基于螺旋理论的3-RPS型并联机器人运动学分析

3-RPS型并联机构具有三个结构对称的支链形式,各支链由一个转动副连接机座、一个球面副与动平台相连接,转动副与球面副由移动副所连接。采用螺旋理论及空间机构构型原理,通过约束形式分析得出该类型并联机器人运动性质,采用矢量分析方法对其运动学正解/反解进行求解,得出该并联机构运动学方程。基于对称非齐次性少自由度并联机构Jacobine矩阵,进一步对该类型并联机器人结构奇异性进行分析与总结。     

非对称式6/6-SPS型Stewart并联机构运动学正解的研究

对具有非对称式结构的6/6-SPS型Stewart并联机构的运动学正解进行研究。建立了一类具有非对称式结构的6/6-SPS型Stewart并联机构运动学正解的数学模型,构造了一个关于该并联机构动平台位置参数及姿态参数的多元多项式方程组。基于该方程组并采用Mathematica符号计算软件,编制了基于Mathematica语言的非对称式结构的6/6-SPS型Stewart并联机构运动学正解的求解程序,计算结果表明,对于任意给定的该并联机构的结构参数以及六个驱动杆杆长,该类6/6-SPS型Stewart并联机构的运动学正解在复数域内最多有28组解析解。并联机构运动学正解的研究为该类并联机构的工作空间分析、轨迹规划及控制奠定了重要的理论基础。     

6/6-SPS型Stewart并联机构运动学正解的研究

对具有半对称结构的6/6-SPS型Stewart并联机构的运动学正解进行了研究.建立了一类具有半对称结构的6/6-SPS型Stewart并联机构运动学正解的数学模型,构造了一个关于该并联机构动平台位置参数及姿态参数的多元多项式方程组.基于该方程组并采用Mathematica符号计算软件,编制了基于Mathematica语言的6/6-SPS型Stewart并联机构运动学正解的求解程序,计算结果表明,对于任意给定的该并联机构的结构参数以及六个驱动杆杆长,该类6/6-SPS型Stewart并联机构的运动学正解在复数域内最多有28组解析解.并联机构运动学正解的研究为该类并联机构的工作空间分析、轨迹规划及控制奠定了重要的理论基础.     

利用约束螺旋理论综合的空间对称2-DOF并联机构

首先按运动功能对两自由度空间并联机构进行分类,得到了空间2Ryz型（绕y轴和z轴转动)和1Rz1Tz型(绕z轴转动和沿z轴移动）的两自由度机构;给出了两类并联机构的分支约束螺旋系和机构约束螺旋系,以及保证所有分支约束螺旋的合成是期望的机构约束螺旋系的几何条件。对这两种空间并联机构运用约束螺旋综合理论进行系统的型综合,得到了可实现连续运动的具有绕定平台平面内两轴转动的并联机构以及沿着定平台法线方向移动和绕其转动的两自由度并联机构;得到了两自由度并联机构各种类型的分支链结构,以及两类机构的结构约束特性。将少自由度对称并联机构类型由原来的9类扩充到11类,丰富了机构类型。     

基于方位特征集的两转动（0T-2R）并联机构的型综合及其应用

应用基于方位特征集的并联机构拓扑结构设计理论与方法,对两转动（0T-2R）输出的并联机构进行了型综合;在阐述基于方位特征集的并联机构型综合一般过程和步骤的基础上,给出了两转动输出并联机构拓扑结构设计的具体方法,综合得到了14种两转动输出并联机构,其中,6种机构为该方法综合得到,然后按它们的结构特性进行了初步分类,并将优选的一种两转动并联机构用于太阳能二轴跟踪机构的研制。该型综合方法运算规则少,数学方法简单,几何与物理意义明确,适用于所有无过约束和一般过约束机构。     

3-PUU并联机构工作空间分析与优化设计

提出一种新型3-PUU并联机构,对该并联机构进行运动学分析,得到了3-PUU并联机构的运动学反解,在此基础上,分析了移动副和虎克铰对工作空间的限制。采用三维极限搜索法求解了工作空间。对该并联机构的工作空间进行了优化分析,为并联机构的构型设计和进一步研究奠定了基础。研究结果表明,该种机构具有较好的实际应用前景。     

基于拓扑解耦准则的球面并联机构解耦条件研究

具有输入输出解耦特性的并联机构,由于其易于控制,深受欢迎。基于提出的并联机构拓扑解耦准则,针对一种球面解耦并联机构进行了解耦性分析,给出了该机构更一般的解耦条件;更进一步,基于拓扑解耦准则构造了一种更一般的新型球面解耦并联机构。基于拓扑解耦准则进行并联机构解耦特性分析和型综合的方法,对具有拓扑解耦特性并联机构的创新设计和应用具有深远意义。     

平面3自由度并联机构滑模变结构控制研究

平面3自由度并联机构具有良好的机构特性且实用价值较高,为提高机构的轨迹跟踪精度,提出了一种基于平面3-RRR并联机构的低通滤波滑模变结构控制(SMC)策略.在分析机构动力学方程和控制器Lyapunov稳定性基础上,搭建了平面3-RRR并联机构的控制系统框图,对机构的位移轨迹跟踪进行了实时控制.仿真结果表明:机构采用低通滤波SMC算法后,位移轨迹跟踪误差明显降低;该算法简单易实现,有效削弱了系统抖振,提高了控制系统的精度.     

空间3自由度并联机器人机构智能化型综合

基于单开链单元的欠秩并联机器人机构型综合方法理论,提出用VB编程实现并联机器人机构型综合智能、系统、有效的新方法.该方法按动平台输出运动特性及自由度数;能快速生成所要求的一系列机型,能为优选机型并对机构进行运动学及动力学分析等提供基础.运用此方法对空间3自由度并联机构进行型综合,达到型综合自动化的目的,该方法可用于其他自由度并联机构的智能化型综合,具有普遍意义.提出的智能化型综合法改善了过去建立在人工劳动基础上且过程重复繁琐、工作量大、易发生疏漏现象、效率低的型综合方法,为型综合的研究发展开辟了一条新途径,具有良好的应用前景.     

一种改进型三平移并联机构的工作空间与运动灵活性分析

根据Delta机构的结构,设计提出了一种改进型三平移并联机构。在位置逆解的基础上,讨论了机构输入与输出速度关系的逆雅可比,并进一步对该并联机构作业空间的几何性质、机构的运动灵活性进行了分析,给出了几何参数变化对机构作业空间及运动灵活性的影响规律。分析表明,该机构具有几何形状规则的作业空间及较好的运动灵活性,是一种较为理想的实现三维移动的并联机构机型。     

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.