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A novel 3D radius compensation method of probe stylus tip in the free-form surface profile curve scanning measurement
Measurement Science and Technology ( IF 2.4 ) Pub Date : 2020-05-27 , DOI: 10.1088/1361-6501/ab786c
Zhenyou Wang 1 , Xu Zhang 1 , Yijun Shen 2 , Limin Zhu 2 , Sebastieen Bessse 3
Affiliation  

The normal vectors of the free-form surface profile curve are generally not in the same plane, even if the profile curve is generated from the interaction between a plane and a surface. If the 2D compensation vector is adopted to reduce the cosine error, the accuracy is limited because the normal direction of the curve plane is not considered. In this paper, a novel radius compensation method adopts the 3D compensation vector instead of the 2D compensation vector like most existing works. An approximating method is proposed to estimate the 3D compensation vector, which is composed of two parts. One is the projection of the 3D vector in the curve plane that is calculated by the normal vector of the non-uniform rational Bezier spline fit curve. The other is the normal vector of the curve plane passing the measuring point. In addition, the deviation between the workpiece and CAD model may degrade the accuracy of the radius compensation. Through theoretical analysis, the influence of the deviation cannot be ignored when the deviation is larger than 0.2 mm. By setting up this threshold, under various levels of torsion angles and deviations for the free-form surface, the results show that the compensation accuracy of the proposed method has a better performance than traditional 2D compensation methods, which decreases the maximum error from 70.8 to 2.6 μm.

中文翻译:

自由曲面轮廓曲线扫描测量中测头针尖3D半径补偿新方法

自由曲面轮廓曲线的法向量通常不在同一平面内,即使轮廓曲线是由平面和曲面之间的相互作用生成的。如果采用二维补偿矢量来减小余弦误差,由于没有考虑曲线平面的法线方向,精度受到限制。在本文中,一种新颖的半径补偿方法采用 3D 补偿向量代替大多数现有工作中的 2D 补偿向量。提出了一种近似方法来估计 3D 补偿向量,它由两部分组成。一种是由非均匀有理贝塞尔样条拟合曲线的法向量计算出的3D向量在曲线平面上的投影。另一个是通过测量点的曲线平面的法向量。此外,工件与 CAD 模型之间的偏差可能会降低半径补偿的精度。通过理论分析,当偏差大于0.2mm时,偏差的影响不可忽视。通过设置该阈值,在自由曲面在各种水平的扭转角和偏差下,结果表明该方法的补偿精度比传统的二维补偿方法具有更好的性能,最大误差从70.8降低到2.6 微米。
更新日期:2020-05-27
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