【作者】 何海涛；

【导师】 陈立平； 赵建军；

【作者基本信息】 华中科技大学 ， 机械设计及理论， 2005， 硕士

【摘要】 参数化设计在现代CAD 技术中占据着越来越重要的地位,几何约束系统的建模、管理与求解是该技术的关键,对约束如何进行方便、有效的管理一直未能得到很好的解决,因而在设计的过程中,约束的动态管理显得至关重要。本文从几何约束的动态管理出发,研究了参数化设计中几何约束的归约策略,基于几何约束的图表示阐述了几何约束的虚拟基归约技术,并探讨了几何约束的一致性检验问题。首先,结合面向对象的设计方法以及AutoCAD 平台的一些特性,本文分析了参数化设计过程中几何约束的动态管理对其宿主平台的要求,并建立了设计系统中几何约束动态管理的外挂式参数化计算模型。其次,在外挂式参数化设计计算模型的基础上,本文结合AutoCAD 平台研究了约束的动态管理问题,介绍了对象的持久存储,并建立了约束的实时计算模型。对于单纯完备和复合完备的几何约束系统,本文分别讨论了它们的归约计算方法并对其进行维护。再次,在对几何约束的约束网格图进行自动维护的前提下,研究了约束的显示、添加、删除和修改,从而可以使几何约束系统的操作变得完备,并实现了参数化设计过程中的Undo/Redo 机制。最后,基于上述研究,我们运用面向对象的设计方法实现了一个二维参数化设计系统,为构造全约束的CAD 系统提供了技术基础, 此系统体现了几何约束的动态管理思想。更多还原

【Abstract】 Parametric design technology has become more and more important now. Modeling, management and solving of geometry constraint system are the key technologies in this field. But how to maintain the constraint conveniently and effectively had not been achieved well, so it is vital to manage the constraint dynamically in the design procedure. In this thesis the reduction strategy of geometry constraint in parametric design is researched from the dynamic management point of view. On the basis of using graph to describe the geometry constraint, the author expresses the virtual-base technology, and discusses how to check the constraint consistence. Firstly,in accordance with the oriented-object method and the performance of AutoCAD platform, the author analyses the demands of host platform characteristic for geometry constraints during the process of parametric design, and then constructs the calculating model for the dynamic management of geometry constraint system. This model can be implemented on other systems. Secondly,on the foundation of the above model and AutoCAD platform, the author pays much attention to the problem of dynamic management and permanent object storage, and finally builds the dynamic calculating model of geometry constraint. At the same time, the author discusses how to maintain pure complete geometric system and compound complete geometric constraint system under different circumstances. Thirdly,under the condition of maintaining the geometry constraint graph, the author researches how to show, add, delete and modify constraint to geometry constraint system, including the Undo/Redo mechanism. Finally,based on the research above, the author accomplishes a 2D parametric design system with the help of oriented-object thinking to support full-constraint CAD system. This module shows the thinking of dynamic management well.更多还原