6-TPS并联机构动力学分析

建立了6-TPS并联机构全部构件和关节与动平台速度加速度的解析关系。用凯恩法建立机构运动微分方程,该方程采用了机构输出速度作为独立变量,可作为动力学控制模型对机构进行完全闭环控制。利用矩阵范数导出了主动关节驱动力相对变化量与惯量矩阵以及加速度相对变化量之间的摄动关系,提出量化机构加速度性能和动力学优化的指标。通过实例得出机构加速度性能指标是以惯量矩阵在工作空间的奇异轨迹为极限的结论,这可以用来选取动力学性能优良的工作空间。     

基于Adams的4R机械手生产参数仿真研究

针对4R机械手,通过三维实体建模仿真模型,利用三维软件与Adams的接口导入,建立虚拟样机,在不同的速度、轨迹、节拍下进行动力学仿真,得出关节力矩曲线,分析了动力学模型下机械手设计的可行性,为提高性能和减少研发成本提供依据.     

新型集装箱板材上下料机械手动力学建模与仿真

为提高集装箱折弯板材上下料的效率,提出一种新型上下料机械手.该机械手采用2-P(Pa)并联机构与抓取机构相结合的结构,实现了折弯工序对板材的快速搬运.文中介绍了集装箱角柱折弯的加工工艺与新型机械手的结构组成,建立了并联机构的位置方程,利用解析法推导出了并联机构的位置正反解、末端执行机构的速度与加速度方程,为动力学分析奠定基础.利用拉格朗日方程建立了机械手的动力学方程并进行了实例仿真验证.验证结果表明:理论驱动力值与仿真驱动力值误差较小,说明所建立的机构运动学模型及动力学模型的正确性,为机械手后续的动载分配优化及系统控制提供了理论指导.     

一种手腕同步驱动码垛机械手设计

根据啤酒箱码垛系统工艺流程要求,对码垛机械手运动轨迹进行了设计,在此基础上建立码垛机械手模型;设计了一种手腕同步驱动机构,对同步驱动机构进行动力学分析并对驱动转矩参数进行优化。最后,利用ADAMS软件对该机构进行仿真分析。     

3-PRS并联机构的动力学惯量耦合特性分析

针对3-PRS并联机构动力学惯量耦合特性的问题,在关节空间中建立了机构的动力学模型,对机构主动支链之间存在的惯量耦合进行了研究.首先,给出了机构的运动学模型,针对动平台广义位姿、速度、加速度存在耦合的问题,分别通过约束方程、一阶影响系数矩阵、二阶影响系数矩阵,对其进行了解耦,并建立了各支链与动平台末端速度、加速度的映射...     

风洞试验偏航机构动力学优化研究

为了提高风洞试验偏航机构的驱动能力、传力性能及平稳性,对偏航机构的参数进行了灵敏度分析和优化。针对影响性能的因子,通过运动学和动力学求解,提出了偏航机构动力学性能的评判指标。以Isight软件为平台,结合MATLAB,对偏航机构压力角、旋转部件转动惯量和直线滑块加速度等因子进行灵敏度分析。在此基础上,建立多目标优化模型,对影响因子进行了优化计算。结果表明:偏航机构压力角最大值降低了12.47%,旋转部件转动惯量减少了6.7%,直线滑块加速度均方根值减少了43.72%。     

折臂式弃料机械手的参数优化与动态仿真分析

针对煤炭采样车提出一种折臂式弃料机械手设计方案,并设计了末端操作器。对该机械手建立数学模型,进行主要结构参数优化;基于动量矩定理建立了动力学模型,推导出机构的动力学方程,对该机构在运行过程中的关键受力位置所需动力进行理论分析;将在Solidworks中建立的机械手模型导入ADAMS中验证空间工作点,仿真分析带载情况下的运行状况,对该折臂式弃料机械手中的驱动部件选型安装有指导意义。     

基于ADAMS的单缸内燃机动力学分析与研究

引起内燃机振动的一个重要因素是其曲柄连杆机构往复运动产生的惯性力和惯性力矩.基于动力学仿真软件ADAMS和Pm/E,建立了单缸内燃机的虚拟样机参数化实体模型,进行了动力学仿真分析,并将速度、加速度等分析值与理论分析结果比较,结果吻合验证了所建模型的正确性;研究了惯性力对机体产生干扰力和力矩的影响以及惯性力平衡问题.通过参数优化分析,确定了构件的最佳质量特性参数,改善了机构的动力学性能,同时提高了设计效率.     

交通锥回收机械手参数优化

针对单自由度齿轮连杆式交通锥回收机械手,在运动学分析的基础上,研究了杆件尺寸、传动比等参数对回收机械手末端执行器速度及轨迹的影响。基于减小所占空间、主臂转角以及水平加速度峰值等优化目标建立了数学模型,利用Matlab软件对主臂转角,主臂、副臂水平夹角及齿轮传动比等参数进行优化。根据优化前后的设计参数,通过ADAMS软件对回收机械手进行了动力学仿真验证,结果表明,优化后回收机械手尺寸减少了10.3%,主臂转角减小了13.6%,水平加速度峰值减小了19.8%。     

高速共轭凸轮打纬机构柔性动力学分析

共轭凸轮打纬机构广泛应用于高速剑杆织机中,对其进行全面深入的动力学特性研究,将提升织机整体性能,提高生产效率。基于有限元法对打纬机构柔性构件进行有效离散化,为建立精确的动力学模型提供物理模型基础;应用Kane方程结合模态综合技术建立共轭凸轮打纬机构动力学模型,不仅形式简单,求解时也可大大节约计算资源。基于该动力学模型,分别对凸轮转速、打纬阻力、结构参数对动态响应的影响进行仿真。结果表明,转速提高和打纬阻力带来的机构变形不足以影响打纬性能,但转速变化对机构加速度影响明显。研究结果为改善各实际工况和结构参数下打纬机构的动态性能提供了依据,也为更精确地动态优化设计高速打纬机构奠定了理论基础。     

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.