汽車引擎蓋鈑件特徵辨識與搜尋

Abstract

模面設計目前沒有法則可以參照，皆以自身的經驗與試誤法(trial and error)進行開發。從舊有產品進行相似性搜索出外形相近的鈑件，修改部份模面造型後再利用，可提升模面設計流程整體效能。因此，本研究以案例式推理的方法建立汽車引擎蓋鈑特徵辨識與相似性搜尋系統。目前特徵辨識研究多是依照鈑件上的特徵進行檢索，但是汽車引擎蓋鈑為平緩無特殊造型的曲面，若是直接將文獻中的方法套用在汽車引擎蓋鈑上，會造成模面套用上的困難。 本研究依模面設計需要提出汽車引擎蓋鈑特徵辨識法則，以 STEP檔案取得CAD模型資訊或STL檔案取得三角網格資訊進行汽車引擎蓋鈑邊界之特徵判斷。此外，本研究亦建立從模面萃取主成型面之系統以解決前端資料不足導致資料庫內參考鈑件短少的問題。

So far, there is no standard procedure for the design of die face; the development process of die face design mainly depends on the own experiences of designers by using more traditional methods, and trial and error. However, a new die face design can be developed from the existing design by searching for the automobile sheet metal with same features from the existing products, and then revising the die face in order to increase the efficiency of the whole development process. In this research, the feature recognition and retrieval system of automobile hood are discussed and established through the case-based reasoning (CBR) methodology. Although several techniques have been developed for assessing the similarity among sheet metals, most feature recognition methods still can not apply to the design of automobile hood due to its featureless surface. The feature protocol of automobile hood for the die face design is proposed in this research by taking the geometric and topological data from STEP format and STL mesh file as the input in the feature recognition system. Besides, this thesis presents the extraction rule of hood appearance from the die face, in order to solve the problem of shortage of reference CAD model in the database.