Definition and Recognition of Volume Features for Process Planning

Abstract A generic form feature recognition method called “spatial decomposition and composition” has been developed. The method can recognize all the features that are interpretable from the B-rep of a solid model regardless whether they intersect or not. Recognized features can be presented as both volume features and surface features. To specify and aid in understanding the type of volume features involved, this work first defines a concept of cavity volume to conform with our notion of cavity and then, a generic volume feature is defined as a cavity volume that has a pre-defined set of topological and geometric characteristics. A user can define a set of topological and geometric characteristics for each specific type of feature interactively with computer graphics. The spatial decomposition and composition method of feature recognition decomposes the space surrounding a solid model into minimal convex cells with the geometric surfaces of the solid model. Combinations of the cells are then composed into volumes and checked to determine if they are volume features. The exhaustive nature of the method enables the recognition of all the features, but also poses the problem of computational explosion. Some initial approaches to cope with computational explosion are introduced in this work. In addition, the on-going research on applying this feature recognition method to process planning is briefly discussed.