视觉辅助下的激光振镜模型参数分步标定

Two-step parameter calibration for galvanometric laser scanners using binocular stereo vision

激光振镜内部结构较为复杂,如何对其进行高效、准确的标定一直都是基于激光振镜相关应用的核心问题。提出了一种基于模型参数分步式求解的激光振镜扫描系统标定算法。根据振镜扫描系统物理模型各参数对出射光光路产生的影响将其划分为影响出射光方向的参数和影响出射光位置的参数两类,并分别给出了求解方向参数与位置参数的优化模型。此外,分析了入射光方向偏差对现有反射镜偏转角度估计算法造成的影响,提出了相应的估计算法。以建立的系统模型为基础进行了模拟标定实验,模拟实验结果表明该算法具有良好的稳定性。利用标定好的实际振镜扫描系统完成了平面靶圆中心与空间闭合三维曲线的投影定位实验;靶圆中心的定位投影误差在0.5 mm左右,实际激光曲线与目标空间曲线在像平面内的位置偏差的均方根误差为0.42 pixel。

Due to the complex inner structure of the galvanometric laser scanning(GLS) system, the precise and efficient calibration is the core problem for the GLS-based applications. Based on the physical model of the GLS system, a two-step calibration method is proposed in this study. The parameters of the physical model are divided into two categories. The first are the direction parameters for determining the direction of the outgoing laser beams. The second are the position parameters for determining the positon of the outgoing laser beams. The optimization models for solving the direction parameters and the position parameters are given respectively. Besides, a new estimation is presented to solve the deflection angle of the GLS system, since the actual incident laser beam deviates from the theoretical direction set in the physical model. Based on the formulated model, a simulation experiment of the calibration is carried out. Simulation results show that the proposed calibration method is stable. With the calibrated GLS system, the projection positioning experiments of the centers of target circles and the 3 D contour curves are completed. The positioning error of the center of the target circle is around 0.5 mm and the root mean square error of the positional offset between the actual laser curve and the target contour in the image plane is 0.42 pixel.