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INTRODUCTION Since the phenomenon of piezoelectricity in natural crystals was discovered in 1880, it has been applied in many fields, such as smart structure, sensing devices and active control, because of its special properties. Combining electrical behavior with mechanical deformation is the special property which attracted great interest of researchers. Many models have been developed for studying piezoelec- tric effects. Dunn and Wienecke (1996) used Green’s functions for transverse… 相似文献
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Novel high torque bearingless two-sided rotary ultrasonic motor 总被引:3,自引:0,他引:3
LI Xia CHEN Wei-shan XIE Tao LIU Jun-kao 《浙江大学学报(A卷英文版)》2007,8(5):786-792
Applications are limited at present because the currently available ultrasonic motors (USMs) do not provide suffi-ciently high torque and power. The conventional travelling-wave USM needs the bearing to support, which required lubricant. To solve the above problem, a bearingless travelling-wave USM is designed. First, a novel structure of the two-sided USM consisting of a two-sided teeth stator and two disk-type rotors is designed. And the excitation principle of the two-sided travelling-wave USM is analyzed. Then, using ANSYS software, we set up the model of the stator to predict the excitation frequency and modal response of the stator. The shape of the vibration mode was obtained. Last, the load characteristics of the USM are measured using ex-perimental method. The maximum stall torque and the no-load speed were obtained. The results showed that the characteristics of the two-sided USM are better than those of the conventional one-sided USM. 相似文献
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针对微小弹体舵机控制系统对位置伺服的实时性和可靠性要求,设计了以FPGA为控制器的新型数字控制系统。该系统采用FPGA作为核心控制元件、舵机作为基本的执行机构,搭建了具体的硬件电路,对舵机控制硬件电路及其控制逻辑进行了详细阐述,并说明了该控制电路的具体应用实现。提出了一种分时成组原理,利用这一原理,实现了一种基于FPGA的舵机控制用PWM信号生成方法。实验结果表明,该舵机控制器不仅控制参数设定方便、控制精度高且稳定性好,而且增加了系统使用的灵活性和可靠性。 相似文献
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A profilometer used for 3 dimension measurement of micro-surface topography is presented. The instrument is based on the vertical scanning microscopic interferometry (VSMI). A Linnik type interference microscope is used and the interferograms which present changes of surface profile are recorded with a CCD camera. A developed nano-positioning work stage with an integrated optical grating displacement measuring system realizes the precise vertical scanning motion during profile measurement. By a white-light phase shifting algorithm of arbitrary step, frames of interferograms are processed by a computer to rebuild and evaluate the measured profile. Because of the specialty of VSMI, the profilometer is suitable for both smooth and rough surface measurement. It can also be used to measure curved surfaces, dimension of micro electro mechanical systems (MEMS), etc. The vertical resolution of the profilometer is 0.5 nm, and lateral resolution 0.5 μm. 相似文献
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王佑恩 《三明高等专科学校学报》2013,(6):9-16
研究Delta算子描述的线性不确定时滞系统的可靠保性能控制问题。考虑系统含有具有凸多面体不确定性参数和连续模型执行器故障,根据Lyapunov稳定性理论,给出对于所有允许的不确定性和执行器故障.均使闭环系统渐近稳定且给定性能指标具有一定上界的状态反馈控制器的存在条件,由此提出相应控制器的设计方法。通过数值算例验证了设计方法的可行性。 相似文献
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文强 《柳州职业技术学院学报》2021,(1)
执行元件工作是自动变速器形成动力挡位的基础,而自动变速器换挡是通过执行元件的切换来实现的,因此,执行元件的工作状态直接影响着自动变速器的动力传递。U340E自动变速器有8个执行元件,执行元件数量增多,变速器出故障的概率增加。通过对执行元件的故障分析,可以缩小自动变速器的故障范围,以便快速诊断出自动变速器的某类故障,缩减故障诊断时间,降低维修成本。 相似文献
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INTRODUCTIONDuetotheirwideapplicationsinengineer ing ,piezoelectriccrystalplatesattractedmuchattentionandhadbeenextensivelystudiedasre ported .However,mostworkswerebasedonva rioustwo dimensionalapproximations (Dokmeci,1 980 ;Lawson ,1 942 ;Mindlin ,1 952 … 相似文献