坐标测量机动态测量不确定度评定研究

目前人们对三坐标测量机动态测鼍小确定度仍采用静态测量理论来评定,与其实际使用情况不符,带来一定的评定误差.本文分析了触发模式下三坐标测量机测头的主要动态误差源,通过改变测量速度和逼近距离对测头(Renishaw MH20i)动态误差的影响进行了实验测试,采用Monte Carlo方法对三坐标测量机测头动态测量不确定度进行评定,与使州传统的测量小确定度A类和B类评定结果相比较,本方法不受直接测量量相关性的限制,受问题条件限制小,评定更符合实际情况.     

复杂机电系统耦合与解耦设计--现代机电系统设计理论的探讨

针对现代大型复杂机电系统的性能与运行状态多物理过程和多参数全局耦合结果的实,提出了对复杂机电系统进行全局耦合分析及合并行设计的基本思想,探讨了全局耦合分析与设计的基本理论框架,以其研究复杂机电系统功能,奇异工况的生成机制,实现,复杂机电系统的全局耦合最优设计。     

产品拆解混合图模型构建与能量评估方法

基于拆解过程存在不确定特性的本质,结合定义的能量可拆解度概念,构建了产品拆解能量分析的理论模型。基于图论思想和面向对象技术,在定义拆解混合图基本元素的基础上,以压缩盘结构装配体为例构建拆解混合图,并生成该产品完全拆解序列及目标拆解序列。同时应用设计的Monte Carlo求解算法,对其进行完全能量可拆解度和目标能量可拆解度计算的举例分析,为实现产品拆解过程的量化评估提供了一定的理论基础。实例仿真结果表明,所提模型和方法可以有效地实现产品拆解过程的随机评估。     

An MCMC algorithm based on GUM Supplement 1 for uncertainty evaluation

This paper describes a simple Markov chain Monte Carlo algorithm for evaluating measurement uncertainty according to Bayesian principles. The algorithm has two phases, the first coinciding with the Monte Carlo method described in GUM Supplement 1 (GUMS1), the second a simple Metropolis–Hastings algorithm. The second phase can be regarded as a post-processing add-on to the GUMS1 calculation and can be used whenever a GUMS1 approach is adopted. The algorithm allows users freedom to choose their preferred prior distribution for the measurand, rather than that implicitly assigned in the GUMS1 approach, thereby avoiding some of the problems that can arise when applying GUMS1 to certain types of measurement model. The post-processing can be implemented in a few lines of software, so that many of the practical difficulties in implementing Bayesian approaches to measurement uncertainty evaluation are largely removed.     

Comparison of GUM and Monte Carlo methods for evaluating measurement uncertainty of perspiration measurement systems

Measurement uncertainty is an important parameter to express measurement results including means and reliability. The uncertainty analysis of the biomedical measurement system needs to be established. A perspiration measurement system composed of several sensors was developed. We aim to estimate the measurement uncertainty of this system with several uncertainty sources, including airflow rate, air density, and inlet and outlet absolute humidity. Measurement uncertainty was evaluated and compared by the Guide to the expression of the uncertainty in measurement (GUM) method and Monte Carlo simulation. The standard uncertainty for the perspiration measurement system was 6.81 × 10⁻⁶ kg/s and the uncertainty percentage <10%. The major source of the uncertainty was airflow rate, and inlet and outlet absolute humidity. The Monte Carlo simulation could be executed easily with available spreadsheet software programs of the Microsoft Excel. GUM and Monte Carlo simulation did not differ in measurement uncertainty with precision to two decimal places. However, the sensitivity coefficient derived by GUM provided useful information to improve measurement performance, which was not evaluated with the Monte Carlo simulation method.     

磁光阱异面空间角度测量及测量不确定度评定

随着空间几何量精密测量技术在装备制造工业的制造与装配过程中应用越来越广泛,角度计量正在从平面角度向空间角度发展。针对磁光阱的异面空间角度进行测量,使用平行平晶作为标准平面引出待测面法向量,并将其空间角度有效的划分成水平投影角和竖直投影角两个平面角度进行测量,保证了空间角度的可溯源性,得到磁光阱各待测面法向量间的空间角度偏差最大值为0.286 0 mrad;然后通过蒙特卡洛法评定该方法的测量不确定度为0.095 9 mrad;最后与三坐标测量机法比对结果中偏差最大值为0.184 2 mrad,在考虑待测面平面度指标为±0.145 4 mrad时,二者的一致性良好。目前该方法已在NIM5铯原子喷泉钟物理真空子系统的研制中进行了应用,证明了该方法能够满足测量的准确度要求。     

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.     

Generalized expressions of second and third order for the evaluation of standard measurement uncertainty

The Guide to the Expression of Uncertainty in Measurement (GUM) requires the use of a first-order Taylor series expansion for propagating uncertainties. However, when the measurement function is strongly non-linear the use of this linear approximation may be inadequate and therefore higher order terms from the Taylor series cannot be neglected. The present paper aims to derive generalized expressions of second and third order for the evaluation of the estimate of a measurand and its associated standard uncertainty. A case study is given to illustrate an application of the proposed methods and the results obtained with the GUM method are compared to the corresponding ones when applying the method proposed in GUM Supplement 1.     

六自由度机械臂参数校准不确定度评定方法

六自由度机械臂的结构参数校准对其定位精度影响较大,为了评价其参数化校准效果,采用蒙特卡洛法建立了六自由度机械臂参数校准不确定度评定模型。首先,根据空间坐标系的几何转换关系建立六自由度机械臂结构参数校准模型,分析主要误差来源对校准参数的影响,建立各校准参数的不确定度分量的函数关系;其次,采用现场校准数据集的抽样统计,分析各不确定度分量的概率密度函数,获得真实分布规律;最后,采用蒙特卡洛法建立各校准参数的不确定度分量与机械臂模型之间的数学关系,通过大规模随机数值模拟,实现机械臂校准不确定度的评定。为了验证本文方法的有效性,利用激光跟踪仪对六自由度机械臂进行了校准实验。结果表明,当采用正则化方法进行机械臂校准时,各坐标轴的相对扩展不确定度分别优于0.542 2%,1.325 9%, 0.015 4%。     

三坐标机测量齿轮齿廓的不确定度评价

介绍了坐标测量中几种常用的不确定度评价方法.指出传统的三坐标测量机的测量不确定度评价方法大都不适用于评价坐标测量中面向对象的测量不确定度,并对使用蒙特卡洛方法评价测量不确定度进行了研究.首先,根据三坐标测量机详细标定文件及补偿策略说明建立测量模型.然后,将测量中的采样点通过测量模型生成大量测量结果,并以此评价测量不确定度.在齿廓评价实验中,评定齿廓误差的测量不确定度为0.96 μm时,多次评价结果之间的最大差值不超过0.03 μm,具有可靠的理论依据和较稳定的评定结果.文章指出,目前商用三坐标测量机大都不能为特定的测量对象提供测量不确定度报告,使用蒙特卡洛方法有希望改变此现状.     

Monte carlo method for the uncertainty evaluation of spatial straightness error based on new generation geometrical product specification

Straightness error is an important parameter in measuring high-precision shafts. New generation geometrical product specification(GPS) requires the measurement uncertainty characterizing the reliability of the results should be given together when the measurement result is given. Nowadays most researches on straightness focus on error calculation and only several research projects evaluate the measurement uncertainty based on "The Guide to the Expression of Uncertainty in Measurement(GUM)". In order to compute spatial straightness error(SSE) accurately and rapidly and overcome the limitations of GUM, a quasi particle swarm optimization(QPSO) is proposed to solve the minimum zone SSE and Monte Carlo Method(MCM) is developed to estimate the measurement uncertainty. The mathematical model of minimum zone SSE is formulated. In QPSO quasi-random sequences are applied to the generation of the initial position and velocity of particles and their velocities are modified by the constriction factor approach. The flow of measurement uncertainty evaluation based on MCM is proposed, where the heart is repeatedly sampling from the probability density function(PDF) for every input quantity and evaluating the model in each case. The minimum zone SSE of a shaft measured on a Coordinate Measuring Machine(CMM) is calculated by QPSO and the measurement uncertainty is evaluated by MCM on the basis of analyzing the uncertainty contributors. The results show that the uncertainty directly influences the product judgment result. Therefore it is scientific and reasonable to consider the influence of the uncertainty in judging whether the parts are accepted or rejected, especially for those located in the uncertainty zone. The proposed method is especially suitable when the PDF of the measurand cannot adequately be approximated by a Gaussian distribution or a scaled and shifted t-distribution and the measurement model is non-linear.     

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。     

Use of coordinate measuring machine to measure angles by geometric characterization of perpendicular planes. Estimating uncertainty

The purpose of this paper is to estimate the uncertainty of angle measurements using a Coordinate Measuring Machine (CMM), through the geometrical characterization of two concurrent sides of a steel angle gauge block with four perpendicular sides.For the calculation of the uncertainty associated with the measurement and investigating the errors of the CMM associated with orientation and length in the work volume, two models: linear statistical model behavior of CMM and the Mitutoyo model behavior are used and compared. After having established two behavioral models for the CMM we have determined the values of the angles and their uncertainty by using Monte Carlo Method. The results show that the proposed methods are suitable to investigate CMM hardware performance and determine the contribution of machine variables to measurement uncertainty. We can affirm that the statistical model behavior is more immediate and less laborious in terms of calculation and implementation time than the Mitutoyo model.     

复杂机械系统方案创新设计阶段符号方案的自动化生成

基于机构组合创新思想进行复杂机械系统方案设计的自动化方法研究。在实践上,开发了机构组合创新应用软件。阐明了采用该软件进行复杂机械系统方案设计的工作流程,给出了应用实例。同时,从系统的角度出发,对概念设计阶段符号方案的自动化生成进行了较为深入的研究。     

Evaluating a task-specific measurement uncertainty for gear measuring instruments via Monte Carlo simulation

Evaluating the measurement uncertainty for gears with analytical or experimental methods is usually very time- and cost-consuming. In this paper we therefore present a Monte Carlo based method for evaluating the measurement uncertainty of gear measurements on gear measuring instruments, the VCMM-Gear, which is based on the method of the VCMM for coordinate measuring machines. Necessary extensions of the mathematical model of the measurement process in order to consider the significant uncertainty influences from rotary tables, workpiece clamping and scanning are described. Additionally the statistical reliability of the evaluated measurement uncertainty and the consideration of systematic error contributions to the measurement uncertainty are discussed. Finally the results of some first verification measurements are presented, giving a reliable impression of the capability and suitability of the VCMM-Gear.     

Improvements to estimate ADCP uncertainty sources for discharge measurements

The use of moving boat ADCPs (Acoustic Doppler Current Profilers) for discharge measurements requires identification of the sources and magnitude of uncertainty to ensure accurate measurements. Recently, a tool known as QUant was developed to estimate the contribution to the uncertainty estimates for each transect of moving-boat ADCP discharge measurements, by varying different sampling configurations parameters through the use of Monte Carlo simulations. QUant is not only useful for estimating ADCP discharge measurement uncertainty, but also for identifying contributions of the various sources of uncertainty.However, the software requires long computational times, and the method to estimate the uncertainty of multiple-transect measurements does not consider the correlation of the variables between transects. Therefore, improvements in QUant are needed to optimize its application for practical purposes by hydrographers immediately after discharge measurements.This work presents four approaches for optimizing the performance of QUant to estimate the contribution to the uncertainty of different selected variables on ADCP discharge measurements and describes a new method of estimating multi-transect uncertainty with the QUant model that considers the correlation of errors in selected variables between transects. The approaches for optimization and the new multi-transect uncertainty method are evaluated using a dataset of 38 field measurements from a variety of riverine settings.     

Evaluation of measurement uncertainty of the high-speed variable-slit system based on the Monte Carlo method

Frontiers of Mechanical Engineering - This paper presents a dynamic and static error transfer model and uncertainty evaluation method for a high-speed variable-slit system based on a...     

基于复杂网络的产品服务系统评价

产品服务系统具有的高阶次、多回路、非线性和不确定性等特点,使得分析和评价产品服务系统十分困难.针对这一问题,定义了服务、服务型制造网络和产品服务链等概念,并从不同视角描述产品服务系统.运用复杂网络的理论,从成本、质量、工时、可靠性、稳定性和鲁棒性多个维度剖析产品服务系统微观构成和服务间耦合机理,并以此构建了产品服务系统评价体系.该体系的建立为服务组织的检测、监控和优化提供了理论支撑.通过实例验证了评价体系的有效性和实用性.     

产品形态创新设计及其评价体系研究现状与趋势

产品形态创新评价是通过对产品形态创新的相关属性进行综合的、指标化的评判,对产品的形态创新结果进行客观、公平和合理的评价。评价结果将被应用于设计方案优选和指导设计改进。文中对产品形态设计及其相关技术、产品形态创新评价体系研究的现状进行了综述,对产品形态创新评价体系的理论基础、评价模型与指标体系进行了深入讨论,提出了产品形态创新设计评价体系研究的主要内容。