摘要
提出双目视觉结合单帧多曝光技术的粒子轨迹测速(PSV)方法,通过长短曝光组合判断速度方向,采用灰度拟合法识别轨迹特征,并采用轨迹中心点进行速度计算以提高速度测量的准确性。该方法采用最邻近点匹配及倾斜角约束对同一颗粒的多段轨迹进行匹配与排序,利用极线约束对轨迹特征点进行双目匹配,对三维重建后的特征点进行B样条拟合以计算粒子的三维速度,而多曝光粒子轨迹法可以降低双目匹配的难度。形成了双目多曝光PSV的实验系统及相应图像处理流程。采用发光小孔进行了不同三维速度下的验证实验,分析了不同轨迹特征点选择对速度测量结果的影响。结果表明,利用轨迹中点计算速度,得到的平均相对误差小于4.2%,同时其标准偏差较小,故采用轨迹中点相较于采用轨迹端点的速度计算方法更优。并对一射流流场进行了实测,结果表明此方法能够可靠地用于三维流场测量。
The particle streak velocimetry(PSV)method based on binocular vision and single-frame multiple exposure was proposed in this paper.To be specific,the velocity direction was judged by the combination of long and short exposure and the gray-level fitting was used to identify the trajectory features.In addition,the trajectory midpoint was employed to calculate the particle velocity in order to improve the measurement accuracy.This method adopted nearest neighbor matching and angle of inclination constraints to match and sort multiple trajectories of the same particle,epipolar constraints to accomplish binocular matching based on trajectory feature points,and B-spline fitting of the three-dimensional reconstructed feature points to calculate the three-dimensional velocity of particles.The multi-exposure PSV method can simplify binocular matching.As a result,an experimental system and the corresponding image processing flow were formed for binocular multi-exposure PSV.We applied the small luminous holes to verification experiments at different three-dimensional velocities and analyzed the influence of different trajectory feature points on the velocity measurement.The results show that the average relative error obtained by the trajectory midpoint is less than 4.2%,and the standard deviation is small,demonstrating the advantage of velocity calculation with the midpoint rather than with the end.The actual measurement of the flow field in a water jet test bench indicates that this method can be reliably used for three-dimensional flow field measurement.
作者
周骛
王芳婷
王宵宵
唐欣然
蔡小舒
Zhou Wu;Wang Fangting;Wang Xiaoxiao;Tang Xinran;Cai Xiaoshu(School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai 200093,China;Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering,Shanghai 200093,China)
出处
《光学学报》
EI
CAS
CSCD
北大核心
2021年第12期154-162,共9页
Acta Optica Sinica
基金
国家科技重大专项(2017-V-0016-0069)
国家自然科学基金(51576130)。
关键词
机器视觉
双目视觉
粒子轨迹测速
多曝光
灰度拟合
三维速度
machine vision
binocular vision
particle streak velocimety
multiple exposure
gray-level fitting
three-dimensional velocity