The Research Of Re-evaluation Mechanism Based On Cellular Model In Semantic Feature Modeling System

The semantic feature modeling system, which adopts completely semantic constrains to define feature and create model, can satisfy all the engineering designer's intents. But it is more complex than the former system based on parameter and history. It uses FDG as data model, cell-based model as geometric model, and view model as user interface. Designing model means modifying, and modifying causes re-evaluation, so its re-evaluation is an important part for the system. In the course of re-evaluation, not only must it be edited easily but also it can maintain its high efficiency and semantic conformity. The key problems are how to protect designer's intents, how to maintain its semantic conformity, the stability and integrality of product information.This paper will research the key issues for the model re-evaluation from the two aspects, theory and system design, combine the cell-based geometric model and FDG-based data model to analyze the constrain-based feature semantic, the updating for the FDG, the solving research of cell-based geometric model, and the updating sequence, and bring forward the new methods and new thought for the model's re-evaluation, with the associated algorithm. This paper presents a new constructive solving approach for systems of geometric constraints. The solver is based on the cluster rewriting approach; the new solving approach extends the class of problems that can be solved, while retaining the advantages of the cluster rewriting approach. This allows us to solve many additional problems that cannot be decomposed into rigid clusters, without resorting to expensive algebraic solving methods. The research result can be applied in HUSTCAID, and have accelerate the speed of design and can contribute to the enterprise's profits; furthermore, it can have some effect on the Graphic & CAD field in demotic even international area, and promote the CAD technology to advance more.