基于单目视觉的机器人标定方法

为了辨识出机器人模型的准确参数,提出一种利用单目视觉标定机器人的方法.将摄像机安装在机器人或其延长杆上,使其随机器人转轴转动并拍摄固定的平面点靶标,利用基于径向排列约束(Radial-alignment-constraint,RAC)的标定法对摄像机进行标定并求出摄像机光心在世界坐标系中的坐标.利用得到的光心的坐标,即可获得关节轴线在世界坐标系下的轴线方程.建立机器人运动学模型,利用关节轴线方程得到了模型的准确几何参数.试验结果表明,此方法具有较高的精度,且该方法标定过程简单,便于实际应用.     

一种基于机器视觉的机器人标定方法

机器人标定是离线编程技术实用化的关键技术之一.提出了一种基于机器视觉的机器人标定方法,利用双目视觉测量机器人上的目标点,通过目标点位置的测量撮出机器人的关节轴线,根据相应的运动学模型求出机器人的几何参数,并解决了在测量过程中摄像机视野小的问题.实验结果表明该方法能够实现机器人几何参数的标定,提高了机器人的绝对精度.     

基于量子粒子群优化算法的机器人运动学标定方法

基于量子粒子群优化算法,提出一种同样适用于串联机器人和并联机器人的运动学标定方法。利用闭环矢量链方法和Denavit-Hartenberg矩阵法,分别建立并联机器人和串联机器人的运动学误差模型,将运动学误差模型内的几何误差源作为相应的机构参数修正量。由于机器人运动学误差模型表现有较强的非线性,因此确定模型内的机构参数修正量为优化变量,将机器人运动学参数标定问题转化为非线性系统的优化问题。采用量子粒子群优化算法对优化问题进行求解,利用优化获得的参数修正量更新运动学模型,以达到提高机器人运动精度的目的。以五轴并联机床的平面约束机构为研究对象,通过试验验证该标定方法的标定效果,并与模糊插值标定方法进行比较分析,结果表明在较大的工作空间内基于量子粒子群优化的运动学标定方法更为有效。     

工业机器人误差补偿及冗余参数研究

针对现有工业机器人定位精度较低,提出了通过机器人运动学标定对误差进行补偿的方法。基于D-H运动学模型和微分变换法建立机器人位姿误差模型,然后对误差模型进行冗余参数分析,消除冗余参数得到可辨识的线性方程,最后用迭代最小二乘法进行求解,修正几何参数进而提高机器人定位精度。通过在自主研发的机器人上试验验证,该方法补偿效果明显,增加了参数辨识的准确性和鲁棒性,为机器人标定技术的发展奠定了一定的基础。     

基于CPA方法的串联工业机器人运动学标定精度试验研究

几何参数误差是影响工业机器人定位精度的主要误差源,约占总误差的80％以上.基于圆点分析法(circle points analysis,CPA)所标定的几何参数与机器人的实际结构相关,并且能够将几何参数误差与其他误差源解耦.研究表明CPA方法的测量策略对其标定精度具有较大影响.针对基于CPA方法的串联工业机器人运动学标...     

基于旋量理论的六自由度机械臂逆解算法

机器人求逆解过程中主要采用D-H参数法和旋量法来建立机器人运动学模型。D-H参数法机器人运动学分析中应用较多,但由于D-H参数法需要在每个关节处建立坐标系,因此建模过程较为繁琐。旋量法中机器人各连杆坐标系相对于底座建立,建模较为方便并且几何意义更明确。基于旋量理论建立的机器人运动学模型,其逆解一般采用Paden-Kahan子问题方法进行求解。针对6R模块化机械臂,该机械臂后3个关节轴线相交于一点,基于旋量理论建立机械臂的运动学模型,利用几何关系与Paden-Kahan子问题,对该机械臂进行了逆运动学求解,得到了该机械臂的解析解。利用Matlab编制运动学算法程序,验证了逆解算法的正确性。     

6自由度关节机器人运动学反解的共形几何代数方法

机器人运动学模型的建立普遍利用Denavit-Hartenberg(D-H)参数法和旋量法,但是D-H参数法的几何意义不够明确,旋量法则有低自由度、关节轴线相交于1点的结构限制。针对6自由度关节机器人反解问题提出一种利用共形几何代数求解的新方法。首先以旋转关节轴线和旋转平面为基础建立无坐标系机器人模型,并定义肩部、肘部和腕部3种机器人结构设计形式。然后在上述模型和机器人结构下利用已知共形点建立直线、平面、圆周和球体等共形几何对象,通过几何对象的约束关系进行简单的代数运算完成各关节轴的旋转角计算。另外,该方法在进一步简化代数运算的基础上,利用2直线对象和旋转平面法矢量的约束关系唯一确定旋转角,从而完成运动学反解计算。最后,以常用的人机协作的UNIVERSAL ROBOT UR5 6自由度关节机器人为例,利用该算法进行运动学反解的验证,计算结果表明该算法的正确性。     

一种基于EIH的装配机器人标定方法

针对配置单目手眼相机(Eye in hand,EIH)的六自由度(Six degrees of freedom,6-DOF)串联装配机器人标定问题,提出了一种基于平面靶标的机器人标定方法。将平面靶标固定放置在工作台上,安装在机器人末端执行器处的EIH随机器人各关节依次转动,并拍摄靶标图像。利用ZHANG两步标定法对EIH进行标定,求出各拍摄位置处相机光心在靶面坐标系下的坐标。根据各关节单独运动时相机光心轨迹构成的圆,采用空间圆曲线拟合方法计算圆心坐标和转动关节轴线方向,并通过三焦张量约束优化各轴线方向,得到机器人各关节旋量。在此基础上,采用指数积建立机器人运动学模型。整个标定过程只需要一次安装,一组采集的标定图像。试验结果表明,该方法建立的机器人运动学模型简单有效。     

机器人加工装备运动学镜像模型建立方法与实验研究

在数字空间建立加工装备的镜像模型是实现智能制造的基础,镜像模型与加工装备构成数字孪生体,从而在数字空间中实现加工装备的加工模拟、仿真与参数优化。利用轴旋转法获得物理机器人各轴轴线及其位型,实现物理机器人几何参数与零位的解耦标定。采用坐标变换法建立物理机器人的运动学方程并利用牛顿迭代法求取运动学逆解。在数字空间中,利用标定的几何参数建立物理机器人的镜像模型,并集成刀轨迹生成与后处理模块。实验结果表明,由数字空间镜像模型生成的加工轨迹,物理机器人不变姿态的加工误差最大值为0.28 mm,机器人变姿态的加工误差范围为-0.83～+0.52 mm。     

基于病态参数分离的机器人运动学标定测量构型优化

针对一种高灵巧性机器人及其连杆参数高敏感性与高定位精度需求,为解决机器人运动学标定随机测量构型存在绝对 定位精度低、参数辨识效果及标定结果鲁棒性较差的问题,提出一种病态参数分离与 DETMAX-改进差分进化(DETMAX-IDE) 算法的机器人运动学标定测量构型分步优化方法。 首先,建立机器人位置误差模型。 其次,建立一种可观性综合指标,评价不 同机器人标定测量构型的总体可观测性和灵敏度。 最后,分离机器人运动学位置误差模型的病态参数,建立测量构型优化目标 函数和约束条件,提出一种基于 DETMAX 算法与改进差分进化算法结合的分步迭代优化算法(简称为 DETMAX-改进差分进化 算法,简写为 DETMAX-IDE 算法),开展机器人运动学标定测量构型分步迭代优化。 通过机器人运动学标定仿真与实验,验证 了所提方法的有效性。 实验结果表明,与随机测量构型相比,所提方法对应的机器人绝对定位精度的平均值和均方差分别降低 了 62. 09% 和 62. 45% 。     

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.