面向复杂机械零件形貌测量的高精度三维重建方法

High-precision 3D reconstruction method for topography measurement of complex mechanical parts

机械零件的精确测量可为零件的加工制造、虚拟仿真、缺陷检测等应用提供依据,基于条纹投影的双目视觉方法由于其高精度的特点广泛应用于机械零件的形貌测量中。在该方法中,绝对相位曲线的质量决定着三维重建的最终精度。由于环境噪声、场景不连续或零件表面复杂结构等的影响,绝对相位曲线往往存在着大量的噪声点和不同程度的形变。为了提高重建精度,针对绝对相位曲线存在的问题提出了相应的改进方法;针对难以去除的远离相位曲线的噪声点,提出逐区域相位校正方法,该方法将每一行的相位曲线分为若干区域,以区域内相位值的中位数为阈值,去除此类噪声点;针对相位曲线的形变区域,在基于点基元的立体匹配方法的基础上引入曲线拟合方法,并对匹配后得到的视差图进行精化,能够改善相位曲线形变区域立体匹配结果不佳的情况,提高了匹配方法的鲁棒性与精度。使用该方法对复杂零件FSW逆变器进行重建,标准偏差可降至0.1 mm以内。实验结果表明:所提方法重建精度更高,对于表面结构复杂的机械零件,能够实现精确测量。

Accurate measurement of mechanical parts can provide a basis for parts processing and manufacturing,virtual simulation,defect detection and other applications.The binocular vision method based on fringe projection is widely used in the topography measurement of mechanical parts due to its high-precision characteristics.In this method,the quality of the absolute phase curve determines the final accuracy of the 3D reconstruction.Due to the influence of environmental noise,discontinuity of the scene,and complex surface structure of the parts,absolute phase curve often has a large number of noise points and varying degrees of deformation.In order to improve the reconstruction accuracy,a corresponding improvement method is proposed for the problems existing in the absolute phase curve.Aiming at the noise points far away from the phase curve that are difficult to remove,a region-by-region phase correction method is proposed.This method divides the phase curve of each row into several regions,and uses the median of the phase value in the region as the threshold to remove such noise points.For the deformed area of the phase curve,the curve fitting method is introduced on the basis of the point primitive-based stereo matching method,and the disparity map obtained after the matching is refined,which can improve the poor matching result in the deformed area of the phase curve and improve the robustness and accuracy of the matching method.The method is used to reconstruct complex part FSW inverter,and the standard deviation can be reduced to within 0.1 mm.Experiments have proved that the reconstruction accuracy of this method is higher.For mechanical parts with complex surface structure,the proposed method can achieve accurate measurement.