基于复合控制策略的柔性关节机械手轨迹跟踪研究

目前常用的柔性关节机械手运动控制策略设计中,存在的主要问题是关节的加速度与跃度必须准确已知,这对测量带来了极大的困难,同时会对系统引入测量噪声.为解决该问题,提出了复合控制策略.将系统分为刚体模型与柔性模型的组合,对两个模型分别设计控制器以达到机械手关节轨迹跟踪的目的.以一个双臂柔性关节机械手轨迹跟踪为例,仿真结果表明,该复合控制策略可以实现柔性关节机械手的轨迹跟踪要求,具有一定的可行性.     

基于输入整形技术的柔性关节机械手控制研究

柔性机械手具有双时标特性,现有控制策略中需要对电机转角及机械臂转角的状态反馈,增加了控制策略的复杂性.建立了柔性关节机械手动力学模型,针对目前控制策略存在的算法复杂问题,提出了基于输入整形技术的柔性关节机械手运动控制策略.以电机转角作为反馈,根据机械手末端输出与目标输入之间的传递函数,设计了脉冲序列,通过与目标轨迹的卷积进行整形,可以实现轨迹跟踪.通过仿真实例表明,通过对目标轨迹的整形,能够有效减小超调和残余振动,具有一定的可行性.     

Backstepping在柔性关节机械手控制中应用研究

给出了柔性关节机械手的动力学模型,针对该模型,将反演算法引入机械手的运动控制中,设计了控制器及控制律,利用Lyapunov函数证明了系统的稳定.采用Adams与Simulink联合仿真的方法对单臂机械手进行运动仿真,通过实例表明,该方法在柔性关节机械手运动轨迹跟踪中具有一定的可行性.     

一种基于六构件变胞机构的气动柔性抓取机械手的设计

变胞机构与常见的定自由度机构相比,具有特殊的性能。阐述一种以气体为驱动力的自适应变胞机械手,该机械手简化为两个手指,以一个气缸驱动,每个手指有两个转动关节,在每个手指夹持部位衬以硅胶并贴以力传感器,控制气缸压力,致使夹持力可在一定设定范围内进行调整,是一种具有一定柔性的执行器。该执行器将变胞机构的工作原理和气体柔性驱动技术相结合,是一种基于六构件变胞机构的气动自适应柔性抓取机械手。阐述了该机械手的机构结构原理,并对该机械手进行了运动分析。该机械手在果蔬采摘,人体推拿执行器中具有广阔的应用前景。     

气动柔性机械手手指运动学研究

气动柔性五指机械手手指由自制的两种柔性关节通过连接盘串联组成。根据关节变形规律,在手指上选取特征点,通过齐次坐标变换建立了机械手手指的运动学模型。在柔性关节静力学实验的基础上,进行了柔性手指的运动学仿真,获得了机械手手指的工作空间。仿真结果表明,该柔性机械手具有较好的灵活性和较大的工作空间,通过手指间的协同配合可以完成抓、握和夹等动作。     

三杆柔性机械手运动学分析及仿真研究

在平面内运动的三杆柔性机械手运动学方程的建立是对其动力学分析和进行准确控制的基础.应用浮动坐标系,矢量法和D-H变换矩阵法建立了机械手的运动学模型,通过机械手各构件关节变量求解出机械手末端执行器的笛卡尔坐标空间位姿.使用Matlab软件对机械手末端运动轨迹和角度变化等进行了仿真实验,证明了柔性机械手弹性变形在空间准确定位中的影响,提出了一些减小误差的方法,为进一步研究柔性机械手较为精确的动力学和控制模型奠定了良好的基础.     

内置式机械手柔性加工单元的设计

内置式机械手相对桁架式机械手和关节式机械手的柔性加工单元具有结构简单、占地面积小、制造成本低等优点.根据某用户的需求,在的某型车削加工中心基础上,设计了内置式机械手柔性加工单元.设计了专用夹具;将原来的转塔刀架改为排刀结构;配备内置式气动上下料机械手和振动料仓,并具有自动检测功能.自动上下料时间可以控制在10秒钟以内,...     

基于奇异摄动的柔性机械手预测控制

讨论了柔性机械手末端位置的控制问题。采用奇异摄动方法将柔性机械臂系统动力学方程分解为慢变(刚性 )和快变 (弹性 )两个子系统。给出了一种预测控制与 I/ O反馈线性化相结合的混合控制方法。该方法采用预测控制消除柔性机械手的弹性振动 ,可避免逆动力学和 I/ O反馈线性化控制遇到的零动力学不稳定问题。通过一个柔性机械手的仿真表明 ,本文提出的控制方法可实现柔性机械手末端轨迹的准确跟踪 ,同时能消除柔性机械手的弹性振动。     

柔性机械手振动的粘弹性阻尼控制

对柔性机械手进行粘弹性的束阻尼处理可抑制柔性振动,改善控制系统稳定性,提高定位精度。本文给出了粘弹性阻尼构件机械手的动力学有限元方程及振动响应的求解方法。对一台实验用二关节柔性机械手进行了粘弹阻尼减振的效果预测分析和实验研究。     

柔性吞咽机械手的结构设计与样机试验

为解决表皮较为脆弱的果实抓取过程中易造成损伤的问题,基于柔性3D打印材料提出了一种结构精简、具有吞咽功能的柔性机械手。对柔性机械手的吞咽动作流程进行了分析,结合D-H坐标法和常曲率变形建立了单手腕的连杆参数表,得到了单手腕的运动学方程;在搭建柔性机械手样机的基础上,对气动元件的形变量进行了测试试验,采用Matlab进行数据拟合,得到了驱动角度与驱动气压的关系式;利用摄像机对机械手抓取西红柿的过程进行了拍摄,通过Get Data获得驱动元件的角度,得到了机械手抓取过程与驱动角度的关系。试验结果表明:通过角度的改变可以实现对柔软果实的良好抓取和吞咽效果。     

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.