Najam A. Anjum

A model-driven ontology approach for manufacturing system interoperability and knowledge sharing

The requirements for the interoperability of semantics and knowledge have become increasingly important in Product Lifecycle Management (PLM), in the drive towards knowledge-driven decision support in the manufacturing industry. This article presents a novel concept, based on the Model Driven Architecture (MDA). The concept has been implemented under the Interoperable Manufacturing Knowledge Systems (IMKS) project in order to understand the extent to which manufacturing system interoperability can be supported using radically new methods of knowledge sharing. The concept exploits the capabilities of semantically well-defined core concepts formalised in a Common Logic-based ontology language. The core semantics can be specialised to configure multiple application-specific knowledge bases, as well as product and manufacturing information platforms. Furthermore, the utilisation of the expressive ontology language and the generic nature of core concepts help support the specification of system mechanisms to enable the verification of knowledge across multiple platforms. An experimental demonstration, using a test case based on the design and manufacture of an aerospace part, has been realised. This has led to the identification of several benefits of the approach, its current limitations as well as the areas to be considered for further work.

Extending product lifecycle management for manufacturing knowledge sharing

Product lifecycle management provides a framework for information sharing that promotes various types of decision-making procedures. For product lifecycle management to advance towards knowledge-driven decision support, then this demands more than simply exchanging information. There is, therefore, a need to formally capture best practice through-life engineering knowledge that can be fed back across the product lifecycle. This article investigates the interoperable manufacturing knowledge systems concept. Interoperable manufacturing knowledge systems use an expressive ontological approach that drives the improved configuration of product lifecycle management systems for manufacturing knowledge sharing. An ontology of relevant core product lifecycle concepts is identified from which viewpoint-specific domains, such as design and manufacture, can be formalised. Essential ontology-based mechanisms are accommodated to support the verification and sharing of manufacturing knowledge across domains. The work has been experimentally assessed using an aerospace compressor disc design and manufacture example. While it has been demonstrated that the approach supports the representation of disparate design and manufacture perspectives as well as manufacturing knowledge feedback in a timely manner, areas for improvement have also been identified for future work.

Manufacturability verification through feature-based ontological product models:

To achieve efficient, fast and cost effective production, designers must consider all the manufacturing stages a product has to go through. A case study in a manufacturing setup shows that owing to the differences in perception of an engineering component, the coordination between design and manufacturing becomes difficult. Semantic interoperability problems are therefore faced when knowledge sharing for the purpose of manufacturability verification is attempted through computer-based knowledge bases. Ontologies have a reputation for solving semantic interoperability problems. Combined with shape feature-based models of components, ontologies provide a basis for seamless knowledge sharing. This article demonstrates the use of ontologies for analyzing the manufacturability of engineering components in the early design stages. This is done by developing shape feature-based ontological models of these components and associating manufacturability knowledge with these models. To achieve this, an ontological modelling technique is proposed that uses shape feature-based geometrical models of engineering components as building blocks. The knowledge associated with these models to demonstrate their use for manufacturability verification is derived from the findings of a case study also detailed in this article.

Gap analysis of ontology mapping tools and techniques

Mapping between ontologies provides a way to overcome any dissimilarities in the terminologies used in two ontologies. Some tools and techniques to map ontologies are available with some semi-automatic mapping capabilities. These tools are employed to join the similar concepts in two ontologies and overcome the possible mismatches.Several types of mismatches have been identified by researchers and certain overlaps can easily be seen in their description. Analysis of the mapping tools and techniques through a mismatches framework reveals that most of the tools and techniques just target the explication side of the concepts in ontologies and a very few of them opt for the conceptualization mismatches. Research therefore needs to be done in the area of detecting and overcoming conceptualization mismatches that may occur during the process of mapping. The automation and reliability of these tools are important because they directly affect the interoperatbility between different knowledge sources.

Verification of knowledge shared across design and manufacture using a foundation ontology

Seamless computer-based knowledge sharing between departments of a manufacturing enterprise is useful in preventing unnecessary design revisions. A lack of interoperability between independently developed knowledge bases, however, is a major impediment in the development of a seamless knowledge-sharing system. Interoperability, being an ability to overcome semantic and syntactic differences during computer-based knowledge sharing, can be enhanced through the use of foundation ontologies. Foundation or core ontologies can be used to overcome differences existing in more specialised ontologies and to ensure seamless knowledge sharing. This is because these ontologies provide a common grounding for domain ontologies to be used by different functions or departments. This common base can be used by mediation and knowledge verification systems to authenticate the meaning of knowledge understood across different domains. For this reason, this research proposes a knowledge verification framework for developing a system capable of verifying knowledge between those domain ontologies which are developed out of a common core or foundation ontology. This framework makes use of ontology logic to standardise the way concepts from a foundation and core concepts ontology are used in domain ontologies and then, by using the same principles, the knowledge being shared is verified.

Mediation of foundation ontology based knowledge sources

Ontologies are helpful in giving interoperable structures to sources of knowledge and information. This interoperability, however, is greatly hindered by the heterogeneity of independently developed ontologies which in turn increases the requirements for mediation systems to reconcile the differences. A core concepts ontology for a certain domain contained by a foundation ontology can be used to alleviate this problem and to facilitate the reconciliation efforts. Possible differences in the use of concepts from the core concepts to model entities in domain ontologies can be prevented by binding the domain ontology developers to some rules. These rules can be particularly useful for domain ontologies requiring some kind of traceability of their concepts in the foundation ontology. The mediation system can then use this traceability to establish similarities between two ontologies. Software applications, like the one explained in this paper, can then be developed to perform the mediation task automatically and accurately.