与历史无关的三维参数化模型构造方法

Constructing Descriptive 3D Parametric Model for History-Independent Modeling

针对解析曲面构成的B-rep模型,提出了一种陈述性三维几何约束模型的构造方法·基于位置和姿态自由度解耦思想给出了几何实体的外形描述,借助空间矢量正交或平行条件定义了基本约束单元,并推导出常见工程约束的代数方程·讨论了陈述式约束模型自动构造过程,开发了三维模型变形设计原型系统,并验证该方法的可行性·

This paper introduces a new approach to constructing descriptive 3D geometric constraint models for the B-rep models composed of analytic surfaces. Based on the principle of decoupling for the degrees of freedom of position and posture, the geometric representations of analytic surfaces are first presented. Then, according to the perpendicularity or parallelism of spatial vectors, several elementary constraints are defined, and the algebraic equations for some general engineering constraints are derived. _After analysing the process of automatically constructing descriptive geometric constraint models, a prototype software package for directly editing 3D shapes is developed to verify the feasibility of the proposed method.