3-PPPS并联机翼调姿机构运动学标定

为解决一种3-PPPS并联机翼调姿机构因制造、装配过程中存在的误差因素所引起的调姿精度不高的问题,考虑了调姿系统结构误差因素对调姿机构位姿精度的影响。采用空间矢量链建立机翼部件调姿位移逆解方程,通过微分机构运动学方程,得到包含39项误差源的调姿机构位姿误差与几何误差之间的映射方程。利用激光跟踪仪测量调姿机构测量机翼参考点位置和定位器各轴的实际驱动量。通过最小二乘迭代法辨识出定位器结构误差,修正定位器反向驱动位移求解参数。经过运动学标定实验后,调姿平台的位置最大误差由2.68 mm降为0.82mm,角度最大误差由0.481°降为0.167°,从而验证了标定方法的有效性。     

飞机装配大部件自动调姿控制系统的设计

基于飞机数字化装配技术设计了一套飞机大部件自动调姿系统,介绍了控制系统的结构,包括系统构成、硬件设计和软件设计。整个控制系统采用Twin CAT 3作为中央控制核心,通过Profinet总线技术与下位机Rexroth的Indra Control L65实现实时通信。利用激光跟踪仪还原飞机装配坐标系,建立数字化测量系统,以力传感器反馈数据为调姿过程参数,调用调姿算法控制数控定位器的调姿和自动托架的辅助支撑。     

基于理想驱动力的中机身调姿多项式轨迹规划

为实现飞机中机身的自动对接装配,提出一种新型的冗余驱动中机身自动调姿机构。该机构由4个离散的定位器组成,定位器1和定位器3的底层滑块、中间层滑块、伸缩柱都有独立的驱动;定位器2和定位器4只有伸缩柱有独立的驱动,其他方向均为随动。定位器通过球铰式工艺接头与托架相连,托架通过勾头螺栓与中机身保持固连。联动控制所有定位器,实现中机身位姿的自动调整。该调姿机构工作空间大、调姿部件大,既具有冗余驱动的优点,又避免了冗余驱动数过多导致控制系统复杂的不足。针对中机身调姿的特点,提出基于理想驱动力的中机身多项式轨迹规划方法。仿真实验结果表明,该轨迹规划方法高效、可行。     

基于三坐标定位器的大部件调姿机构误差分析

针对基于3个三坐标定位器联动实现大型部件位姿调整机构的位姿误差问题,采用多体运动学理论分析了机构运动学关系,在不考虑大部件变形的情况下,利用矩阵微分法并结合冗余驱动的特点建立了该调姿机构的位姿误差模型,从而可定量分析各原始误差对调姿对象位姿误差的影响,并通过蒙特卡洛法对调姿误差进行了仿真研究。为获取各原始误差对调姿误差的影响比重,对机构进行了误差敏感度分析,研究结果表明,各导轨的直线度、平行度及三坐标轴间的垂直度等引起的角误差对应的敏感度较大。     

飞机自动钻铆并联调姿托架标定方法

为提高飞机自动钻铆并联调姿托架的运动精度,提出了一种改进的外部标定方法。利用空间矢量链建立机构的运动学方程并微分,将微分后的所有约束方程纳入误差模型,建立有关机构位姿误差与结构误差的关系表达式并提高建模精度;采用矩阵降维的方式处理结构误差项系数矩阵,提高误差辨识精度。经仿真验证,该标定方法的误差辨识与补偿精度较高,并且能够利用误差模型辨识单个主驱动的定位器主动移动副角度误差,满足了飞机装配对托架调姿精度的要求。     

针对大部件位姿调整、装配的一种随动固持方法

在飞机等大部件位姿调整、装配应用中,如何保持调整后的位姿并对大部件进行可靠固持一直是个技术难题。提出一种基于低熔点合金相变原理的大部件随动固持方法,并制造了称之为随动定位器的专门固持工装。将圆筒状金属体中的低熔点合金加热熔化,将与大部件刚性连接的心轴插入到液态低熔点合金中,液态低熔点合金冷却、固化后,锁紧与圆筒状金属体刚性连接的内筒,即可在大部件位姿不发生改变的条件下实现对其可靠固持。将低熔点合金加热熔化就可以释放与大部件刚性连接的心轴,使大部件恢复到调姿状态。通过低熔点合金材料性能试验、随动定位器固持强度试验、冷缩过程横向附加作用力试验、有限元计算,证明所提方法简单、易行、可靠。     

机翼调姿对接运动仿真技术研究

以飞机机翼调姿对接运动仿真为研究内容,通过CATIA建立运动仿真模型。利用五次多项式对机翼调姿对接轨迹进行规划,将对接过程划分为3个阶段。根据刚体位姿描述方法,用MATLAB逆解出定位器驱动量,并将结果导入运动仿真模块,完成调姿对接过程中机翼速度和加速度的运动仿真分析。仿真结果表明,机翼运动速度、加速度曲线光滑连续,调姿对接规划满足运动学要求。     

大尺寸弱刚性构件对接装配系统轨迹规划

通过对大型弱刚性构件位姿调整系统的运动学和动力学分析,建立了大尺寸弱刚性体在笛卡尔坐标空间与装配系统驱动关节空间之间的位移、速度和加速度映射关系,以及关节驱动力与调姿装配系统惯性力之间的映射关系.为降低弱刚性体在调姿过程中的变形量,提高调姿精度,采用多点支撑装配系统.将定位器驱动轴分为非冗余驱动和冗余驱动两组,对非冗余驱动轴进行基于S型速度曲线的轨迹规划,并通过运动学正反解映射模型对非冗余驱动轴进行同步规划,数值仿真结果表明该方法安全高效.     

基于WinCC的飞机大部件自动对接系统开发

针对飞机大部件对接装测控一体化需求开展相关装备研究,结合大部件对接实际工艺需求,突破了定位器布局优化、上下位机通信、自动化测量、多轴同步运动控制、调姿路径规划、对接软件集成等多项关键技术,开发了基于WinCC的飞机大部件自动对接系统,包括定位器系统、自动测量系统和集成控制系统等.该系统集自动化和过程控制于一体,以数据库...     

基于ADAMS的机翼调姿动力学仿真

阐述了飞机机翼调姿技术及调姿算法,利用五次多项式对机翼运动轨迹进行规划。在CATIA中完成了机翼调姿仿真模型,通过SIMDESIGN接口软件将CATIA模型导入ADAMS,利用ADAMS对机翼调姿过程进行动力学仿真。仿真结果表明,机翼调姿算法能满足机翼调姿动力学约束条件,且调姿误差在允许的范围内。     

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.