Ontological approach for products-centric information system interoperability in networked manufacturing enterprises

Standardisation initiatives (ISO and IEC) try to answer the problem of managing heterogeneous information, scattered within organizations, by formalising the knowledge related to products technical data. While the product is the centred object from which, along its lifecycle, all enterprise systems, either inside a single enterprise or between cooperating networked enterprises, have a specific view, we may consider it as active as far as it participates to the decisions making by providing knowledge about itself. This paper proposes a novel approach, postulating that the product, represented by its technical data, may be considered as interoperable per se with the many applications involved in manufacturing enterprises as far as it embeds knowledge about itself, as it stores all its technical data, provided that these are embedded on a common model. The matter of this approach is to formalise of all technical data and concepts contributing to the definition of a Product Ontology, embedded into the product itself and making it interoperable with applications, minimising loss of semantics.     

Developing distributed applications for integrated product and process design

A heterogeneous computing environment characterizes today's manufacturing situation. This is a stumbling block for the efficient implementation of manufacturing concepts such as integrated product and process design (IPPD). A computing environment for IPPD would require the seamless integration of the various product and process design software systems. The exchange of information between these systems should be efficient, compatible and synchronous. This article presents an approach for developing distributed manufacturing applications that are compatible and synchronized and thus, able to support IPPD. The approach involves the use of a common manufacturing application ‘middleware’, which is distributed between a central geometric modelling server and application clients. The portability of the middleware is ensured through the use of Java for code portability and XML for data portability. The compatible product model problem is solved through the use of common data structures developed using reusable application client classes. Efficient transfer of product data is proposed using compressed model information embedded in a product data XML schema. Synchronization of design changes among all applications is achieved through the creation of relationships on an Application Relationship Manager.     

Enriching standards-based digital thread by fusing as-designed and as-inspected data using knowledge graphs

Realizing the digital thread is essential for linking and orchestrating data across the product lifecycle in smart manufacturing. Linking heterogeneous lifecycle data is critical to maintain associativity and traceability in a digital thread. Recently, researchers have successfully leveraged ontology models with knowledge graphs in engineering domains for threading different lifecycle data. One of the most successful of such efforts is OntoSTEP which enables the formal capture of information embedded in the STandard for Exchange of Product model data (STEP) data representation, or ISO 10303. Meanwhile, an emerging inspection standard, called the Quality Information Framework (QIF), has garnered significant attention as it can bring quality information into the digital thread. Implementing more automated methods for product quality assurance is challenging due to the lack of unified information models from design to inspection. To this end, we propose an approach to fuse as-designed data represented in STEP and as-inspected data represented in QIF in a standards-based digital thread based on ontology with knowledge graphs. Specifically, we present an automated pipeline for generating knowledge graphs representing STEP and QIF data, a mapping implementation to integrate STEP and QIF knowledge graphs, and rules and queries to demonstrate the integration’s potential for better decision making with respect to product quality assurance.     

Integration of product design,process planning,scheduling, and FMS control using XML data representation

An efficient model for communications between CAD, CAPP, and CAM applications in distributed manufacturing planning environment has been seen as key ingredient for CIM. Integration of design model with process and scheduling information in real-time is necessary in order to increase product quality, reduce the cost, and shorten the product manufacturing cycle. This paper describes an approach to integrate key product realization activities using neutral data representation. The representation is based on established standards for product data exchange and serves as a prototype implementation of these standards. The product and process models are based on object-oriented representation of geometry, features, and resulting manufacturing processes. Relationships between objects are explicitly represented in the model (for example, feature precedence relations, process sequences, etc.). The product model is developed using XML-based representation for product data required for process planning and the process model also uses XML representation of data required for scheduling and FMS control. The procedures for writing and parsing XML representations have been developed in object-oriented approach, in such a way that each object from object-oriented model is responsible for storing its own data into XML format. Similar approach is adopted for reading and parsing of the XML model. Parsing is performed by a stack of XML handlers, each corresponding to a particular object in XML hierarchical model. This approach allows for very flexible representation, in such a way that only a portion of the model (for example, only feature data, or only the part of process plan for a single machine) may be stored and successfully parsed into another application. This is very useful approach for direct distributed applications, in which data are passed in the form of XML streams to allow real-time on-line communication. The feasibility of the proposed model is verified in a couple of scenarios for distributed manufacturing planning that involves feature mapping from CAD file, process selection for several part designs integrated with scheduling and simulation of the FMS model using alternative routings.     

Parametric CAD/CAE integration using a common data model

This paper proposes a CAD/CAE integration method using a “common data model” (CDM) containing all the required parametric information for both CAD modeling and CAE analysis. CDM is automatically generated by a knowledge embedded program code. The CDM is used as a parametric data model repository and the supply source of input for those associative entities of CAD and CAE models and thus maintaining the associative dependences among them. The structure as well as the data flow in the CDM is governed according to the general and widely used design processes. Thus designers can relate the expected scenarios with the engineering changes proposed and can take the parametric actions accordingly. CDM acts as the centralized parametric input for computer modeling software tools through their APIs. Throughout the design process the common data model gets modified during each development cycle according to designer’s intent, the changes in it are consistently reflected in both CAD and CAE models through regenerations and analysis iterations semi-automatically. The same data model in a suitable file format can be used to work with different CAD and CAE packages. As CDM, CAD and CAE work as different modules interconnected through a develop software prototype package which integrates APIs and knowledge rules embedded in the engineering procedures. However, each of the software tools used for each purpose can vary as per the original data requirement without hindering the process structure. The data model is reusable and the whole process is automated as far as possible so that the embedded expertise in the cycles of the adaptive design and manufacturing can be consistently applied iteratively during product development processes. Also being a data file in a suitable format generated via computer programming, the CDM is convenient to record and store information associated to all the product design revisions.     

A novel methodology for cross-technology interoperability in CNC machining

In CNC part programmes, the lack of standardisation for representing part geometry and semantics of manufacturing operations leads to the necessity for existence of a unique part programme for each machine. Generating multiple programmes for producing the same part is not a value adding activity and is very time consuming. This wasteful activity can be eliminated if users are given the ability to write an NC program for a specific machine and robustly convert the program to syntax suitable for another CNC machine with a different structure. This, cross-technology interoperability, would enable for parts manufactured on old CNC machines using legacy code to be manufactured on new CNC machines by automatically converting the programmes. Every NC programme is written based on various categories of information such as: cutting tool specifications, process planning knowledge and machine tool information. This paper presents an approach for cross-technology interoperability by refining high-level process information (i.e., geometric features on the part and embedded manufacturing resource data) from NC programmes. These refined items of information stored in compliance with the ISO14649 (STEP-NC) standard may then be combined with new manufacturing resource information to generate NC code in a format that is compatible with machines based on different technologies. The authors provide a framework for this process of identification, semantic interpretation and re-integration of information. The focus of this paper is on asymmetric rotational components as the initial application area. To demonstrate the proposed cross-technology interoperability approach, a C-axis CNC turn–mill machine and a 4 axis CNC machining centre have been used with a simple test component.     

Decision on the memory size of embedded information systems in an ubiquitous maintenance environment

Over the last decade, emerging information communication technologies have changed our stereotype of manufacturing and service companies. Now products equipped with embedded systems can be wirelessly networked, which leads to gathering and analyzing product status, and taking appropriate actions for maintenance operations during product lifecycle in an ubiquitous way. In this environment, it is necessary to determine the appropriate memory size of embedded systems for minimizing total maintenance system costs because the memory cost is a main cost factor for implementing the ubiquitous maintenance environment. We call it memory size decision problem in this study. We have formulated this problem with a non-linear model having constraints. The decision variable is the memory size of each embedded system. To solve this problem, we have proposed a meta heuristic search method based on genetic algorithms. To show the usefulness of the proposed heuristic, we have carried out computational experiments.     

复杂产品制造信息集成规划内容与方法

分析了复杂产品制造业信息化的历程、面临的信息孤岛问题和企业信息集成规划需求的迫切性．结合企业的实际,提出了基于两化融合的复杂产品制造企业信息集成规划与实施的总体思路,并重点论述了其中数据管理规划、基于BOM的业务信息数据关联模型、系统集成的数据关联定义和规范化“就源取数”管理关键技术内容和示例．     

Using views for product data exchange

Proprietary data structures complicate data sharing by making it difficult to save a product model from one software tool and load it directly into another tool. Engineers may want, for example, to verify with an analysis tool that all design constraints have been met or to prepare a design for manufacturing. In such cases, software developers must find a means of moving the product model from the proprietary data structures of a CAD system to those of the analysis system and the manufacturing system, with minimal loss of information. A database view, used in conjunction with data exchange standards, can facilitate the sharing of product model data between software tools in design and manufacturing computing environments     

Supporting management and maintenance of manufacturing knowledge in design automation systems

Many companies base their business strategy on customized products. To enable a high level of product adaptation in an engineer-to-order approach companies invest time and resources to develop design automation systems. Initially, when implementing a design automation system, the focus is on successfully developing a system that generates design variants based on different customer specifications (i.e. the execution of system embedded knowledge and system output). However, in the long run, two important aspects are the management and maintenance of the knowledge that governs the designs. Further, the increasing emphasis on deploying a holistic view of a product’s properties and functions implies an increasing number of life-cycle requirements. The knowledge to adapt the product to fulfil these requirements should also be used and consequently incorporated into the knowledge-base, allowing for correct decisions to be made. In a system for automated variant design, the implications on the product of these life-cycle requirements have to be expressed as algorithms, production rules and/or computational statements to be intertwined with the design calculations. The number of requirements can be significantly large, and the knowledge scattered over different application systems used for the realisation of the design automation system. This makes it difficult to manage and maintain the system as the product life-cycle environment changes and evolves.In this article, the focus is on the requirements related to manufacturing. For that, an approach for the modelling of manufacturing requirements, supporting both knowledge execution and information management, in systems for automated variant design is introduced. The approach has been applied and refined when developing a design automation system in cooperation with a company to demonstrate and verify the approach’s usability.     

Towards a sales assistant using a product knowledge graph

The phenomenal growth in the consumer electronics industry over the last decade is mainly due to rapid advances in integration technologies. The market is ever evolving with new products made available on a frequent basis. However, typically, the average consumer tends to have insufficient knowledge of the features and functions of an electronic device. Although most manufacturers provide product specifications, they are often difficult for consumers to understand and it is hard for customers to grasp the details of a product. This study introduces the concept of a product knowledge graph, which is constructed by transforming a set of data from a product management system and external data. This study overcomes the technical barriers for customers with the use of knowledge graph technologies. To construct large-scale product knowledge, an ontology model is designed and a platform for knowledge extraction and transformation is also developed. Then, a sales assistant called God of Sales is demonstrated. This study provides a novel approach to explaining product features and functions in a comprehensive manner with semantic recommendations.     

A feasible approach to the integration of CAD and CAPP

Although current CAD systems are declared to be feature-based, in fact, the so-called feature is just a modeling macro or menu name such as Protrusion, Revolution, Cutout, Block, etc., instead of a design feature or manufacturing feature in accordance with engineering practice. Consequently, product model data insufficiency and incompatibility between varieties of application systems are still the major barriers to system integration, especially the integration of design and process planning. This paper proposes a practical solution for a bi-directional integration of CAD and CAPP on the platform of commercial CAD systems. The key techniques such as feature recognition and conversion, feature parameter and constraint extraction, feature tree reconstruction, technical information processing, process planning, automatic process drawing marking and 3D material stock CAD model generating are discussed. And the extracted features and their related technical information and knowledge are encapsulated together with the geometry-oriented CAD model to form an integrated product information model to facilitate effective integration with the downstream activities. The integrated CAD/CAPP system is implemented on a commercial CAD package, UGS/SolidEdge. A case study and industry implementation illustrate the feasibility of the approach proposed.     

A demerit-fuzzy rating system,monitoring scheme and classification for manufacturing processes

For monitoring online manufacturing processes, the proportion of weights imposed on each type of product’s defects (nonconformities or demerits) has a profoundly effective impact on control charts’ performance. Apparently, the demerit-chart approach is superior than the widely-used c-chart scheme, because it allows us to place relative precise weights (real numbers) on defects according to their distinctly inferior degrees affecting the product quality so that the abnormal variations of processes can be literally exposed. However, in many applications, the seriousness of defects is evaluated partially or entirely by the inspectors’ perceptive judgement or knowledge, so with the precise-weight assignment, the demerit rating mechanism is considered to be somewhat constrained and subjective which inevitably leads to the targeted manufacturing process with limited and possibly biased information for online surveillance. To cope with the drawback, a demerit-fuzzy rating system and monitoring scheme is proposed in this paper. We first incorporate fuzzy weights (fuzzy numbers) to properly reflect the severity measures of defects which are categorized linguistically. Then, based on properties of fuzzy set theory and proposed approaches for fuzzy-number ranking, we develop the demerit-fuzzy charting scheme which is capable of discriminating process conditions into multi-intermittent statuses between in-control and out-of-control. This approach improves the traditional process control techniques with the binary-classification restraint for the process conditions. Finally, the proposed demerit-fuzzy rating system, monitoring scheme, and classification is elucidated by an application in garment industry to monitor textile-stitching nonconformities conditions.     

Seeking intelligent product development—an integrator environment based on STEP

Rapid Prototyping (RP) is an emerging technology with different applications in the cycle of product and process development used during the conceptual and specification phases. To support it, the usage of a Data Base Management System (DBMS) and an Expert Systems (ES) are important to manage the data, support the identification of errors and check product conformance and production viability during this cycle, seeking intelligent product development. The underlying concept of RP and ES is very straight forward, but still exists a major problem that concerns the integration in the CAD/CAM environment. CAD data can have a variety of formats depending on the model used in the CAD system, as well as on ES' data and knowledge structure, that usually relies on the expert system shell's where it was developed. To support and speed up the integration process of these tools in a manufacturing environment, is essential to have an integrator environment where a standard is adopted for the data and knowledge exchange process, providing the software applications with a neutral format interface, becoming these tools open and standard compliant, ready to be used in any other standard environment. UNINOVA, in the scope of European and National projects, developed a STEP-based Platform for Integration of applications (SIP) to support and aid the software integration in industrial environments using the standard ISO10303-STEP, already used in different industrial domains. This paper addresses the integration aspects using STEP within industrial environments from the technical point of view, and proposes an architecture and a toolkit for the integrator environment, highlighting the implementation efforts required to have RP technology, ES and DBMS focused towards a STEP-based intelligent product development.     

A Conceptual Approach for Data Integration in Business Analytics

We present some basic concepts of a modelling environment for data integration in business analytics. Main emphasis is on defining a process model for the different activities occurring in connection with data integration, which allow later on assessment of the quality of the data. The model is based on combination of knowledge and techniques from statistical metadata management and from workflow processes. The modelling concepts are presented in a problem oriented formulation. The approach is embedded into an open model framework which aims for a modelling platform for all kinds of models useful in business applications.     

A semantic knowledge management system for laminated composites

The engineering of laminated composite structures is a complex task for design engineers and manufacturers, requiring significant management of manufacturing process and materials information. Ontologies are becoming increasingly commonplace for semantically representing knowledge in a formal manner that facilitates sharing of rich information between people and applications. Moreover, ontologies can support first-order logic and reasoning by rule engines that enhance automation. To support the engineering of laminated composite structures, this work developed a novel Semantic LAminated Composites Knowledge management System (SLACKS) that is based on a suite of ontologies for laminated composites materials and design for manufacturing (DFM) and their integration into a previously developed engineering design framework. By leveraging information from CAD/FEA tools and materials data from online public databases, SLACKS uniquely enables software tools and people to interoperate, to improve communication and automate reasoning during the design process. With SLACKS, this paper shows the power of integrating relevant domains of the product life cycle, such as design, analysis, manufacturing and materials selection through the engineering case study of a wind turbine blade. The integration reveals a usable product-life-cycle knowledge tool that can facilitate efficient knowledge creation, retrieval and reuse from design inception to manufacturing of the product.     

Knowledge graph construction for product designs from large CAD model repositories

Product Design based Knowledge graphs (KG) aid the representation of product assemblies through heterogeneous relationships that link entities obtained from multiple structured and unstructured sources. This study describes an approach to constructing a multi-relational and multi-hierarchical knowledge graph that extracts information contained within the 3D product model data to construct Assembly-Subassembly-Part and Shape Similarity relationships. This approach builds on a combination of utilizing 3D model meta-data and structuring the graph using the Assembly-Part hierarchy alongside 3D Shape-based Clustering. To demonstrate our approach, from a dataset consisting of 110,770 CAD models, 92,715 models were organized into 7,651 groups of varying sizes containing highly similar shapes, demonstrating the varied nature of design repositories, but inevitably also containing a significant number of repetitive and unique designs. Using the Product Design Knowledge Graph, we demonstrate the effectiveness of 3D shape retrieval using Approximate Nearest Neighbor search. Finally, we illustrate the use of the KG for Design Reuse of co-occurring components, Rule-Based Inference for Assembly Similarity and Collaborative Filtering for Multi-Modal Search of manufacturing process conditions. Future work aims to expand the KG to include downstream data within product manufacturing and towards improved reasoning methods to provide actionable suggestions for design bot assistants and manufacturing automation.