基于线结构光的冰横截面轮廓测量

为实现冰横截面轮廓非接触测量,提出了基于线结构光的冰横截面轮廓测量方法:将面激光垂直投射在冰块上,利用摄像机拍摄冰块表面变形激光线,并根据事先标定的激光平面与摄像机间几何关系,计算冰面激光线三维坐标点,这些三维坐标点在激光平面上的投影即为冰块横截面轮廓。设计了基于线结构光的冰轮廓测量简易装置,开发了测量程序,并针对冰面激光线反射能量弱导致的激光线图像对比度低的问题,研究了冰面激光中心线提取方法。对冰箱冻结的已知半径圆柱冰块进行了横截面轮廓测量,平均相对误差为0.018,最大相对误差为0.052;还对二元翼型结冰冰块进行了横截面轮廓测量,得到了初步测量结果;为开展结冰试验中结冰生长过程冰形在线三维测量奠定了技术基础。

Ice cross sectional profile measurement based on line structured light

To realize the ice cross sectional profile measurement in a non-contact way,a line structured light based measurement is adopted.Firstly a laser sheet is proj ected vertically on the ice surface.Secondly,the image of the deformed laser line on the ice surface is captured by a camera.Finally,the 3D coordinates of the laser line on the ice surface are calculated upon the cal-ibrated geometric relationship between the laser sheet and the camera.Then the proj ection of these 3D coordinates on the laser sheet is the ice cross sectional profile.In this paper,a simple line structured light measurement device and a measurement procedure are developed.To deal with the problem of the low image contrast due to the low reflected laser energy on ice,a novel laser line center extraction method is provided.In the experiments,an ice sheet frozen by a re-frigerator with its radius known is measured.The maximum relative error is 0.052,and the mean relative error is 0.018.A preliminary measurement result of the icing on two elements air-foil generated in an icing wind tunnel is also obtained.It lays a technical foundation for the 3D ice shape online measurement during ice accretion in icing wind tunnels in the future.