基于旋转工件轮廓智能输入系统二维视图的三维重构技术

为了解决虚拟三坐标测量软件对军工涉密项目中零件检测路径规划问题,提出了一种基于二维视图的三维重构技术,设计了旋转工件轮廓二维视图的智能输入系统;操作人员根据提示输入图纸上旋转体母线的关键信息;系统软件对输入信息进行连续性、交叉性和封闭性判断,以构成正确轮廓母线;环绕旋转轴旋转母线重构出三维实体模型,按照标准IGES文件格式输出,从而实现二维视图的三维实体重构、生成的IGES文件提供给坐标测量机系统软件,可实现坐标测量机的自动化测量．联合运用该输入系统与虚拟三坐标测量机,解决了军事涉密项目中零件检测的路径动态规划问题     

Research on the theory and the virtual prototype of 3-DOF parallel-link coordinate-measuring machine

First, this paper describes the structure, the measuring theory, and characteristics of a new kind of coordinate measuring machine (CMM) using the parallel-link mechanism with three spatial degrees of freedom (3-DOF). Then, its measurement model is established according to the theory of the spatial mechanics, and the workspace of the probe is calculated and verified by computer simulation. Finally, the virtual prototype of the new CMM is studied by using the graphical functions in the OpenGL graphic library based on Windows 98 and Visual C++ 6.0. This research gives the foundation for manufacturing the real prototype of the parallel-link CMM.     

大尺寸航空发动机叶片的高效型面检测方法

介绍了一种基于三坐标测量机的高效型面检测方法。在传统叶片型面测量方法基础上,优化了传统扫描路径,提出了分区域、曲率自适应变速扫描方法,有效地解决了大尺寸叶片传统测量方法中频繁更换测针的问题。研究了一种过度扫描策略,通过高级编程对采集数据进行滤波,并采用数学拼接的方法得到完整叶型封闭曲线,用来分析叶片的几何参数。提出的大尺寸叶片检测方法在保证检测精度的同时,提高约40%的检测效率,并完善了传统检测方法叶型曲线不完整的问题。     

Automated feature accessibility algorithm for inspection on a coordinate measuring machine

In this paper, the issue of inspection planning for a coordinate measuring machine (CMM) is addressed. A method is presented for the automation of the probe selection decision, with the ultimate goal of determining the set of workpiece orientations recommended for use on a CMM equipped with an indexable probe. The methodology uses a computer-aided design (CAD) model of the workpiece and a list of tolerance information as input to a feature accessibility algorithm. For each inspection feature, the algorithm generates a feasible set of probe orientations using information about potential probe/workpiece collisions, and computes an estimate of its percentage accessibility.     

Virtual prototyping and manufacturing planning by using tri-dexel models and haptic force feedback

This paper presents a new method of using the tri-dexel volumetric models and a haptics force feedback for virtual prototyping and manufacturing planning. In the proposed method, the initial polyhedral surface model is converted to a tri-dexel volumetric model by using a depth-peeling dexelization algorithm. In the virtual prototyping process, the tri-dexel volumetric model is updated by the swept volume of a moving cutter via a haptic force feedback interface device. A collision detection algorithm is proposed for the virtual sculpting and the pencil-cut planning with real-time haptic force feedback to the users. Tool paths are generated for machining the virtual sculpted parts via the simulation and verification on a virtual CNC machine tool before they are actually machined. Computer implementation and practical examples are also presented in this paper. The proposed method enables the haptic-aided virtual prototyping and manufacturing planning of complex surface parts.     

Virtual prototyping and manufacturing planning by using tri-dexel models and haptic force feedback

This paper presents a new method of using the tri-dexel volumetric models and a haptics force feedback for virtual prototyping and manufacturing planning. In the proposed method, the initial polyhedral surface model is converted to a tri-dexel volumetric model by using a depth-peeling dexelization algorithm. In the virtual prototyping process, the tri-dexel volumetric model is updated by the swept volume of a moving cutter via a haptic force feedback interface device. A collision detection algorithm is proposed for the virtual sculpting and the pencil-cut planning with real-time haptic force feedback to the users. Tool paths are generated for machining the virtual sculpted parts via the simulation and verification on a virtual CNC machine tool before they are actually machined. Computer implementation and practical examples are also presented in this paper. The proposed method enables the haptic-aided virtual prototyping and manufacturing planning of complex surface parts.     

叶片型面的三座标检测程序自动生成系统

本文叙述了叶片型面的三座标检测程序自动生成系统的体系结构与功能,并介绍了系统实现的技术关键,包括叶片型面的数学建模、测头检测路径规划及测量结果的处理。     

基于商用坐标测量机的3D微纳米计量

以测量精度为1μm的商用坐标测量机（CMM）为基础,构建了测量范围为25mm×40mm×25mm、测量不确定度约为O．15μm的PTB微纳米专用坐标测量机．研究了CMM的运动控制系统、恒温室的空调系统以及CMM的被动隔振系统等对测量结果的影响．由测量结果可以看出,CMM的运动控制系统产生的噪声水平约为其他误差源的2倍．通过FFT运算,发现未优化系统的短时最大漂移量发生频率为750Hz,对应为运动控制的工作频率．文中还介绍了测量力为1州光纤探针的测量原理,并给出了对2．5mm短轴的测量结果．     

ICF靶丸表面形貌及球度误差检测

为了对ICF靶丸的表面形貌及球度误差进行高精度测量,开发了一台五轴坐标测量机,并采用锥光全息技术的激光测头实现对靶丸表面的高精度、非接触检测。首先,根据靶丸表面的结构特点,改进了基于最小二乘的球度误差评价算法;然后,介绍了作为实验平台的五轴坐标测量机的整体配置,推导了该坐标测量机的测量数学模型,该坐标测量机可实现在多个姿态下对靶丸的非接触取点测量;最后,在相同条件下,进行了5次实验测量,其结果表明:靶丸球度误差测量的均值为0.0021 mm,标准差为2.07 x10^-4 mm。该检测方法可以满足对靶丸表面形貌及球度误差高精度、高稳定性的测量要求。     

Experimental study of the effect of digitizing parameters on digitizing uncertainty with a CMM

Planning of an automated digitization or inspection process takes time and requires experience. The accuracy of digitization and inspection depends directly on the planning of digitization strategies. This paper uses the fractional factorial experimentation approach to investigate the relationship between digitizing (inspection) uncertainty and digitizing (inspection) parameters with a coordinate-measuring machine (CMM). The parameters include travel speeds, pitch, probe angles (part orientations), probe sizes and feature sizes. Robust digitization (inspection) strategies are identified given the part geometry, dimensions and accuracy. Finally, future research directions are highlighted.     

Collision-free path planning for coordinate measurement machine probe

This paper focuses on the method of collision-free path of the coordinate measurement machine (CMM). In terms of the collision-free path, the cut face method is used to plan the displaced tracking along the boundary loop. In addition, the 'maximum angle between tangential vectors method' and the heuristic algorithm designated by the displacement characteristic among the feature faces are used to reduce the number of intermediary points. This can also reduce the distance of the displacement. The turning of the probe aims at the contact with the workpiece surface in the normal direction. If the contact position in the normal vector direction is impossible, the probe angle closest to the normal direction is adopted. The normal direction contact with the workpiece can, on the one hand, achieve better measuring position and, on the other hand, accompany with the cut face method and thus make a collision-free path possible.     

基于HCGA的三坐标测量路径优化

针对传统遗传算法(GA)进行三坐标测量路径优化时收敛速度慢且过早收敛的问题,提出基于爬山遗传算法(HCGA)的三坐标测量路径优化方法。根据三坐标测量路径优化的数学模型,构造适合于测量路径优化问题的遗传编码、初始种群、选择、交叉、变异等参数,通过增加爬山操作,加快GA的迭代收敛速度。仿真实验结果表明,基于HCGA的三坐标测量路径优化方法能有效提高局部寻优能力与收敛速度,可获得很好的最优解并提高了测量效率。     

Automated accessibility analysis and measurement clustering for CMMs

The aim of inspection planning tasks is to ensure the generation of efficient operation for coordinate measurement machines (CMMs). This paper presents a methodology to automatically define the accessibility domain of measurement points and then group them into a set of clusters. The methodology uses the computer-aided design (CAD) model of the workpiece and tolerance information as input to an algorithm for defining points accessibility. For each measurement point, the algorithm determines all feasible inspection probe orientations, as a subset of the total set of available orientations for a given CMM probe. A heuristic algorithm then groups the measurement points into a set of clusters which provide the maximum number of probe orientations. This methodology was applied to three examples which contain solid model and free-form surface representations.     

Comprehensive design of experiments-based framework for optimal CMM inspection and uncertainty analysis of form tolerances

In the coordinate measuring machine (CMM) measurement environment, uncertainty can arise from various sources. Previous literature has focused on how to measure uncertainty in a CMM system using segregated approaches. We developed a framework to verify bias and variance tendencies deriving from form errors. Two types of form tolerances, namely flatness and circularity, are addressed here. By studying the nature of the CMM measurement uncertainty impact, this paper targets three objectives: (1) developing a design of experiments (DOE)-based measurement performance approach to integrate critical measurement strategy factors; (2) optimizing identified controllable measurement factors; and (3) synthesizing the impact of CMM uncertainty issues. Consequently, the paper fully explores the influence and interplay of these contributing factors, resulting in robust and optimal guidelines for the CMM flatness and circularity measurement strategy. Extensions of the framework for other form tolerances are discussed.     

微纳米三坐标测量机接触扫描探头稳定性分析(英文)

对微纳米三坐标测量机(CMM)高精度扫描探头的稳定性进行了分析.该扫描探头由带有球头的光纤探针、悬浮机构、二维角度传感器和微型迈克尔逊干涉仪4部分组成.光纤探针和悬浮片固定在一起,当光纤探针的球头受到触碰时,会带动悬浮机构的悬线发生形变,进而导致贴在悬浮片上的平面反射镜倾斜或在竖直方向上发生位移,前者由二维角度传感器进行感测,后者由微型迈克尔逊干涉仪进行感测.实验结果表明,环境温度的变化是影响探头稳定性的主要因素,探头中机械结构和部件对温度变化的敏感性要远远大于探头中光电器件对温度变化的敏感性.只要将探头放到一个恒温箱中,待恒温箱温度稳定4 h再开始测量,探头即可达到1 nm的分辨力和30nm的测量标准差.     

叶片型面测量编程与误差处理技术

针对航空发动机叶片三坐标测量机(CMM)测量,进行了自动测量编程与误差处理两个方面的研究。提出了一种基于已知叶片CAD模型提取测量点理论坐标值与计算法向矢量的方法,矢量计算采用微平面法。数据处理时,采用ICP算法进行配准消除了系统误差,从而得到叶片型面误差。开发了测量点坐标值与矢量计算以及配准程序。实例证明该方法可靠、有效。     

基于坐标测量机的步距规激光校准系统

该文介绍坐标测量机与激光干涉仪对步距规进行校准的测量原理和测量过程,测量结果与DKD证书进行对比,并分析测量结果的不确定度。     

坐标测量机面向任务的测量不确定度评定

基于产品几何技术规范,分析了坐标测量机面向任务的测量不确定度主要来源;重点讨论了量值特性指标测量复现性的定义与特点,并针对坐标测量机的测量任务,提出引起坐标测量复现性的主要因素,研究了进行复现性指标评价的实验方案,建立了复现性评定的数学模型;通过孔径测量实例分析,介绍了坐标测量机面向任务的测量不确定度评定方法。结果表明,孔径测量结果的合成标准不确定度为3.2 μm,其中测量复现性的不确定度分量高达2.5μm,在测量结果不确定度中所占比重最大。     

坐标测量机发展的新方向--虚拟坐标测量机

虚拟坐标测量机是虚拟现实技术与坐标测量技术相结合的必然产物,是虚拟制造技术发展的需要。本文提出了三坐标测量机的一个新的发展方向－虚拟坐标测量机（ＶＣＭＭ）,介绍了虚拟坐标测量机的体系结构和基本功能以及虚拟坐标测量机仿真运行所需要的软硬件环境。     

Tolerance specification and comparative analysis for computer-integrated dimensional inspection

Two important issues in the development of a computer-integrated dimensional inspection environment for manufactured parts are described, namely tolerance specification and comparative analysis. These two issues are related directly and therefore, should be addressed together. For supporting the computer-integrated dimensional inspection, a geometric dimensioning and tolerancing (GD&T) specification module and a comparative analysis module are developed and integrated with CATTA of the IBM CAD/CAM system. The proposed specification module supports ISO and ANSI geometric tolerances and allows multiple tolerance assignments on each single feature as well as on a group of same pattern features. Using this specification module, various tolerance information can be directly specified to the 3D CAD model of a part and can be used to support the subsequent planning and operation for manfacturing and inspection. The comparative analysis module is created to work with the GD&T module for constructing datum reference frames and comparing the actual measurement data with nominal design. After specifying all necessary tolerance information, using discrete measurement data from coordinate measuring machines (CMM), one can evaluate the dimensional quality of an actual feature through the comparative analysis module.