10~(-6)量级精密离心机输出加速度测量模型及不确定度评定

为了给高精度惯性仪表校准试验提供高精准的加速度输入值,研究了精密离心机输出加速度的建模、测量及不确定度评定方法。建立了适用于10-6量级高精度精密离心机的加速度测量模型及不确定度传递模型。基于本课题组提出的高精度测量方法,完成了10-6量级精密离心机的静动态半径、静动态俯仰失准角等重要分量的高精度测量。分析、归纳了测量不确定度源,分别基于建立的加速度测量不确定度传递模型和蒙特卡洛方法完成了该精密离心机输出加速度的测量不确定度评定。最后,讨论和总结了高精度精密离心机输出加速度建模和精度评定的相关问题。结果表明:该精密离心机对1g~100g输出加速度的相对标准不确定度均小于3×10-6,其精度与目前国际上公开的最高精度离心机处于同一数量级;建立的测量模型及测量不确定度评定方法可以为相关精度等级的精密离心机研制和评价提供参考。     

An application-oriented mathematical meta-model of measurement

The need for broader use of concepts of modelling in the development of a conceptual basis for measurement science is ascertained. A brief review of basic concepts of mathematical modelling is provided, and a class of models, most frequently used in measurement science, is characterised. A meta-model of measurement, unifying many existing methodologies of mathematical modelling in measurement science, is proposed. Its applicability is illustrated with a set of diversified examples.     

Finite-element and experimental analysis of dynamic behaviours of a micro-stamping tool system

As demands on the forming of micro-products increase, ensuring the high-quality design of machine–tool systems becomes increasingly more important. This is particularly due to a need to address smaller geometries and finer tolerance requirements, compared to those of conventional forming. Finite-element (FE) simulation of the dynamic behaviour of machines and tools is particularly useful for supporting design optimisation. Detailed finite-element modelling of stamping tool systems has, however, not been addressed previously. Difficulties tend to arise when many tool parts need to be considered in the modelling. In this paper, dynamic analysis of a micro-sheet-forming system driven by a linear motor is presented. Parameters that influence dynamic behaviours of the micro-stamping tool were investigated using the finite-element analysis and the results of experimental measurement. The findings provide useful information for the improvement of the design of micro-stamping tools as well as for the design of micro-forming-machine systems.     

The use of expert systems in the design of multi-echelon production distribution systems

Strategic decision making within multi-echelon production distribution systems is a difficult task due to the complex chain structures and inherent operating uncertainties of such systems. Hence there is a need for the application of expert systems methodology in this field. This paper reviews an approach in which industrial dynamics modelling techniques are used to simulate the dynamic behaviour of target systems over specified time horizons. Subsequently, control design techniques are utilised for performance sub-optimisation in order to generate a scenario-oriented knowledge base. A method is also presented for optimised design selection, based on interactive management performance objectives. Mutually conflicting objectives both within and between sub-systems in a multi-echelon production distribution system are also resolved as part of the optimised design. It is felt that such techniques are key components in an expert system for improving the design of high volume process production and distribution chains.     

Optimizing the design and operation of measurements for control: Dynamic optimization approach

We shall present approaches to optimize the design of a measurement system and to schedule dynamically a versatile measurement resource. The analysis is based on expressing the system management task as a dynamic programming problem in which the system state is partially observable. We shall review the well-known linear-quadratic-Gaussian case, and discuss and give example solutions of discrete state systems with approximate dynamic programming methods to solve such problems in practice. Design problem is then studied by assessing the long-term performance of control and how it depends on properties of measurements. A simple design example is presented for a discrete state system.     

基于误差传播理论的PnP问题姿态精度分析

提出了一种在辨识一组典型特征点误差关系的基础上,建立间接测量值与直接测量值之间的最有利函数关系,并根据误差传播理论综合其他特征点的误差影响,最终获得完整的方位、俯仰和倾斜角误差数学模型的PnP问题误差分步分析新方法。以P4P问题研究为例,推导得到了单目视觉测量中相关参数和变量的误差函数解析式,揭示了影响姿态测量精度的误差规律。经P4P姿态解算仿真,验证了误差数学模型的正确性,以及基于误差传播理论的误差分步方法的有效性。分析误差数学模型可以看出:在单目视觉测量参数确定的条件下,方位角测量误差与方位角值无关,与相机高度和合作标志尺寸的比值成正比,在较大范围内俯仰和倾斜角变化对方位角测量误差影响小;俯仰/倾斜角的测量误差与俯仰/倾斜角值有关,与相机高度和合作标志尺寸比值的平方成正比;方位角测量误差小于俯仰/倾斜角测量误差。给出的分析方法和误差解析数学模型对单目视觉测量系统设计有指导作用。     

基于虚拟仪器的互相关流速测量系统设计

采用计算机模拟与实验相结合的方式,建立了基于虚拟仪器平台的互相关测量系统。系统采用LabVIEW函数选板中信号运算部分提供的互相关和自相关函数模块,设计了使用函数互相关、极性互相关和差动自相关3种算法实现互相关流速测量的程序。使用随机信号对上述3种算法进行验证,并对计算结果进行比较,验证结果表明互相关和差动自相关算法较为理想。     

气压测量装置橡胶管老化应对措施

橡胶管老化对气压测量装置功能的影响不可小视,对球载系统的安全运行构成巨大威胁。如何从多方面多措施防止橡胶管老化是需要考虑的一个关键性问题,文章从管道接头形式、橡胶管道路径优化、以及热设计三大方面综合改善了气压测量单元中橡胶管在使用过程中的材料物理状态和使用环境,使得气压测量装置的整体安全系数满足并超过了设计输入的技术标准要求。     

基于迈克尔逊干涉原理的孔径测量及装置设计

由于测量空间限制和孔本身的特点,孔径测量难度较大。本文设计一种简单易行、高精确度的测量方案,并对孔径载物台进行了设计。其干涉原理采用迈克尔逊干涉原理,数据的采集则采用CCD传感器。可以在大多数情况下实现孔径的测量,其测量精度达到微米级别。     

基于PSD的旋转机械振动传感器

研究了基于二维光位置敏感探测器(position sensitive detector,简称PSD)的激光振动传感器,重点介绍了PSD的结构、位置和振动检测原理,给出了位置坐标函数表达式和相应的输出信号检测电路框图,分析了影响该传感器检测精度的因素,提出了相应的解决办法,提供了传感器检定数据和实测振动波形。试验结果表明,该传感器各项性能指标完全满足旋转机械轴振测量要求,为旋转机械振动提供了一种新的可靠测量方法。     

基于GSM/GPRS的海上导航灯器远程监测系统

给出了基于GSM／GPRS的海上导航灯标信息的远程监测系统设计方案。系统主要由海上导航灯标现场检测子系统和陆上信息中转子系统两部分组成。考虑到系统的通用性，信息中转子系统还设计了标准的MODBUS协议，可以很容易地和任何装有MODBUS协议的监管设备进行通讯。现场检测子系统和信息中转子系统之间以GSM短信方式实现信息和指令交换，信息中转子系统和监管设备之间以标准的MODBUS协议进行通讯。监管设备一方面可对任一导航灯标进行设置，另一方面也可通过现场检测子系统的“定时发送”和“遇变则报”两种方式实现对多个导航灯标的信息进行轮回和实时的检测。在通讯方面，重点介绍了基于GSM的通讯协议设计方法。经现场调试运行，证明了方案的可行性。     

飞机数字化测量网络布站设计

考虑大尺寸、高精度要求的飞机或特殊机型飞行器需要采用多仪器组合测量网络来完成数字化测量任务,本文对测量网络进行了最优布站设计.介绍了传统的飞机调平理论,提出了飞机数字化调平变换算法,并建立了其不确定度模型.通过不确定度分析和误差依赖性仿真得出飞机各基准点不确定度和水平点位置对测量不确定度的影响.结合由激光雷达、iGPS组成的飞机数字化测量网络的测量特性,提出了飞机数字化测量网络的最优布站设计方案.对某机型飞机水平测量实验验证表明,经布站优化设计后的测量结果精度为0.402mm,提高了约20％.结果显示提出的布站设计方案有效、可行,其分析方法为寻找高准确度、高效率的飞机数字化测量的布站设计提供了参考依据.     

雷达结构精度影响因素与测量的分析研究

随着高集成、大功率和大口径雷达的发展,雷达结构精度对雷达低副瓣电平、测角精度等影响日趋明显。为提高结构精度指标分配的科学合理性,需梳理结构精度指标与电讯指标的对应关系,并详细分析各结构精度对应的影响因素,使雷达结构精度既能满足使用要求,又能降低实现成本。文中结合雷达结构中与电讯高度关联的阵面表面精度、天线座轴系精度、阵面位置精度和标校精度,逐个分析了各误差影响因素对结构精度的影响,并结合典型雷达给出具体分配方案,形成天线系统结构影响测角精度的定量计算方法。根据分析结果给出了结构精度测量与标定的技术实例,为类似雷达结构精度设计与测量提供借鉴。     

球度测量及其评定方法现状分析

通过介绍国内外球度测量发展的现状,得出非接触测量在提高球度测量精度等方面优于接触式测量,球度的评定建立在测量基础之上。专家们在基于四种数学模型基础上提出了许多评定方法,同时随着进化算法的发展,出现了许多新型优化评定方法。袁巨龙等人提出了基于研磨轨迹均匀性的球度评定方法,间接而巧妙地对球度进行了评定。球度测量与评定将会朝着更高精度、高效率和低成本方向发展。     

基于点云数据的复杂型面数字化检测技术研究

针对设计制造流程中复杂型面检测难的问题,建立了由数据获取、点云与计算机辅助设计模型匹配及偏差分析组成的数字化测量系统。采用格雷码加相移技术的三维非接触式光学测量技术,获取了待测零件的表面数据。为满足光学三角法要求,在测量机构中采用了定制光栅,提出了具有小扰动的改进最邻近点迭代算法进行点云与计算机辅助设计模型的准确匹配。在偏差分析中采用多分辨率层次分析法对测量点云与计算机辅助设计模型进行比较,为设计人员及时提供了精度分析数据,使设计制造检测成为一个反馈系统。以某型号轿车车灯配光镜为例,验证了该系统的可行性。     

Measurement uncertainty evaluation of conicity error inspected on CMM

The cone is widely used in mechanical design for rotation, centering and fixing. Whether the conicity error can be measured and evaluated accurately will directly influence its assembly accuracy and working performance. According to the new generation geometrical product specification(GPS), the error and its measurement uncertainty should be evaluated together. The mathematical model of the minimum zone conicity error is established and an improved immune evolutionary algorithm(IIEA) is proposed to search for the conicity error. In the IIEA, initial antibodies are firstly generated by using quasi-random sequences and two kinds of affinities are calculated. Then, each antibody clone is generated and they are self-adaptively mutated so as to maintain diversity. Similar antibody is suppressed and new random antibody is generated. Because the mathematical model of conicity error is strongly nonlinear and the input quantities are not independent, it is difficult to use Guide to the expression of uncertainty in the measurement(GUM) method to evaluate measurement uncertainty. Adaptive Monte Carlo method(AMCM) is proposed to estimate measurement uncertainty in which the number of Monte Carlo trials is selected adaptively and the quality of the numerical results is directly controlled. The cone parts was machined on lathe CK6140 and measured on Miracle NC 454 Coordinate Measuring Machine(CMM). The experiment results confirm that the proposed method not only can search for the approximate solution of the minimum zone conicity error(MZCE) rapidly and precisely, but also can evaluate measurement uncertainty and give control variables with an expected numerical tolerance. The conicity errors computed by the proposed method are 20%-40% less than those computed by NC454 CMM software and the evaluation accuracy improves significantly.     

Design of product polar quantizers for A/D conversion of measurement signals with Gaussian distribution

In this paper, a design of product polar quantizers for A/D (analog-to-digital) conversion of measurement signals and an analysis of their performances in the wide range of variances are considered, in a general manner, i.e. for any compression function. Special attention is devoted to the design of robust product polar quantizers, applying the developed theory on μ-law logarithmic compression function, which is very important since a lot of measurement signals are nonstationary. The proposed quantizers achieve much better performances than scalar quantizers (they have higher the maximal SQNR (signal-to-quantization noise ratio) for about 2.5 dB and they are more robust), without increasing of complexity. Theory is proved by simulation. These quantizers can be applied for many different types of measurement signals and can be used in many measurement systems (telemetry, telemedicine, wireless sensor networks, etc.).     

Soil moisture assessment by means of compressional and shear wave velocities: Theoretical analysis and experimental setup

In previous works, the authors presented the outline of a method for measuring the moisture content in agricultural soils via elastic waves, along with experimental results obtained on a specimen of sandy soil. This work illustrates other aspects and results of the research, regarding both the underlying theory and the design and realization of an improved measurement system. Firstly, the derivation of the simplified equations which are at the basis of the moisture measurement is thoroughly illustrated and discussed, starting from the more complex (and generally unmanageable) equations of elastic waves in unconsolidated porous media. The analysis suggests that by measuring the velocities of low-frequency compressional and shear waves in soils, it is possible not only to measure the water content, but also the uniformity in the water distribution. Secondly, the design and the practical realization of an experimental setup, which is able to measure the velocity of compressional and shear waves in soils, is illustrated in detail. The use of custom-built compressional and shear waves electromechanical actuators, together with geophones, low noise preamplifiers, and suitable signal processing techniques, brought to the realization of an effective and reasonably accurate measurement system.     

核料位开关在密闭容器物位测量中的应用

针对物位计普遍存在着灰尘对波的漫反射而导致误判断这一突出问题,在研究了仪表的构成与工作原理基础上,利用γ射线穿透的方法设计了测量密闭容器物位测量方案。该设计方案在物位测量领域有着较大的应用前景。