基于CAD模型的自由曲面自适应采样策略  

Adaptive sampling strategy for free-form surface based on CAD model

作　　者：何改云[1] 贾红洋[1] 

机构地区：[1]天津大学装备设计与制造技术天津市重点实验室,天津300072

出　　处：《电子测量与仪器学报》2012年第10期835-840,共6页Journal of Electronic Measurement and Instrumentation

基　　金：国家自然科学基金(编号:50975200)资助项目

摘　　要：自由曲面的数字化测量是曲面类零件加工质量检测的关键环节,而数字化测量的基本要求是实现采样点随曲面曲率特征的自适应分布。传统的采样方法局限于对已知数学模型的自由曲面进行采样点规划,而对已知CAD模型的采样问题研究较少。首先提出了基于STL模型的离散数据点提取算法,将已知CAD模型的自由曲面采样转化为多组自由曲线采样问题。通过对各组离散点B样条插值,获取各截交线的参数表达;以曲率为基础,定义曲率测度函数,并以之为密度计算样条质量,提出了一种基于均分样条质量的自由曲线采样新方法。在此基础上,对自由曲面制定了详细的采样方案,实现了自由曲面采样点随曲率特征的自适应分布。计算机仿真表明,利用本文方法能高精度地逼近曲线、曲面几何特征。The digital measurement of free-form surface is the key to machining quality inspection for surface parts,and the basic requirement of digital measurement is how to realize the adaptive distribution of sampling points with the curvature.The traditional sampling methods are limited to the surface with mathematical model instead of CAD model.Firstly,the extracting algorithm of discrete theoretical points is proposed,which transforms the free-from surface into curves.Secondly,the B-spline interpolation is utilized to acquire the parameter expression of each section curve.The curvature measurement function is defined on the basis of the curvature,and the spline mass is determined taking the curvature measure as density.A new sampling method is presented based on dividing the spline mass equally.On this basis,the sampling process for surface is formulated,which realizes the adaptive distribution for surface.The computer simulation shows that the proposed method can approximate the curves and surfaces with higher precision.

关 键 词：自由曲面 曲率测度 自适应分布 采样 数字化测量 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]