Resolving non-uniqueness in design feature histories

Abstract

Nearly all major commercial computer-aided design systems have adopted a feature-based design approach to solid modeling. Models are created via a sequence of operations which apply design features to incremental versions of a design model. Even surfacing, free-form surface shapiing, and deformation operations are internally represented in modeling systems as features in a "history tree" that generates the final. design. Much in the same manner that Constructive Solid Geometry (CSG) trees for an individual model can be non-unique, these design feature histories for solid models might be ordered in a number of ways and still result in the same final geometry and topology.We formulate this problem symbolically and present geometric reasoning techniques to generate a canonical form for certain classes of design feature histories. We define this representation as a Model Dependency Gmph (MDG) and show how it can be used as a basis for developing techniques for managing database.s of solid models. Using the MDG, we introduce algorithms that can assess the similarity of solid models based on design features. We believe these techniques can be used to build intelligent CAD knowledgebases and to identify me:aningful part families from large sets of designs. Lastly, we describe experimental results and petformance metrics for our approach.

Shape-based searching for product lifecycle applications

“…Ascher et al [24] simplify parts into maximal feature subgraphs (MFSG) which are matched to obtain a similarity measure. Other FR-based methods are discussed in [25][26][27][28]. 7.…”

Managing digital libraries for computer-aided design

“…[31,32] and in Section 4.3, we know that making extensive use of engineering domain knowledge and domain-specific heuristics significantly improves the performance, both reducing the number of isomorphism-based equivalence checks and directing the search toward application of more promising operators.…”

“…Executing a query to the Repository is a matter of searching the Knowledge Repository for other models and assemblies with similar graph-based structures. In this effort, we have created a specific instance of the general problem described in Section 3 for indexing and retrieval of individual solid models based on their design features [31].…”

Enhancing Stochastic Search Performance by Value-Biased Randomization of Heuristics

“…Stochastic search algorithms are often robust, scalable problem solvers. Examples of the success of such stochastic search algorithms abound: Space Telescope Scheduling (Bresina, 1996), Project Scheduling Smith, 1999, 2002), Solid Model Similarity Assessment (Cicirello, 1999;Cicirello and Regli, 1999, 2001, Satisfiability (Selman, Kautz, and Cohen, 1996;Prestwich, 2001;Boyan and Moore, 1998), VLSI Channel Routing (Boyan andMoore, 1997,1998), Graph Coloring (Prestwich, 2001), Constraint Satisfaction (Freuder et al, 1995), and N-Queens (Prestwich, 2001)-just to mention a few.…”