关键词: 特征, 定位约束, 参数化法, 特征模型

Abstract:

A systematized module of three dimensional parameterization, including variational geometry, sweeping orientation parameterization and feature position constraint parameterization, is proposed. For the last one with main characters of three dimensional parameterization, first the coordinate representing approach of constraints between features is presented and the coordinate systems needed are defined, then the existing constrained elements are analyzed and their constraint relations classified and the transform matrices of general position constraint relations deduced with more generality than late works. In addition, the loss of freedom (abbrev. lf) of all the cases are analysed for the needs of analysis, judgement and process of the constraint condition (redundant, under , over or equal constraints).

Key words: signatures, position-constraints, parameterization, signature-models