Xenia Fiorentini

OntoSTEP: Enriching product model data using ontologies

The representation and management of product lifecycle information is critical to any manufacturing organization. Different modeling languages are used at different lifecycle stages, for example STEPs EXPRESS may be used at a detailed design stage, while UML may be used for initial design stages. It is necessary to consolidate product information created using these different languages to build a coherent knowledge base. In this paper, we present an approach to enable the translation of STEP schema and its instances to Ontology Web Language (OWL). This gives a model-which we call OntoSTEP-that can easily be integrated with any OWL ontologies to create a semantically rich model. As an example, we combine geometry information represented in STEP with non-geometry information, such as function and behavior, represented using the NISTs Core Product Model (CPM). A plug-in for Protege is developed to automate the different steps of the translation. As additional benefits, reasoning, inference procedures, and queries can be performed on enriched legacy CAD models. We describe the rules for the translation from EXPRESS to OWL, and illustrate the benefits of OWL translation with an example. We will also describe how these mapping rules can be implemented through meta-model based transformations, which can be used to map other languages to OWL.

OntoSTEP: OWL-DL Ontology for STEP

The Standard for the Exchange of Product model data (STEP) [1] contains product information mainly related to geometry. The modeling language used to develop this standard, EXPRESS, does not have logical formalism that will enable rigorous semantics. In this paper we present an OWL-DL (Web Ontology Language Description Logic) [2] version of STEP (OntoSTEP) that will allow logic reasoning and inference mechanisms and thus enhancing semantic interoperability. The development of OntoSTEP requires the conversion of EXPRESS schema to OWL-DL, and the classification of EXPRESS instances to OWL individuals. Currently we have considered AP203 [3] the most widely used Application Protocol (AP) for the exchange of Computer-Aided Design (CAD) files and STEP Part 21 [4] CAD files CAD files conformant to the data exchange format defined in Part 21 for schema level conversion and instance level classification respectively. We have implemented a web application to demonstrate OntoSTEP. We are currently extending OntoSTEP to include information such as function, behavior, and assembly requirements. Keyword: STEP, OWL, ontology, reasoning, semantics

A Semantic Product Modeling Framework and Its Application to Behavior Evaluation

Supporting different stakeholder viewpoints across the product lifecycle requires semantic richness to represent product-related information and enable multiview engineering simulations. This paper proposes a multilevel product modeling framework enabling stakeholders to define product models and relate them to physical or simulated instances. The framework is defined within the Model-Driven Architecture using the multilevel (data, model, metamodel) approach. The data level represents real-world products, the model level describes models (product models) of real-world products, and the metamodel level describes models of the product models. The metamodel defined in this paper is specialized from a web ontology language enabling product designers to express the semantics of product models in an engineering-friendly way. The interactions between these three levels are described to show how each level in the framework is used in a product engineering context. A product design scenario and user interface for the product metamodel is provided for further understanding of the framework.

Extending the notion of quality from physical metrology to information and sustainability

In this paper we intend to demonstrate the need for extending the notion of quality from the physical domain to information and, more comprehensively, to sustainability. In physical metrology there are well established principles such as fundamental units, precision, accuracy, traceability and uncertainty. In order to understand and define quality for information and sustainability we need to develop metrological concepts similar to those of physical metrology. Research efforts related to information quality (IQ) are scattered. IQ is primarily defined in terms of several characteristics (dimensions) which lack consensus definitions and are sometimes subjective. However, the notion of IQ is currently in practice and has provided some useful insights towards defining formal approaches to IQ. In order to extend the notion of quality to sustainability we need, as in the case of information, a well defined metrology similar to physical metrology. Sustainability is currently getting attention in many areas of human endeavor. One proposal is to measure sustainability in terms of a triple bottom line, namely social, economical and environmental aspects of human endeavor. Sustainability metrics are continuously evolving and their clear definition is fundamental to the understanding of the notion of sustainability quality. As an example we consider evaluation of carbon footprint, as a metric towards sustainability, for manufacturing a simple turned part. After analyzing the current literature, we identify the following needs for characterizing the notion of sustainability quality: (a) standardized terminology of terms and concepts, (b) metrics and metrology, (c) harmonization and extension of standards, (d) conformance testbeds for standards and (e) development of information models that support sustainability.

An Analysis of Description Logic Augmented with Domain Rules for the Development of Product Models

The languages and logical formalisms developed by information scientists and logicians concentrate on the theory of languages and logical theorem proving. These languages, when used by domain experts to represent their domain of discourse, most often have issues related to the level of expressiveness and need specific extensions. In this paper, we first analyze the requirements for the development of structured knowledge representation models for manufacturing products. We then explore how these requirements can be satisfied through the levels of logical formalisms and expressivity of a structured knowledge representation model. We report our analysis of description logic (DL) and domain-specific rules with respect to the requirements by giving an example of a product ontology developed with ontology web language-description logic (OWL) and augmented with semantic web rule language (SWRL) rules. Clearly, increasing the expressivity of a product ontology also improves that of domain-specific rules, but there exits the usual tradeoff between the expressivity of languages and the complexity of their reasoning tasks. We present a case study of an electromechanical product to validate the analysis and,further show how the OWL-DL reasoner together with the rule engine can enable reasoning about the product ontology. We finally discuss the open issues such as capabilities and limitations related to the usage of DL, OWL, and SWRL for product modeling.

Description Logic for Product Information Models

The languages and logical formalisms developed by information scientists and logicians concentrate on the theory of languages and logical theorem proving. These languages, when used by domain experts to represent their domain of discourse, most often have issues related to the level of expressiveness of the languages and need specific extensions. In this paper we analyze the levels of logical formalisms and expressivity requirements for the development of ontologies for manufacturing products. We first discuss why the representation of a product model is inherently complex and prone to inconsistencies. We then explore how these issues can be overcome through a structured knowledge representation model. We report our evaluation of OWL-DL in terms of expressivity and of the use of SWRL for representing domainspecific rules. We present a case study of product assembly to document this evaluation and further show how the OWL-DL reasoner together with the rule engine can enable reasoning of the product ontology.

An Evaluation of Description Logic for the Development of Product Models

The languages and logical formalisms developed by information scientists and logicians concentrate on the theory of languages and logical theorem proving. These languages, when used by domain experts to represent their domain of discourse, most often have issues related to the level of expressiveness and need specific extensions. In this paper we first analyze the requirements for the development of structured knowledge representation models for manufacturing products using ontologies. We then explore how these requirements can be satisfied through the levels of logical formalisms and expressivity of a structured knowledge representation model. We report our evaluation of Description Logic (DL) with respect to the requirements by giving an example of a product ontology developed with OWL (Ontology Web Language-Description Logic). In order to represent a product, we also need to combine both DL expressivity and domainspecific rules. Domain-specific rules are defined to add specific constraints in the knowledge base and we have used SWRL (Semantic Web Rule Language) for this purpose. We present a case study of an electro-mechanical product to validate the evaluation and further show how the OWL-DL reasoner together with the rule engine can enable reasoning of the product ontology. We finally discuss the open issues such as capabilities and limitations related to the usage of DL, OWL and SWRL for product modeling.

Formal Representation of Product Design Specifications for Validating Product Design

As collaborative efforts in electro-mechanical design have scaled to large, distributed groups working for years on a single product, an increasingly large gulf has developed between the original stated goals of the project and the final design solution. It has thus become necessary to validate the final design solution against a set of requirements to ensure that these goals have, in fact, been met. This process has become tedious for complex products with hundreds of design aspects and requirements. By formalizing the representation of requirements and the design solution, tools can be developed to a large extent automatically perform this validation. In this paper, we propose a formal approach for relating product requirements to the design solution. First, we present a formal model for representing product requirements. Then, we introduce the Core Product Model (CPM) and the Open Assembly Model (OAM) for representing the design solution. Finally, we link these models formally and provide an example with an actual consumer device.

Towards a method for harmonizing information standards

Designers and engineers use various engineering authoring tools, such as CAD, CAE, and PDM,, to generate information objects (engineering objects). On the business side, enterprise level business process modelers use various business authoring tools, such as ERP, CRM, and LCA, to generate information objects (business objects). These information objects, both engineering and business, are represented using information standards. These standards are used to exchange information about engineering and business systems for enterprise level interoperability. One of the main problems of designers, engineers and process modelers is the selection of appropriate standards for interoperability. To ensure enterprise level interoperability, it is absolutely critical that information standards are compared and harmonized as there are overlapping and dissimilar standards available. In this paper, we will sketch a method towards comparing and harmonizing standards based on: 1) informal approach, 2) typology of standards, 3) use-case scenarios, and 4) ontologies. The method is explained using some engineering and business standards.

Product modeling framework and language for behavior evaluation

Supporting different stakeholder viewpoints across the products entire lifecycle requires semantic richness for representing product related information. This paper proposes a multi-layered product-modeling framework that enables stakeholders to define their product-specific models and relate product-specific models to physical or simulated instances. The framework is defined within the Model-driven Architecture and adapted to the multi-layer approach of the architecture. The data layer represents real world products, the model layer includes models of those products, and the meta-model layer defines the product modeling language. The semantic-based product modeling language described in this paper is specialized from a web ontology language enabling product designers to express the semantics of their product models explicitly and logically in an engineering-friendly way. The interactions between these three layers are described to illustrate how each layer in the framework is used in a product engineering context.