An object-oriented software development environment for geometric modeling in intelligent computer-aided design

The concept of intelligent CAD systems to assist a designer in automating the design process has been discussed for years. It has been recognized that knowledge engineering techniques and the study of design theory can provide certain solutions to this approach. A major issue in developing intelligent CAD systems for geometric modeling is the integration of the design geometry with the representation of the design constraints.; Current commercial computer aided design (CAD) systems are used primarily for recording the results of the design process. Using conventional CAD systems, a design engineer either must create the geometry of the design object with precise coordinates and dimensions, or start his design from an existing geometry of a previous design. It is difficult to propagate a dimensional change throughout an entire model--especially solid models. This rigidity imposed by conventional CAD systems discourages a designer from exploring different approaches in creating a novel product.; None of the commercial CAD systems can perfectly fulfill all the requirements of complicated design activities, and most users still must develop their own software to complement the functional shortage. A software development environment with an open architecture seems very desirable to an organization with versatile design activities since it provides substantial software building components to the users. To create such a software development environment, a powerful approach is essential and critical. Among all available software approaches, the object-oriented programming (OOP) paradigm is the best choice because it copes with the intellectual complexity of software development very efficiently and the products created are highly reusable.; In this dissertation, a new, unique, method is proposed to integrate the design geometry with the constraints imposed by the design process. Design components are represented by invoking a combination of geometric object classes with an object-oriented programming (OOP) environment.; The generation of design models starts from the creation of high-level abstractions, i.e. the form features and constraints, to low-level abstractions, i.e. the boundary representation solid model. Both levels of abstractions are represented uniformly by geometric class objects.; Form features convey the semantics of the design process by taking the dimensions as the major constraints on the geometric model and by maintaining the relationships between those dimensions. Low-level boundary representation solid models are used for further applications such as mass property analysis and graphical visualization.; A prototype system based on these ideas has been designed and implemented. The templates that are used to create objects, call classes in popular OOP terminology, are aggregated to form an open-architecture class library. The class library is a software development environment to help programmers create intelligent CAD systems for geometric modeling in design.