分层近似粒子滤波及其在陀螺寻北中的应用

针对粒子滤波的粒子退化和匮乏等问题,在粒子滤波和网格近似的基础上,提出了一种采用分层近似策略的粒子滤波改进算法.改进算法利用高斯分布对后验概率密度进行近似,并在连续分布的后验概率密度上进行分层近似,从而获得更具效率的粒子,提高了粒子滤波的精度.光纤陀螺的寻北精度主要取决于光纤陀螺自身的性能以及所采用的寻北方案,将采用分层近似策略的改进粒子滤波算法应用于光纤陀螺的寻北方案中,能够有效地解决光纤陀螺寻北中的非线性状态估计问题,提高光纤陀螺的寻北精度.     

机器人姿态解算算法研究

在机器人惯性导航研究中,针对传统滤波方法在非线性系统模型下误差大的问题,提出了一种基于改进粒子滤波的机器人姿态解算方法。粒子滤波精度较高且不受系统模型非线性程度的影响,与扩展卡尔曼滤波算法相比在非线性系统应用中有巨大的优势。使用扩展卡尔曼滤波对系统状态进行预测,使粒子分布向高似然区移动。对粒子滤波算法的重采样过程进行了改进,提升了算法的效率。不同的地面环境下系统噪声有较大变化,将地面环境信息作为观测信息融合到系统中,对算法参数进行实时修正能够获得更高的精度。实验结果表明,应用此算法进行姿态解算精度较高,且性能优异。     

基于MCMC方法的正则粒子滤波算法及其应用

粒子退化现象是一般粒子滤波无法避免的问题.通过分析该现象产生的原因.提出了将MCMC(马尔可夫链蒙特卡罗)方法应用于正则粒子滤波算法(RPF),与采样重要重采样(SIR)粒子滤波算法比较.此算法不仅克服了粒子退化现象,而且解决了重采样带来的采样枯竭的影响.仿真和实验结果表明:该算法在滤波精度和自适应调整粒子个数方面比SIR粒子滤波有很大的提高.     

微纳卫星陀螺阵列系统信息融合

为了实现微纳卫星MEMS陀螺动态在线滤波,对MEMS陀螺阵列建模,设计可应用于动态过程的最优在线数据融合算法,建立陀螺阵列测试系统,并对融合滤波的陀螺系统的性能对比分析。首先,建立多个陀螺的量测模型。接着基于信息融合模型,使用Kalman滤波算法,对预测的协方差矩阵进无求逆运算迭代;然后,基于误差估计,对动态时变信号滤波模型建模,并给出了融合滤波方法;最后,搭建6个MEMS陀螺在线滤波系统,验证该算法的有效性。实验结果表明：滤波误差可降低为单陀螺采样误差的1/15,精度提高一个数量级;运算量相比层序式滤波减少为1/4,计算时间减少为1/3。本文所提算法在提高精度的基础上,显著提高了MEMS陀螺系统的性能指标,拓展了MEMS陀螺在微纳卫星的应用范围。     

基于智能陀螺经纬仪实现快速初寻北

机械陀螺经纬仪初寻北时间的长短是决定其寻北效率的关键因素.从陀螺仪寻北的原理出发,在智能寻北系统中引入了一种快速寻北新方法--加速度判定法.该方法通过计算光标运动的速度与加速度值,能够在陀螺开始寻北数秒后即测量出真北值,并且能够弥补电子罗盘初寻北精度过低的问题,是全自动寻北策略的重要组成部分.以JT-15陀螺仪为样机的寻北实验表明,将加速度判定法应用于智能寻北系统中,仪器初寻北测量精度优于3′54″,满足了JT-15陀螺仪精寻北的条件要求,保证了全自动寻北的速度和精度,对于机械陀螺的快速及智能化寻北具有现实意义.     

基于改进粒子滤波算法的人眼跟踪方法

针对粒子滤波计算量大、粒子匮乏等问题,提出了2种策略来改进粒子滤波算法,一方面基于Galerkin投影法产生良好的粒子滤波参考分布函数;另一方面将BP神经网络引入粒子滤波,提出了一种提高粒子多样性的重采样策略。在此基础上,将改进的粒子滤波算法应用于人眼跟踪问题,运用颜色和纹理复合的观测模型,实现了人眼的准确跟踪。实验结果表明,改进算法有效提高了粒子滤波的估计精度和运算速度,避免了粒子退化和样本匮乏现象。     

基于动调陀螺的多位置捷联寻北仪研制

为了提高大型光电跟踪设备和惯性导航设备自主定向的性能,根据动调陀螺的工作原理,设计了一种多位置捷联寻北仪。针对多位置捷联寻北系统的数学模型,采用改进的最小二乘拟合算法,对正弦曲线进行参数估计,解算出北向方位角。寻北仪主要由精密位置转台及转位控制系统、惯性测量系统、温度控制系统、数据采集与处理系统及其它配套部件组成。综合考虑寻北时间和寻北精度两个技术指标,进行了时间模式和精度模式的研究和实验。在时间模式下,当寻北精度为35.4″时,寻北时间仅为4.5 min;在精度模式下,当寻北时间为9 min时,寻北精度可达到23.9″。这两项指标均高于国内同类产品。     

一种改进的交互式多模型粒子滤波算法

在实际的目标跟踪与识别的过程中,机动目标的跟踪不仅受非线性和非高斯现象的影响,而且它所采用的交互式多模型粒子滤波算法还存在着粒子权值退化和重要性密度函数选择的问题,导致跟踪误差较大。针对这一问题,提出了一种交互式的多模型的迭代容积粒子算法。该算法通过融合最新量测值产生更加接近系统的真实值,从而使粒子利用率得到进一步的提高。此外为了解决粒子的多样性减少的问题,还引入了MCMC重采样方法。仿真的结果表明,对于机动目标的跟踪与识别,改进的算法的精度要比IMM-PF算法的精度高、误差小,且通过改进的算法得到的重要性密度函数更加接近系统的后验概率分布。     

基于改进模糊推理的光纤陀螺温度漂移建模

光纤陀螺温度漂移建模是实现其温度补偿,提高测量精度的有效手段。通过实测数据分析,验证光纤陀螺的输出受温度和载体角速度的共同作用呈现复杂非线性。为准确描述这种复杂非线性关系以实现温度漂移高精度补偿,基于神经网络设计一种新型光纤陀螺温度漂移模糊系统结构,提出一种基于改进模糊推理的光纤陀螺温度漂移模型辨识新方法。由确定的模型结构设计模糊系统的模糊规则,并基于实测数据构建训练样本以被用于自适应调整变量隶属度函数的参数,从而建立基于误差方均根最小准则的光纤陀螺温度漂移补偿模型。试验结果表明,应用此方法得到的光纤陀螺温度漂移模型具有很高的精度、良好的适用性和预测性能。     

支持向量回归粒子滤波器的故障预测方法

为了对系统进行故障预测,针对粒子滤波在故障预测中出现的样本贫化与退化问题,提出了一种支持向量回归粒子滤波器。采用支持向量回归方法建立粒子状态与其权值的非线性函数来估计粒子的连续后验概率密度模型。基于该模型进行重采样获得新的粒子集并更新各粒子的权重,增加样本的多样性与有效性,提高对故障的监控与预测能力。仿真结果表明,该方法是可行的,能够准确预报系统故障。     

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.