基于图论的可控装载机构构型设计及其应用

基于图论相关理论对一种新型装载机工作装置进行了全面、系统的构型设计与研究。利用胚图插点法对九杆以内只含单铰转动副的平面闭环两自由度机构进行了构型综合,得到了51种拓扑图;根据可控装载机构拓扑结构要求、功能性要求、约束条件要求以及拓扑结构最简原则对得到的拓扑图进行了拓扑综合,共筛选出了22种满足构型要求的拓扑图;再根据提出的机架存在条件、铲斗存在条件、动臂存在条件对得到的所有拓扑图进行了特定化;最后提出可控装载机构优选原则,对拓扑图特定化方案进行优选和具体化,获得了11种可控装载机构。通过样机研制验证了构型设计的合理性。     

基于功能分析的新型装载机构型综合研究

传统的机械式工程机械采用单自由度机构,所能完成的动作单一,动作轨迹不能变化;液压式工程机械可以灵活地执行各种工程动作,但其液压系统零部件的精度要求和成本高、可靠性不理想、易漏油、传动效率低等不足。这个棘手问题长期未能有效解决。将变胞机构和多自由度可控机构应用于工程机械等领域,可克服现在的机械式和液压式工程机械的各自不足,既能像液压式工程机械那样变化运动轨迹、执行各种动作,又没有液压系统的缺陷,具有良好的应用前景。研究这类新型机构的型综合问题,针对现有典型装载机产品的特点,采用工作机理的动作表达方法,将液压式装载机的工作机理作为依据和出发点,把其转化为工艺动作过程。结合变胞机构、可控机构、及并联机构等有关研究成果,综合应用构型演化法、基于螺旋理论的约束综合法等机构创新设计理论和方法,在功能分析的基础上完成了装载机新型执行机构的概念设计。获得了一批新型多自由度可控机构式装载机构构型,包括具有变胞功能的可控机构式装载机构构型,并由试验验证了多自由度可控机构用于装载机等工程机械的可行性,为这类机构的应用提供了一定的参考。     

内力封闭自适应机构初始运动链综合的胚图支链法

根据内力封闭型自适应机构初始运动链的自由度特征,提出了一种运动链构型综合的新方法,即胚图支链法。此方法视运动链由多元素杆和支链两部分构成,并通过一种有序分步的方法构建运动链的拓扑胚图,然后在拓扑胚图上配置支链形成广义拓扑图,再转化为运动链。利用此方法,综合出了自由度为0或-1的9杆、10杆运动链的全部独立构型,为内力封闭自适应机构的创新设计提供了理论依据。     

具有变胞功能的电动装载机构构态进化拓扑结构分析与基因建模

变胞机构是一类具有多功能阶段变化、多拓扑结构变化、多自由度变化等特征的机构。将其应用于装载机研究发明的新型电动装载机构,可按不同阶段的工作需求改变其执行机构的拓扑结构,只需一台驱动电动机就能完成传统两自由度液压装载机铲装、翻转、抬升、卸料等工作任务。采用电动机驱动、连杆传动的方式,能有效克服液压系统零部件加工装配要求高、维护保养困难、易产生漏油等缺点;且电动机均安装在机架上,避免了传统串联式机械手的驱动电动机大都安装在铰链处,导致的刚性差、惯量大等问题。介绍变胞装载机构的变胞源机构以及实现变胞功能的几何变胞方法,利用邻接矩阵和拓扑图描述了各工况对应的子工作阶段机构的拓扑结构变化,分析其工作原理和构态转化特点,得到机构构态演变过程的生物学进化特性。针对机构的结构和连接特点,研究变胞进化生长过程中构型的转化方式和蜕化方法,对各个构型单元分别进行进化计算,得到变胞源机构的基因模型表达式。     

平面3-DOF混联机构构型综合及其同构分析

通过应用Assur杆组法及图论理论对平面3-DOF全转动副机构进行了构件分类和构件组合,得到了一种最基本的3条支链对称的运动链结构。然后运用拓扑胚图插点法画出了其拓扑胚图,对其支链进行分类并插入拓扑胚图中,再进行同构分析得到了6种运动链构型。最后,运用一种新的基于构件关系的图论描述方法推导出了此机构的混联构型,并对其进行了应用研究。这些为以后非全转动副平面3-DOF机构的研究打下了基础。同时,通过研究平面3-DOF机构也更加有利于空间少自由度机构的研究。     

基于图论的新型变胞挖掘机构构型综合研究

本文基于图论理论,首先对传统挖掘机构进行结构分析,得出了新型可控连杆式挖掘机的设计要求;采用杆件类配综合法得到新型挖掘机构所有的构件组合方案,再利用胚胎插点法在拓扑胚图上进行插点,获得挖掘机构的所有基本构型。然后根据传统挖掘机的结构特点和工作性能要求,提出了挖掘机构拓扑图功能性判定准则,以便从获得的拓扑图中获得最合适的构型;根据现实可行性和机构工作可靠性对筛选出的挖掘机构进行改进,并为了减少驱动元件的数量,提出一种主动变胞方法,得到本文的新型变胞挖掘机构,并对其进行了三维建模;采用邻接矩阵法对该新型变胞机构进行拓扑结构变换分析,并对计算了各构态的自由度,然后对该新型变胞挖掘机构的各工况进行了分析,初步证明了利用主动变胞方法减少主动杆数量的可行性。     

含四杆机构单元的重载转运机器人构型综合

针对用于轴类物料抓取及卸载的重载转运机器人机构形式单一、转运范围局限大等问题,进行了重载转运机器人新构型的研究。首先分析了重载转运机器人机构的结构特点和工作原理,发现含有四杆机构单元的重载转运机器人具有灵活性高、承载能力大等优势,为构型综合和新方案优选提供依据。其次基于图论对只含转动副的平面机构进行构型综合,得到七杆、九杆机构拓扑胚图,利用胚图插点法对拓扑胚图进行插点,建立拓扑图,进而转化成对应的运动链,得到构型图谱。然后根据重载转运机器人机构中的四杆机构单元和功能构件,对拓扑图进行特定化标记,提出重载转运机器人优选条件,分析和优选特定化标记的拓扑图,得到其最佳构型。最后,利用Adams软件对一种优选机构进行仿真分析,结果表明,该机构在平面运动过程中可以同时实现远距离抓取和大范围俯仰运动,从而验证了该机构构型设计的合理性。     

可控装载机构的运动学分析与仿真

针对一种新型装载机工作装置进行了运动学分析和仿真研究。根据装载机性能要求,确定可控装载机构性能要求;利用解析法建立了运动学逆解模型,并对可控装载机构进行尺度参数设计,通过对逆运动学模型进行数值求解,获得了主动杆运动规律及电传动系统驱动参数。利用ADAMS软件建立可控装载机构虚拟样机模型,在各典型作业工况下对可控装载机构进行正运动仿真,仿真结果证明,该可控装载机构在工作空间内能够顺利完成各作业动作,各构件尺度参数设计合理,铲斗倾角、卸载角等均符合装载机设计要求,为可控装载机构的进一步研究在一定程度上提供了基础。     

液压装载机工作装置的构型综合与优选

研究11杆2自由度液压装载机工作装置的构型综合与优选。首先,介绍平面多环运动链单色与双色拓扑图的表达方法与平面多环机构多色拓扑图的建立方法;其次,基于平面11杆2自由度运动链图谱库,提出液压装载机工作装置构型综合方法,综合得到35个单铰液压装载机工作装置构型和35个复铰液压装载机工作装置构型,并绘制符合液压装载机工作装置结构特征的平面多环机构简图;第三,提出液压装载机工作装置的优选原则,优选得到18个可用于液压装载机工作装置的构型;最后,针对优选的液压装载机工作装置构型建立虚拟样机,模拟液压装载机实际作业工况,验证液压装载机工作装置创新构型的实用性。该机构构型综合与优选方法研究为具有自主知识产权的新型工程机械装备的研发提供了新思路。     

基于功能分析的船用克令吊执行机构构型综合

传统港作起重机械多为平面开链式机构,整体结构稳定性不足,输出动作单一、欠柔性,且多采用液压驱动,存在易漏油、加工装配要求高、维护保养成本高等缺点。针对此类问题,以船用克令吊为结合点,在全面分析其工作原理和输出动作要求的基础上,通过工作机理的行为表达方法将其转化为工艺过程,基于功能分析,结合多自由度可控机构以及并联机构,采用胚图插点法完成执行机构的运动链数综合,获得一批新型多自由度可控机构式船用克令吊机构构型,为此类机构以及其它港作机械的进一步创新设计及研究提供参考。     

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.     

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.