Semantics of families of objects
Delft University of Technology, (2008)Abstract
In current Computer-Aided Design (CAD) systems for mechanical and industrial design, a model is built from parametric features. Such a parametric model can be interpreted as representing a family of objects, where the members of the family are all possible objects that can be obtained by varying the parameters. A model of a family of objects is useful for manufacturing series of products, for customisation of products, and for reuse of part models. However, there are several major obstacles when using current CAD systems for modelling families.
Firstly, the semantics of features and families cannot be adequately specified in and maintained by current CAD systems. As a result, a modelled family may contain undesirable members or may not contain all desirable members. Therefore, we present a new Declarative Family of Objects Model, in which semantics are specified by geometric and topological constraints. Members of the model are determined by solving the those constraints, for which we have developed new methods.
Secondly, current CAD systems do not provide sufficient tools for creating and using families of objects. We present a method to determine the range of allowable values for any parameter of a model, which can help users with instantiating family members. We also present a method to determine the critical parameter values for which topological changes occur in the model. These critical values can help users inspect the semantics of families.