工件轮廓线参数计算方法研究

Research on Computing Methods of the Parameters of a Workpiece Contour

轮廓仪因探针容易发生沾污、缺陷、扫描位置不准等问题而致轮廓线数据常常失真,从而对工件表面质量的评价带来影响。本文就数据失真时轮廓线参数的计算问题展开研究,以降低对工件表面质量评价的影响。为轮廓线上曲线间的节点及曲线方程的计算问题建立了最小化损失函数的优化模型,设计了基于非线性回归的最优逼近算法,求解上述优化模型以获得最优逼近解,并对计算结果进行整体微调以得到全局最优逼近解。基于全局最佳逼近解获得轮廓线的节点坐标、圆弧方程等基本参数,再进一步计算轮廓线的斜线段倾角、圆弧长度等参数。研究结果为工件表面质量的评价提供了相对准确的数据。

Profilometer is a precision instrument to obtain the contour line of a workpiece.Because of the problems of its probe’s contamination,defects,or inaccurate scanning positions,and so on,the contour data is often distorted,which affects the evaluation of workpiece surface quality.In order to reduce the influence on the evaluation,this paper studies on computing the parameters of the contour with respect to the distorted data.The optimization models of minimizing the loss function are established for computing the nodes’coordinates and the equations of curves,and the optimal approximation algorithms based on nonlinear regression are designed to solve the optimization models.By overall fine-tuning the global optimal approximation solution is obtained.Based on the global optimal approximation solution,the basic parameters of the contour line are obtained,such as nodes’coordinates and circular arcs’equations,etc.And then the basic parameters are applied to compute the other ones,such as the inclination angles of oblique line segments,and circular arcs’length.These results provide relatively accurate data for the evaluation of workpiece surface quality.