验来验证理论分析结果。研究表明,压电材料层对整体阻尼的影响主要取决于基板与压电材料的弹性模量比;压电材料每个振动周期的电能损耗与悬臂梁长度的三次方成正比,与宽度成反比;而决定振幅放大因子的阻尼比并非随结构尺寸单调变化。实验结果与理论模型的误差为2.5%~14.7%,证明了理论模型的可靠性。分析表明,在可承受极限载荷相同的情况下,静态特性最优的变曲面悬臂梁动态特性并非最佳,得到的结果对于压电振子的优化设计具有现实意义。