【作者】 张伟；

【导师】 陈文建；

【作者基本信息】 南京理工大学 ， 光学工程， 2024， 硕士

【摘要】 激光三角测距技术是实现非接触式距离测量的重要手段,该技术可以快速检测出目标的位移、厚度、振动等信息,具有测量速度快、精度高、适用范围广等优点,适用于在线检测领域。本课题应用于列车厢底与轨道间距的实时监测,根据厢底高度选择200至500mm量程的位移传感器作为设计与优化对象,开展了中距离大量程的激光三角位移传感器的设计研究,主要进行了以下工作:首先从理论上对激光三角法原理进行了分析研究,比较斜射式与直射式激光三角法,选择确定直射式激光三角法作为系统测量方案,并分析了主要结构参数对器件性能的影响。同时,为提高激光三角测量的线性度以及减小仪器尺寸,在接收光路中设置了平面转像反射镜实现光路折叠,并利用引力搜索算法优化了系统结构参数,获得了更均匀的灵敏度分布。其次进行了光学系统与硬件电路的设计,根据激光三角测距原理,结合已确定的光路结构确定了光学系统技术指标,利用ZEMAX光学设计软件设计出符合成像要求的沙姆物镜。设计了以FPGA硬件平台作为控制核心的CMOS图像传感器光电转换与信号处理电路,最终实现了激光三角位移传感器的硬件研制。接着设计了软件算法以实现光斑信号的滤波及中心定位处理,比较各种光斑中心定位算法的效果并选择了最准确的高斯拟合法进行中心位置定位,使用卡尔曼滤波方法代替常用的时间平均算法,取得了更佳的时间稳定性。根据光斑与被测面距离的对应关系,编写上位机程序实现数据处理与距离显示。最后使用设计搭建的传感器测量了实验数据,将实验数据与理论曲线进行对比,验证了相关理论的可行性,并进行误差分析。结果表明,本系统对0.1mm位移量的测量绝对误差小于0.02mm。更多还原

【Abstract】 Laser triangulation ranging technology is an important means to realize non-contact distance measurement,which can quickly detect the displacement,thickness,vibration and other information of the target,and has the advantages of fast measurement speed,high precision,wide application range,etc.,which is suitable for online detection field.This topic is applied to the real-time monitoring of the distance between the bottom of the train car and the track.According to the height of the bottom of the car,the displacement sensor with a measuring range of 200 to 500mm is selected as the design and optimization object,and the design and research of the laser triangular displacement sensor with a large measuring range are carried out.The main work is as follows:Firstly,the principle of laser triangulation is analyzed theoretically.Comparing oblique laser triangulation with direct laser triangulation,direct laser triangulation is selected as the system measurement scheme,and the influence of main structural parameters on device performance is analyzed.At the same time,in order to improve the linearity of laser triangulation and reduce the size of the instrument,a planar image transfer mirror is set in the receiving optical path to realize the optical path folding,and the gravity search algorithm is used to optimize the system structure parameters,and a more uniform sensitivity distribution is obtained.Secondly,the optical system and the hardware circuit are designed.According to the principle of laser triangulation,the technical index of the optical system is determined by combining with the established optical path structure,and the Scheimpflug objective that meets the imaging requirements is designed by using ZEMAX optical design software.The photoelectric conversion and signal processing circuit of CMOS image sensor with FPGA as the control core is designed,and the hardware development of laser triangular displacement sensor is realized.Then,a software algorithm is designed to realize the filtering and center location processing of the spot signal.The effect of various spot center location algorithms is compared and the most accurate Gaussian fitting method is selected for center location.The Kalman filter method is used to replace the commonly used time average algorithm,and better time stability is obtained.According to the corresponding relationship between the spot and the measured surface,the computer program is written to realize the data processing and distance display.Finally,the experimental data are measured with the designed sensor,and the experimental data is compared with the theoretical curve to verify the feasibility of the relevant theory,and the error analysis is carried out.The results show that the absolute error of 0.1mm displacement measurement is less than 0.02mm.更多还原