Optical measuring equipments. Part I: Calibration model and uncertainty estimation

This study aims to propose and describe a procedure for calibrating the “vision subsystem” of digital optical machines, based on the affine camera model, valid for telecentric optical equipment. From this procedure, it is possible to systematise the calculation of the uncertainty of the calibration parameters associated with the “vision subsystem” by using the Monte Carlo method. The identification and characterisation of the calibration parameters of the “vision subsystem” and its associated uncertainty, obtained through this study, make it possible to characterise the metrological properties of the indicated optical equipment and ensure the metrological traceability of the measurements that have been subsequently taken.This work is divided into two parts. Part I focuses on developing a mathematical model of the “vision subsystem” and calculating the uncertainties of its parameters. Part II develops an example of measuring and calculating measurement uncertainty, based on the theoretical development of Part I.     

现代光学测量技术及设备在大型相控阵雷达天线标校上的应用

主要论述了在大型相控阵雷达天线机械轴的标校中如何使用现代光学测量技术和设备,从而提高测量的精度和测量的效率。介绍了测量设备的系统组成,同时论述了测量的原理,以及测量的具体操作过程。     

PLC在流量计自动标定系统中的应用

该文介绍了PLC结合体积管进行流量计自动标定的工作原理和过程,介绍了系统构成及仪表的设置与控制。着重说明了PLC在流量计自动标定系统中应用的技术特点及其应用效果。     

分层实体制造激光光路分析与快速校准

文章介绍了分层实体制造激光快速成型机的光路系统组成,分析了光路系统偏差对零件尺寸形状误差的影响,最后介绍了浙江光路快速校准的方法。     

自行车碟刹制动距离测试系统的设计与实现

随着碟刹的使用越来越普及,刹车的可靠性测试显得尤为重要,而国内市场上尚没有针对碟刹的测试系统.针对这一问题,设计了一套自行车碟刹制动距离测试系统.首先建立了自行车的刹车模拟装置,然后在模拟装置上安装了拉力传感器和速度传感器对其进行实时监测,传感器信号由数据采集卡采集并上传至上位机,上位机软件分析数据后下发命令控制模拟装置的刹车过程,并实时显示拉力值、速度值和制动距离等.通过多次制动距离测试,求平均值,确定了碟刹的制动距离,最后进行了试验验证.研究结果表明,该测试系统能够较准确地测量出自行车的制动距离,并且性能稳定,简单易操作,实用性强,具有良好的实际应用价值.     

Determination of optimum measurement points via A-optimality criterion for the calibration of measurement apparatus

A procedure for optimal selection of the measurement points to get the best calibration characteristics (for the chosen optimality criterion) of measuring apparatus is proposed. The coefficients of the calibration characteristics are evaluated by the classical least squares method. For this work, the A-optimality criterion has been used as an optimality criteria. As an example, the problem of optimal selection of the standard pressure setters (the piston gauges) during calibration of the differential pressure gage is solved. Obtained values of the optimum measurement points for the calibration of the differential pressure gage are checked via actual experiments.     

Liquid low-flow calibration rig using syringe pump and weighing tank system

A calibration rig consisting of a syringe pump and a weighing tank system that can operate in the flow rate range of 0.02–60 L/h was developed in this study. This paper discusses the design considerations of the calibration methods, the development of the rig, the calibration results, and the uncertainty analysis conducted on the rig. A weighing tank system that minimizes the effects of outlet tube contact and evaporation was developed. The syringe pump system was designed using a servomotor, a precise ball screw, and a linear encoder, and it was calibrated using the developed weighing tank system via the standing start and stop method over the target range of flow rates with light oil and industrial gasoline. Several flowmeters were calibrated using the syringe pump via the flying start and finish method. During the flowmeter calibration stage, the effect of the evaporation error was eliminated because the calibration rig can form a closed pipeline system. The influence of dissolved gas and the position dependence of the syringe pulse factor on the calibration accuracy were investigated experimentally. As a result, all obtained syringe pulse factors were found to be within ±0.02% of each other. The preliminary expanded uncertainties (k=2) of the calibration rig were estimated to be 0.066% and 0.070% for mass and volumetric flows, respectively.     

A humidity generator with a test chamber system

For the calibration of relative humidity hygrometers and dew-point hygrometers with an open sensor, a test chamber system was constructed and connected to a dew-point generator. The system includes several small chambers connected in series. By reversing the flow direction, humidity and temperature gradients in the test chamber system are monitored during calibration measurements. This paper reports the construction of the test chamber system and the improvements in the construction and the analysis of the dew-point generator. A full uncertainty analysis is presented. The expanded uncertainty of the dew-point temperature and the relative humidity with the coverage factor k=2 are from ±0.05°C to ±0.08°C and from ±0.1%rh to ±1.0%rh, respectively. Although the dew-point temperature range is from −40°C to +77°C, the limits for the temperature range of the test chamber system are −20°C and +60°C. The system was not tested with relative humidity values lower than 10% or higher than 95%.     

Simulation and experimental verification of a fuel calibration system based on metering cylinder

Simulation and experimental verification of a fuel calibration system based on hydraulic metering cylinder has been carried out in this paper. A novel hydraulic metering cylinder is designed for more accurate flow rate measurement. The calibration workbench with this cylinder is presented and mathematically modeled. Also, the calibration system is numerically simulated in AMESim. The simulation results show that the calibration system can work smoothly. In addition, the impact of given plunger speeds and calibration strokes on the accuracy of the calibration results is experimentally verified. It can be found that stroke of approximate 600 mm and a medium given speed are the most effective ways to reduce the measuring error under the experimental condition provided in this paper. Moreover, a calibration error less than 0.5% is achieved in the fuel calibration system.     

Angular velocity calibration system with a self-calibratable rotary encoder

Gyroscopes are essential components of electronic stability control systems (ESC), which are currently incorporated in automobiles to reduce car accidents. To meet the traceability requirements of gyroscopes in ESC testing system, a novel type of angular velocity calibration system was developed at the National Metrology Institute of Japan. The system is equipped with a self-calibratable rotary encoder (SelfA), operating on the same self-calibration principle as the national angle standard in Japan. To evaluate the performance of the system, the stability of the measured angular velocity was examined in both time domain and in terms of Allan variance. The noise effect from the slip ring was also measured. The calibration procedure was demonstrated by monitoring the response of a fiber-optic gyroscope from −180°/s to 180°/s at 30°/s intervals. The results confirmed that the system performance satisfies the requirements for angular velocity calibration of mid-performance MEMS gyroscopes.     

常开式压钳盘式制动器的新结构及设计要点

介绍常开式液压钳盘制动器的一种新结构形式，工作原理及特点，并研究了关键元件特性参数的确定方法，给出了具体的计算公式。     

Optical deflection measuring system

A system for accurate real-time measurement of deflections was developed. A stable laser source is, by means of a single-mode fiber, coupled to an optical head located at one end of deformed structure. A detector circuit with a quadrant detector and processing electronics, located at the other end of the structure, communicates the resolved 2D position of the incident beam over a common digital bus. Experiments using interferometers were conducted in a climate-controlled chamber to evaluate system performance and verify the accuracy. A resolution of 0.1  m is attainable in dynamic measurements. The system was calibrated and tested to yield measurement accuracy of ± 0.8  m for ± 2σ probability over the measurement range of ± 300  m. Drift of the system in the experimental setup was determined to be less than 2  m for measurement in both degrees of freedom within the 10 h period under constant environmental conditions.     

Optimal combined set-up and calibration policy

The optimal level to which the mean of a critical variable should be set-up, and the optimal number of repetitions until recalibration, has been jointly determined for the case where the variable is distributed normally and the mean changes linearly with the number of repetitions. It was proven that the optimal set-up level should be below the midpoint between the specification limits by a distance which depends on the slope of change of the mean and on the recalibration cycle, in such a manner that just prior to the recalibration the mean reaches the same distance above the midpoint. A method has been outlined for the numerical evaluation of the optimal number of cycle repetitions, and a general approximation formula was derived, which allows its closed-loop determination. A numerical example and sensitivity analysis are provided.     

光学三维测量技术与应用

光学三维测量技术是一种可视化的测量技术,能完成复杂形体的点、面、形的三维测量,能实现非接触测量,在制造业和航空航天领域得到广泛应用。航空三维激光扫描与摄影测量技术利用激光测距原理和航空摄影测量原理,与基于全球定位系统(GPS)和惯性测量装置(IMU)的机载定位定向系统(POS)联接,可以快速获取大面积地球表面三维数据。本文对光学三维测量技术和航空三维激光扫描技术做一简单介绍,给出三维激光扫描技术在航空航天领域的几个应用。     

Design and calibration test of a support force measuring system for hypersonic vehicle aerodynamic measurement

With the development of air-breathing integrated vehicle test models equipped with engines, the designing of traditional internal balance force measuring systems has become complicated. This is partly because hypersonic vehicle models have slender bodies, and engine systems inside such model cavities are densely distributed, thereby limiting the space available to house traditional internal balance systems. Moreover, traditional force measuring systems are assembled mechanical systems, and their dynamic force transmission characteristics are inevitably degraded under extremely short test time conditions. Thus, herein, we propose a support force measuring system that integrates the traditional internal balance system with a support in an integral design. The designed internal triangular concurrent force system considerably reduces the additional moment generated by the thrust/resistance force. Calibration tests reveal that the new system demonstrates good linearity and repeatability, and the results prove the correctness of the triangular concurrent force system structure principle.     

Testing and calibration of coordinate measuring arms

Portable coordinate measuring arms with rotational axes have found their place in many industrial areas. To establish and confirm the accuracy of these measuring devices, related test methods and appropriate devices are needed. After an introduction, a new high precision measuring device for testing and calibration of portable coordinate measuring arms is presented. Analysis showed that the best results can be obtained with a device for measuring along a straight line adjusted in various spatial directions. We discuss the design and construction of this measuring system and provide a theoretical calculation of its measurement accuracy, which was confirmed by experiments carried out on a prototype of a high precision measuring device in both unloaded and loaded conditions.     

氧浓度光学检测方法及其新应用

基于氧对荧光的猝灭作用,氧浓度光学检测方法可用于实验流体力学中表面压力测量,即光学压力测量技术。它是一种无接触、实时的氧浓度或表面压力测量的新技术,能够快速获得复杂流场中模型表面压力分布的连续图像。光学压力测量已在航空、航天、建筑和车辆的设计等领域显示其独特的优越性。本文介绍OPM技术的基本原理和特点,以及目前研究和应用的进展。     

Uncertainty evaluation procedure and intercomparison of bell provers as a calibration system for gas flow meters

Many NMIs (national measurement institutes) and calibration laboratories worldwide use a bell prover as a calibration system for gas flow meters. The basic definition and procedure to estimate the bell prover uncertainty have been given in previous studies. After the announcement of a mutual recognition agreement (MRA) in 1998 by the BIPM (Bureau International des Poids at Mesures), many NMIs have needed to have more details of uncertainty evaluation procedure of the bell prover. In this study, more details of the test procedure of bell prover uncertainty are presented with a modification of position of the temperature and the pressure sensor to measure more exact values. The other modification is to use three precise guide rods with bearings to make the pressure in the bell more stable. Furthermore, a laser interferometer is used to enhance the measurement accuracy of the testing time and the traveling length of the bell. The uncertainty of the bells estimated by the procedure given in this study is 0.13% at the confidence level of 95%, rather than 0.17% of the previous one. Recently, the results of CCM.FF-K6, which is an international comparison of NMIs organized by the CIPM (Comité International des Poids et Mesures), show that the uncertainty of the KRISS (Korea Research Institute of Standards and Science) bell prover estimated by this study is reasonable.     

盾构掘进中刀盘振动分析

针对不均匀地层中盾构施工引起的刀盘振动问题,建立刀盘有限元计算模型,并基于振动结构模态分析理论,分析盾构刀盘的模态特性,得到刀盘振型分析的结果同盾构掘进中出现的实际问题现象相一致。另外,以模态分析的结果为依据,分别从刀盘底座直径及柔度变化的角度分析对刀盘模态的影响,提出增大刀盘模态的方法及对刀盘结构设计的建议,从而可避免由于刀盘所受冲击与振动所致的联接螺栓松动及联接部件裂纹。此设计建议可应用于其它盾构刀盘的结构设计中,具有较大的工程实用价值。