NON-CONTACT MEASUREMENT SYSTEM OF FREEFORM SURFACE AND NURBS RECONSTRUCTION OF MEASUREMENT POINTS

Based on the development of the non-contact measurement system of free-formsurface, NURBS reconstruction of measurement points of freeform surface is effectively realized bymodifying the objective function and recursive procedure and calculating the optimum number ofcontrol points. The reconstruction precision is evaluated through Ja-cobi's transformation method.The feasibility of the measurement system and effectiveness of the reconstruction algorithm aboveare proved by experiment.

Non-contact measurement and multi-objective analysis of drilling temperature when drilling B_4C reinforced aluminum composites

Non-contact measurements of machining temperatures were performed with optical pyrometer when drilling particle（B4C） reinforced metal matrix composites（MMCs） with different drills. The effect of particle content, cutting speed, feed rate and tool material on the maximum drilling temperature was investigated. The drilling parameters were optimized based on multiple performance characteristics in terms of the maximum cutting temperature and tool wear. According to the results, the most influential control factors on the cutting temperatures are found to be particle fraction, feed rate and interaction between the cutting speed and particle content, respectively. The influences of the cutting speed and drill material on the drilling temperature are found to be relatively lower for the used range of parameters. Minimum cutting temperatures are obtained with lower particle fraction and cutting speed, with relatively higher feed rates and carbide tools. The results reveal that optimal combination of the drilling parameters can be used to obtain both minimum cutting temperature and tool wear.

Machine Vision for Non-Contact Automated Countersink Measurement

The slug rivet is widely used in wing assembly due to its longer fatigue life and better sealing performance compared with other connection technologies.As a countersink with dual-angle is widely adopted for this type of connection,the countersink diameter and depth are key factors that affect assembly quality.Therefore,it is of great importance to efficiently inspect the countersink quality to ensure high accuracy.However,contact measurements are susceptible to the loss of accuracy due to cutting debris and lube build-up,while the hole-scanning method using laser profilometry is time consuming and complex.In this paper,a non-contact method for countersink diameter and depth measurement based on a machine vision system is proposed.The countersink diameter can be directly measured by the machine vision system,while the countersink depth is determined through the countersink diameter indirectly.First,by means of image processing technology together with an improved edge detection algorithm,the countersink diameter can be obtained.Then,a 3D microscope is employed to measure the countersink depth,which helps to model the countersink.As a result,once the countersink diameter is measured,so is the depth.The experimentation demonstrated that this method has strong feasibility and enables time saving,which is conducive to improve the riveting efficiency.

A LASER-SCANNING NON-CONTACT MEASURING METHOD FOR ROUNDNESS ERRORS

利用激光狭缝扫描原理和光电传感技术，提出了一种用于测量大型回转体类零件圆度误差的激光扫描非接触测量方法和测量系统。本文详细论述了测量系统及其测量原理、工件安装偏心误差的分离技术和计算机实时数据处理系统，实验结果证实了这种测量方法的可行性。

Accurate Measurement Method for Tube's Endpoints Based on Machine Vision

Tubes are used widely in aerospace vehicles, and their accurate assembly can directly affect the assembling reliability and the quality of products. It is important to measure the processed tube＇s endpoints and then fix any geometric errors correspondingly. However, the traditional tube inspection method is time-consuming and complex operations. Therefore, a new measurement method for a tube＇s endpoints based on machine vision is proposed. First, reflected light on tube＇s surface can be removed by using photometric linearization. Then, based on the optimization model for the tube＇s endpoint measurements and the principle of stereo matching, the global coordinates and the relative distance of the tube＇s endpoint are obtained. To confirm the feasibility, ll tubes are processed to remove the reflected light and then the endpoint＇s positions of tubes are measured. The experiment results show that the measurement repeatability accuracy is 0.167 mm, and the absolute accuracy is 0.328 ram. The measurement takes less than 1 min. The proposed method based on machine vision can measure the tube＇s endpoints without any surface treatment or any tools and can realize on line measurement.

Deep-Hole Inner Diameter Measuring System Based on Non-contact Capacitance Sensor

A precise aperture measuring system of small deep holes with capacitance sensors is presented. Based on the working principle of non-contact capacitance sensors, influence of the edge effect of gauge head is studied, and one capacitance sensor for measuring the aperture of the small blind holes or through holes is introduced. The system is composed of one positioning device, one aperture measuring capacitance sensor, one measuring circuit, and software. This system employs visual CCD and two-dimensional mic...

Study on Coaxiality Measurement System of Compound Gear Shaft Based on Non⁃contact Optic

Aiming at the shortcomings of traditional contact measurement methods such as low measurement efficiency,high cost and low accuracy,a non-contact optical measurement method based on the laser displacement sensor is proposed.According to the relevant regulations of the coaxiality error evaluation standard and the structural characteristics of the compound gear shaft,we have designed and built a set of supporting software system as well as a hardware test platform.In this paper,the distance difference threshold and scale threshold methods are used to eliminate outlier data.The least squares circle is selected to calculate the center of the circle and the minimum containment cylinder axis method is used as the reference axis of the composite gear shaft.Compensated by the standard step shaft calibration,the coaxiality error of the composite gear shaft can be measured to be within 0.01 mm in less than two minutes.The range value of the multi-section measurement test is 0.065 mm.The average coaxiality error is∅0.476 mm.

Application of Three-dimensional Body Measurement System

The configuration principles and functions of the non-contact three-dimensional （3D） body measurement system （BMS） developed by the Textile/Clothing Technology Corporation （[TC]^2） are described in this paper. The advantages of this new system, compared with traditional contact body measurement instruments （ Martin instruments ） are discussed by selecting 40 female undergraduates of Donghna University as the scan objects. In the experiments both the Martin instruments and [TC]^2 BMS were used respectively. According to the data of different position （Bust Circumference, Full Waist, Full Hips, Bust Height, Front Waist Height and Back Waist Height） obtained from both of the methods we can get the correlation coefficient which is close to 1, indicating that the results of both methods have comparability. Finally some suggestions for the further applications of the non-contact BMS in the apparel development of China are given.

Three-Dimensional Measurement and Reconstruction of Fabric Drape Shape

This paper introduces a new method of measuring the three-dimensional drape shape of fabrics with structural light. First, we apply parallel annular structural light to form light and shade alternating contour stripes on the surface of fabrics. We then collect the images of contour stripes using Charge Coupled Device (CCD). Subsequently, we process the images to identify the contour stripes and edges of fabrics, and obtain the fabric contour lines of curved surfaces. Finally, we apply three-dimensional curved surface modeling method based on a network of polar coordinates, and reconstruct the three-dimensional drape shape of fabrics. Experiments show that our method is effective in testing and reconstructing three-dimensional drape shape of fabrics.

A Novel Approach for Warhead Fragments Velocity Measurement Based on Laser Screen

The velocity of warhead fragment is key criteria to determine its mutilation efficiency.We have designed an optoelectronic system to accurately measure the average velocity of warhead fragments.The apparatus including two parallel laser screens spaced apart at a known fixed distance for providing time measurement start and stop signals.The large effective screen area is formed by laser source,retro-reflector and large area photo-diode with a central hole.Whenever a moving fragment interrupts two optical screen,the corresponding photometers senses the event,due to partial obscuration of the incident energy.Experiments have been performed to measure velocity of the different kinds of projectiles and fragments within various size and velocity ranges,including 7.62 mm bullet shooting experiments,prefabricated steel-ball exploding experiments.They were proved that the system is adequate to measure the velocity of larger than 5 mm,less than 1 000 m/s in the range,when fixed trajectory,test the velocity of the projectile average relative deviation is less than 4.21%.The system can perform satisfactorily with a lot of advantages such as larger effective light screen area,quick response speed,low uncertainty,strong repetition and reliability,etc.

Inspection of Complex Internal Surface Shape with Fiber-optic Sensor II: for Specular Tilted Surface Measurement

Complex surface shape measurement has been a focus topic in the CAD/CAM field. A popular method for measuring dimensional information is using a 3D coordinate measuring machine (CMM)with a touch trigger probe. The measurement set up with CMM, however, is a time consuming task and the accuracy of the measurement deteriorates as the speed of measurement increase. Non-contact measurement is favored since high speed measurement can be achieved and problems with vibration and friction can be eliminated. Although much research has been conducted in non-contact measurement using image capturing and processing schemes, accuracy is poor and measurement is limited. Some optical technologies developed provide a good accuracy but the dynamic range and versatility is very limited. A novel fiber-optic sensor used for the inspection of complex internal contours is presented in this paper, which is able to measure a surface shape in a non-contact manner with high accuracy and high speed, and is compact and flexible to be incorporated into a CMM. Modulation functions for tilted surface shape measurement, based on the Gaussian distribution of the emitting beam from single-mode fiber (SMF), were derived for specular reflection. The feasibility of the proposed measurement principle was verified by simulations.

Permittivity Measurement of Low-Loss Substrates Based on Split Ring Resonators

In this paper, we present the complex permittivity measurement of low-loss substrates based on a microstrip-line-excited split-ring resonator (SRR). Permittivity of an unknown substrate is calculated based on the change in oscillation frequency of SRR caused by the material-under-test (MUT) above the SRR. Theoretical analysis and results of the simulations and experiments demonstrate the microstrip-line-excited SRR can be used to effectively improve measurement sensitivity. Simple equations for measurement of low-loss substrates using SRR are proposed and experimentally verified.

混合式K边界/X荧光密度计测铀钚质量浓度的不确定度分析

为检验混合式K边界技术测量混合溶液中铀钚质量浓度的精度,使用混合式K边界/X荧光密度计(hybrid K-edge/XRF densitometer,HKED)对不同混合溶液进行了铀、钚质量浓度测量实验。根据实验数据计算了测量结果的不确定度,并分析了测量过程中的偏差来源。通过对测量结果及不确定度的分析,验证了混合式K边界技术测量铀、钚质量浓度可达到核安全导则《核燃料后处理厂核材料衡算》中的测量精度,对标定范围内铀质量浓度的测量不确定度小于0.28%,钚质量浓度的测量不确定度基本小于0.94%,精度较高,能够满足生产中的衡算要求;总结了测量中的主要偏差来源和优化方向,为进一步提高测量精度和拓展混合式K边界技术在锕系元素测量中的应用提供数据支持。

不同摆位对骨密度测量仪测量结果的影响

目的研究不同摆位对骨密度测量仪测量结果的影响。方法选取天津市河西区柳林医院2021年1月至2022年12月收治的46例骨质疏松患者为研究对象,分别在标准内旋位和自然体位下应用骨密度测量仪对患者进行骨密度测量,将测量结果分别记为对照组和观察组。观察两组骨密度测量图像数据结果和半定量分析结果。结果观察组转子骨密度、总骨矿盐含量、总骨密度、转子T值、转子Z值、总T值和总Z值等均显著高于对照组(P<0.05),观察组分类半定量评分为(2.62±0.52)分,显著高于对照组的(1.76±0.51)分,P<0.05,观察组骨折危险性半定量评分显著低于对照组(P<0.05)。结论不同摆位情况下骨密度测量结果存在明显差异,自然体位检测得到的骨密度结果相对偏高。内旋位是标准的检查方法,自然位双能X线吸收测量仪检查可能会“高估”骨密度,“低估”骨折风险。

Clinical study using novel endoscopic system for measuring size of gastrointestinal lesion

AIM: To verify the performance of a lesion size measurement system through a clinical study.

A Contact and Non-Contact Hybrid Profilometer with Large Range

A novel hybrid instrument of contact and non-contact measurement with large range is developed, and both measurement systems are based on a Linnik interference microscope and on white-light interference measuring techniques. The ambiguity presented in conventional monochromatic interferometers is not present in the contact and non-contact measurement, and they have a virtually unlimited unambiguous range. For the contact measurement, the vertical measuring range is ±5 mm with a resolution of 1 nm and the horizontal measuring range is ±25 mm in x-range and y-range with a resolution of 1.25 μm; for the non-contact measurement, the vertical measuring range is ~5 mm with a resolution of 1 nm and the horizontal resolution better than 0.5 urn.

绞吸挖泥船管路微波浓度计实验测量研究

绞吸挖泥船施工时浓度、流量往往是评价挖泥船能力和生产效益的最重要指标。由于挖泥船输送介质具有浓度高、组成复杂、大粒径岩土砾石众多等特点,因此对于管路浓度的测量,多采用放射性γ射线密度计,该方法具有非接触、精度高等特点,但是会对环境造成一定的污染,所以亟需寻求可以替代放射性测量的非核浓度计测量方法。因此,针对挖泥船输送液固两相流介质特点,以现有管道输送试验台为对象,该文提出了微波浓度测量方法,通过测量管路中的水分含量,获取固体物料的含量,从而有效避免了物料粒径过大、气泡等对测量精度的影响。该文通过模型实验验证了泥浆浓度测量的准确性,并针对温升造成的传感器数据偏差,利用LABVIEW编写了温度补偿程序作为初步解决方法,最后利用实验验证该解决方法的可行性。该方法能够降低温度导致的浓度变化量,达到减小误差的目的。

Posture-invariant hybrid scaling weight measurement algorithm for live eels

To obtain higher economic benefits,large eel breeding companies classify live eels by weight.Due to their strong mobility and smooth body surface,living eels are not suitable for traditional mechanical weight measurement.In this study,a live eel sorting machine based on machine vision was developed,and a novel method was developed for obtaining live eel weight measurements through images.First,a backlit workbench was designed to capture static images of eels,and then the projection area and skeleton length of the images were obtained by image preprocessing.For the eel's body shape,which is generally cylindrical and gradually transitions to a flat tail,the tail posture changes affect the shape of the images;thus,a weight measurement model combining the projected area and the skeleton length was proposed.The optimal scale division coefficient of the weight model was found to be 0.745 by experimentation.Then,select eels of different weight ranges were used for model error verification and to obtain the correction function of the error.The weight gradient was used to confirm the corrected eel weight model.Finally,the system calculation results were compared with the actual measurement results.The root mean square error(RMSE)was 12.94 g,and the mean absolute percentage error(MAPE)was 2.12%.The results show that the proposed method provided a convenient,fast,and low-cost non-contact weight measurement method for live eels,reduced the damage rate of live eels,and can meet the technical requirements of actual production.

Non-Contact Measurements of Water Jet Spreading Width with a Laser Instrument

Jet spreading width is one of the important characteristics of water jets discharging into the air.Many researchers have dealt with measuring this width,and contact measuring methods on the water jet surface were employed in a lot of the cases.In order to avoid undesirable effects caused by the contact on the jet surface,we introduce non-contact measuring methods with a laser instrument to the measurements of jet spreading width.In measurements,a transmitter emits sheet-like laser beam to a receiver.The water jet between the transmitter and the receiver interrupts the laser beam and makes a shadow.The minimum and maximum values of the shadow width are measured.In addition,pictures of the water jet are taken with a scale,and the shadow width is measured from the pictures.The experiments on various needle strokes were performed.Three kinds of width consistent with the jet structure were obtained.In the results,it can be concluded that our non-contact measuring methods are feasible.The data of jet spreading widths and jet taper were obtained and are useful for future applications.

一种基于单片机的智能化便携振动管式液体密度计的研制

介绍了一种便携式U -型振动管液体密度计 ,该仪器具有使用方便、性能稳定、测量精度高且样品种类广等优点 ,可广泛用于各类高精度密度测量。文中介绍了振动管式液体密度传感器的组成结构和工作原理 ,论述了传感器安装方式对振动管振动的影响 ,详细阐述了密度信号频率的软同步测量方法 ,并简要介绍了密度计的硬件电路和软件流程及系统的低功耗设计。