基于三次拟合方程畸变校正的光电测量系统

在大视场光电测量系统中,光学系统产生的畸变使目标在线阵CCD上的成像偏离了理论成像点,导致系统产生测量误差.为了减小该误差,提高系统的测量精度,根据畸变产生机理,设计了由11个等距目标点组成的畸变检测装置.根据检测得到的系统实际畸变变化情况,需要拟合出系统测量时目标点在线阵CCD上成像位置的补偿方程.以检测装置测量拟合得到的三次补偿方程作为畸变校正的数学模型编写了测量校正程序,对光电测量系统进行了实验检测.测量结果表明,当目标物物高为200.115mm时,按照拟合的补偿方程进行计算补偿,可将畸变误差从校正前的-2.08mm提高到校正后的0.05mm,并使系统整体检测精度从1.039%提高到0.025%.     

图像对准系统中提高精度的软件补偿技术

本文根据分层制造对准系统的精度要求,研究了改善精度的软件补偿措施:设计了SUSAN和多帧平均降噪结合的无损滤波算法以减小滤波过程对标记图像产生的畸变;以频域能量谱函数作为系统的聚焦测度函数实现自动聚焦,消减了由离焦引入的对准误差;以校正残差均方差的大小和稳定性为依据确定了三次多项式畸变模型,校正后畸变引入标记定位误差小...     

f-(θ)物镜非线性扫描误差的检测研究

在振镜和f -q 线性扫描物镜构成的线性扫描机构中,f -q 物镜的设计、加工误差会引起一定的非线性扫描误差,影响扫描成像的质量。为了检测f -q 物镜的非线性扫描误差,使用基于线阵CCD的检测电路和扫描光点位置检测算法进行了实验研究,得到了可用于校正的扫描光点位置以及振镜摆角的对应关系曲线和f -q 物镜的非线性扫描误差曲线。     

激光内径测量系统参数校正及算法优化

基于激光位移扫描的大尺寸内径测量系统中,测量数据存在多个系统误差参数并易受到粗大误差的影响.在分析该系统工作原理的基础上,分析了测量传感器安装倾斜误差和回转臂偏心误差,并提出了相应的校正补偿方案.针对动态测量、管壁划痕、斑迹等引入的粗大误差对测量数据的最小二乘圆拟合精度影响较大的问题,提出了一种剔除粗大误差的方法:根据最小平方中值法构建基准圆,剔除孤立点,再用最小二乘法拟合,实验结果表明该算法的精度优于直接最小二乘法5倍.     

基于扫描线模型的电子激光经纬仪自动瞄准方法研究

为了提高基于视觉引导的经纬仪测量系统的测量效率,提出了一种对空间平面上目标点坐标进行精确瞄准测量的方法。利用激光电子经纬仪对目标做单轴扫描,进一步获得像平面扫描轨迹的平行网格模型,通过该模型建立了扫描线长度与经纬仪单轴旋转角度的关系,并对镜头畸变进行校正,最后利用插值算法得到经纬仪瞄准目标点时的精确角度值。实验结果表明,在矫正畸变后在 10 m×10 m空间内精度可达到 3″,该方法可以有效提高测量效率,保证测量精度。     

三轴地磁传感器参数的在线校正算法

针对复杂磁环境下传统的地磁传感器误差补偿算法效果不理想的问题,分析了地磁传感器各种误差来源,建立了完整的地磁传感器误差模型,提出了基于递推最小二乘的在线校正方法,实时求取椭球模型系数.利用椭球系数推导地磁传感器误差补偿系数.利用补偿系数对姿态测量系统输出的地磁矢量进行校正.实验结果表明,校正后的磁场强度和实际磁场强度基本一致,非盲区位置的滚转角误差减小到5°以内,基本可以满足简易制导弹药对姿态角解算的精度要求.     

基于MATLAB对三维激光扫描数据的精度评定

针对三维激光扫描存在对扫描精度难以评定的问题,该文提出了1种基于(结合)MATLAB的三维激光扫描数据的精度评定方法。首先,对三维激光扫描测量的数据进行预处理,获得被扫描体表面的点云数据;其次,切割被扫描体的点云曲面,获得点云剖线;再次,通过MATLAB拟合点云曲线,将其转成离散点位;最后,依托TS30高精度的特点,对三维激光扫描数据进行精度评定。     

基于距离精度的测量机器人标定模型及算法

对机器人绝对位置误差进行检测和补偿时,通常要涉及到测量系统坐标系与机器人基础坐标系间的坐标变换,由于这个变换很难精确测定,从而导致测量机器人的绝对位置精度降低.为了克服这一情况,可改用空间两点间的距离精度来衡量机器人的绝对位置精度,这样可简化测量过程.利用距离精度的定义,建立了机器人的距离误差模型,该模型可以避免坐标转换带来的误差,降低对测量系统的精度要求.同时,激光跟踪仪测试技术的应用,使得机器人的位姿测量变得非常容易.最后给出了此模型及算法在IRB2400机器人上的应用实例.     

星敏感器参数标定及误差补偿

针对CCD星敏感器光学系统存在焦距不准确、CCD平面倾斜和旋转及光学镜头畸变等误差因素,在理想针孔模型的基础上,用几何方法建立了星敏感器模型。利用地面实验数据,以最小二乘法解算该数学模型,求出焦距、CCD平面倾斜和旋转因子及畸变因子等待标定参数。将标定出的参数代回数学模型,便可由星象点测量坐标直接计算并修正入射光方向矢量,从而对光学系统的误差进行了补偿。计算结果表明:星对角距统计偏差由标定前41″降到了17″,提高了计算精度。     

转镜-振镜扫描的非线性及非对称性研究

根据几何光学原理,推导出转镜-振镜扫描系统物镜前振镜上光斑移动速度的解析表达式。 系统本身的结构特点是产生扫描非线性和非对称性的根源,并会引起图像畸变。对设计的40面,半径40mm,转速为23437.5rmin-1的转镜-振镜系统的数值计算结果表明,行扫描中最大速度差约为6m.s-1,时间对称中心从32祍改变到约30.7477祍。此结果可作图像畸变修正的参考。     

基于多边法的三维坐标测量系统自标定最优方案

研究了基于多边法的三维坐标测量系统的自标定问题 ,并首次给出了四路激光跟踪干涉仪和测量点布局的一些指导性原则。首先从系统自标定的数学模型入手 ,指出影响系统自标定的各个因素。通过大量的计算机仿真 ,研究各个因素对系统自标定的影响规律。最后综合得到了系统自标定应遵循的一些指导性原则 ,这些原则对于实际操作时进行合理的系统自标定、提高自标定精度乃至提高整个系统的测量精度具有重要意义     

High-accuracy calibration for multi-laser powder bed fusion via in situ detection and parameter identification

Multi-laser powder bed fusion (ML-PBF) adopts multiple laser-scanner systems to increase the build envelope and build speed, but its calibration is an iterative and time-consuming process. In particular, multiple large-scale scan fields have a complex distortion in the overlap area, challenging the calibration process. In this study, owing to the enormous workload and alignment problems in the calibration of multiple scan fields, a novel calibration system is designed in this study to realize in situ auto-detection of numerous laser spots in the build chamber to ensure high efficiency and accuracy. Moreover, because the detectable area could not cover the entire build area and the detection data still contained errors, a virtual laser-scanner system was established by identifying the assembly defects and galvo nonlinearities of the ML-PBF system from the detection data, which served as the system's controller to improve calibration accuracy. The multi-field alignment error was less than 0.012%, which could avoid the intersection and separation of scan paths in multi-laser scanning and therefore meet the requirements for high-precision ML-PBF. Finally, the reliability of the method was verified theoretically using principal component analysis.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00392-3     

Development of an In-Situ Laser Machining System Using a Three-Dimensional Galvanometer Scanner

In this study, a three-dimensional (3D) in-situ laser machining system integrating laser measurement and machining was built using a 3D galvanometer scanner equipped with a side-axis industrial camera. A line structured light measurement model based on a galvanometer scanner was proposed to obtain the 3D information of the workpiece. A height calibration method was proposed to further ensure measurement accuracy, so as to achieve accurate laser focusing. In-situ machining software was developed to realize time-saving and labor-saving 3D laser processing. The feasibility and practicability of this in-situ laser machining system were verified using specific cases. In comparison with the conventional line structured light measurement method, the proposed methods do not require light plane calibration, and do not need additional motion axes for 3D reconstruction; thus they provide technical and cost advantages. The in-situ laser machining system realizes a simple operation process by integrating measurement and machining, which greatly reduces labor and time costs.     

一种浮空器气囊体积测量装置的现场校准方法探讨

介绍一种浮空器气囊体积测量装置的现场校准方法,通过设定现场校准区域,构建地面控制点的局部三维坐标;在被测对象侧边的6个地面控制点设立测站,用激光全站仪和棱镜组件按照极坐标法观察得到被测对象侧边精密标定杆上所有准校点的局部三维坐标,建立校准参考坐标系,构建完整的现场校准场。测量装置对在校准参考坐标系中的精密标定杆上校准点进行拍摄获得图片,解算得到测量装置的每个相机的外方位元素,得到其位置和姿态,完成校准工作。本文提出的现场校准方法解决了测量装置在任意场景下浮空器囊体体积测量的应用问题和测量装置使用中需要搬动情况下的校准问题。     

Inconel 625镍基高温合金激光增材制造翘曲变形行为研究

为了明晰激光增材制造翘曲变形行为,获得相关变形规律。对Inconel 625高温合金激光增材制造工艺对零件变形量的影响进行了分析,实验结果表明:扫描路径的长度决定翘曲变形量的大小;不同工艺参数对翘曲变形量的影响程度不同;激光增材制造加工过程一般会同时引起两个方向的翘曲变形;同时翘曲变形量随着激光功率的增加而增加,随着扫描速度的增加而增加,随着送粉速度的增加而减少。     

三维重构视觉系统的标定

文章基于改进两步法的标定思想,在三维重构中提出了一种新的视觉系统参数标定与镜头畸变修正方法.该方法根据图像中心附近点畸变量较小的性质,利用中心附近点和全场视点对CCD相机和DLP投影仪的内外部参数标定和镜头畸变修正进行分离.在标定过程中,所设计的带标准圆阵列的靶标和伪随机连续方形编码可以实现特征点的自动识别和匹配.实验表明,该方法能快速、方便地对视觉系统参数进行标定和镜头畸变修正.     

大型硅晶片平面度精密纳米计量技术

描述了一种基于斜率传感器的大型硅晶片平面度扫描测量系统．采用二维斜率传感器对晶片表面扫描，以获得表面绕X和Y轴的倾斜度．斜率传感器装在X向滑板上，而晶片固定在可绕Z轴转动的主轴上．对斜率传感器Y向的输出积分，得到晶片表面各个同心圆上轮廓截面高度．对斜率传感器X向的输出积分，得到晶片表面沿X向的截面轮廓，从而获得各同心圆轮廓之间的关系．构建了一个包括基于自准直原理的小型斜率传感器、气浮主轴、气浮导轨的实验系统，提出一种斜率传感器现场标定方法，用此系统测量了直径300mm的硅晶片平面度。     

计算机单目视觉测量系统

为了精确实现对空间物体的测量,提出了利用线激光、单CCD相机、小孔成像与激光面约束模型的激光线测量法。引进三维信息已知的标准阶梯块,作为激光面约束的标定块。由计算机控制摄像头对实物连续拍摄和实时处理,提取激光线上的像素坐标,利用建立的模型将二维坐标转换成三维坐标,再以点云的形式重构出物体,实现三维自动测量。实践中检测系统测量精度可达到0.05mm。     

A Dual-Platform Laser Scanner for 3D Reconstruction of Dental Pieces

This paper presents a dual-platform scanner for dental reconstruction based on a three-dimensional (3D) laser-scanning method. The scanner combines translation and rotation platforms to perform a holistic scanning. A hybrid calibration method for laser scanning is proposed to improve convenience and precision. This method includes an integrative method for data collection and a hybrid algorithm for data processing. The integrative method conveniently collects a substantial number of calibrating points with a stepped gauge and a pattern for both the translation and rotation scans. The hybrid algorithm, which consists of a basic model and a compensation network, achieves strong stability with a small degree of errors. The experiments verified the hybrid calibration method and the scanner application for the measurement of dental pieces. Two typical dental pieces were measured, and the experimental results demonstrated the validity of the measurement that was performed using the dual-platform scanner. This method is effective for the 3D reconstruction of dental pieces, as well as that of objects with irregular shapes in engineering fields.     

Scanning laser differential-heterodyne interferometer for flying-height measurement

With conventional optical interferometry flying-height testing, a stationary measurement beam and a two-axis moving stage are used to measure slider-disk spacing at different points on the slider. Pitch angle or roll angle is calculated on the basis of the measurement results. We report on a scanning differential-heterodyne interferometer, which measures the continuous flying-height variation along the edge of a slider with two continuously scanning laser beams. Pitch angle or roll angle can be obtained directly from the scanning measurement. The system can also measure points individually to obtain the absolute flying height at different locations on the slider. Experiments were performed to demonstrate the concept of scanning measurement. The flying-height variation along the slider edge was measured by continuous scan and by point-to-point moving. The measurement results from continuous scan coincided with those of conventional methods.