Research On The Constraint Model And Solver Based On Cellular

In recent years, the structure of CAD software is undertaking significant reforms, changing from solid modelling centered systems which are called "geometric CAD" to the feature and constraint based ones , which are called "applied CAD". As an indispensable part in any CAD systems, technology concerning constraint modeling is highly emphasized, and many useful solutions have been raised which encourage the reform and application of CAD systems. At the same time,the concept of cellular model is applied to feature-based design system,where the feature can be adjusted ,which improves the efficiency of designing process.So, the semantic feature modeling technique based on cellular model has become very important in most CAID systems.HUST-CAID(Computer Aided Industry Design System developed by Harbin University of Science and Technology)is a parametric modeling design system based on feature.This system describes entities based on mixed model of boundary representation,CSG tree and feature description tree(FDT),in which the design of solid model and feature-editing can be completed with rebuilding CSG tree and feature description tree.But,in the feature modeling,with the number of features increasing,the design model becomes more and more complex.The efficiency of designing is decreased.In order to maintain the intent of designers and satisfy them, the concept of the cellular model is put forward based on old design system.Methods of naming topological entities and managing constraints are illustrated in this system. After the research of methods of constraint-solving and feature-editing in old system, a new optimozation method of constraint-solving is presented,in which the type of constraint between features is attained and then homotopy is applied in the process of solving.