导航信息滞后补偿实现高速无人机对地精确定位

针对高速无人机光电侦查平台的实时对地目标定位误差,研究了基于惯导信息的光电平台目标定位算法。利用目标定位数学模型和误差模型,分析了影响目标定位精度的因素,建立了参数误差对于定位精度影响的数学仿真模型。通过仿真分析确定了卫星导航信息的实时性是造成定位误差的主要因素,提出了通过修正卫星导航信息延时时间来解决了光电侦察平台实时目标定位误差问题。进行了飞行试验以验证提出论点的正确性,结果表明:通过修正卫星导航信息延时时间,有效补偿了载机坐标信息滞后,提高了光电侦察平台目标定位精度,定位误差由补偿前的100m减少到小于40m。研究结果对高速飞行器的相关应用具有重要的参考价值。     

大角度倾斜成像航空相机对地目标定位

针对大角度倾斜成像航空相机拍摄距离远,激光测距设备作用距离有限的问题,提出了一种不依赖距离测量设备的直接对地目标定位算法。依据载机POS测量的载机位置、姿态信息以及航空相机中位置编码器测量的框架角位置信息,利用齐次坐标变换的方法求解目标在大地坐标系下的指向,再利用地球椭球模型和数字高程模型确定目标点的经纬度信息。采用蒙特卡洛法仿真分析载机位置姿态测量误差及相机框架角位置误差对视轴指向精度的影响,相比于仅采用地球椭球模型的目标定位算法,该算法有效降低了地形起伏对目标定位影响,在目标区域地形起伏标准差大于10m时,大角度倾斜成像的定位精度明显提高。采用飞行试验数据验证了该目标定位算法的有效性,在飞行高度18 000m拍摄框架横滚角小于63°时,目标定位圆概率误差小于70m,可满足工程实际需要。     

基于激光测距的机载光电成像系统目标定位

针对小型机载光电平台无法准确获取视轴指向问题,设计了一种基于激光测距的目标定位算法。利用机载光电侦察平台锁定跟踪目标的特性,对同一目标多次测量,采用激光测距装置获取目标与载机间的距离信息。根据WGS-84定义的地球椭球模型建立系统的测量方程。考虑到测量方程的非线性,利用扩展卡尔曼滤波对目标位置进行估计。该定位方法精度只受到GPS接收机定位精度和激光测距机测量精度的影响,目标定位误差与机载光电侦察设备视轴指向测量无关。采用蒙特卡洛法仿真分析载机位置测量误差及激光测距系统位置误差对目标定位的影响,结果显示该算法定位精度较高。采用飞行试验数据验证了该目标定位算法的有效性,在飞行高度8 000 m时,目标定位精度优于8 m。相比于传统定位算法,该方法可将定位精度明显提高。同时此定位方法易于部署,可操作性强,具有较大的应用价值。     

机载测量平台中的坐标转换误差分析

为了提高机载测量平台的定位精度和引导精度,利用齐次坐标转换法推导了从大地坐标系到望远镜坐标系的转换方程,并在此基础上建立了误差分析的数学模型.运用蒙特卡罗法的思想,综合分析了机载测量系统中各参数对结果的影响.提出了改善平台测量精度首先要解决的就是载机姿态精度;其次是载机(或目标)的位置精度;此外,通过数据处理来提高定位精度也是有效的方法.实验结果表明:姿态精度从0.3°提升至0.1°后,定位精度和引导精度都可提高30%;载机位置精度从20 m提升至5 m后,定位精度可提高9%.分析过程和结果对机载测量平台的设计有一定的参考价值.     

航空光电成像平台的目标自主定位

为了提高航空光电成像系统对地面目标的定位精度,提出了平台目标自主定位的方法,并给出了实现的方法和途径,即将GPS系统和航空姿态测量系统直接固联在航空光电成像平台上,与光电成像平台系统结合直接实现目标定位。分析了影响目标定位精度的因素,分析结果表明,目标自主定位的方法可以消除传统方法中减振器带来的误差。一般情况下,平台自主定位比飞机系统定位的精度至少高25%。     

机载GPS测量定位技术研究

为了得到侦察目标的大地坐标以及引导载机捕捉已知目标,提出了机载GPS测量定位方法.应用GPS技术,获取载机及已知目标的位置信息,利用齐次坐标转换方法进行定位引导过程的坐标转换,从而得到目标定位引导数据.通过实验对机载GPS测量定位方法进行了检验.实验结果表明:定位精度达到了30 m,引导精度为2°.用蒙特卡洛法对实验误差进行了分析并得到了精度误差范围,其结果在期望的误差范围内,表明机载GPS测量定位技术具有一定的实用和推广价值.     

空间目标天基双星立体天文定位

为了提高天基光学传感器观测空间目标的定位精度,基于天文定位原理,提出了一种天基空间目标双星立体天文定位方法.首先,根据光学载荷固有参数,分析了空间目标在光学传感器上成像特性,选择阈值质心法精确提取目标在二维像平面上位置.接着,基于目标到观测传感器全链路坐标投影变换关系,建立了地球惯性坐标系下目标的观测矢量模型.然后,结合最小二乘法准则,建立了双星立体天文几何定位模型,完成空间目标从二维图像信息到三维空间信息的投影变换.最后,搭建地面实验生成了含空间目标的星空图像,并完成了定位算法验证和误差仿真分析.实验结果表明:当定位模型中没有误差时,定位精度可达10-5 m;当同时存在卫星位置误差、卫星姿态误差、卫星轨道误差、相机安装误差和图像处理误差时,定位误差分布为均值为零,标准差为114.62 m的高斯分布,基本满足定位需求.本文的研究工作可为天基空间目标的高精度检测定位提供参考.     

基于代数神经网络信息融合的侧向定位的实验研究

为提高移动机器人的工位定位精度,通过实验分析了超声波传感器的测量距离d和入射角α对测量精度的影响.基于代数神经网络能实现样本空间的精确映射并具有较好非线性逼近能力,设计了一种移动机器人侧向定位融合模型.经实验比较,该定位融合模型具有较高的精度,使得位置误差小于0.9957mm,角度误差小于0.2966°.将该定位融合模型应用于自主研发的移动机器人的定位实验中,定位位置精度可达到±2.5mm,姿态角精度可达到±0.42°,满足定位要求.     

一种小型无人机无源目标定位方法及精度分析

为了提高小型无人机无源目标定位的精度,设计了一种新的目标定位算法。首先确定目标定位过程中的坐标转换关系并推导出视轴角的计算模型;然后,利用光电侦察平台锁定跟踪目标的特性,提出了对同一目标点多次测量的目标定位框架,建立了系统状态方程和测量方程,考虑到测量方程的非线性,将无迹卡尔曼滤波应用于目标位置估计;最后,针对加性高斯白噪声的非线性目标定位系统,推导出理论上的定位误差的克拉美-罗下限。仿真结果表明,该算法具有较高的目标定位精度,滤波器估计误差均方差已逼近非线性系统的克拉美-罗下限。现场试验结果表明,在离地面约1000 m的空中,无人机对地面目标定位精度可达8.1 m。该算法易于部署,可操作性强,具有较大的实用价值。     

基于MEMS/GNSS的多机协同无源定位

为了对多机协同定位算法进行研究,使用采集到的某款较高精度的MEMS惯组的噪声数据替代仿真噪声数据,模拟采用MEMS/GNSS组合导航算法的载机平台,使得定位算法的使用条件更加接近真实应用水平,并对在仅有视线角测量情况下的无源定位算法进行了精度分析和改进.以MEMS惯组真实数据为依据设置组合导航算法的参数,并在模拟载机的过程中加入真实惯组噪声,通过组合导航解算获得载机的位置坐标.建立仅有视线角量测的无源定位算法数学模型,在组合导航定位的计算结果稳定之后,利用获得的自身位置数据,基于扩展卡尔曼滤波估计目标的位置及速度信息.最后,利用联邦滤波算法,将该定位算法扩展为多机协同定位算法,进一步提高定位系统的容错性能.通过分析对比双机定位模型的几何精度误差与双机协同定位算法的表现,可知文中算法能够将定位精度从100 m量级降到10 m量级,实现了仅有视线角测量情况下的多机协同定位,定位精度高,且分析结果更符合实际情况.     

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.