分插推培机构非圆齿轮节曲线设计分析与加工

针对高速水稻插秧机作业效率和质量的功能要求,提出了将非圆齿轮行星轮系作为分插机构的传动部件,并设计出非圆齿轮插秧旋转箱与双针推培插植机构。用解析方法建立了偏心齿轮-非圆齿轮旋转前插式水稻插秧机关键部件-分插机构运动学模型,并依据圆柱插齿刀范成法加工非圆齿轮的原理,构建了插齿刀与非圆齿轮毛坯的节曲线在相互啮合时的几何位置关系,建立圆柱插齿刀和非圆齿轮节曲线数学模型,为采用非圆齿轮行星轮系分插机构的高速插秧机的设计提供了理论依据。     

非圆齿轮行星轮系参数化设计及运动仿真分析

非圆齿轮行星轮系是非圆齿轮液压电动机的核心部件,其节曲线设计是整体结构设计的关键.针对4～6阶非圆齿轮行星轮系节曲线的参数不唯一、设计困难等问题,基于4～6阶非圆齿轮行星轮系节曲线的设计方法,选取偏心率作为控制参数,设计出不同非圆齿轮行星轮系的节曲线;对比分析了偏心率对非圆齿轮行星轮系运动特性的影响.结果表明,非圆齿轮行星轮系在传动过程中,行星轮中心加速度和行星轮角加速度均会出现突变,突变的位置均在内齿圈向径最大位置处,且随着节曲线偏心率的增大,行星轮中心加速度和行星轮角加速度的突变值均为增加趋势.     

基于输出摆角分析的抽油机换向机构优化设计

针对一种无游梁式抽油机用椭圆齿轮行星轮系换向机构输出摆角小、不能满足长冲程需求的问题,分析了该机构输出摆角大小的影响因素,将结果以图形面积表现在一对非圆齿轮副的传动比曲线中。根据分析结果,构造了满足应用需求的非圆齿轮副传动比曲线,求解非圆齿轮的节曲线方程,建立该机构的三维模型并进行运动仿真,得到输出摆角和输出角速度幅值曲线。分析结果表明,与原来的椭圆齿轮行星轮系换向机构相比,该机构增大了输出轴的摆角,从而可以增大抽油机的冲程。     

变中心距非圆行星齿轮机构节曲线设计

关于非圆行星齿轮机构的研究,到目前为止,所发表的研究成果主要是针对行星轮与中心轮(或固定轮)之间的中心距是固定的这样一类非圆行星齿轮机构。而本文所研究的是行星轮与中心轮(或固定轮)之间的中心距是变化的这样一类非圆行星齿轮机构。为了区别这两类不同的非圆行星齿轮机构,首次提出了变中心距非圆行星齿轮机构的概念,并给出了给定中心轮和行星轮的节曲线方程,求固定轮的节曲线方程的一般步骤。     

基于非圆齿轮的机械臂重力补偿机构研究

目前大多数机器人工作过程中需要消耗大量能量来克服自身重力,为了降低能耗并提高机器人性能,提出一种用于转动关节机械臂的重力补偿装置,该装置采用非圆齿轮行星轮系扭转弹簧机构,可实现机械臂任意可达工作空间的重力补偿;建立机械臂静平衡力学模型,根据静平衡约束条件设计非圆齿轮行星轮系,对非圆齿轮行星轮系传动比分配进行讨论,得到满足力矩平衡的最简轮系;以2R平行四杆机构机械臂为例进行设计分析,并导入ADAMS中进行验证,仿真结果表明,重力补偿机构有效降低了驱动力矩。     

自动装盒机椭圆-圆齿轮行星轮系取盒机构轨迹分析与设计

自动装盒机连续旋转式行星轮系取盒机构与间歇式往复摆杆取盒机构相比,机构振动小,速率更高。基于行星轮系取盒机构输出末端内摆线运动特性要求和非圆齿轮传动比可变的特点,提出一种椭圆-圆齿轮行星轮系代替现有的圆齿轮行星系取盒机构,使输出末端运动轨迹和特性得到优化。建立圆齿轮行星系取盒机构和椭圆-圆齿轮行星轮系取盒机构的运动学模型,分析两种机构的工作原理和运动特性,对机构进行轨迹仿真和运动特性求解,分析出机构主要参数对机构运动轨迹和特性的影响。利用人机交互的方法,对椭圆-圆齿轮行星轮系取盒机构的参数优化,得到一组较优的结构参数,并建立三维仿真模型。参数优化后的椭圆-圆齿轮行星轮系取盒机构运动特性与圆齿轮行星系取盒机构对比,在取盒和放盒工位的速度变化减小14.3%,最大加速度减小9.9%。上述研究可为行星轮系高速吸盒机构的设计提供理论依据。     

MATLAB在非圆行星齿轮节曲线设计中的应用

以n阶椭圆组成的连续光滑的封闭曲线作为太阳轮的节曲线,依据非圆行星轮系的基本运动关系建立了其配偶内齿圈节曲线设计的数学模型。依据微分几何原理推导出主从动非圆齿轮的节曲线封闭及轮齿均布的判定条件,运用MATLAB语言开发了求解该节曲线设计数学程序,最后导出一种非圆齿轮低速大扭矩液压马达节曲线公式。     

基于MATLAB的非圆齿轮节曲线设计

利用非圆齿轮行星系或圆齿轮差动机构和非圆齿轮机构的配合,可以再现一定种类的非单调函数.本文选取极角和极径变量作为参数来构造设计非圆齿轮节曲线,利用MATLAB软件,给定一种再现函数,绘出其节曲线和传动比函数曲线,可以很好的分析是否满足要求的变传动比.     

椭圆齿轮传动后插旋转式分插机构动力学分析与试验

采用刚体复合运动微分方程和动力学方程组逐次求解的方法,对椭圆齿轮传动后插旋转式分插机构进行动力学分析,建立其动力学模型和编写辅助分析软件,得到插秧过程中中心轮轴心、中间轮轴心、行星轮轴心及链条受力与行星架转角的关系,最后进行了试验验证,结果表明该分插机构比曲柄摇杆式分插机构具有更优的动力学特性.     

水稻钵苗旋转式拔秧机构

通过分析国内外水稻钵苗移栽机的缺点与不足,根据水稻钵苗移栽机的特征与优点,提出一种新型的以非圆齿轮行星轮系机构传动的旋转式水稻钵苗拔秧机构。通过试制与试验,结果表明该拔秧机构能够按确定的轨迹准确地拔取秧苗并摆放到摆秧台,具有结构简单、秧苗损伤小等优点,为水稻钵苗拔苗机构的设计奠定了基础。     

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...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

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.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

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.