基于MEMS机构装配的微夹持器研究

微夹持器作为末端执行装置,直接决定了微装配的效率。MEMS机构中包含许多微小的活动部件和功能元件,为实现这些微小器件的稳定夹取和自动装配,设计了一种采用压电陶瓷驱动、基于柔性铰链的二级放大微夹持器结构。对该微夹持器的节点应力、刚度及最大张合量等进行了分析计算,并对微夹持器进行了试制。实验与分析结果表明,该夹持器最大张合量是245μm,放大倍数约为12.3倍,满足MEMS机构的装配要求。在此基础上,重点对张合量与夹持力进行了系统测试,通过对测试数据的非线性回归,推导出99.99%可靠度的驱动电压计算公式,实现了微夹持的精确控制。     

基于柔性铰链的二级放大微夹持器的研究

微夹持器是微装配系统的关键部件,设计了一种以柔性铰链为基础的二级位移放大机构的夹持器,该夹持器由压电陶瓷驱动。计算了夹持器的放大倍数和柔性铰链的节点应力,并对夹持器的最大张合量、放大倍数、夹持力和刚度进行有限元仿真分析。分析结果表明:夹持器的结构设计满足实际应用要求,对实现微小零件的自动装配有实际意义。     

用于微装配的二级放大微夹持器的设计与实验

微装配系统中的重要工具之一就是微夹持器,因此设计了利用压电陶瓷驱动的二级放大的微夹持器并利用Pro/E对其建模,计算了其放大倍数和节点应力,同时采用有限元方法对所设计的微夹持器进行张合量、放大倍数、应力、刚度及夹持力的分析计算,最后对微夹持器进行试制,实验测试,测试结果表明该微夹持器设计合理,基本符合要求。     

新型集成三维微力检测微夹持器

提出了一种以压阻检测技术为基础,压电陶瓷为微驱动元件,具有两级位移放大且集成三维微力传感器的微夹持器。采用有限元软件对微操持器放大机构和传感器弹性体进行分析,并给出了传感器的标定方法。实验证明,该传感器具有无耦合、测量分辨率高、线性度好、标定简单的优点,满足了预计的设计要求,传感器最大量程为10 mN,X向与Y向的分辨率均为2.4 μN,Z向的分辨率为4.2 μN;同时也验证了所设计的微夹持器的合理性和实用性,当压电陶瓷驱动电压取200 V时,微夹持器的张合量达到最大值274 μm。     

复合式MEMS微夹持器研制

研制了一种针对亚毫米微小构件实施稳定夹取及可靠释放的微夹持器,应用MEMS体硅工艺将静电梳齿驱动与真空驱动集成构成复合式驱动,设计了微夹持器静电驱动控制系统以及真空控制系统。在80V的驱动电压下,微夹持器末端夹爪位移25μm。设计了两种尺寸的微夹持器,一种张合量为100µm～150µm,另一种为150µm～200µm。针对100～200µm的小球进行了微操作实验,实验结果证明静电梳齿驱动结合真空吸附能够使夹取操作更加稳定,基于闭环控制的正压气流能有效克服小球与夹爪之间的粘附力,实现了可靠的释放操作。     

基于SMA的微夹持系统实验研究

微夹持技术是微器件装配的关键技术之一。采用柔性铰链机构设计了三自由度微夹持操作平台，并进行了有限元仿真模拟分析；利用形状记忆合金原理进行设计并研制了环状微夹钳，通过形状训练达到了双程形状记忆效应，并建立了微夹持力计算模型；对微夹持系统的运动精度进行了试验分析，结果表明：该系统沿X，Y，Z方向的位移分辨率达0．01μm，微夹持钳最大张开量达0．2mm，基本满足了系统性能要求。     

基于体硅工艺的静电致动微夹持器制作工艺分析

介绍了一种基于体硅工艺的大尺寸、大深宽比梳状静电致动微夹持器的制作工艺。对微夹持器制作中的关键工艺进行分析,重点分析ICP蚀刻工艺的蚀刻时间对结构的影响,总结导致器件失效的原因,探讨了减少失效的方法。加工过程中采用分步加工的办法控制蚀刻时间,成功的释放了宽6μm,厚60μm,等效长度达5470μm的悬臂梁型微夹持臂。研制出一种良好性能的具有S形柔性结构夹持臂的梳状静电致动微夹持器。     

复合式MEMS微夹持器的研制

为实现对亚毫米微小构件稳定夹取及可靠释放等操作,研制了一种复合式微夹持器.采用有限元软件分析了微夹持器的机构及动力特性.应用MEMS体硅工艺将静电梳齿驱动与气动吸放集成构成复合式驱动,气动吸放的引入改善了微夹持器的操作性能,S形柔性梁结构的设计将梳齿驱动的直线运动转化成末端夹爪的转动实现了夹持操作.两种不同尺寸的微夹持器,有效扩展了微夹持器的夹持范围.根据微夹持器的操作控制需求,设计了微夹持器静电驱动控制系统以及气压控制系统.在80 V的驱动电压下,微夹持器末端夹爪位移可达25 μm.针对100～200 μm的小球进行了微操作实验,实验结果表明,静电梳齿驱动结合真空吸附能够使夹取操作更加稳定,基于闭环控制的气路正压力能有效克服小球与夹爪之间的粘附力,实现可靠的释放操作.微夹持器基本满足100～200 μm微小构件的操作需求.     

面向某微小型平板类零件的微装配系统研究

针对平板类微小型零件装配中出现的自动化程度低、可靠性差的问题,提出基于主机+从控制器+多种传感器的微装配控制系统;设计了吸附式微夹持器代替卡爪式微夹持器,解决了平板类微小型零件难以夹持的问题;同时设计了基于单摄像机的光学自动对位系统,以完成装配件与装配基体之间的精确对位检测.实验中所搭建的微装配系统可较好地完成平板类微小型结构件的装配.     

基于LIGA技术的3K-2型微行星齿轮减速器的设计和制造

使用同步辐射光和X射线掩模板的LIGA技术能够制造大深宽比的三维微结构。详细讨论了基于该技术的微行星齿轮减速器的设计和制造，包括微行星齿轮减速器的设计、微齿轮X射线掩模板的CAD技术、X射线深层光刻、微齿轮的微电铸和微复制，以及微行昨齿轮减速器的微装配。目前已经得到了金属镍的厚度为400μm的太阳轮、行星轮，厚度为200μm的固定内齿轮、旋转内齿轮，其齿数分别为15、11、36、39。用这些微齿轮装配成了一台模数为0.03mm、减速比为44.2、最大外径为2mm的微行星齿轮减速器，并将其成功地应用在直径为2mm的北型微马达上。     

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...     

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。     

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.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.