基于参考靶标的线结构光传感器标定
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摘要
为提高线结构光传感器(LSLS)的标定精度,提出了一种基于平面参考靶标的标定方法。给出了相机坐标系下参考靶标点中心坐标及激光平面方程的计算方法;将参考靶标点中心向激光平面投影,并以左下角投影点为原点建立世界坐标系,得到了靶标点中心像素坐标所对应的世界坐标;采用多项式拟合得到了任意像素点到世界坐标的转换关系,实现了传感器的标定,标定结果仅为多项式的系数,便于存储和使用;对标定误差进行了分析。结果表明,所提方法得到的各测试点与第一个点间距离误差的均方根值为0.0216 mm,相对于传统方法减少了22%,所提方法在LSLS高精度标定方面具有一定的优越性。
To enhance the calibration accuracy of the line structured light sensor(LSLS), we propose a novel calibration method based on the planar reference target. A method is brought out to calculate the coordinates of the reference target point centers and the laser plane equation in the camera coordinate system. These reference target center points are projected onto the laser plane. The world coordinate system is established with the projection point of the lower left corner as the origin. The corresponding world coordinates for each center of the target point, which has known pixel coordinates, can be obtained. The mapping relationship between the arbitrary pixel coordinates and the world coordinates is achieved via the polynomial fitting and the calibration of sensor is finished. The calibration results are the coefficients of the polynomials, which are convenient for storage and use. The calibration accuracy is analyzed. The results show that the root mean square of distance error between each testing points and the first point is 0.0216 mm, which is 22% lower than the classical method. The proposed method has certain advantages in high-precision calibration of LSLS.
To enhance the calibration accuracy of the line structured light sensor(LSLS), we propose a novel calibration method based on the planar reference target. A method is brought out to calculate the coordinates of the reference target point centers and the laser plane equation in the camera coordinate system. These reference target center points are projected onto the laser plane. The world coordinate system is established with the projection point of the lower left corner as the origin. The corresponding world coordinates for each center of the target point, which has known pixel coordinates, can be obtained. The mapping relationship between the arbitrary pixel coordinates and the world coordinates is achieved via the polynomial fitting and the calibration of sensor is finished. The calibration results are the coefficients of the polynomials, which are convenient for storage and use. The calibration accuracy is analyzed. The results show that the root mean square of distance error between each testing points and the first point is 0.0216 mm, which is 22% lower than the classical method. The proposed method has certain advantages in high-precision calibration of LSLS.
引文
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[18] Lu M X,Ge W L,Zhou A G,et al.Calibrating laser scanning probe with double virtual circle target[J].Acta Optica Sinica,2014,34(10):1015005.陆敏恂,葛卫梁,周爱国,等.基于双重虚拟圆靶标的激光扫描测头标定[J].光学学报,2014,34(10):1015005.
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[25] Wu Q H,He T,Shi T L.A calibration method for line structured-light vision sensor based on a plane target[J].Journal of Optoelectronics·Laser,2013,24(2):297-301.吴庆华,何涛,史铁林.一种基于平面标靶的线结构光视觉传感器标定方法[J].光电子·激光,2013,24(2):297-301.
[26] Zou Y Y,Zhao M Y,Zhang L.Direct calibration method of laser stripe vision sensor based on gauge block[J].Chinese Journal of Lasers,2014,41(11):1108002.邹媛媛,赵明扬,张雷.基于量块的线结构光视觉传感器直接标定方法[J].中国激光,2014,41(11):1108002.
[27] Tsai R Y.A versatile camera calibration technique for high-accuracy 3D machine vision metrology using off-the-shelf TV cameras and lenses[J].IEEE Journal on Robotics and Automation,1987,3(4):323-344.
[28] Li Y H,Zhou J B,Huang F S,et al.Sub-pixel extraction of laser stripe center using an improved gray-gravity method[J].Sensors,2017,17(4):814.
[2] Lu X Q,Gu D X,Wang Y D,et al.Feature extraction of welding seam image based on laser vision[J].IEEE Sensors Journal,2018,18(11):4715-4724.
[3] Guo J C,Zhu Z M,Yu Y F,et al.Research and application of visual sensing technology based on laser structured light in welding industry[J].Chinese Journal of Lasers,2017,44(12):1200001.郭吉昌,朱志明,于英飞,等.焊接领域激光结构光视觉传感技术的研究及应用[J].中国激光,2017,44(12):1200001.
[4] Zhan D,Yu L,Xiao J,et al.Multi-camera and structured-light vision system (MSVS) for dynamic high-accuracy 3D measurements of railway tunnels[J].Sensors,2015,15(4):8664-8684.
[5] Li Y H,Zhou J B,Liu L J.Research progress of the line structured light measurement technique[J].Journal of Hebei University of Science and Technology,2018,39(2):115-124.李玥华,周京博,刘利剑.线结构光测量技术研究进展[J].河北科技大学学报,2018,39(2):115-124.
[6] Li T T,Yang F,Li S G,et al.Method of line structured light stripe center extraction based on Gauss-Lorenz multi-peak fitting[J].Laser & Optoelectronics Progress,2019,56(7):071201.李涛涛,杨峰,李石庚,等.基于高斯-洛伦兹分峰拟合的线结构光条中心提取方法[J].激光与光电子学进展,2019,56(7):071201.
[7] van Gestel N,Cuypers S,Bleys P,et al.A performance evaluation test for laser line scanners on CMMs[J].Optics and Lasers in Engineering,2009,47(3/4):336-342.
[8] Zhang X,Zhang J.Summary on calibration method of line-structured light[J].Laser & Optoelectronics Progress,2018,55(2):020001.张曦,张健.线结构光标定方法综述[J].激光与光电子学进展,2018,55(2):020001.
[9] Dewar R.Self-generated targets for spatial calibration of structured light optical sectioning sensors with respect to an external coordinate system[J].Society of Manufacturing Engineers,1988:5-13.
[10] Duan F J,Liu F M,Ye S H.A new accurate method for the calibration of line structured light sensor[J].Chinese Journal of Scientific Instrument,2000,(1):108-110.段发阶,刘凤梅,叶声华.一种新型线结构光传感器结构参数标定方法[J].仪器仪表学报,2000,(1):108-110.
[11] Zhou F Q,Zhang G J.Complete calibration of a structured light stripe vision sensor through planar target of unknown orientations[J].Image and Vision Computing,2005,23(1):59-67.
[12] Wei Z Z,Zhang G J,Xu Y.Calibration approach for structured-lighted-stripe vision sensor[J].Chinese Journal of Mechanical Engineering,2005,41(2):210-214.魏振忠,张广军,徐园.一种线结构光视觉传感器标定方法[J].机械工程学报,2005,41(2):210-214.
[13] Han J D,Lü N G,Dong M L,et al.Fast method to calibrate structure parameters of line structured light vision sensor[J].Optics and Precision Engineering,2009,17(5):958-963.韩建栋,吕乃光,董明利,等.线结构光传感系统的快速标定方法[J].光学精密工程,2009,17(5):958-963.
[14] Chen X Y,Ma Z,Chen T F,et al.Calibration model for line structured light vision sensor[J].Optics and Precision Engineering,2012,20(11):2345-2352.陈新禹,马孜,陈天飞,等.线结构光传感器模型的简易标定[J].光学精密工程,2012,20(11):2345-2352.
[15] Xie Z X,Wang X M,Chi S K.Simultaneous calibration of the intrinsic and extrinsic parameters of structured-light sensors[J].Optics and Lasers in Engineering,2014,58:9-18.
[16] Zhang Z.A flexible new technique for camera calibration[J].IEEE Transactions on Pattern Analysis and Machine Intelligence,2000,22(11):1330-1334.
[17] Liu Z,Zhang G J,Wei ZZ,et al.An accurate calibration method for line structured light vision sensor[J].Acta Optica Sinica,2009,29(11):3124-3128.刘震,张广军,魏振忠,等.一种高精度线结构光视觉传感器现场标定方法[J].光学学报,2009,29(11):3124-3128.
[18] Lu M X,Ge W L,Zhou A G,et al.Calibrating laser scanning probe with double virtual circle target[J].Acta Optica Sinica,2014,34(10):1015005.陆敏恂,葛卫梁,周爱国,等.基于双重虚拟圆靶标的激光扫描测头标定[J].光学学报,2014,34(10):1015005.
[19] Wei Z Z,Shao M W,Zhang G J,et al.Parallel-based calibration method for line-structured light vision sensor[J].Optical Engineering,2014,53(3):033101.
[20] Chen T F,Zhao J B,Wu X.New calibration method for line structured light sensor based on planar target[J].Acta Optica Sinica,2015,35(1):0112004.陈天飞,赵吉宾,吴翔.基于共面靶标的线结构光传感器标定新方法[J].光学学报,2015,35(1):0112004.
[21] Liu Z,Li X J,Li F J,et al.Calibration method for line-structured light vision sensor based on a single ball target[J].Optics and Lasers in Engineering,2015,69:20-28.
[22] Liu Z,Li X J,Yin Y.On-site calibration of line-structured light vision sensor in complex light environments[J].Optics Express,2015,23(23):29896-29911.
[23] Ma Y Y,Peng K,Yang W D,et al.Application technology of radom sample consensus algorithm in line structured light vision measurement system[J].Science Technology and Engineering,2018,18(3):68-73.马媛媛,彭凯,杨伟东,等.随机抽样一致性算法在线结构光视觉测量系统中的应用[J].科学技术与工程,2018,18(3):68-73.
[24] Xie Z X,Zhang A Q.Simultaneous calibration of the intrinsic and extrinsic parameters of ultra-large-scale line structured-light sensor[J].Acta Optica Sinica,2018,38(3):0315001.解则晓,张安祺.超大尺度线结构光传感器内外参数同时标定[J].光学学报,2018,38(3):0315001.
[25] Wu Q H,He T,Shi T L.A calibration method for line structured-light vision sensor based on a plane target[J].Journal of Optoelectronics·Laser,2013,24(2):297-301.吴庆华,何涛,史铁林.一种基于平面标靶的线结构光视觉传感器标定方法[J].光电子·激光,2013,24(2):297-301.
[26] Zou Y Y,Zhao M Y,Zhang L.Direct calibration method of laser stripe vision sensor based on gauge block[J].Chinese Journal of Lasers,2014,41(11):1108002.邹媛媛,赵明扬,张雷.基于量块的线结构光视觉传感器直接标定方法[J].中国激光,2014,41(11):1108002.
[27] Tsai R Y.A versatile camera calibration technique for high-accuracy 3D machine vision metrology using off-the-shelf TV cameras and lenses[J].IEEE Journal on Robotics and Automation,1987,3(4):323-344.
[28] Li Y H,Zhou J B,Huang F S,et al.Sub-pixel extraction of laser stripe center using an improved gray-gravity method[J].Sensors,2017,17(4):814.