摘要
由于与历史无关的造型系统中约束模型多处于欠约束状态,使求解结果往往不能很好地符合设计意图,为此提出一种基于虚几何元素的约束模型构建方法.该方法根据输入约束的方向特性创建虚几何元素,并将这些约束转换为实体几何元素、虚几何元素间的结构约束和尺寸约束,从而构建基本约束模型;在此基础上,通过几何元素的剩余自由度分析增补相应的几何约束,使约束模型更完备,求解结果更合理.文中方法已在原型系统InteModel中实现,并通过实例验证了其正确性和有效性.
In history-independent modeling system,the constraint model is often in under-constraint status,which may make the resolving result not meet the design intention well.A new approach based on virtual geometric elements is proposed to construct a constraint model,in which virtual geometric elements are defined according to the directional characteristic of input constraints.And then such constraints are converted into structure and dimension constraints among existing geometric elements and virtual geometric elements.In addition,the remaining degrees of freedom(DOFs) of such geometric elements are analyzed,and the complementary constraints are appended so that the constraint model is complete and the resolving results satisfy the design intentions better.The proposed method has been implemented and validated by two examples in a prototype system named InteModel.
引文
[1]Zhang Teng,Cui Zhiqin,Hou Junhai,et al.Modelingtechnologies and their features in CAD evolution[J].Mechanical Engineering&Automation,2011(6):196-197+200(in Chinese)(张腾,崔志琴,侯军海,等.CAD造型技术发展历程及其特点[J].机械工程与自动化,2011(6):196-197+200)
[2]Chung J C H,Hwang T S,Wu C T,et al.Framework forintegrated mechanical design automation[J].Computer-Aided Design,2000,32(5?6):355-365
[3]Raghothama S,Shapiro V.Boundary representationdeformation in parametric solid modeling[J].ACMTransactions on Graphics,1998,17(4):259-286
[4]Hong Rujin.The training course of synchronous technologyon UG NX6[M].Beijing:Tsinghua University Press,2008(in Chinese)(洪如瑾.UG NX6同步建模技术培训教程[M].北京:清华大学出版社,2008)
[5]Zhang Jiancheng,Jia Zhongwen,Yao Mingjun.The quickstart of synchronous technology on solid edge[M].Beijing:Tsinghua University Press,2009(in Chinese)(张剑澄,贾仲文,姚民军.Solid Edge同步建模技术快速入门[M].北京:清华大学出版社,2009)
[6]Gong Xiong,Wang Boxing,Chen Liping,et al.Constructingdescriptive 3D parametric model for history-independentmodeling[J].Journal of Computer-Aided Design&Computer Graphics,2006,18(12):1872-1877(in Chinese)(龚雄,王波兴,陈立平,等.与历史无关的三维参数化模型构造方法[J].计算机辅助设计与图形学学报,2006,18(12):1872-1877)
[7]Wang Yanwei,Chen Liping,Huang Zhengdong,et al.3Dgeometric constraint solving for history-independent modeling[J].Journal of Computer-Aided Design&ComputerGraphics,2004,16(5):648-654(in Chinese)(王彦伟,陈立平,黄正东,等.面向与历史无关造型的三维约束求解方法研究[J].计算机辅助设计与图形学学报,2004,16(5):648-654)
[8]Gong Xiong.Research and implementation of declarativegeometric constraint system[D].Wuhan:HuazhongUniversity of Science and Technology,2007(in Chinese)(龚雄.陈述式几何约束系统的原理与方法研究[D].武汉:华中科技大学,2007)
[9]Chen Liping,Wang Boxing,Peng Xiaobo,et al.An optimalmethod of bipartite graph matching for underconstrainedgeometry solving[J].Chinese Journal of Computers,2000,23(5):523-530(in Chinese)(陈立平,王波兴,彭小波,等.一种面向欠约束几何系统求解的二部图匹配优化处理方法[J].计算机学报,2000,23(5):523-530)
[10]Yi Rongqing,Li Yi,Li Wenhui,et al.A new algorithm tosolve geometric constraints based on direct graph[J].Journalof Engineering Graphics,2009,30(3):22-27(in Chinese)(易荣庆,李谊,李文辉,等.基于有向图的约束求解新算法[J].工程图学学报,2009,30(3):22-27)
[11]Corney J,Lim T.3D modeling with ACIS[M].Stirling:Saxe-Coburg Publications,2001
[12]Wu Yongming.Dynamic recognition and solution of 3Dgeometric constraint loops[J].Journal of Computer-AidedDesign&Computer Graphics,2000,12(8):624-629(inChinese)(吴永明.三维几何约束闭环的动态识别与满足[J].计算机辅助设计与图形学学报,2000,12(8):624-629)
[13]Wang Shiping,Guo Lianshui.2Dgeometric constraint solvingwith directed graph[J].Journal of Engineering Graphics,2010,31(1):54-60(in Chinese)(王世平,郭连水.基于有向图的二维约束求解算法研究[J].工程图学学报,2010,31(1):54-60)
[14]Peng Bei.Parametric technology in apparel pattern-makingbased on constraint graph[D].Beijing:Beijing Institute ofFashion Technology,2011(in Chinese)(彭贝.基于约束图的服装参数化制版技术[D].北京:北京服装学院,2011)
[15]Xiu Y,Wan Z K,Cao W L.Parametric pattern-makingmodeling based on constraint and graph[C]//Proceedings ofInternational Workshop on Intelligent Systems andApplications.Los Alamitos:IEEE Computer Society Press,2010:1-4