Application of traceable sample area measurement in the calibration of online dry grammage measurement used in board production

A method is described for the simultaneous calibration of online grammage and moisture measurement by applying machine reel sampling and traceable sample area measurement. The area measurement is based on a flatbed scanner and image analysis. It is demonstrated that a relative uncertainty of 0.5% can be achieved in dry grammage calibration at the 95% confidence level. The determination of grammage and moisture were performed by applying the EN ISO 536 and the EN ISO 287 standards, respectively. The described technique can also be applied with the calibrations performed for the paper industry.     

Improving integrity of on-line grammage measurement with traceable basic calibration

The automatic control of grammage (basis weight) in paper and board production is based upon on-line grammage measurement. Furthermore, the automatic control of other quality variables such as moisture, ash content and coat weight, may rely on the grammage measurement. The integrity of Kr-85 based on-line grammage measurement systems was studied, by performing basic calibrations with traceably calibrated plastic reference standards. The calibrations were performed according to the EN ISO/IEC 17025 standard, which is a requirement for calibration laboratories. The observed relative measurement errors were 3.3% in the first time calibrations at the 95% confidence level. With the traceable basic calibration method, however, these errors can be reduced to under 0.5%, thus improving the integrity of on-line grammage measurements. Also a standardised algorithm, based on the experience from the performed calibrations, is proposed to ease the adjustment of the different grammage measurement systems. The calibration technique can basically be applied to all β-radiation based grammage measurements.     

储粮温度水分自动测试系统设计

本文利用半导体温敏器件实现储粮温度检测,依据高频阻抗原理实现粮食水分快速检测,研制了融温度、水分快速检测于一体的自动测试系统,系统已在多个粮库中投入使用。     

Online conductivity calibration methods for EIT gas/oil in water flow measurement

Electrical Impedance Tomography (EIT) is a fast imaging technique displaying the electrical conductivity contrast of multiphase flow. It is increasingly utilised for industrial process measurement and control. In principle, EIT has to obtain the prior information of homogenous continuous phase in terms of conductivity as a reference benchmark. This reference significantly influences the quality of subsequent multiphase flow measurement. During dynamic industrial process, the conductivity of continuous phase varies due to the effects from the changes of ambient and fluid temperature, ionic concentration, and internal energy conversion in fluid. It is not practical to stop industrial process frequently and measure the conductivity of continuous phase for taking the EIT reference. If without monitoring conductivity of continuous phase, EIT cannot present accurate and useful measurement results. To online calibrate the electrical conductivity of continuous phase and eliminate drift error of EIT measurement, two methods are discussed in this paper. Based on the linear approximation between fluid temperature and conductivity, the first method monitors fluid temperature and indirectly calibrates conductivity. In the second method, a novel conductivity cell is designed. It consists of a gravitational separation chamber with refreshing bypass and grounded shielding plate. The conductivity of continuous phase is directly sensed by the conductivity cell and fed to EIT system for online calibration. Both static and dynamic experiments were conducted to demonstrate the function and accuracy the conductivity cell.     

A method for discriminating original pulses in online partial discharge measurement

Partial discharge (PD) measurement is a promising method for condition assessment of insulation systems in high voltage equipments. Conventional PD measuring systems have some difficulties in the measurements especially in online conditions and noisy environments. There is a growing tendency to use new measuring systems for separation of PD pulses from different sources and rejection of external noises. In this investigation a new ultra wideband PD measuring system and relevant methodology are discussed. The proposed system uses an efficient detection method for extracting PD pulses embedded in noisy signal, meanwhile, a wavelet multiresolution analysis is applied to reduce background and communication noise level. In this paper some new and modified features for pulse classification procedure have been proposed. The proposed system, methodology and features have been implemented on a hydrogenerator and also a power transformer. Finally performance of the system is discussed.     

基于激光二极管的近红外水分仪研制

本研究开发一种基于近红外光谱技术,采用两只激光二极管(LD)光源,其中1490nm为水分的特征吸收波长,1310nm作为参考波长,使用积分球作为载样器件和使用LabVIEW虚拟仪器程序开发语言编写系统程序的新型近红外水分仪。该仪器去除一般光谱仪器中的分光部件,从而有利于提高系统的稳定性和信噪比。经茶叶和奶粉的实测试验证明,该仪器的检测精度较高,基本能满足实际生产中对水分检测的需要。     

Effect of Time-Domain Reflectometry probe location on soil moisture measurement during wetting and drying processes

In this paper studies on the impact of the location of Time-Domain Reflectometry probes in soil samples on the moisture measurement are presented. In particular, we were interested if the commonly accepted assumption that moisture measurements performed by TDR probes correctly average the value of the soil water content in a soil sample. Soil samples having different physical properties, both undisturbed and disturbed, were used. Our results show that the soil moisture measurement depends on the placement of the TDR probe in the sample, and a TDR probe placed vertically measures the arithmetic mean of soil moisture for the whole sample, for both the wetting and the drying cycles. This result is general and does not depend on the analyzed sample.     

A novelty digital algorithm for online measurement of dielectric loss factor of electronic transformers

There are many inherent performance limitations using traditional algorithms for online measurement of dielectric loss factor including synchronous sampling, no interharmonics and power system frequency must be invariable. In a non-stationary signal environment where power frequency fluctuation and interharmonic components exist, there is no guarantee of measurement accuracy by using traditional methods. The paper proposed a high-accuracy digital algorithm for online measurement of dielectric loss factor of electronic transformers. Theoretical basis of the new algorithm is based on a new data processing procedure including data truncation and data addition which compensates phase distortion as a result of the spectrum of addition data contains offsets. The algorithm can accurately extract the fundamental signal and calculate dielectric loss factor. Measured results from simulations and practical engineering projects show that the new algorithm has good application feasibility without being affected by the limitations rendered above.     

齿轮参数CCD自动测量系统的研究

提出一种齿轮参数CCD自动测量的方法,给出测量步骤,构造测量硬件系统,并用VC++语言编写了系统软件。通过测量实例证明,所研制的自动测量系统达到了预期的效果。     

Monocular-vision-based method for online measurement of pose parameters of weld stud

With the rapid development of stud welding technology, weld studs are extensively used in automobile industry. A weld stud differs from a regular stud in that it has special external features. This study develops a novel non-contact, fast, and high-precision method based on monocular vision for measuring the position and attitude parameters of a weld stud. Under this method, the measuring principle for the weld stud’s position and attitude parameters is derived and an accurate mathematical model is set up. Based on this mathematical model, a precise calibration method for the projective transformation’s corresponding relationship parameters is developed and an optimal observation condition is then introduced as the constraint into the measurement process so as to enhance the location precision. The experiment results show that the proposed method is fast and accurate, and it satisfies the requirement of online, flexible, fast, and high-precision measurement of weld studs’ pose parameters in automobile and other manufacturing industries.     

面向大型工件现场测量的光笔式视觉测量系统

研制了一种面向大型工件现场测量的光笔式视觉测量系统,对其中的关键技术进行了深入研究。该系统主要由带有红外LED光点的光笔、1台CCD摄像机、靶点亮度控制器、一维标定尺以及安装有测量软件的计算机组成。在对LED点光源光强控制方式及成像系统工作原理进行分析的基础上,设计并实现了以多靶点亮度自适应控制技术和主动离焦模糊技术相结合的靶点光斑图像生成技术。该技术保证了在大跨度测量范围内均能获得高质量的靶点光斑图像,解决了对焦成像中摄像机视场范围与景深有限的问题;针对光笔标定问题,提出了一种简便易行的现场标定方法,此方法只需要若干个辅助靶点和2个以上间距已知的圆锥孔,就可以同时确定光笔上各靶点及光笔测头在光笔坐标系下的坐标。实验结果显示:该测量系统在2~10 m空间长度测量标准差不大于0.095 mm,能够满足中等精度的大型工件现场测量要求。     

Optical fibre-based sensor technology for humidity and moisture measurement: Review of recent progress

Humidity and moisture sensing is becoming increasingly important in industry and through a wide spectrum of applications and a review of research activity in the field across a range of technologies was presented previously by some of the authors. Recognizing the major developments in the last few years, especially in the field of fibre optic humidity and moisture sensing, this paper aims to extend that approach to review and categorize recent progress in the optical fibre field for the measurement of humidity and moisture and examine, as a result, the breadth of applications that now are being discussed.     

Soft measurement of paper smoothness based on time-frequency analysis of paper quantization noise

Aiming at the problem that paper smoothness cannot be measured on line, a new method for soft measurement of paper smoothness is put forward on the basis of studying paper quantization distribution. A soft measurement system is established, by which, paper quantization noise is processed by time-frequency analysis and non-linear transformation, so that online paper smoothness can be obtained through a Radial Basis Function Neural Networks (RBFNNs). The results show that this soft computing method is a feasible way with high measuring accuracy.     

线结构光视觉系统标定新法及其振动测控应用

激光视觉是一种在工业检测领域应用广泛的测量方式,其标定是视觉检测系统搭建的基础。为此,提出了一种新型线结构光视觉系统标定方法。采用张氏标定法完成相机标定,通过提取标定板上的激光条纹特征,根据三面共线条件进行处理完成结构光平面的标定,并对标准尺寸进行测量以验证标定结果的准确性。接着基于该系统搭建了柔性臂振动测控实验台,并用其对柔性臂振动进行检测,设计了一种非线性控制器抑制柔性臂的振动。实验结果表明,提出的标定方法三维检测精度可达0.1 mm,得以应用在柔性臂的振动检测上,设计的控制器也可在短时间内抑制柔性臂的振动,以此验证了标定方法的检测效果和振动抑制的有效性。     

基于多点合作目标的多线阵CCD空间物体姿态测量

为了精确测量悬浮试验场内姿态快速变换的空间物体的姿态角参数,提出了一种采用3个线阵CCD相机同时测量多个点合作目标的姿态测量方法,以解决传统的线阵CCD姿态测量系统中相机位置间的约束条件过多造成的非线性系统误差及校准参数多的问题.该方法采用柱面透镜和线阵CCD组成的3个一维相机,对被测物体上的多个点合作目标同时进行测量;并针对测量原理对姿态角限制的问题,采用模拟计算的方法进行姿态角测量范围的计算.由神经网络校准线阵CCD相机,直接给出点合作目标的空间三维坐标,并通过建立基于Rodrigues参数姿态解算模型求解被测物体的姿态角.实验结果表明,本文方法得到的空间点位置测量精度及空间姿态解算精度高于原线阵CCD姿态测量方法,验证了该姿态测量方法进行姿态测量的可行性和有效性.     

基于图像处理的连铸板坯测控系统

本文介绍了基于计算机图像处理连铸板坯长度测量和切割控制系统的硬件构成和软件功能。讨论了摄像机参数标定方法和系统测量误差。     

采用三向光纤照明成像的三维微结构观测系统

为弥补普通光学显微镜照明系统的不足,针对一般三维微结构的显微成像,提出并设计了一个可实现实时调节的三向光纤照明成像观测系统.系统采用计算机、D/A卡、驱动电路等硬件以及自主研制的控制软件,实现对任一光源的光强进行稳定连续的实时调节.通过自主设计的机械结构将光源、光纤、耦合头以及显微镜连接为一整体,实现光束入射方向、入射角和入射距离的任意调节.与通常的底部透射光照明系统进行实验比较,成像质量显著提高,不仅可以清晰观察目标对像的表面结构,还能得到立体感强的三维图像.针对面阵CCD显微测量系统的标定和标定误差问题,提出了螺旋微缝标定法.将螺旋测微计两铁钻形成的微缝作为标定的样本,配以适当的观测手段和计算方法,有效地消除或减小了各种误差,提高了系统的标定精度.通过系统标定和测量比较,系统的标定精度达到±0.0015μm,测量精度达到±1μm.实验结果表明,螺旋微缝标定法可以基本满足CCD测量系统标定的要求.     

流程工业调度与控制集成系统的数据采集与传输

该文分析了数据采集系统的结构与数据采集方式,提出了实时数据库与DCS系统之间实现物理隔离的数据采集方法,研究了基于OPC技术的异构数据集成解决方案,探讨了数据采集系统中实时数据的传输与通信方法,为实现流程工业生产调度与控制系统的集成提供了一种新的数据采集与处理方法。     

双刀架曲轴数控车削在线测量及自动补偿的实现

为提高曲轴数控加工自动化程度,采用了双刀架曲轴数控加工与在线检测集成的方法,开发了上、下刀架刀具磨损自动补偿子程序.实际应用表明在线尺寸检测及自动补偿技术改善了加工质量和提高了加工效率.     

基于双线激光基准的盾尾间隙测量方法研究

针对现有众多盾尾间隙自动测量方法中普遍存在的精度低和可靠性差等问题,提出了一种基于双线激光基准标尺的视觉测量新方法。通过两道平行布设的窄线形激光构建观测基准,利用传统图像处理技术捕获盾壳与管片的关键特征,结合标尺反算误差补偿技术,实现在盾构掘进过程中盾尾间隙测量值的高精度实时解算。现场实验表明,本文所提出的方法的重复性测量精度优于1.2 mm,绝对测量精度优于2 mm,测量误差小于1.5 mm,该方法可以实现盾尾间隙自动化实时精确测量且具备较高的可靠性,现已应用在我国多个地铁隧道施工现场。