MEMS陀螺零偏温度补偿方法

MEMS陀螺零偏是惯性导航系统的主要误差源之一,而外界环境温度变化对MEMS陀螺零偏具有重要影响。针对上述情况,提出基于小波阈值去噪与RBF神经网络相结合的零偏温度补偿方法。通过设计好的实验方案采集与温度相关的MEMS陀螺输出数据,并采用不同的温度补偿方法进行零偏温度补偿。实验结果表明,与原始输出、多项式拟合及RBF神经网络相比,基于去噪RBF神经网络的零偏温度补偿方法精度更高,适应性更强,有效地提高了MEMS陀螺输出精度,进而提高惯性导航系统精度。     

模糊自适应整定PID的MEMS陀螺温控系统设计

MEMS陀螺的零偏、零偏稳定性和重复性等指标与陀螺温度直接相关,MEMS陀螺零偏主要由温度漂移造成。为了提高陀螺性能指标,设计了一套模糊自适应整定PID的MEMS陀螺温控系统。试验表明,该系统静态误差小于±0.3℃,超调小,稳定时间短,而且在各温度环境下升温曲线比较一致,保证了陀螺每次上电的零偏重复性。     

基于RBF神经网络的数字闭环光纤陀螺温度误差补偿

为了消除数字闭环光纤陀螺温度误差,设计了基于径向基函数（RBF）神经网络的温度误差补偿方案,对该方案所采用的标度因数误差模型和偏置误差模型进行了研究。首先,根据光纤陀螺的温度误差分布情况设计了标度因数误差和偏置误差联合补偿的方案。接着,将基于多尺度分析的噪声和趋势项分离算法应用于建模数据预处理,以提高建模数据准确性。然后,建立了RBF神经网络模型,并改进模型的学习方法以防止网络的过拟合。最后,讨论了模型输入向量对神经网络规模的影响。温度补偿的结果表明：标度因数误差模型的残差均方（RMS）达到0.73 ,偏置误差模型的RMS达到0.051 。该建模方法可以满足中、高精度光纤陀螺实时温度补偿的要求。     

基于GA-BP神经网络的光纤陀螺温度补偿

标度因数和零偏的温度特性是影响光纤陀螺工作性能的主要因素,为提高光纤陀螺仪的输出精度,分别建立了基于BP神经网络的标度因数和零偏的温度补偿模型。在此基础上提出了利用遗传算法优化网络参数来弥补BP神经网络算法所存在的不足,最终建立了GA-BP神经网络温度补偿模型。使用在不同温度下的标度因数和零偏测试数据对改进后的神经网络补偿模型进行验证并与原网络模型进行对比分析,实验结果表明,优化过的模型其补偿效果具有很大的提高,其补偿的误差精度提高了一个级别。     

全反射棱镜式激光陀螺温度误差标定及参数辨识方法研究

全反射棱镜式激光陀螺的光路与传统镀膜反射式激光陀螺的光路不同,有较长的光路在棱镜中通过,温度的变化是影响其输出精度的一个重要因素。研究了变化的物理场下,温度、温度变化率和温度梯度对激光陀螺的影响机理,推导了温度变化条件下激光陀螺的零偏二阶模型,刻度系数的三阶模型,设计了激光陀螺的温度误差标定方案,并进行了试验。采用逐步回归分析法和BP神经网络两种方法对温度误差模型参数进行了辨识,通过温度误差补偿结果证明了两种方法的有效性。     

基于改进径向基函数神经网络的激光陀螺温度补偿

传统的径向基神经网络(RBFNN)在激光陀螺零偏的温度补偿过程中会由于随机选取中心不合适而导致算法效率降低和数值病态,故本文提出了一种基于Kohonen网络和正交最小二乘(OLS)算法的RBFNN温度补偿方法。介绍了该方法的原理及建模步骤,设计了常温和变温环境下激光陀螺的数据采集试验及其温度补偿试验。由于结合了Kohonen网络的模式分类能力和OLS的优化选择能力,该方法可以快速、准确地辨识出受温度影响的激光陀螺零偏。利用逐步回归法、RBFNN法及其改进方法对多种温变环境影响的激光陀螺零偏进行了辨识与补偿试验,试验结果表明,在常温环境下,三者的辨识能力相当;随着温变速率的上升,改进RBFNN法不仅节省了时间,其补偿后的零偏也均小于5×10-4(°)/h(1σ),提高精度均能达86%以上。得到的结果表明改进RBFNN法提高了辨识精度且稳定、有效,适用于多种温度变化环境下激光陀螺零偏的温度补偿。     

基于SVM的激光陀螺温度误差建模与补偿方法

激光陀螺误差决定了机载全成孔径雷达(SAR)运动补偿用位置姿态测量系统(POS)的测量精度.针对激光陀螺测量精度受环境温度影响严重的问题进行了研究,分析了激光陀螺的温度误差模型,结合支持向量机SVM的函数拟合功能,提出一种新的陀螺温度误差建模与补偿方法.与基于线性回归以及神经网络的补偿方法相比,该方法具有精度高、泛化能力强等优点.实验结果表明,激光陀螺的温度误差减小约75％,提高了激光陀螺对环境温度的适应能力.     

石英微机械陀螺正交误差补偿研究北大核心CSCD

由于石英微机械陀螺的敏感结构在加工制造时存在工艺缺陷,陀螺会产生耦合误差。耦合误差中与陀螺输出信号正交的误差信号称为正交误差,该误差在陀螺诸多误差中占据主导地位,会严重影响陀螺的测量结果。针对正交误差,简要分析了其产生原因及对陀螺输出信号的影响,提出了一种适用于音叉式石英陀螺的正交校正方法——正交电压补偿法。对于正交电压补偿法,搭建了补偿系统进行了相应的仿真,并制作出样机进行实验。仿真和实验的结果表明该方法可以抑制石英陀螺检测通道的正交误差,零偏不稳定性由补偿前的108.088(°)/h降低到43.815(°)/h,降幅达59.46%,证明了正交电压补偿法的有效性。     

基于RBF神经网络的光纤电流互感器温度补偿

光纤电流互感器在实际运行中易受外界温度影响,其输出精度会出现漂移偏差。为提高光纤电流互感器测量比值误差的温度稳定性,提出了基于RBF神经网络的光纤电流互感器温度补偿方法。将温度和温变率作为神经网络输入、光纤电流互感器的比值误差作为输出,建立了RBF神经网络温度补偿模型。相比BP神经网络,仿真结果显示,基于RBF神经网络的温度补偿模型准确度较高,预测结果误差低于3%。同时,经过RBF神经网络温度补偿,实验结果表明,光纤电流互感器在输出比差小于±0.1%,满足GBT20840.8标准规定的0.2S级准确度。     

磁力仪温度误差的径向基神经网络补偿模型

磁通门磁力仪参数受温度影响明显,直接影响传感器测量精度,需要研究补偿方法,提高测量精度。采用无磁高低温试验箱测量磁通门传感器温度特性;提出基于径向基神经网络的温度误差补偿方法,分别建立磁通门磁力仪零漂误差补偿模型和刻度因子误差补偿模型。结果表明,径向基神经网络能良好逼近磁通门传感器参数的温度特性;与BP神经网络相比,径向基神经网络在零漂补偿中训练时间更短,精度更高,重复性更好,零漂误差的抑制能力更强。补偿后,磁通门磁力仪零漂误差从7.105 5 nT减少到0.766 1 nT;刻度因子误差从6.3E-3减少到7.2E-5;测量值温度误差由213.6 nT补偿到9.1 nT。提出建立通用的温度补偿模型,在不同磁场环境下经过反复测试,采用训练过的模型补偿后,温度误差均降低一个数量级,提高了磁通门磁力仪温度性能和精度。     

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...     

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。     

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.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.