压电陶瓷驱动的线性尺蠖驱动器设计与仿真

为了实现纳米操作中的精确定位,提出了一种压电陶瓷驱动的线性尺蠖驱动器。这个驱动器主要由1个柔性机构和3个压电陶瓷构成,其中一个压电陶瓷用来提供驱动力,另外两个用来交替夹紧线性导轨以用来实现尺蠖运动。建立了反映该尺蠖电机运动特性的理论模型,通过有限元仿真评估驱动器的性能和验证模型的有效性,研究了柔性机构的变形行为和相应的最大应力。     

基于压电驱动的细胞微量注射装置的研究

提出了由压电驱动带动的注射微动平台和电机带动的细胞微载台来构成细胞药物微量注射的机械结构与控制系统。而且也提出了利用压电陶瓷的微位移特性构造了和目前的微量注射针完全不同的微量注射针结构与控制系统,这个压电微量注射针的驱动和注射动作全部由压电驱动器来完成;利用压电陶瓷的微位移和施加在压电陶瓷上的电压在微小位移情况下的线性关系实现了细胞注射系统的精确微定量注射。     

基于显微视觉的亚像素压电陶瓷驱动特性测量

为了得到纳米操作压电陶瓷驱动器高精度的驱动特性,提出一种基于显微视觉的亚像素位移测量方法。本文采用Harris角点初始定位,对标准的栅格图像序列进行角点匹配,获得模板匹配的初始区域。并提出了二元拉格朗日插值与二元非线性Newton-Raphson迭代算法的亚像素位移测量方法,能够在保证良好测量精度的同时有效地减少亚像素匹配中耗时的相关计算。最后使用改进的亚像素图像块匹配方法对实际的压电陶瓷驱动器的驱动特性进行了测量,并与真实结果和理论模型描述结果进行了对比。实验结果表明,该算法位移测量精度高、稳定性好,得到的压电陶瓷驱动特性曲线符合物理分析结果,能够满足高精度的微纳米测量要求。     

基于压电陶瓷驱动器的微动平台控制技术

压电陶瓷驱动器是近年发展起来的一种新型微位移控制器件,利用压电陶瓷的逆压电效应使之产生相应的应力和应变,可以驱动二维柔性铰链微动机构实现微位移,达到二维定位的目的.通过分析压电陶瓷的基本理论及其非线性特性和补偿措施,阐明压电陶瓷驱动器直接驱动徽动平台的控制技术.     

一种旋转压电陶瓷驱动器的设计和研究

为发挥压电陶瓷分辨率高、频响高、功耗低及抗电磁干扰能力强等优点,进一步简化压电旋转驱动器的结构,提高压电驱动工作效率,设计和研制一种新型压电旋转驱动器。驱动器以压电陶瓷双晶片为原动件,通过联接机构联接定子和转子,选用滚子结构的超越离合器驱动机构,将双晶片扭转位移运动转化为输出轴的连续旋转运动。驱动器结构简单,体积小。通过理论分析、有限元仿真和试验研究表明,驱动器的转速与驱动信号的频率、电压近似呈线性关系,具有良好的输出特性,步进精确,运行平稳可靠,适于在微驱动领域应用。     

菱形压电驱动器对称驱动形式的研究

为了提高压电堆栈的位移输出,该文设计了一种菱形压电驱动器。该机构以压电堆栈作为驱动元件,利用菱形位移放大器放大叠层压电陶瓷的输出位移。该文首先对三角放大原理进行了分析,接着对菱形压电驱动器在一端固定一端驱动负载和两端同时对称驱动负载两种不同的约束方式进行了理论分析,然后利用ANSYS软件对菱形压电驱动器的静、动态特性进行了有限元分析。通过分析结果可以得出,该机构的仿真放大倍数为6. 17,接近于机构的理论放大倍数7. 12,而对称驱动下的工作频率可远远高于一端驱动下的工作频率,并对该结果进行了进一步的分析与讨论。     

基于旋转磁铁箝位的压电尺蠖驱动器理论与试验分析

为简化压电尺蠖驱动器信号控制系统并降低摩擦磨损,提出了一种基于旋转磁铁箝位的新型压电尺蠖驱动器。该驱动器利用直流电机带动永磁体转动实现交替箝位,通过激光对射传感器感知永磁体位置产生的激励信号来驱动压电叠堆实现精密直线位移输出。优化了驱动器结构的相关参数,制作了压电尺蠖驱动器样机并对其进行试验测试,结果表明：驱动器性能稳定,最小分辨率为0.119 μm,最高速度和最大载荷分别为481.43 μm/s、950 g。     

压电陶瓷驱动电源的研究现状及进展

压电陶瓷驱动器在电场作用下存在压电效应,从理论上讲,压电陶瓷器件可以获得无限小的位移分辨率,但是由于电源的稳定性和压电陶瓷本身的特性而产生迟滞和蠕变现象,从而降低其定位精度.采用不同方式的驱动电源和控制模型将直接影响压电陶瓷致动器的输出性能.文中从驱动电源的发展和驱动器模型2个角度,总结了国内外不同的驱动方案,进而提出应该优先选用电流源驱动压电陶瓷,并得出根据应用场合不同选择相应驱动电源和控制模型的结论.     

新型精密磨削辅助微进给平台的研制及特性研究

设计了一种用于平面磨削主动控制的新型数控微进给工件平台.该平台由3个压电陶瓷(PZT)驱动器驱动,3个半圆形的弹性铰链构成的弹性环节实现对压电陶瓷驱动器的预紧.通过实验的方法研究了微进给平台的位移输出、静动态刚度等特性.     

压电陶瓷驱动微位移机构迟滞非线性改善方法研究

压电陶瓷驱动器在精密微位移系统中有着广泛的应用,但其固有的迟滞非线性严重影响系统的运动精度,使控制困难.通过数学建模方法建立压电陶瓷的迟滞曲线逆模型,并用此模型对压电陶瓷进行位移补偿,可以有效减小压电陶瓷迟滞非线性对系统精确控制的影响.提出一种用两个压电陶瓷协同驱动微动平台运动的微位移机构,通过基于迟滞逆模型的开环控制方法,对压电陶瓷位移进行误差补偿,可以实现微动平台运动与控制信号较好的线性对应关系.     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.