钢轨全轮廓线结构光双目视觉测量系统标定

Calibration of binocular vision measurement system by line structured light for rail full profile

线结构光视觉测量技术因非接触和精度高的特点被用于钢轨磨耗测量。为解决钢轨断面全轮廓测量和线结构光测量系统现场标定困难的问题,提出了一种基于自由平面靶标的线结构光双目现场标定方法。首先,基于线结构光双目视觉测量模型搭建测量系统,分别采集两侧摄像机公共视角下任意位置的不含和包含线结构光的棋盘格平面图像;然后,采用棋盘格平面标定法获取两侧摄像机内部参数。利用线结构光平面与不同位置标定板相交产生的特征点拟合出线结构光平面在两侧摄像机坐标系中的平面方程,采用罗德里格斯变换原理求解出线结构光平面与两侧摄像机的外部参数;最后,结合摄像机内部参数和线结构光平面与摄像机外部参数实现钢轨全轮廓测量,并进行现场测试。试验结果表明,相机内参数标定误差约为0.03 pixel,结构光平面拟合度达0.999,钢轨断面全轮廓总测量偏差为0.54 mm,满足测量精度要求。

The measurement technology of line structured light vision is utilized for the rail wear measurement due to its non-contact and high precision features.The measurement of rail full profile and field calibration of line structured light visual measurement system are two typical problems.To enhance its performance,a binocular calibration method of line structured light based on free plane targets is proposed for field application.Firstly,the vision measurement system is established based on line structured light binocular visual measurement model.The chessboard images containing line structured light and the chessboard images without line structured light at any positions in the public viewing angle of both sides of the camera are collected respectively.Then,the internal parameters of both sides of the camera are obtained by using the chessboard plane calibration method.The feature points which are generated by intersection of line structured light plane and target plane at different positions are used to fit the planar equations of the line structured light plane in both sides of the camera coordinate system.According to the Rodriguez transform principle,the external parameters between the line structured light plane and two cameras are solved.Finally,the internal parameters and the external parameters are utilized to realize the measurement of rail full profile.The field test is also carried out.Experimental results show that the calibration error of the cameras is about 0.03 pixels,the fitting degree of line structured light plane is 0.999,and the total measurement error of rail profile data is 0.54 mm,which meets the requirement of measurement accuracy.