Virtual spheres gauge for coordinate measuring arms performance test

This work presents a new class of gauges with virtual spheres to check the performance of coordinate measuring arms (CMA). The proposed gauge has two groups of four holes that are used to determine points of two spherical surfaces. These points are fitted to spheres using computational algorithms and the distance between the center of the spheres is calculated. The proposed gauge was named virtual ball bar and an application was performed to test the performance of an articulated arm CMA with rigid probe. The results were compared with the application of the ANSI/ASME B89 volumetric performance test using a conventional ball bar and the proposed virtual ball bar. An additional experiment using fractional factorial design was carried out to complement the comparison of the gauges. The results showed good agreement between the two approaches and it was observed a potential cost reduction compared to ball bar gauge.     

Interferometry-based Kolsky bar apparatus

A new experimental approach of the Kolsky bar system using optical interferometry is presented for determination of dynamic behavior of materials. Conventional measurements in the Kolsky bar system are based on recording the strain histories on the incident and transmitter bars with two strain gauges, and require good adhesion between the gauge and the bar. We suggest an alternative approach, based on measuring the actual velocities of the bars by using fiber-based velocity interferometry. Two fiber focusers illuminate the bars at a small angle and collect reflected Doppler-shifted light, which is interfered with a reference beam. Velocities are calculated from short-time Fourier transform and phase-based analysis, and the dynamic stress-strain curve is derived directly from the measured velocity traces. We demonstrate that the results coincide with those obtained by conventional strain gauge measurements. The new method is non-intervening and thus not affected by bar impacts, making it more robust and reliable than strain gauges.     

Development of a strain measurement system for the study of effect of relative humidity on wood

Wood is a widely used material in various applications where its dimensional stability is of practical interest in the design and performance of wooden materials. The change in geometry of wood depends upon the environmental conditions (such as relative humidity) as well as internal structure and composition of wood. This work presents a measurement technique and development of the associated system for the measurement of strain changes of wood samples with relative humidity. The developed system is capable of measuring the strain change and relative humidity (RH) with temperature compensation. The system comprises of strain gauge based strain measurement unit and RH sensor with its related signal conditioning circuit along with temperature sensor. The strain gauge signal conditioning is based on quarter bridge method with high precision resistors which is excited by an AC source. The whole system is centered on an 8-bit RISC microcontroller (PIC18F43K22). The built in 10-bit analog to digital converter (ADC) is used to read the strain and ambient RH. The temperature is directly read from temperature to digital converter using ZACwire™ interface. The measurement system is calibrated using a cantilever of stainless steel and is used for collecting and analyzing data of four wood samples. The uncertainties associated with the measurements are reported in the paper. Experimental results obtained for a few wood samples are presented.     

温度传感器检定现场核查与实验室核查对比分析

温度传感器作为区域自动站一个观测要素测量仪,需要定期进行检定。文章详细介绍了四线制电阻测量温度的原理,以及现场核查和实验室核查两种方式对温度传感器进行检定的操作步骤。通过数据对比分析,初步判断现场核查数据是否准确。     

Damage identification in composite materials using ultrasonic based Lamb wave method

The paper presents an ultrasonic based Lamb waves propagation method for identifying and measuring the damage location in a material for SHM. The present work determines the experimental and analytical effects of various parameters on the sensitivity of damage detection and a methodology is proposed for estimating and measuring the location of damage in the test specimens. An experimental setup is used for generating A_o Lamb waves by calibrating ultrasonic pulse generation for optimal value of the parameters. The experiment is performed on two carbon fiber reinforced plastic bars in both undamaged and damaged state, where the two damaged states are (1) having a cut partway through the bar, perpendicular to the long axis of the bar and (2) having a circular hole. The Lamb wave propagation parameters are calibrated using the ultrasonic pulse generator test setup and the method was compared with direct measured values of ultrasonic instrument.     

固态存储雨量计及新型数字式雨量传感器的研究

对一种高精度、高稳定性的数字式雨量传器的设计原理、构造、关键技术及其技术性能进行了深入的探讨。该传感器的计量主体是一种高分辨力的数字编码型浮子水位计,它的测量准确度达±0.3％,比翻斗式雨量传感器高一个数量级,且具有测量误差不受雨强变化、沙尘气候环境影响的突出优点。本文同时对这种传感器在降水过程中数据采集记录的应用技术、仪器性能检定方法及适用领域进行了深入的探讨。     

高精度超声波式飞机油量传感器设计

运用超声波测距原理设计了超声波式飞机燃油油量传感器.该传感器具有体积小、重量轻和精度高等优点,可以准确地、实时地测量飞机各油箱的燃油油量,有助于实现飞机燃油系统的精确测控.     

光纤燃气温度传感器及测试系统

本文介绍了一种基于黑体辐射的光纤燃气温度传感器及测试系统,分析了影响传感器性能稳定性的主要因素及产生速度误差的原因,并采取了相应的解决方法。检定及试验结果表明,系统具有精度高,响应快、性能稳定的特点,为航空发动机燃气温度测量提供了一种新的测试手段。     

用于结构光视觉传感器标定的特征点获取方法

提出了一种基于共面参照物自由移动来获取结构光视觉传感器标定特征点的新方法。该方法通过以摄像机三维坐标系为中介,将多个局部世界坐标系下的标定特征点统一到全局世界坐标系中,得到位于光平面上的非共线标定特征点的三维世界坐标。该方法降低了标定设备的成本,简化了结构光视觉传感器的标定过程,从而提高了结构光视觉传感器工程化应用的便捷性。实验表明,该方法切实可行     

Enhancing life cycles of total pressure vacuum gauges in deposition applications (enhancing life cycles of vacuum gauges)

The application of hot cathode ionisation gauges in vacuum deposition processes (PVD, CVD) is critical regarding durability of the sensors, due to the inherent risk of contamination and discharges. Unstable calibration after relatively short periods of operation is an often reported problem, which arises from contamination with film forming substances contained in the residual gas. Furthermore, contamination often lead to early gauge drop outs and consequently to unsatisfyingly short life cycles of the gauges. Research was conducted to obtain improved solutions for prevention of gauge contamination on the one side, as well as optimised sensor designs for improved robustness and insensitivity against contaminants on the other side. This contribution discusses approaches for the desired improvements by evaluating the effectiveness of system-based methods to reduce the exposure of the sensor to contaminations, by indicating interactions between those system-based means and gauges, and by indicating options for improving gauge durability.     

电阻应变片与应变传递原理研究

随着我国衡器和自动称量技术的发展,各种电阻应变式称重传感器的应用也更加普遍。传感器的结构及型式,由常温至高温,由传统的模拟式也逐渐进入数字式。但是人们关心的仍然是传感器的性能及其稳定性。本文试以应变片的测量原理,从应变传递机理方面,把国内外学者在这方面的研究成果介绍给大家。     

Uncertainty analysis of calibration of geometrical gauges

On the calibration of geometrical gauges, such as a ball plate, using a coordinate measuring machine, a gauge block is simultaneously used for compensating the scale error and maintaining traceability to the length standard. A mathematical model of this calibration procedure is presented in accordance with Guide to the Expression of Uncertainty in Measurement (GUM). By considering uncertainty of the calibration, the danger of using a single gauge block is pointed out both theoretically and experimentally, and a solution to avoid the danger is also presented.     

新型桥式起重机轨距偏差自动测量系统设计

针对大跨度长轨距桥式起重机,设计出一种新型轨距测量系统。该系统利用准直长距激光传感器和精密微距激光传感器检测相对轨距和定位,经过单片机控制和计算能够自动检测轨道相对偏差,对超差点准确定位。详细介绍了信号处理电路的设计,使系统测量精度可达0.07 mm,与原有检测方法相比,其检测效率提高约50%。     

Additive manufacturing and characterization of a load cell with embedded strain gauges

In this paper we present the exploitation of Fused Filament Fabrication (FFF) to manufacture a load cell using double extrusion of conductive and non-conductive commercial materials in a single-step printing cycle. A load cell with four embedded strain gauges, manufactured with tailored process parameters and strategies, was used to deposit the conductive filament to obtain near equal electrical resistance values among the four strain gauges, aiming to connect them in a full Wheatstone bridge configuration. Subsequently, several tests were performed, firstly to understand the behavior of each strain gauge and then to characterize the load cell. The tests showed that the strain gauges are sensible to compressive and tensile deformation and that the load cell's voltage, obtained by connecting the four strain gauges in a full Wheatstone bridge, decreases as the force applied increases. This work demonstrates the potential of FFF technology in the sensor manufacturing field and that it is possible to integrate sensitive elements into non-sensitive elements without an additional assembly process by using low-cost commercial filaments and 3D printers.     

Design and testing of an innovative measurement device for tyre-road contact forces

The measurement of tyre-road contact forces is the first step towards the development of new control systems for improving vehicle safety and performances. Tyre-road contact forces measurement systems are very expensive and significantly modify the unsprung masses of the vehicle as well as the rotational inertia of the tyres. Thus, vehicle dynamics results are significantly affected. As a consequence, the measured contact forces do not correspond to the contact forces under real working conditions. A new low-cost tyre-road contact forces measurement system is proposed in this paper that can be applied to passenger cars. Its working principle is based on the measurement of three deformations of the wheel rim through strain gauges. The tyre-rim assembly is thus turned into a sensor for tyre-road contact forces. The influence of the strain gauges position onto the measurement results has been assessed through finite element simulations and experimental tests. It has been proven that, for a large variety of rims, the strain gauge position that leads to high signal-to-noise ratios is almost the same. A dynamic calibration procedure has been developed in order to allow the reconstruction of contact force and torque components once per wheel turn. The capability of the developed device to correctly estimate tyre-road contact forces has been assessed, in a first stage, through indoor laboratory experimental test on an MTS Flat-Trac^® testing machine. Results show that the implemented measuring system allows to reconstruct contact forces once per wheel turn with a precision that is comparable to that of existing high-cost measurement systems. Subsequently, outdoor tests with a vehicle having all four wheels equipped with the developed measuring device have also been performed. Reliability of the measurements provided by the developed sensor has been assessed by comparing the global measured longitudinal/lateral forces and the product of the measured longitudinal/lateral accelerations times the vehicle mass. A good agreement has been found during all the performed manoeuvres.     

On-machine profile measurement of a micro cutting edge by using a contact-type compact probe unit

A new contact-type on-machine measurement system is designed and developed for the evaluation of a micro cutting edge profile. The measurement system is composed of a compact probe unit having a sharp stylus mounted on a flexible beam, an inner displacement sensor for the detection of the stylus displacement, and a two-axis precision positioning system. For the evaluation of tool faces having a steep slope, a new probing procedure with the enhancement of the inner displacement sensor integrated into the probe unit is newly proposed. After the design and development of the probe unit, the feasibilities of the developed measurement system and the proposed probing procedure are demonstrated through some basic experiments. Regarding the out-of-straightness and angular error motion of the two-axis positioning system employed in the developed measurement system, a pair of length gauges is newly employed to reduce the influences of error motions of the stage system. The topographic profile of the micro cutting edge obtained by the measurement system with the modified probe unit is then compared with those obtained by a commercial stylus profiler and a laser confocal microscope. The feasibility and effectiveness of the developed on-machine tool edge profile measurement system are also demonstrated through uncertainty analysis based on the GUM with the Monte-Carlo method.     

基于电容分压法的配网线路智能电压传感器

配网线路电压的准确测量是配网故障检测和诊断的前提。根据导线对地的分布电容及传感器与导线之间的分布电容,构建了输电线路电压测量模型,分析了测量电容、杂散电容、导线对地电容的变化对测量结果的影响,提出了测量电容的选取原则;结合现场应用情况,分析了配网线路敷设高度、环境温湿度和安装点到杆塔距离等因素对测量结果的影响,提出了智能电压传感器的设计及安装原则。最后通过模拟实验和现场试验验证了测量模型的正确性及各影响因素对传感器测量结果的影响。其有望在配网电压测量领域大面积应用。     

厚度无损检测仪器的精度长期稳定性研究

无损检测和结构健康监测是保障工业生产安全、降低维护成本的重要技术。在结构健康监测领域,原位测量仪器的长期稳定性尤为重要。首先介绍电磁、超声无损检测在厚度检测的应用现状,针对随后讨论厚度无损检测检测仪器精度长期稳定性问题。对厚度无损检测仪器现在长期使用过程中的精度变化规律进行研究,探讨三种测厚仪器的工作原理、精密度和准确度与仪器的稳定性的关系。采用三种厚度测量仪器（超声测厚仪、涂覆层测厚仪与楼板测厚仪）测量预标定样本的仪器试验测量方法,得到五年测量数据。再通过分析数据的年平均误差、相对误差和变化速率来讨论电涡流测厚仪、超声测厚仪的长期稳定性,并进行三类仪器间的比较,分析各类型仪器的特点。结果显示电涡流厚度测量仪器具有相对较好的长期稳定性;超声测厚仪和楼板测厚仪精密度维持能力受时间影响,仪器精密度逐年下降,准确度也趋于不稳定。为电磁无损检测技术应用到结构健康监测领域,自校准和补偿奠定了基础。     

第二十二章 基于图像识别与传输的工业仪表无线识读装置设计

针对工业现场中大量传统仪表并不具有数据通信能力,无法与工业无线通信装置连接的问题,提出了一种采用图像传感器获取仪表表盘图像,通过图像识别得到仪表读数并进行本地显示和无线传输的工业仪表识读装置的设计方案。介绍了无线识读装置的主要结构和工作原理。     

超声波测距仪设计

本超声波测距系统采用微控制器AT89S8252作为主控芯片,实现了自动补偿、语音播报、汉字显示等功能。该系统采用脉冲回波的方法测量距离,利用温度传感器DS18B20测量环境温度,通过软件对温度引起的测量误差进行补偿。