三角网格模型法与NURBS曲面重构法相结合的测头半径补偿

Probe Radius Compensation Using Triangle Grid Model Method and NURBS Surface Reconstruction Method

在使用接触式测量法进行检测时,测量数据是测头中心点的数据坐标,与实测点之间存在一定的误差。针对该问题提出一种三角网格模型法与NURBS曲面重构法相结合的方法对测头半径进行补偿。对测头中心采样点进行曲面拟合,并通过三角网格划分该曲面,求解三角网格顶点法矢和实测点。再选取高斯曲率较大或曲面法矢方向与坐标平面夹角较小的区域进行NURBS曲面重构,求出重构后的实测点。仿真实验结果表明:采用该方法补偿后的精度比三角网格模型法提高了95.52%。对未知CAD模型的自由曲面工件进行验证实验,补偿误差最大值为0.0121mm,补偿误差平均值为0.0033mm,验证了该方法的有效性和实用性。

When using the contact measurement for inspection,the obtained data is the data coordinates of the probe center point,and there are errors between the actual measurement point.To address this problem,a method that combines the triangular mesh model method with the NURBS surface reconstruction method is proposed to compensate for the probe radius.The sampling point of the probe center is fitted to a curved surface,then the surface is triangulated,the normal vectors of the triangulated mesh vertices are solved,and the actual measurement points are calculated.The NURBS surface is reconstructed by selecting a region with large Gaussian curvature or a region with a small angle between the normal direction of the surface and the coordinate plane,the actual measurement points after reconstructed are calculated.A simulation experiment results show that the compensated inspection accuracy of this method is improved by 95.52%compared to the triangular grid model method.Validation experiments are performed on the free-form surface of an unknown CAD model.The maximum value of the compensation error is 0.0121mm,and the average value of the compensation error is 0.0033mm.The effectiveness and practicality of the method are verified.