On-Machine Measurement of the Straightness and Tilt Errors of a Linear Slideway Using a New Four-Sensor Method

Although there are some multi-sensor methods for measuring the straightness and tilt errors of a linear slideway, they need to be further improved in some aspects, such as suppressing measurement noise and reducing precondition.In this paper, a new four-sensor method with an improved measurement system is proposed to on-machine separate the straightness and tilt errors of a linear slideway from the sensor outputs, considering the influences of the reference surface profile and the zero-adjustment values. The improved system is achieved by adjusting a single sensor to di erent positions. Based on the system, a system of linear equations is built by fusing the sensor outputs to cancel out the e ects of the straightness and tilt errors. Three constraints are then derived and supplemented into the linear system to make the coe cient matrix full rank. To restrain the sensitivity of the solution of the linear system to the measurement noise in the sensor outputs, the Tikhonov regularization method is utilized. After the surface profile is obtained from the solution, the straightness and tilt errors are identified from the sensor outputs. To analyze the e ects of the measurement noise and the positioning errors of the sensor and the linear slideway, a series of computer simulations are carried out. An experiment is conducted for validation, showing good consistency. The new four-sensor method with the improved measurement system provides a new way to measure the straightness and tilt errors of a linear slideway, which can guarantee favorable propagations of the residuals induced by the noise and the positioning errors.

Application of 2-D Position Sensitive Detector in Spatial Straightness Measurement of Guide Rails

A laser collimating system based on 2-D position sensitive detector (PSD) is presented in this paper. The working principle of PSD is depicted in detail. A calibration device was developed to check the nonlinearity errors of PSD and a multilayer feedforward neural network based on error back-propagation algorithm was used to compensate errors. With the aid of computer-based data acquisition system, an automatic dynamic measuring process was realized. A series of experiments, including comparison tests with laser interferometer, were done to evaluate the performance of the measuring system. The experimental results show that the spatial straightness errors of guide rails can be measured with high accuracy. The maximum differences between the device and laser interferometer are 0.027 mm in Y direction, and 0.053 mm in X direction in the measuring distance of 6 m.

ALTERABLE INTERVAL OPTICALELECTRONIC AUTOCOLLIMATION METHOD FOR STRAIGHTNESS MEASUREMENT OF PRECISION GUIDE

Optical-electronic autocollimation method is commonly used to measure straightness of precision guides in engineering application. However, the traditional fixed interval optical-electronic autocollimation method is not suitable for measuring straightness of an air-bearing guide with a long air-bearing bush or a precision straight guide with a long slide-carriage, because the air-bearing bush and the slidecarriage are actually taken as a big bridgeboard bigger than the length of the bridgeboard with the reflector, which is about 1/4-1/2 of total length of the measured guide. If straightness is measured according to the traditional method, only a few points are sampled so that the guide straightness can not be evaluated fully or accurately. In order to solve the problem, an alterable measuring interval method is proposed for straightness measurement based on analyzing the mutual relations and effects among the tilting angle of the reflector, the length of the bridgeboard, the measuring interval and the straightness of the guide. A straightness calculation model is also developed using the method, and the errors stemming from the method proposed are introduced in brief. A precision air-bearing guide with a long air-bearing bush is measured and evaluated using the method proposed, and the actual measurement and evaluation results prove that the method is correct in theory and practical in operation. The method proposed gives an effective and flexible solution to the straightness measurement of the precision guide with long slide-carriage or air-bearing bush in application. It is an extension of the traditional optical-electronic autocollimation method for straightness measurement.

A Novel Method to Simultaneously Measure the Straightness

A precise two-degree-of-freedom measuring system (2DMS) is developed based on single-mode optical fiber, LD, cube corner retroreflector and four-quadrant photodetector (4-Q), and the simultaneous on-line measurement of lateral and vertical direction straightness errors of the linear stage is carried out. The moving part is wireless, which eliminates any errors introduced by pushing and pulling the wires. The sensitivity of the straightness error measurement can be improved by a factor of 2 with the cube corner retroreflector. This fiber-based optically aligned beam is used to establish a reference line for the straightness measurement of any mechanical system. 4-Q detector is used to receive the laser beam. A chip microcomputer is developed to conduct all data acquisition and signal processing. The beam drift influence can be removed in the greatest extent from the system. The experiments on the measurement system stability, repeatability and its comparison with the HP5528 double-frequency laser interferometer are carried out.

Direct evidence of high temperature superconductivity in one-unit-cell FeSe films on SrTiO_3 substrate by transport and magnetization measurements

Zero resistance and Meissner effect are two crucial experimental evidences of superconductivity in determining a new kind of superconductor, which can be detected by transport and diamagnetic measurements. In this paper, we briefly review the main transport and magnetization results on the one unit cell （1-UC） FeSe films grown on SrTiO3 （STO） substrates from our team in recent years, which identify the high temperature superconductivity in 1-UC FeSe films.

Nodeless superconductivity in a quasi-two-dimensional superconductor AuTe2Se(4/3)

We performed ultra-low temperature thermal conductivity measurements on the single crystal of a new gold-based quasi-two-dimensional superconductor Au Te2Se（4/3）, which has a superconducting transition temperature Tc = 2.70 K. A negligible residual linear term κ0/T in zero magnetic field is observed, which suggests fully gapped superconducting state.Furthermore, the field dependence of κ0/T is similar to that of the multi-band s-wave superconductor Ba Fe1.9 Ni0.1 As2 at low field. These results reveal multiple nodeless superconducting gaps in this interesting quasi-two-dimensional superconductor with Berezinsky–Kosterlitz–Thouless topological transition.

标准核燃料组件几何轮廓校准装置的研制

针对标准核燃料组件竖直状态下几何参数溯源需求,研制了一种标准核燃料组件几何轮廓校准装置。该装置以空间坐标测量为理念,利用多路接触式传感器作为轮廓测量采集单元,结合测量工作台高度位置获得轮廓坐标。通过直线度及扭转度测量与误差补偿,进一步提高了几何轮廓测量精度;并使用集成运动控制和专用测量软件,实现了标准核燃料组件几何轮廓参数(直线度、扭转度、垂直度、平行度)的自动检测。通过分析及实验验证,几何轮廓参数中直线度和平行度测量标准不确定度为0.01 mm,扭转度测量标准不确定度为0.007 mm,垂直度测量标准不确定度为0.017 mm,说明该装置能够满足标准核燃料组件的溯源需求。

上后牙区微种植钉支抗改善露龈笑的回顾性研究

目的分析上后牙区植入微种植钉支抗对露龈笑患者唇齿软硬组织的改善效果,为临床提供参考。方法本研究已通过单位伦理委员会审查批准,并获得患者知情同意。对使用上颌后牙区高位植入微种植钉治疗前突伴露龈笑的年轻女性患者30例进行回顾性研究,其中种植钉植入于上颌第一、二前磨牙根间的患者18例(A组),种植钉位于上颌第二前磨牙与第一磨牙根间且术中配合使用摇椅弓患者12例(B组),治疗前、后分别拍摄头颅侧位片并测量两组术前、术后上中切牙切端至上唇下点距离(U1⁃Stms)、上中切牙切端至腭平面垂直距离(U1⁃PP)、牙槽缘点至腭平面垂直距离(Spr⁃PP)、上中切牙切端至牙槽缘点距离(U1⁃Spr)、上颌第一磨牙近中颊尖点至腭平面垂直距离(U6⁃PP)等相关指标,拍摄微笑照片测量微笑时上前牙区软硬组织暴露量及最大露龈量。结果两组患者矫治后唇齿关系均明显改善,差异有统计学意义(P<0.05),A组U1⁃Stms平均减小2.6 mm,U1⁃PP平均减小2.4 mm,Spr⁃PP平均减小1.4 mm,U1⁃Spr平均减小0.9 mm;B组U1⁃Stms平均减小2.3 mm,U1⁃PP平均减小1.6 mm,Spr⁃PP平均减小1.4 mm,U1⁃Spr平均减小0.2 mm;两组治疗前后U6⁃PP差异均无统计学意义(P>0.05)。A组ΔU1⁃PP、ΔU1⁃Spr大于B组,差异有统计学意义(P<0.05),两组ΔU1⁃Stms、ΔSpr⁃PP差异无统计学意义(P>0.05)。两组患者术后微笑时上前牙区软硬组织暴露量、最大露龈量均减小,A组治疗后上前牙区软硬组织暴露量平均降低至治疗前的70.19%,最大露龈量平均减少至治疗前的24.12%,B组治疗后上前牙区软硬组织暴露量平均降低至术前的76.12%,最大露龈量平均减少至治疗前的31.88%。两组之间的比值差异无统计学意义(P>0.05)。结论对于前突伴露龈笑患者,微种植钉植入于上颌前磨牙根间可有效压低内收前牙改善唇齿关系,从而减少微笑露龈量,微种植钉植入于上颌第二前磨牙与第一磨牙根间配合使用摇椅弓亦可取得良好疗效。

激光干涉仪在机床导轨平行度检测中的应用

为检测机床或测量机等导轨之间的平行度,用激光干涉仪和岩石平尺作为主要测量工具,基于最小二乘法求解直线度的原理,通过线与线之间的平行度计算方法,以激光干涉仪的反射镜光轴为基准,采用基准法评价机床导轨的平行度,分析了激光干涉仪检测平行度的方法、符号判断及影响直线度和平行度的因素。用两种不同测量工具测量线与线之间平行度,比较两种测量工具的优势特点,为激光检测机床导轨的平行度检测提供测量依据。实验结果表明,相比于岩石平尺,激光干涉仪常用于大尺寸导轨直线度和平行度的测试,且具有直观、方便、高精度的测量优势;岩石平尺由于本身的材质原因不便携带,且本身精度对直线度和平行度的测量结果有影响。

Comprehensive analysis of two-dimensional charge transport mechanism in thin-film transistors based on random networks of single-wall carbon nanotubes using transient measurements

Understanding charge transport mechanisms in thin-film transistors based on random networks of single-wall carbon nanotubes(SWCNT-TFTs)is essential for further advances to improve the potential for various nanoelectronic applications.Herein,a comprehensive investigation of the two-dimensional(2D)charge transport mechanism in SWCNT-TFTs is reported by analyzing the temperature-dependent electrical characteristics determined from the direct-current and non-quasi-static transient measurements at 80-300 K.To elucidate the time-domain charge transport characteristics of the random networks in the SWCNTs,an empirical equation was derived from a theoretical trapping model,and a carrier velocity distribution was determined from the differentiation of the transient response.Furthermore,charge trapping and de-trapping in shallow-and deep-traps in SWCNT-TFTs were analyzed by investigating charge transport based on their trapping/de-trapping rate.The comprehensive analysis of this study provides fundamental insights into the 2D charge transport mechanism in TFTs based on random networks of nanomaterial channels.

几何误差测量方法应用分析——以机床导轨和机用虎钳直线度测量为例

设备的几何误差的测量是设备中零件制造、安装过程中重要的质量检测工作之一,测量结果是否准确直接关系到设备安装质量的好坏及后期使用精度。几何误差的测量方法虽然很多,但既能满足精度要求、又能便捷地用于工作设备在作业现场测量的测量方式方法就比较少。文章分别以机床导轨和机用虎钳导轨的直线度误差的测量为例,提炼出了设备实际测量过程中,两种不同工况下的四种常用的测量方案,加以分析、比较,最终推广出可操作性强、精确度高的最合理、最适应的测量方案,进而进行推广和应用。

导轨直线度惯性测量的时空一致技术

针对数控机床需长期检测精度及单一传感器测量信号无法与导轨空间对应的问题,提出了一种导轨直线度惯性测量的时空一致技术。建立了正弦叠加形式的导轨直线度误差模型,基于导轨直线度误差空间频率,采用一种多速测量方案消除了导轨倾角误差并截取了对应频率的误差信号。将限位传感器作为采集卡的同步触发器,实现了导轨直线度误差时空一致性测量。与激光干涉仪和相位延迟测量数据的对比验证了所提测量方法的准确性与有效性。

基于视觉原理的直槽丝锥径向几何参数测量方法研究

针对目前丝锥测量方法测量参数单一、需人工操作的问题,提出了一种基于视觉原理的直槽丝锥径向综合多参数自动测量方法。通过预处理得到丝锥极坐标下的径向轮廓图。对端面刃背到几何中心的最大、最小极径像素拟合圆,得到端部和芯部直径。通过拟合特征曲线,得到两对直线方程,利用夹角公式得到前角和后角值。计算刃背首末像素点间距离得到刃背宽度值。将刃背首末像素极径差值作为铲背量。实验结果表明:对M10丝锥进行10次重复性测量,上述几何参数的测量相对误差均在0.58%之内,平均耗时7 s,能满足高精度、高效率、多参数自动测量的工程需求。

激光轮廓测量中的偏心修正方法

管端直线度是钢管生产中重要的控制指标。以无缝钢管生产线为试点,探索了利用激光轮廓扫描技术进行钢管直线度测量的方法。为了解决钢管直线度测量过程中因测量装置安装误差和现场振动造成的激光带偏心问题,提出了一种基于几何测量模型的自修正方法。该修正方法可以对钢管轮廓数据进行实时在线补偿,有效解决了偏心引起的误差,测量精度达0.1 mm。

基于复合点位移的旋转棒料直线度检测及弯曲定位方法

通过分析现有空间直线度测量方法的优缺点,结合目前企业对于棒料直线度检测的现状和需求,提出了一种基于复合点位移的旋转棒料直线度检测方法并实现弯曲角度定位。通过研究空间直线度、圆跳动、全跳动等形位误差关系,确定采用螺旋线提取法为测量点提取方法,两端点连线法为直线度评价方法。通过激光位移传感器沿轴向运动采集旋转棒料的位移,建立位移变化信息与直线度的数学模型,从而判断棒料的直线度误差;并根据位移变化信息与转动行程的关系实现棒料的弯曲角度定位。基于上述方法,设计开发了一套直线度检测及弯曲角度定位装置,通过实验对测量精度与误差进行分析,结果表明该系统的精度、重复精度、弯曲定位精度满足实际需求。

基于视觉原理的直槽丝锥轴向几何参数测量方法研究

针对目前丝锥测量方法存在自动化程度低和检测时间长的缺点,提出基于视觉原理的直槽丝锥轴向几何参数测量方法。利用Harris角点检测算法获得丝锥关键尺寸图像区域,再使用区域生长法、改进Canny算法和边缘跟踪算法提取丝锥边缘信息;经过牙侧线上一点作一直线垂直于牙侧线,使该点在垂线方向上到相邻牙型角的角平分线距离相等,运用三角形相似法确定牙侧线上的中径点,采用最小二乘法拟合上下牙型中径线,从而测得中径;求出对应牙顶和牙底像素点拟合直线的距离并获得大小径值;用拟合直线测量夹角获得牙型角和切削锥角,将对应牙侧线中径点的距离求均值后获得螺距。实验结果表明:对M14丝锥重复测量10次,上述几何参数的测量相对误差均在0.43%之内,能满足高精度、高效率以及自动测量的工程需求。

涤纶DTY纸管直线度的影响因素及改进措施

针对涤纶拉伸变形丝(DTY)纸管生产中纸管直线度合格率较低的问题,基于现阶段的纸管生产工艺及设备参数分析了纸管直线度的主要影响因素,并通过调整设备参数、优化生产工艺等措施来提高纸管的直线度合格率。结果表明:在涤纶DTY纸管生产中,纸管直线度的主要影响因素有粗切下料高度、磨头叉架距离、气压、油压、烘管温度;对设备和工艺参数进行调整优化,控制粗切下料高度8~10 cm、磨头叉架距离18~22 cm、气压0.25~0.30 MPa、油压0.25~0.35 MPa、烘管温度60~70℃,批量生产1000只涤纶DTY纸管,纸管直线度基本上控制在1.2~1.4 mm,达到了产品标准规定直线度小于1.5 mm的要求,直线度合格率从原来的98.14%提高至99.43%。

Sectional Dimensions Identification of Metal Profile by Image Processing

In steel plants, estimation of the production system characteristic is highly critical to adjust the system parameters for best efficiency. Although the system parameters may be tuned very well, due to the machine and human factors involved in the production line some deficiencies may occur in product. It is important to detect such problems as early as possible. Surface defects and dimensional deviations are the most important quality problems. In this study, it is aimed to develop an approach to measure the dimensions of metal profiles by obtaining images of them. This will be of use in detecting the deviations in dimensions. A platform was introduced to simulate the real-time environment and images were taken from the metal profile using 4 laser light sources. The shape of the material is generated by combining the images taken from different cameras. Real dimensions were obtained by using image processing and mathematical conversion operations on the images. The results obtained with small deviations from the real values showed that this method can be applied in a real-time production line.

一种基于机器视觉的笔杆表面缺陷检测方法

医疗器械产品生产中的笔杆表面缺陷是不可避免的问题,基于机器视觉的自动检测方法可以克服传统人工检测效率低、漏检及误检率高等问题。在分析笔杆结构和缺陷的基础上,文章重点研究笔杆边缘直线拟合、缺陷灰度值差异、图像边缘平滑和稳定等检测方法;通过实验证明,该方法准确率可达到98.8%,每个笔杆的检测时间为8.3 s,相较于人工检测,明显提高了检测精度和速度,可以满足对笔杆实时自动缺陷检测的要求。

陶瓷砖综合测量仪导轨直线度在线校准方法的研究

目前,国内陶瓷砖综合测量仪导轨直线度校准采用非接触式视觉测量,尚无相应的校准规范和方法。本文介绍了采用激光干涉仪校准导轨直线度的方法,通过试验数据得出导轨直线度等测量参数,为陶瓷企业产品平整度检测提供技术支持。