Synthesis of the measurement system on the machine tool

The design methodology of a 2½-dimensional measurement and inspection system realized on a machine tool using a touch trigger probe and measuring G codes is studied in this paper. The reliability of measuring results, the agility of measurement, and user friendliness are synthesized in the design process. Algorithms for calibration and compensation of measuring errors are proposed to ensure the measuring accuracy by using a laser interferometer and ring gauges. Classification of probing feedrates and a collision-check algorithm can reduce measuring time and implement stylus-fracture-free measurements. To improve the previous onmachine measurement processes, all functions required for measurement and inspection processes are constructed as measuring G codes with similar forms of machining G codes. The interactive measuring program generating tool, which can automatically generate measuring G codes, is developed and potted in a ROM of a CNC, and can be called to perform an operation by the CNC without interfacing with personal computers. The validity and effectiveness of the developed system are verified on a horizontal machining centre with a Fanuc 15MA.     

飞机表面划痕非接触测量仪的研究

介绍了一种飞机表面划痕非接触测量仪。它以激光三角传感器为主要组成部件，并附以机械扫描装置，可完成被测飞机表面划痕的非接触测量。在分析了被测表面散、反射特性的基础上，给出了激光三角传感器正确放置方式，并提出改善测量精度的传感器姿态调整法。针对浅划痕测量时噪声较大的特点，提出利用子波分析的方法突出被测划痕形貌的信号处理方法，实验表明了此方法的可行性。本测量仪具有非接触测量、测量范围大、精度高、结构简单、成本较低的特点。     

CNC数控机床在线测量系统的校准装置研究

目前,国内尚无针对CNC数控机床在线测量系统的相关的标准和校准规范。为统一技术要求,本文研究了CNC数控机床在线测量系统的工况条件及其计量特性参数,提出了有别传统三坐标测量机校准方法的校准方案,研制了符合基于公差带位置判别废品原理的标准器组,以在线测量系统的测工件的方式,反向校准CNC在线测量系统的尺寸精度,解决其量值溯源问题。     

四发射单接收光学非接触测头

研究开发了一种具有4个发射光源和1个CCD摄像机作为接收装置的光学非接触测头．测头可以用来测量包括具有强反射表面的曲面．测头基于三角法工作原理．在恰当设计的情况下,至多只有1路从工件表面反射回来的光,能够进入CCD摄像机．通过将相应通道切断,很容易消除镜面反射光的影响．这时测头就相当于1个三发射单接收光学非接触测头．测头可以同时用来测量表面的位置和方向．对于具有很大倾斜的表面具测头仍能正常工作,采用干涉滤光片消除了环境光的影响．提出了一种系统的标定方法．通过对量块的测量证实了系统工作的正确性和有效性并给出了实验结果．     

CNC机床在线测量系统校准方法研究

目前CNC机床在线测量系统的校准方法在国内有用激光干涉仪、标准量块等一些用于企业的针对性方法,缺少适用于计量校准机构的校准方法,本文根据该系统的工作原理,对CNC机床在线测量系统的校准方法进行研究,提出几项计量特性参数,并结合实际情况设计了校准方案,研制了校准用计量标准器,分析了数据的处理方法.经研究表明,本文的校准方...     

用于纳米级表面形貌测量的光学显微测头

为了满足纳米级表面形貌样板的高精度非接触测量需求,研制了一种高分辨力光学显微测头。以激光全息单元为光源和信号拾取器件,利用差动光斑尺寸变化探测原理,建立了微位移测量系统,结合光学显微成像系统,形成了高分辨力光学显微测头。将该测头应用于纳米三维测量机,对台阶高度样板和一维线间隔样板进行了测量实验。结果表明：该光学显微测头结合纳米三维测量机可实现纳米级表面形貌样板的可溯源测量,具有扫描速度快、测量分辨力高、结构紧凑和非接触测量等优点,对解决纳米级表面形貌测量难题具有重要实用价值。     

工件车削尺寸变化在线检测的研究

报道了一个工件车削尺寸在线控制的实验系统。它用一个激光三角法检测装置测量工件车削尺寸的变化量,然后将此尺寸变化量作为反馈信号,由微机控制刀具进行加工尺寸的适时补偿。着重介绍了车削加工尺寸变化量在线检测实验装置的研究情况。系统配置了一个低通滤波器,可以有效地消除切削振动及工件表面刀痕对测量的影响。     

Sculptured surface reconstruction from CMM measurement data by a software iterative approach

The reverse engineering approach is being widely applied in designing and manufacturing of sculptured surfaces. The first step in the reverse engineering process is collection of data lying on the surface. When using a coordinate measuring machine (CMM) with a touch trigger probe for digitizing data points, the probe radius must be compensated according to normal vectors. Previous works were addressed on the iterative measurement procedure to reduce the error caused by the compensation. The major problem of iterative methods is time consumption in digitization. This paper proposes a new architecture based on look-up table that keeps the estimated normal vectors of the measurement data to refine the data points digitized by CMM. The digitized data are first fitted into several NURBS curves by interpolation. The skinning method is then applied to interpolate these curves. Thus a smooth NURBS surface can be constructed and more accurate normal vectors of the measurement points can be obtained to compensate for the probe radius. By using this software iterative technique, we need only one digitization procedure. Therefore, much time can be saved and the efficiency of reverse engineering can be improved.     

数控机床在线测量系统校准技术研究

数控机床在线测量技术广泛应用于薄型、复合材料等大型加工工件的在线测量,以确保工件的加工质量符合要求。针对目前数控机床在线测量系统校准工作中存在的工作现场环境条件干扰和校准过程耗时较长问题,本文根据实际工作中的技术要求,采用双频激光干涉仪、成组球规等标准器组成校准系统,提出一种适用于企业内部的数控机床在线测量系统校准技术,结合补偿技术提供单位间距的修正量,确保轴线长度示值误差符合技术要求。经实验证明,该校准方法准确性好,工作效率高,具有技术推广价值。     

室内GPS发射器角度校准装置的设计与分析

室内GPS利用测量的水平角和垂直角来定位,其测角误差直接影响到系统的综合测量误差,结合室内GPS的测角误差,提出了室内GPS角度校准装置的技术要求,并分别对俯仰角校准和水平角校准所需准确度进行估计,最终利用新型同轴调整装置结合精密转台和竖轴激光导轨研制了一套室内GPS发射器角度校准装置,试验数据表明该装置的俯仰角测量误差小于0．9″,水平角测量误差小于1．6″,解决了室内GPS发射器水平角和俯仰角的校准问题。     

几何量数字化测量方法与装备的现状及发展趋势

几何量数字化测量方法与测量装备的发展对制造业影响深远,随着测量任务的多样化与复杂化,对几何量数字化测量方法与测量装备的要求越来越高.本文以现有的典型测量系统为例,根据传感单元工作原理的不同对这些测量系统进行了分类,分别介绍了激光跟踪仪、激光雷达、激光跟踪干涉仪、移动空间坐标测量系统、室内GPS、数字摄影测量系统的数学模...     

Development of an In-Situ Laser Machining System Using a Three-Dimensional Galvanometer Scanner

In this study, a three-dimensional (3D) in-situ laser machining system integrating laser measurement and machining was built using a 3D galvanometer scanner equipped with a side-axis industrial camera. A line structured light measurement model based on a galvanometer scanner was proposed to obtain the 3D information of the workpiece. A height calibration method was proposed to further ensure measurement accuracy, so as to achieve accurate laser focusing. In-situ machining software was developed to realize time-saving and labor-saving 3D laser processing. The feasibility and practicability of this in-situ laser machining system were verified using specific cases. In comparison with the conventional line structured light measurement method, the proposed methods do not require light plane calibration, and do not need additional motion axes for 3D reconstruction; thus they provide technical and cost advantages. The in-situ laser machining system realizes a simple operation process by integrating measurement and machining, which greatly reduces labor and time costs.     

纳米三坐标测量机接触式测头预行程测量

提出了一种用于纳米三坐标测量机接触式测头预行程测量的方法.确定了预行程需侦测接触点和触发点两个关键点.为了对该高灵敏度的测头进行标定,整个实验系统需要3个基本条件：纳米级驱动器,高分辨率传感器和多级速度控制算法.本研究使用一种超声波马达HR4在同一平台上实现大行程粗略驱动以及微位移调整.位移测量使用光栅传感器LDGI（linear diffraction grating interferometer）,其分辨率可达1nm.在测试过程中采用高速逼近和低速触发,使用＂双触发＂方式获得触发点位置.接触点位置的侦测使用开关电路.触发信号和位移信号由同一块数据采集卡同步采集.实验表明,使用该方法测量预行程,单方向重复性在±5nm以内.     

基于激光三角测量原理的自动机运动测试方法

为研究自动武器自动机运动规律,提出了一种基于激光三角测量原理的自动机运动参数测试方法,测试系统由线性CCD激光位移传感器、信号调理电路及信号处理软件构成.采用该系统对某一自动武器连发射击时的自动机运动位移参数进行了测试,与现有的方法相比,此系统操作简单,抗干扰性能好,所获取的实验数据具有较高的精度.     

纳米坐标测量机的三维接触式测头机构

介绍了一种新型的用于纳米坐标测量机的三维微纳米接触触发式测头机构.本测头以灵敏度高、抗干扰性强的布拉格光纤光栅(FBG)为测量的敏感元件,根据FBG对轴向应变变化敏感的特点,开发了一套有效触发测量力小的柔性悬架机构,该机构为三悬丝-六边中心连接体的悬架结构,相间隔的3边延伸悬臂与3根布拉格光纤光栅相连,当测球发生预行程变化时,由测杆带动柔性悬架机构产生偏摆,从而带动3根FBG发生轴向的拉伸或压缩,进而产生传感信号的输出.由于测头结构复位性是衡量测球和工件分离后能否回到初始位置的标准,是测头其他各项指标的基础,因此结合激光干涉仪和精密微动平台,采用光学非接触干涉测量方法对该测头机构的实际复位性能进行了测量.结果表明,测头系统采用15 N的预紧力安装悬丝,可得到较好的复位性和灵敏度,该测头机构复位性精度在20 nm以内,满足微纳米量级高精度测量的需要.     

自由曲面的自适应跟踪测量方法研究

 激光传感器在测量自由曲面中有着非接触、精度高等优点，其应用越来越广泛． 但是激光测头的线性测量
范围较小，难以测量起伏变化较大的曲面． 针对这一问题，提出了激光测头的跟踪测量方法，使激光测头随曲面的
高度变化作上下调整，从而可以测量任一表面起伏的曲面，且能根据当前曲面的曲率大小自适应选择跟踪方式，实
现测点的自适应分布．最后，对一个工件分别进行了等间距测量和自适应跟踪测量，并对两种方法的测量结果做了
比较，证明了自适应跟踪测量方法的可行性和有效性，为自由曲面的测量提供了一种新的方法．     

五轴加工中心的在机检测系统研究

为了避免加工与检测过程中出现重复定位误差,研究了用于复杂空间型面的在机检测方法。通过将测头系统应用于五轴加工中心,分析对应机床在机检测的运动学模型并开发了后置处理程序。将传统的旅行商问题转化为最优匹配问题进行局部快速求解,获取行程段路径规划轨迹。同时提出一种干涉检验方法,利用图形求交判断的方式对检测干涉进行预处理。实现了“S”试件曲面的在机检测,并将获取偏差数据与三坐标测量机的采样数据进行对比,在数据整体一致的条件下,前者的变异系数相对后者降低了7.3%。     

激光瞄准大轴半径测量方法的研究与应用

提高大型轴类工件轴径在线测量精度，其主要困难在于用非接触法时如何精确地确定测量点的位置。采用特殊的机械装置，使激光光斑落在被测工件表面上，通过CCD摄像及图像分析，可获得优于0．01mm的定位瞄准精度。实验表明，对于300mm以下的轴径，这种方法的测量误差不超过0．015mm。     

热轧异型钢材截面尺寸在线检测系统研究

提出了一种用于热轧异型钢材截面尺寸在线检测的光电三维尺寸传感与测量系统。计算机在此基础上用有效的除噪技术和最小二乘法进行轮廓尺寸的计算。     

Development and Application of Multiple‐Probe Scanning Probe Microscopes

In the research of advanced materials based on nanoscience and nanotechnology, it is often desirable to measure nanoscale local electrical conductivity at a designated position of a given sample. For this purpose, multiple‐probe scanning probe microscopes (MP‐SPMs), in which two, three or four scanning tunneling microscope (STM) or atomic force microscope (AFM) probes are operated independently, have been developed. Each probe in an MP‐SPM is used not only for observing high‐resolution STM or AFM images but also for forming an electrical contact enabling nanoscale local electrical conductivity measurement. The world's first double‐probe STM (DP‐STM) developed by the authors, which was subsequently modified to a triple‐probe STM (TP‐STM), has been used to measure the conductivities of one‐dimensional metal nanowires and carbon nanotubes and also two‐dimensional molecular films. A quadruple‐probe STM (QP‐STM) has also been developed and used to measure the conductivity of two‐dimensional molecular films without the ambiguity of contact resistance between the probe and sample. Moreover, a quadruple‐probe AFM (QP‐AFM) with four conductive tuning‐fork‐type self‐detection force sensing probes has been developed to measure the conductivity of a nanostructure on an insulating substrate. A general‐purpose computer software to control four probes at the same time has also been developed and used in the operation of the QP‐AFM. These developments and applications of MP‐SPMs are reviewed in this paper.