稳定平台中活动线缆的虚拟布局设计方法

针对稳定平台中活动线缆布局设计不合理造成的弹性干扰力矩较大的问题,提出一种基于运动仿真的活动线缆虚拟布局设计方法。该方法首先从拉伸、弯曲和扭转等方面考虑了线缆的物理属性,并建立基于Cosserat弹性杆理论的线缆物理模型,在此基础上建立了以活动线缆干扰力矩最小为目标的布局优化模型,针对无干涉约束、无过弯约束和长度约束进行了仿真过程中的约束条件检测,并以线缆两端的位置、姿态和线缆长度为变量参数,通过交互的和自动相结合的优化迭代方法获得了最小干扰力矩值下的布局方案。最后以某产品的稳定平台为实例,分别进行了仿真计算和实物布线,并对比分析了初始布线方案与优化后的布线方案相对应的弹性干扰力矩,结果表明提出的方法能够有效减小活动线缆所引入的干扰力矩值。     

流体输送管路中悬浮体运动稳定性数值分析

为了解流体驱动管道机器人在流体输送管路中的运动稳定性,以悬浮体为研究对象,采用计算流体动力学(CFD)软件对其运动进行仿真,通过欧拉角、角速度、线速度、受力和力矩等参数随时间的变化规律分析其稳定性.计算结果表明,悬浮体在转弯过程中稳定性最差,而在整个运动过程,悬浮体所受力和力矩值较小,且欧拉角变化频率低于3 Hz,有利...     

基于干扰补偿的稳定平台控制系统设计

为克服机电伺服系统的摩擦以及其它力矩干扰问题,提出一种基于LuGre模型的摩擦前馈补偿和基于扰动观测器反馈补偿的复合控制策略。以某型号惯性稳定平台的单轴转台为例,首先对单轴转台进行建模分析,根据不变性原理,设计摩擦前馈补偿控制,再根据观测器输入和输出之间存在的数学关系,利用陀螺反馈的角速度信号,设计了基于扰动观测器的力矩补偿控制,最后在试验平台上,采用位置环为离散增量式PID算法,速度环为抗积分饱和PI算法,对提出的复合控制方法进行验证分析。稳定平台的实验结果表明所设计的惯性稳定平台控制系统能有效地抑制机电伺服系统中的摩擦及其它力矩干扰因素,一定程度上提高了惯性稳定平台的稳定性和动态跟踪性能。     

基于滑模变结构控制的车载摄像稳定平台的干扰力矩补偿研究

车载摄像在工作时会随着车辆颠簸。这会造成摄像焦点难以捕捉的问题。本研究所设计的稳定平台传统框架结构具有三维的传动轴进行补偿,保障了摄影器材能够跟踪拍摄物体。考虑到实际工况中会有干扰力矩对稳定平台造成控制误差,本研究采用滑模变结构控制方法对平台进行控制以实现干扰力矩补偿,并将指数趋近律和幂次趋近律相结合以消除抖振的影响。经仿真实验表明,本研究所设计的车载摄像稳定平台采用的控制方法相较于传统PID控制,具有更快的响应速度,并且能消除由于摩擦产生的平顶现象,相较于指数趋近律,采用指幂趋近律的控制方法能够补偿由于负载不平衡带来的角度偏转误差,并能明显消除抖振影响。     

基于模糊干扰观测器的电动Stewart平台自适应模糊控制

建立了一个电动Stewart平台的统一动力学模型,并基于它设计了一种新型的自适应模糊控制算法。这个统一的动力学模型在任务空间中使用了Newton-Euler方法建立,同时结合了平台动力学和执行器动力学模型。自适应模糊控制算法使用计算力矩方法设计运动平台标称模型的逆动力学控制器,然后使用基于模糊干扰观测器的自适应模糊控制器对模型的不确定性和外部扰动进行补偿。通过数值仿真分析表明,在不引入高增益控制器的情况下,成功地消除了平台参数的不确定性和外部干扰的影响,保证了平台的跟踪性能。     

一种结合扰动观测器的惯性稳定平台稳定回路设计

介绍了大型重力测量惯性稳定平台的典型陀螺稳定回路设计,在此基础上以稳定回路闭环传递函数为被控对象设计了扰动观测器,实现了扰动观测器与陀螺稳定回路的结合。进行了没有扰动观测器和带有扰动观测器的稳定回路控制仿真对比,仿真结果表明,结合扰动观测器的稳定回路,具有更好的抗低频干扰力矩和高频陀螺测量噪声的能力。     

传动钢带弹性对惯性稳定平台的稳定精度影响仿真分析

针对反射镜稳定方式下的某型惯性稳定平台,考虑基座扰动、摩擦力矩、传动钢带的弹性和预紧力等影响因素,推导了系统的动力学方程,并在ADAMS中建立了系统的动力学模型。用Matlab/Simulink进行机电联合仿真,重点分析并得到了钢带在不同刚度和预紧力下对稳定精度的影响。研究结果为惯性稳定平台的设计提供了依据。     

光滑平面约束下的活动线缆物性建模与运动仿真技术

针对活动线缆在安装和服役过程中受到单面约束时的运动过程仿真问题,提出一种基于弹性细杆静力学理论的光滑平面约束下的活动线缆物性建模与仿真方法。该方法通过分析活动线缆在光滑平面约束下的受力情况,将活动线缆所受到的约束力用拉格朗日乘子表达,将节点与平面的相对空间位置关系作为限制活动线缆运动的约束方程,得到分布力作用下的活动线缆Kirchhoff平衡方程,并建立活动线缆的物理模型。进而采用非线性约束优化方法求解模型。最后根据不同假设条件进行算例测试,通过比较活动线缆的仿真形态和实际形态,验证模型和数值解法的正确性。结果表明,该模型和解法能充分真实地表达活动线缆的基本物理特性和活动线缆受到光滑平面约束时的形变特点。     

旋转导向钻井惯导平台动力学分析与运动研究

将受到井下复杂扰动力矩作用的惯导伺服平台稳定控制在某一特定方位角度,是推靠式全旋转导向钻井系统实现准确导向的关键,但该平台对作用力矩非常敏感,小的扰动即可使其振荡失稳甚至单向旋转。通过对平台主要作用力矩的分析,建立一个考虑摩擦、水力冲击、质量分布偏心、安装误差偏心和涡轮电动机电磁作用等作用力矩的非线性动力学模型。基于该模型,仿真分析平台在无扰动和复杂扰动下的运动,得出了平台结构和扰动作用参数对平台运动影响的一般规律,水力驱动下的力矩测试试验验证了动力学分析的合理性。这些工作为改进系统机械设计和平台控制方法研究奠定了基础。     

3自由度飞行模拟运动平台动力学参数辨识试验研究

以一种具有一平动两转动的3自由度新型并联飞行模拟运动平台为研究对象,为满足飞行模拟动感要求,研究其动力学参数的试验辨识方法,以进一步提高动力学模型的精度。针对模拟平台样机,采用分步辨识法辨识动力学参数。将电机的驱动力矩分为:减速器惯性力矩、丝杠惯性力矩、综合摩擦力矩和负载力矩,并分别辨识。再根据负载力矩分两步辨识平台的主要动力学参数。设计平台参数辨识试验的激励轨迹,采用加权最小二乘法计算出待辨识参数,并代替理论模型中的对应参数。最后通过试验和ADAMS仿真对比验证参数辨识策略的正确性。     

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.     

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....     

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。     

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.