دانلود رایگان مقاله بررسی ویژگی ها مبتنی بر ادبیات هستی شناسی

Abstract

Feature-based product modeling is the leading approach for the integrated representation of engineering product data. On the one side, this approach has stimulated the development of formal models and vocabularies, data standards and computational ontologies. On the other side, the current ways to model features are considered problematic since it lacks a principled and uniform methodology for feature representation. This paper reviews the state of art of feature-based modeling approaches by concentrating on how features are conceptualized. It points out the drawbacks of current approaches and proposes a high-level ontology-based perspective to harmonize the definition of feature.

6. Discussion and conclusions

This paper provided a critical review of the state of art of feature-based product knowledge representation with emphasis on conceptualization problems and on drawbacks of existing unifying approaches. Our work departs from previous reviews of the literature which typically focus on how features are implemented in CAx systems. Instead, our modeling concerns led us to discuss the concepts behind existing feature models, their understanding and their characterization. As a result of the literature review, we claimed that todays lack of interoperability is due to application-driven representational choices in the information systems for product lifecycle. In particular, we argued that a high-level distinction should be set to separate information features (I-feature) and physical features (P-feature). This basic distinction, already adopted in several engineering standards and methodologies, has been disregarded in the literature on features. The consequence is a conceptual ambiguity that has impeded, in our view, the development of a unifying view. In the last section, we motivated this distinction with ontological arguments. The same arguments, we argue, can be exploited to pursue a new approach for feature classification. From the literature, a feature should be modeled as an entity intentionally created or selected for a product development purpose. Since features are introduced for application purposes, they are the result of experts’ agreements, creativity and modeling choices. In this sense, a feature is an entity intentionally introduced in the physical product or in its model, thus made (created) or described (selected) on purpose to satisfy certain requirements. Also, an I-feature can be qualitatively and/or quantitatively characterized, which means that the corresponding properties can be given in terms of value ranges, tolerances, granularity, etc. Finally, no feature can exist by itself. Rather, it needs to be related to some other entity, typically the product (or workpiece) for a P-feature and the product model for an I-feature. Nonetheless, we do not exclude the possibility of having features of features, e.g. the color feature of a part feature, although the pros and cons of this modeling flexibility should be better investigated.