Performance evaluation experiments on a laser spot triangulation probe

Laser triangulation probes are increasingly used for dimensional measurements in a variety of applications. At the National Institute of Standards and Technology, we have recently explored the use of laser spot triangulation probes to determine dimensional features such as height and width of channels in a fuel cell plate. To assess the suitability of the probes for performing these dimensional measurements, we designed several experiments that highlighted different error sources in the probes. This report is a summary of those experiments. Numerous studies have been reported in the literature on error sources in laser triangulation probes utilizing artifacts of varying shape (form), color, reflectivity, surface finish, etc. However, our experiments are targeted towards establishing bounds on errors when measuring simple linear dimensions such as height and width on prismatic objects of a single color and material. Our scope is indeed narrow, but intentionally so; it is our objective to highlight the influence of a number of “hidden performance attributes” [1] that impact accuracy of even simple linear dimensional measurements so that it may be of use to others who perform similar measurements.     

非接触测量激光光学探头

阐明了激光三角测量的原理, 推导了有关的公式, 对影响测量精度的诸因素进行了分析。介绍了基于三角测量原理的非接触激光光学探头的设计, 给出了实验结果, 展望了应用前景。     

非接触测量中激光扫描探头的研究

本文基于光学三角测量原理设计了一种高精度、多功能的非接触激光扫描探头装置,对该装置的性能特点进行了系统地研究,并用所设计的探头装置对几种不同的漫射面进行了实际测量,给出了实验结果,实验表明该装置精度优于2μm。     

在役套管的激光测量法研究

介绍激光三角测量法在套损检测中的应用，激光三角法的测量原理、结构组成及CCD信号采集。提出双层4探头交叉测量方法对套管内壁腐蚀缺陷的检测，实现了单探头单通道测量，通过数据处理判断腐蚀缺陷的位置和深度。     

基于PSD的小型激光测头的设计

利用位置敏感探测器(PSD)频率响应高、接口电路简单、数据采集快等特点,设计了一种小型、动态激光三维测头。该测头采用激光三角法原理,利用凹凸双透镜光学系统进行激光缩束以提高测量精度,利用平面反射镜增加光程以减小体积,并对各具体参数和整体结构进行了详细的设计。该测头系统拥有体积小,精度高,反映快的优点。     

Non-Contact Triangulation Measurement of Distances to Mirror Surfaces

Metrological analysis of triangulation laser sensors for measuring distance to mirror surfaces was performed. Theoretical and experimental studies have established that the measurement range of distance depends on the angle of incidence of the laser beam, and the main factor that affects the measurement accuracy is the rotation of the sensor in the plane of incidence. A non-contact sensor for measuring distance to liquid surfaces which provides signaling upon reaching a prescribed value is designed. An overview of triangulation measurement systems is given.     

基于激光三角法原理的轮对几何参数自动检测系统

介绍了一种基于激光三角法原理的轮对几何参数在线自动检测系统。运用CCD摄像机、线激光光源、数字图像采集与处理技术,研制出了一种列车轮对外形几何尺寸高速在线检测系统。经过在上海轨道交通1号线上的实际运用,验证了本系统的可行性与可靠性,实现了对列车轮对直径、轮缘高度、宽度、轮缘角等重要几何参数的测量。     

铁路货车底部超限测量系统

铁路货物运输中，底部超限测量一直是安全监测上的难点。介绍了一种利用线激光投影结合图像量测进行铁路货车底部超限测量的方法。系统采用激光三角法的原理，利用红光线激光器和CCD传感器组成测量系统，并提出了一种快速的基于边缘提取的激光线提取算法；设计了精确的标定装置，提出了相应的标定方法，使超限货物能被准确地测出。描述了完整的系统硬件组成和软件结构，经过了多次实验，结果证明测量系统准确可靠。     

HYBRID CONTROL OF HYDRAULIC PRESS MACHINE BASED ON ROBUST CONTROL

A robust control algorithm is proposed to focus on the non-linearity and variables of the hydraulic press machine with the proportional vatve. The proposed robust controller does not need to design stable compensator in advance, which is simple in design and has large scope of uncertainty applications. The feedback gains of the proposed robust controller are small, so it is easily implemented in engineering applications. The theoretical and experimental research on the position and speed control of the hydraulic press machine is carried out. The control requirements of the hydraulic press machine during the working process are met in the position and speed at the same time. Experimental results show that the proposed controller has better robustness subject to load variables and adaptability of parameter variations of the hydraulic press machine with the proportional valve.     

激光非接触式彩管荫罩Q值测量机研制

为提高彩管荫罩Q值测量的效率和精度，提出了一种综合运用开放式数控和激光非接触式测量原理的测量方法，并研制出了Q值测量机样机。介绍了系统的主体结构，机械传动执行机构和控制结构；激光三角测量法和Q值测量的原理及软件功能。给出了测量实例数据，通过与现有接触式测量机的测量数据比较，得出了在保证测量精度的基础上，该测量机可以大大提高测量效率的结论。     

激光三角法扫描测头特性的研究

在分析了激光三角法位移测量原理的基础上,以ＩＢ－１２型激光三角法位移传感器为实例,研究了激光三角法位移传感器的使用特性,补偿非线性误差、倾斜角误差,提高了测量精度,使其能够作为非接触式扫描测头用在三坐标测量机上,完成空间自由曲面的非接触扫描测量。     

NON-CONTACT MEASUREMENT OF SCULPTURED SURFACE OF ROTATION

A method for measuring the sculptured surface of rotation by using coordinate measuring machine (CMM) and rotary table is proposed. The measurement is realized during the continuous rotation of the workpiece mounted on the rotary table while the probe moves along the generatrix of the surface step by step. This method possesses lots of advantages such as simplicity of probe motion, high reliability and efficiency. Some key techniques including calibration of the effective radius of the probing system, determination of the position of axis of rotation, auto-centering of the workpiece, data processing algorithm, are discussed. Approaches for determining the coordinates on measured surface, establishing workpiece coordinate system and surface fitting are presented in detail. The method can be used with contact or non-contact probes. Some fragile ceramic and plaster parts are measured by using the system consisting of a CMM, rotary table, motorized head and non-contact laser triangulation probe. The measurin     

轴类零件参数综合检测

以轴直齿类零件为例 ,提出一种快速、能同时测量轴向尺寸和径向尺寸的非接触、多参数综合测量方法。它利用基于光学三角法的激光位移传感器获得轴类零件的径向尺寸 ,利用半导体激光器与光电二极管组成的扫描式发讯传感器和光栅传感器的组合获得轴向尺寸。探讨了该系统的检测性能 ,给出了实测结果     

激光主动测距法在盘煤系统中的应用

针对大型露天煤场设计了一种激光主动测距盘煤系统。对煤堆不需要进行前期整形,就可以测量出煤场的存煤量。这个系统运用了激光扫描技术,通过主动三角测距法对煤堆体积进行自动测量。先对整个区间进行划分,然后对每个区间的几个点进行测量,拟合出煤堆表面轮廓形状,求出每个区间的体积,再累加即可得到整个煤堆的体积。给出了三角测距法的测量公式,并进行了精度分析。介绍了激光盘煤系统的组成,工作原理以及转台的设计,并进行了试验检验。通过试验证明,盘煤系统结构可靠、测量精度满足使用要求。     

基于激光三角法和嵌入式的微位移实时检测系统

基于激光三角法和嵌入式的微位移实时检测技术,采用激光三角法测距和灰度重心法提取激光条纹中心的原理,使线结构光、透镜、CCD位置信息满足Scheimpflug共轭清晰成像条件。通过图像处理获取像面坐标系位移信息,得到待测物体物面坐标系的位移,利用灰度重心法实时提取结构光条纹中心的特点,结合嵌入式系统尺寸小、稳定、便携的特性,实现对待测物体进行实时、非接触和微位移测量。     

Effect of slice thickness on the profile accuracy of model maker rapid prototyping measured by a circular triangulation laser probe

The objective of this research is to investigate the effect of slice thickness on the profile accuracy of the model maker (MM) rapid prototyping (RP) system, layer by layer, through non-contact laser probe measurement. A circular triangulation laser probe, model OTM-3A20, made by Wolf & Beck Co., was mounted on a coordinate measuring machine (CMM), as the non-contact sensor. An adjustment device for the laser probe was designed to minimise the cosine error caused by assembly inaccuracy. The alignment test of the measuring laser beam was carried out using a calibrated specimen. The systematic accuracy of the circular triangulation laser probe with respect to the surface roughness and the surface slope of the RP workpiece was investigated using a HP5529A laser interferometer system. The maximum error of 21/2D RP part profile accuracy can be improved from 220 μm to 131 μm, and the average error can be improved from 78 μm to 46 μm as the slice thickness changed from 0.127 mm (0.005 in.) to 0.0127 μm (0.0005 in). However, the machining time increases by about seven fold based on the experimental results. An overall error of 197 μm as measured by the laser probe is attainable using the finest slice thickness 0.0127 mm (0.0005 in.) for the 3D profile accuracy. To verify the accuracy of non-contact laser probe measurement, the 3D profile of the RP part was also measured by a CNC CMM, with good consistency.     

基于PSD的孔径测量系统设计

为了适应现代化生产和在线检测,提出了应用位置敏感探测器及激光三角法原理实现非接触内径测量的测量系统设计方案。分析了位置敏感探测器工作原理,系统测量原理,及电路原理和电路元件参数,实现了微弱电流的提取、放大、转换。整个测量系统的测量范围为1mm,采用加工精度为1μm、直径为90mm的内径标准件对测量系统进行精度校验,实验表明,在1mm测量范围内系统测量精度高于5%。     

高精度压力膜片光学测量系统设计

介绍了利用高精度激光位移传感器为主要探测元件,结合高精度伺服机构、精密X-Y平台、伺服控制卡和信号采集卡开发的汽车传感器压力开关膜片测试系统.系统主要实现压力位移测试和膜片表面形状精确测试两项功能.应用高速采样板卡和双缓存数据读取机制,实现了压力位移数据实时采集;高精度伺服机构和自动定位扫描算法相结合,提高了扫描平面分辨率.系统通过高性能测试元器件和合理的软件设计,实现了膜片压力位移曲线和表面形状的精确测量,为压力开关的设计和分析提供科学的检测手段.     

Butt autogenous laser welding of AA 2024 aluminium alloy thin sheets with a Yb:YAG disk laser

Higher productivity, lower distortion and better penetration are the main advantages provided by laser welding in comparison with conventional processes. A Trumpf TruDisk 2002 Yb:YAG disk laser is used in this work to increases productivity and quality. Aluminium alloys lead to many technological issues in laser welding, resulting in shallow penetration and defects. In particular, AA 2024 aluminium alloy in a thin sheet is investigated in this paper, being it is used extensively in the automotive and aerospace industries. Bead-on-plate and butt autogenous laser welding tests with continuous wave emission on 1.25 mm thick AA 2024 aluminium alloy sheets were examined morphologically and micro-structurally. The geometric and mechanical features of the welding bead were evaluated via a three-level experimental plan. In addition to the power and speed which are traditionally referred to, beam defocusing was considered as an additional governing factor in a central composite design scheme because it massively affects keyhole conditions. Softening in the fused zone is discussed via Vickers micro-hardness testing and magnesium loss through energy dispersive spectrometry. After properly performing the modelling and optimisation of the fused zone and the cross-section shape factor as the response variables, the laser welding conditions for thin sheets of AA 2024 aluminium alloy are suggested. X-ray and tensile tests were conducted on the specimens obtained with the recommended processing parameters to characterise the AA 2024 disk laser welded beads.     

激光三角法内孔测量传感器的光学成像分析

为了实现对孔类零件特别是深孔零件的孔深测量,设计了一套激光内孔测量传感器.该传感器基于激光三角测量的方法,利用梯形棱镜的全反射特性将光路限制在狭窄的空间内,从而实现对深孔或盲孔的测量.针对该传感器的光学成像规律做出了深入的分析,并结合目前存在的问题提出了几种改进方案.实验结果表明:梯形棱镜能够较好地解决测量内孔时物理空...