一种基于数字图像的圆度测量方法

本文主要研究基于数字图像处理技术进行非接触测量轴类零件圆度的方法,首先对CCD摄像机采集到的图像进行处理,然后对处理后的图像进行边缘检测,最后运用极点拟合法进行圆度误差的评定。该方法具有很好的实时性,可以实现在线式非接触测量。通过实验证明,使用极点拟合法评定圆度误差,不仅可以提高测量精度,并且避免了圆度误差评价的非线性求解问题,运算简单,速度快,可应用于实际圆度测量数据的处理。     

基于虚拟仪器的圆度误差评定实验教学平台设计

针对互换性与技术测量课程中圆度误差评定传统实验教学中学生不易理解掌握、评定误差大的问题,利用虚拟仪器平台进行实验教学设计,基于LabVIEW技术构建集数据采集、保存、评定功能于一体的圆度误差评定开放性实验教学平台系统,系统给出了圆度误差中最小二乘圆法的评定结果,可显示采样点的轮廓曲线、最小二乘圆半径、最小二乘圆圆心坐标、最小二乘圆轮廓、采样点的数值和圆度误差,实验平台具有界面友好、易扩展、测量精度高及可视化的优点,相对于传统的实验平台,基于虚拟仪器的实验平台增强了学生对评定方法原理、工作台的构建、数据采集、数据标定及误差评定整个测量评定过程的理解,使学生能更好地理解测量原理及参数的评定过程,通过实际操作与计算机虚拟平台结合的实验教学方式,以更加直观、形象的教学方式培养学生的设计能力和实践创新能力,为实验提供了新的平台,改进了教学的内容,体现了教学的开放性,提高了工程测试技能训练素质,有利于学生综合和创新设计能力的培养。     

工件圆度误差测量不确定度评定

为了实现工件圆度误差的不确定度评定,对基于三坐标测量机的工件圆度轮廓数据的采样策略、圆度评定方法及不确定度评定方法进行研究。首先,根据工件圆度轮廓特征进行实验测量,获取不同工件的多个样本。接着,基于最小二乘法和微分进化优化算法对样本的圆度误差进行了误差评定。然后,在分析比较误差大小的基础上,说明了采用的采样策略和微分进化评定算法。最后,基于圆度误差评定结果运用了测量不确定度表示指南(GUM)和蒙特卡洛方法(MCM)进行不确定度评定。实验结果表明:微分进化算法与最小二乘法相比均值差最大达到1.1μm, MCM方法比GUM方法得到的标准不确定度均值小0.02μm。合理的采样点数、微分进化算法及MCM不确定度评定方法可以得到更稳定可靠、精度高的评定结果。     

滚动轴承零件的圆度和波纹度测量标准

本文对JB/T6642--1993《滚动轴承零件圆度误差测量及评定方法》的修订提出了理论依据和修订方法。阐述了圆轮廓波纹度的定义和圆度波纹度与轴承振动的关系，提出了圆度波纹度测量数据处理的研究方向。     

智能圆度测量装置的推理机制的研制

为了在圆度测量中克服人工数据处理存在着效率低和准确性差的缺陷,需研制智能圆度测量装置,实现圆度误差的自动检测及评定。本文针对圆度误差的评定属求解非平凡问题的特点,提出采取推理和搜索的方法建立智能评定模块,并将它建成由规则集、综合数据库和控制系统构成的产生式系统。文中还根据评定圆度误差的最小包容区域法的原理,在对智能评定模块推理机制的研制中采用了穷举搜索的方法和深度优先的搜索策略,设计了数据处理中的算法——围点甄别法。文章最后以系统测试实例说明了该圆度测量装置具有真实数据自动采集和模拟数据人工输入之功能,能高效且准确地根据所获数据显示出圆度误差评定的最小包容区及其检测结果。     

基于误差转换及图像域的圆度评定方法

针对工程应用中圆度误差评定方法存在理论深奥、计算复杂、检测效率低且不适用于大容量采样点的问题,提出了一种基于误差转换及图像域的圆度误差评定方法。该方法首先将图像域测量得到的原始圆度误差进行转换,使其满足误差评定的要求;然后以最小二乘圆为起始圆,寻求半径或半径差的“极大中的极小”,通过对最小二乘圆进行小尺度平移,并用遗传算法得到该平移规划坐标,从而获得平移后的理想圆并求得圆度误差值;最后对某型号零件进行试验,试验结果与用三坐标测量得到的结果相吻合,表明该方法可以有效、正确地进行圆度误差的评定。     

基于蒙特卡罗方法的圆度测量不确定度评定

利用蒙特卡罗方法对圆度测量的不确定度进行评定。首先,根据最小二乘法得到圆度的误差模型;然后采用蒙特卡罗仿真方法对测量值进行模拟仿真,从而得到圆度误差的不确定度;最后将评定结果与传统评定方法的结果进行比较。结果表明该方法是可行的,且计算更为简便。     

AutoCAD在圆度误差评定中的应用研究

在圆度误差测量中,圆度误差的数据处理和评定一般都是采用绘制简图及用同心模板逼近的方法完成,但这种方法处理效率及准确度偏低。应用AutoCAD软件的绘图和标注功能对圆度误差进行评定的方法,能够很好的弥补传统方法的不足。     

基于计算机视觉的轴套零件尺寸测量北大核心

针对轴套零件的几何尺寸测量提出了一种基于机器视觉的检测方法。阐述了在Visual C++平台下,采用数字图像处理技术非接触测量轴套几何参数的方法,包括图像的预处理、边缘检测、轮廓提取以及圆度误差检测技术等。通过实验得到测量数据,分析了测量误差的原因。分析及试验表明,用该方法对轴套的几何尺寸及圆度误差进行测量及分析评定在实际应用中是可行的,并具有高效性和实用性。     

圆度误差的神经网络评定及测量不确定度研究

为了更为准确的而又简便的评定圆度误差及其不确定度,根据最小二乘法建立圆度误差模型,基于BP神经网络算法优化目标函数的参数,阐述了BP神经网络优化算法的原理和实现方法。通过求解实例表明该方法对于圆度误差评定的非线性优化问题能得到最优解。采用传统的测量不确定度表示指南方法和蒙特卡洛方法计算得到圆度误差的不确定度,通过实例验证蒙特卡洛法的可靠性和准确性。该方法不需要求出数学模型中的传递系数,利用MATLAB操作简单,为圆度误差测量结果不确定度评定提供了更加简便的方法。     

圆度误差检测方法现状与展望

介绍了目前的圆度误差检测方法的原理和特点,着重讨论了近年来出现的新型圆度误差检测手段,最后展望了圆度误差检测方法的发展趋势。     

Application of Monte Carlo simulation for estimation of uncertainty of four-point roundness measurements of rolls

Large-scale rotors in the paper and steel industry are called rolls. Rolls are reground at regular intervals and roundness measurements are made throughout the machining process. Measurement systems for roundness and diameter variation of large rolls (diameter <2000 mm) are available on the market, and generally use two to four sensors and a roundness measurement algorithm. These methods are intended to separate roundness of the rotor from its movement. The hybrid four-point method has improved accuracy, even for harmonic component amplitudes. For reliable measurement results, every measurement should be traceable with an estimation of measurement uncertainty. In this paper, the Monte-Carlo method is used for uncertainty evaluation of the harmonic components of the measured roundness profile under typical industrial conditions. According to the evaluation, the standard uncertainties for the harmonic amplitudes with the hybrid method are below 0.5 μm for the even harmonics and from 1.5 μm to 2.5 μm for the odd harmonics, when the standard uncertainty for the four probes is 0.3 μm each. The standard uncertainty for roundness deviation is 3.3 μm.     

Intersecting chord method for minimum zone evaluation of roundness deviation using Cartesian coordinate data

Minimum zone evaluation of roundness deviation is a very important and complex problem in precision measurement. Along with the continuous development of precision machining technology, it has become an increasingly prominent issue of how to quickly and accurately evaluate the minimum zone roundness deviation from a large number of coordinate data. In this paper, an intersecting chord method is first proposed to realize the minimum zone model of roundness deviation with coordinate data. The new modelling method uses the crossing relationship of chords to construct the intersecting structure and the 2 + 2 evaluation model of the minimum zone roundness deviation, which can not only accurately determine the position of minimum zone centre but also greatly improve the computational efficiency of modelling process. Using the related chords and their extreme points to generate a virtual centre, this may reduce the deviation between the intersecting chords structure and the centre of the minimum zone evaluation. The proposed method makes use of the geometric relationship of chords, so the minimum zone roundness deviation can be obtained without the optimal method or the point-by-point method. The validation test of the proposed method is designed to analyze a coordinate dataset published in other literature. Comparing the proposed method with the published method, it is easy to show that the relative error between two results is less than 0.4%. Finally, an experiment is also given to indicate that the calculation accuracy and the evaluation efficiency of the proposed method achieve a satisfactory conclusion.     

基于双激光位移传感器的超长深孔圆度检测研究

面向超长深孔管道内壁截面圆度的高精度与快速检测难题,针对基于单个激光位移传感器的传统检测方式存在效率 低,受轴心晃动影响大的不足,本文提出了基于两个激光位移传感器的点式检测方案,并通过建立数学模型与数值仿真的方式, 对检测装置旋转轴的偏心参数与两个激光位移传感器的安装偏差参数进行了仿真,分析了各参数对深孔管道圆度评价结果的 影响。 在此基础上,提出了存在安装误差的两个激光位移传感器数学校正模型,并搭建了管道圆度检测实验系统,验证了该模 型的有效性。 结果表明,相比于两个激光位移传感器所采集的数据直接进行圆度评价,对校正之后的数据进行圆度评价,其圆 度值从 0. 30~ 0. 50 mm 范围降低到 0. 05~ 0. 15 mm 范围,测量时间由 18. 7 s 缩短到 9. 8 s。     

基于小波变换方法的非接触圆度误差检测

针对圆度误差非接触检测过程中噪声对原始信号产生干扰的问题,提出采用小波变换进行信号降噪处理;讨论了小波理论中的快速变换算法及阈值降噪法的基本原理和处理实测信号的具体步骤;分析了基于小波变换的最小二乘圆法评定圆度误差的算法,并推导了其理论模型;运用Matlab小波工具箱通过实验说明了小波分析处理圆度误差的方法和效果。     

Research on the uncertainties from different form error evaluation methods by CMM sampling

As a part of the new measurement uncertainty system proposed in the new generation of Geometrical Product Specifications and Verification, the evaluation methods of uncertainties to form errors have been researched in mechanical engineering, which are calculated based on the error propagation principle and statistical concept under certain conditions. In this paper, the evaluation datum is obtained by using both the least squares method and the genetic optimization algorithm. Their computation uncertainties to flatness and roundness were compared with each other using the sample data from a coordinate measurement machine (CMM). The results show that the uncertainties obtained from the genetic algorithm-based method are similar to those from the least squares method according to their evaluation parameters. The evaluation uncertainties from different methods become a little smaller with more sample points. A more significant conclusion is that the evaluation uncertainties from two methods are so small that they almost do not affect the measurement uncertainties to form error, which, in fact, mainly comes from the CMM sampling. Therefore, for the efficiency and simplification of calculation, especially for the cylintricity with more parameters, the uncertainties from evaluation methods can be neglected where the precision is not so strict.     

基于最大内接圆法的圆度误差测量实现方法

介绍了一种在直角坐标系下利用最大内接圆法评价圆度误差的方法,建立了圆度测量模型。针对圆度误差最大内接圆评价,提出了一种最大内接圆心搜索方法,达到了快速、精确评价的目的,实现了在直角坐标系下三坐标测量机对圆度误差的最大内接圆法评价。     

圆度误差算法的研究

阐述了圆度误差的定义,介绍了评定圆度误差的几种方法,研究了迭代法、单纯形法等优化算法求解圆度误差的优缺点,对于进一步研究圆度误差的算法提供了一定的依据。     

Simple and efficient algorithms for roundness evaluation from the coordinate measurement data

A common problem of quality control and inspection of circular parts is the measurement of their roundness. Recently, the coordinate measuring machines (CMMs) have been used to measure roundness errors by collecting a large number of points from the profile of the rounded parts to meet the international standards. Direct evaluation of roundness from this large number of pointes is complex and time consuming. Therefore, efficient algorithms should be designed to meet the standards and to simplify and accelerate the computation process. This paper introduces simple and efficient algorithms to evaluate the roundness error from the large number of points obtained by CMMs using three internationally defined methods: Minimum Circumscribed Circle (MCC), Maximum Inscribed Circle (MIC) and Minimum Zone Circles (MZC). A software has been developed using C++ to apply these algorithms on the data obtained by CMMs. The developed algorithms were verified by comparing their results with the results obtained by a commercial instrument and the maximum variation between the two results did not exceed than ±2.27%. The efficiency of the introduced algorithms was verified in terms of computation time and the results proved the efficiency of the developed algorithms.     

基于新一代GPS的产品检验符合性不确定度评定*

新一代产品几何技术规范将测量不确定度的概念拓展至符合性不确定度,但并未给出相对应的评定方法。为全面估计产品检验中测量结果与产品规范所有可能的差异,基于新一代产品几何技术规范,研究产品检验符合性不确定度评定。基于产品几何技术规范定义,提出规范不确定度、方法不确定度、符合性不确定度的评定方法;借助不确定度的黑箱模型,通过测量结果统计学量值特性指标,评定执行不确定度。以产品圆度检验为例,研究符合性不确定度评定操作过程,基于符合性不确定度划分产品检验的合格区间。实例分析结果表明,规范不确定度和方法不确定度的量值与执行不确定度相当,不可忽略;由于符合性不确定度包含测量结果与图纸规范所有可能的不一致性,基于符合性不确定度进行产品合格判定更为可靠。