宏微双级驱动精密定位平台的建模与控制

为实现定位系统在大行程中高精度定位,设计了一种宏微双级驱动精密定位平台。采用金属波纹管直接驱动宏动平台,实现了系统大行程进给。安装在宏动平台上的音圈电机驱动微动平台,补偿宏动平台产生的误差并实现系统的高精度定位。采用双光栅检测方案,增量式光栅反馈宏动平台的位置信号,绝对式高精度光栅反馈微动平台的位置信号,实现二级精密驱动定位系统的全闭环控制设计。分别对宏动平台和微动平台建立数学模型,提出宏动平台带前馈的PID闭环控制和微动平台的神经网络PID复合控制方案。实验结果表明:该定位系统能满足大行程高精度的定位要求,在50mm的行程中重复定位精度能达到0.6μm。     

一种宏微双重驱动精密定位机构的建模与控制

提出一种宏微双重驱动精密定位机构,采用高性能直线电机直接驱动宏动平台,实现系统大行程微米级精度定位;安装在宏动平台上的压电陶瓷驱动微动平台,实现纳米级的分辨率和定位精度,以高频响动态补偿系统的定位误差;采用精密光栅尺反馈微动平台输出端的位置信号,实现定位机构的全闭环反馈控制。在分别建立宏动、微动、宏微机构模型的基础上,提出复合型宏动控制和模糊自校正PID微动控制的宏微控制策略。实验研究表明:系统的动态和稳态性能良好,该定位机构的最大工作行程100 mm,稳定时间小于40 ms,重复定位精度10 nm。     

宏/微结合双驱动进给控制系统的建模与仿真研究

采用宏/微结合双驱动进给系统能使系统在大行程范围内具有较高的定位精度。本文设计的宏/微结合双驱动进给系统,由交流伺服电机驱动滚珠丝杠作为宏动机构,压电陶瓷驱动柔性铰链工作台作为微动机构。分别对宏动机构和微动机构进行了数学建模。采用双伺服环控制策略,由宏动机构跟踪输入信号,由精密光栅尺检测宏动机构的实际位移进行反馈构成内伺服环;微动机构将宏动机构的跟踪误差作为输入信号,实时进行补偿,构成外伺服环,实现了宏/微结合双驱动进给系统的连续跟踪控制。最后进行了仿真研究,仿真结果表明跟踪幅值为1mm频率为0.4Hz的正弦曲线,采用宏/微结合双驱动进给系统比只采用宏动机构跟踪误差由±1.6μm减小到了±6nm。     

高加速度宏微运动平台研究

对高加速度宏微运动平台进行了研究,在分析宏微复合驱动技术的基础上,采用一种新型的宏微驱动方式,研制了基于压电陶瓷的高加速度宏微运动平台。宏运动由音圈电机驱动,可实现高加速度、大行程运动;微运动由安装在音圈电机轴上的压电陶瓷驱动,用以补偿宏动所产生的定位误差,达到高精度的设计目标。在微动过程中,由绝对式直线光栅尺实现闭环位置反馈。根据设计要求,搭建了宏微驱动高加速度高精度定位平台,通过实验验证其性能。实验结果表明,该宏微运动平台加速度大于10g,重复定位精度小于1μm。     

具有角度修正功能的大行程二维纳米工作台

基于宏微组合驱动方式,提出一种具有角度修正功能的大行程二维纳米工作台设计方案来减小精密测量系统中由于工作台定位及角度误差引入的测量误差.首先,从原理上对设计方案进行了论证.该方案中宏动工作台和微动工作台共用位置反馈系统构成闭环控制,并基于压电陶瓷致动器及柔性铰链设计的六自由度微动工作台对宏动工作台进行直线定位误差及角度误差的综合补偿.然后,基于设计方案设计了宏动工作台及微动工作台的结构.最后,对安装调试后的宏微工作台系统进行了直线组合定位测试及角度误差修正测试.实验结果表明,该工作台系统的宏动行程达到了200 mm×200 mm;在闭环控制下,通过六自由度微动工作台的补偿作用可使各角度偏差由上百秒降至10″以内,由此工作台系统在全行程内的直线定位误差可由3μm降至25 nm以内.实验结果验证了提出的组合定位系统的有效性.     

基于机器视觉的宏/微双驱动与控制系统的研究

针对目前单一的驱动方式日益不能满足越来越多的微操作的要求;提出了利用步进电机和压电驱动器组成宏/微双驱动的微操作平台.步进电机实现大行程移动和定位,压电驱动器进行高精度定位误差补偿.同时为了解决宏/微双驱动两部分的协调控制问题,提出了利用全局机器视觉的协调控制方法,将末端执行器与目标点的距离作为控制阈值;如果当前距离大于设定的控制阈值,则启动宏动台进行驱动定位;否则启动压电驱动器进行定位误差补偿.试验结果表明:系统的定位速度快,定位精度为1μm,稳定定位时间小于40ms.     

大行程精密定位平台偏摆误差的补偿方法

精密定位平台在导轨动连接处刚度较差,在高速高动态工作中这里易产生偏摆振动。为了减小偏摆误差对定位平台的影响,提高定位精度,通过对直线电机驱动、气浮导轨支撑和导向的高精度定位平台进行研究。根据定位平台偏摆误差的动态特性,采用偏摆误差补偿方法,设计一种偏摆误差检测系统,采用平尺和微位移传感器相结,具有高频响、非接触式的特点。设计了一种基于压电陶瓷驱动的x,y两维微位移补偿机构。同时,通过将气浮导轨滑块副简化成弹簧、质量和阻尼相结合的系统,推导出了定位平台两自由度的偏摆振动模型。基于误差补偿系统的偏摆误差补偿实验表明,精密定位平台的定位精度得到了较大提高,定位平台的定位精度优于2μm。     

纳米工作台定位控制研究

介绍了基于宏微两级驱动方式的纳米工作台定位系统,重点在对宏微动态切换时宏动台固定与否对其自身振动情况的影响进行测试分析。研究表明,宏动台被锁定后可以明显减小其台面振动幅度,对后面微动台以及整个系统定位精度的提高起着关键性作用。     

基于激光干涉仪的垂直轴宏微复合平台直线度测量及误差分析

设计了一个垂直轴宏微复合平台,宏动台采用交叉滚柱导轨,直线电机驱动,微动台采用柔性铰链导向机构,压电陶瓷驱动,对微动台固有频率进行了测试,其固有频率为351 Hz,响应速度快。然后基于激光干涉仪搭建了宏微复合平台直线度测量系统,获得了-100 mm~100 mm的直线度误差值,分别用两端点连线法以及最小二乘法分析了实验数据,得到了平台导轨的直线度误差25.32μm。最后测试了微动台的低频动态位移输出,可达56.59μm,能满足宏动台直线度补偿要求,该研究为直线度误差补偿提供了依据。     

细胞注射机三坐标微位移台结构设计

为实现细胞工程中细胞显微注射的要求,提出了一种用X—Y—Z三坐标微位移台来完成细胞微量注射微动平台定位和注射的装置,X—Y—Z三坐标微位移台微量注射装置的定位和注射动作全部由直流步进电机驱动,步进电机在高细分驱动器驱动下,步进精度达0.004μm,滑台的定位精度达0.3μm,而生殖细胞尺寸通常处于1~100μm范围,基本满足细胞显微操作精度要求,普通国产三轴控制器即可实现所需控制功能,和目前国内外的其他细胞微量注射装置相比,其主要特点是定位精度和注射精度都比较高、成本低。     

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.     

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....     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.