三种无内部奇异的平面冗余驱动并联机构及其性能分析

提出了4-RPR型、4-RRR型、4-PRR型等三种新型无内部奇异的平面三自由度冗余驱动并联机构。运用螺旋理论分析了各机构的运动自由度,讨论了工作空间内部的非奇异性及其参数条件,建立了运动学模型,通过数值方法获得了各机构的定姿态工作空间,并通过数值仿真分析了各机构的可操作度性能指标,结果表明这三种并联机构的工作空间内部均无奇异,且具有良好的运动灵活性。     

三自由度并联姿态测量机构及其运动学参数最优化设计

提出了基于并联结构的三自由度姿态测量机构，将其连接到三自由度串联结构位置测量装置末端可以实现对被测物体六自由度位姿的综合测量。该测量机构克服了并联机构运动学正解的困难，得到运动平台姿态坐标参数的显式解。建立了基于全微分理论的姿态测量机构坐标参数误差模型，实现机构运动学参数的优化设计。误差因子分析使得机构运动学参数设计更为合理。     

平面三自由度并联机构的惯性力平衡

讨论了微电子装备中的重要设备之一贴片机采用平面三自由度并联机构作为定位和姿态调整机构而带来的惯性力平衡问题。平面三自由度并联机构惯性力平衡的条件是其质心在惯性坐标系中是固定的。为了获得这个惯性力平衡的条件 ,首先平面三自由度并联机构的质心矢量表示成平台的位置和方向的函数 ,然后 ,从质心矢量的表达式中推导惯性力平衡的条件。最后给出实例来应用惯性力平衡条件。     

三自由度三排并联行星变速器传动方案

采用等效杠杆法分析三自由度三排并联行星变速器传动方案,明确三自由度三排并联行星变速器能实现的档位数,得出了五档和六档自动变速器结合元件布置的一般规律,并给出合理的传动方案。     

五自由度3D打印并联机器人设计及分析

为实现多向3D打印,设计了一种新型五自由度3D打印并联机器人,该机器人具有两个转动自由度和三个平动自由度,其特点是采用铰接的动平台以获得大的工作空间。根据建立的运动学模型,计算了该机器人机构的运动学反解,分析了定姿态位置工作空间和定位置姿态工作空间,用螺旋理论方法建立了速度雅可比矩阵,在此基础上分析了五自由度3D打印并联机器人的奇异性、灵巧性,并进行了运动仿真分析。研究结果表明,所设计的五自由度3D打印并联机器人具有大的位置工作空间和姿态工作空间,该机器人在工作空间内存在奇异位置,通过添加冗余驱动后可以消除奇异位置,并且具有良好的灵巧性,适合多向3D打印。     

开放式三自由度并联机器人机构实验平台的研究和展望

随着并联机器人技术的发展，具有三自由度的并联机器人机构也得到越来越广泛的研究和应用。本文对我们白行设计的开放式三自由度并联机器人机构实验平台的基本结构、运动控制和仿真作了较为全面的介绍，并着重分析了实验平台的开放性。该实验平台很适合作多种三自由度机器人机构的综合和比较研究，针对此类机构的进一步研究对实际应用有着重要意义。     

解耦三轴平面并联操作手的新机构及分析

为适应大幅面光电产品检测和大型工件操作(加工、焊接、喷涂)时变位姿的需要,提出一种结构简易的3滑块在3个平行导轨上驱动且易实现大工作空间的平面型解耦并联操作手的新型机构,推导了该机构运动学正反解解析公式,计算了末端执行器在定位置和定姿态情况下的工作空间,仿真分析了定姿态时3滑块的运动规律及特性,建立了三维虚拟样机模型,为其物理样机研制、实时控制及工业应用奠定了基础.     

一种新型三自由度平面并联机构的运动学研究

文中提出一种新型的三自由度平面并联机构,对其结构特点进行概述,并且针对其进行了运动学正解和逆解分析,得出了四组正解装配模式和八种逆解工作模式.另外利用极坐标搜索法得到了机构的定姿态工作空间,画出了其工作空间分布图.     

构造仿生关节的 3自由度并联机构运动特性

论述用并联机构构造仿生关节的原理,讨论仿生关节的结构特点,分析生物关节的运动特性及控制特点。采用三自由度具有与生物关节相似机械结构的滑块式并联机构;对采用的并联机构进行结构原理设计。建立机构位置方程,建立基于智能控制的位姿变换矩阵。设计仿生关节机构的结构参数;应用数值解法对机构的结构参数作仿真,并对其结论作分析。     

多自由度并联平台在科普展项中的应用

对多自由度并联平台在科普展项中的应用进行了描述,分析了六自由度并联平台位置姿态及求解。对六自由度伺服液压平台在大型互动科普展项"飞机模拟驾驶"中的应用及三自由度伺服电动缸平台在大型互动科普展项"血管漫游"中的应用进行了介绍。     

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.     

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....     

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.     

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.