Keith Case

Feature technology - an overview

Abstract The proper integration of the activities of computer-aided design (CAD) and computer-aided manufacture (CAM)is an objective that has become more urgent within the wider context of a total computer integrated manufacturing (CIM) environment. In seeking this integration it is recognized that the diversity of activities and consequent needs for data can best be served by a single representation for design, design analysis and manufacturing planning, and that a strong candidate for this descriptive role is a feature representation. This paper briefly overviews the primary methods of the use of features through feature recognition and design by features, particularly in the process planning application area.

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.

Component grouping for GT applications—a fuzzy clustering approach with validity measure

The variety of the currently available component grouping methodologies and algorithms provide a good theoretical basis for implementing GT principles in cellular manufacturing environments. However, the practical application of the grouping approaches can be further enhanced through extensions to the widely used grouping algorithms and the development of criteria for partitioning components into an ‘optimum’ number of groups. Extensions to the fuzzy clustering algorithm and a definition of a new validity measure are proposed in this paper. These are aimed at improving the practical applicability of the fuzzy clustering approach for family formation in cellular manufacturing environments. Component partitioning is based upon assessing the compactness of components within a group and overlapping between the component groups. The developed grouping methodology is experimentally demonstrated using an industrial case study and several well known component grouping examples from the published literature.

HADRIAN: a virtual approach to design for all

This article describes research into the area of ‘design for all’. The research addresses two common needs for designers working towards developing inclusive products and environments, namely, data on users that are accessible, valid and applicable, and a means of utilising the data to assess the accessibility of designs during the early stages of development. The approach taken is through the development of a combined database and inclusive human modelling tool called HADRIAN. Data were collected on 100 people, the majority of whom are older or have some form of impairment. These individuals provide a browsable resource spanning size, shape, capability, preferences, and experiences with a range of daily activities and transport-related tasks. This is partnered with the development of a simple, CAD-based task analysis system. Tasks are carried out by the virtual individuals in the database and accessibility issues are reported, allowing excluded people to be investigated in order to understand the problems experienced and solutions identified. HADRIAN is also being expanded to include a more accessible journey planner that provides accessibility information to both end users and transport professionals. Together, HADRIAN allows more informed choices to be made either in travelling, or in the designing of products and environments.

An evaluation of failure modes and effects analysis generation method for conceptual design

Failure modes and effects analysis (FMEA) is used in the manufacturing industry to improve product quality and productivity. However, the traditional approach has many shortcomings that affect its effectiveness and limit its usefulness, especially in the early stages of design. Automating the FMEA report generation process seems to answer some of these problems, and there has been much past and on-going research in this area. However, most of the work is limited to specific applications. This paper proposes a method for FMEA generation for a generic application using minimum information during the conceptual design stage. Prototype software has been created for the proposed method. It has been evaluated using case studies from the design and manufacture of two-way radios. The evaluation revealed the feasibility of the proposal, as well as some weaknesses that need further improvement. Generally, the capability of the method to generate FMEA report with minimum information is demonstrated.

Towards a formal manufacturing reference ontology

Due to the advancement in the application of Information and Communication Technology (ICT), manufacturing industry and its many domains employ a wide range of different ICT tools. To be competitive, industries need to communicate effectively within and across their many system domains. This communication is hindered by the diversity in the semantics of concepts and information structures of these different domain systems. Whilst international standards provide an effective route to information sharing within narrowly specified domains, they are themselves not interoperable across the wide range of application domains needed to support manufacturing industry due to the inconsistency of concept semantics. Formal ontologies have shown promise in removing interpretation problems by computationally capturing the semantics of concepts, ensuring their consistency and thus providing a verifiable and shared understanding across multiple domains. The research work reported in this paper contributes to the development of formal reference ontology for manufacturing, which is envisaged as a key component in future interoperable manufacturing systems. A set of core manufacturing concepts are identified and their semantics have been captured in formal logic based on exploiting and extending existing standards’ definitions, where possible combined with an industrial investigation of the concepts required. A successful experimental investigation has been conducted to verify the application of the ontology based on the interaction between concepts in the design and manufacturing domains of an aerospace component.

Feature-based representation for manufacturing planning

Improved integration using product models in a computer aided design and manufacture environment implies that there is an enhanced need to provide information support across a wide range of applications. In a typical situation concerned with mechanical products, these applications are likely to include detail design, process planning and assembly planning. Features have frequently been used to support these and other applications individually, but single feature representations that simultaneously meet the information needs of a number of applications are unusual. Assembly and process planning are two important aspects of an integrated design and manufacture system, and a formal structure for their representation in a feature-based design system is presented. Features are considered to be machined volumes and are described in a hierarchical taxonomy that is designed to be useful across a range of machined components. The assembly structure is also defined hierarchically with the (machining) features forming the basic entities in the assembly. Assembly relationships among features are defined in the form of mating relationships that are carried by the features. A set of mating relationships between pairs of features has been defined after having studied the literature and a number of engineering products. An integrated data structure containing process planning information from earlier research work and the assembly mating relationships is presented and forms the basis of class definitions for each level in the assembly hierarchy. Object-oriented programming techniques have been used to implement a prototype system using the ACIS solid modelling kernel. The research has illustrated the feasibility of using a single feature representation to support a number of activities within a computer integrated manufacturing environment.

Virtual fitting trials in ‘design for all’

Abstract ‘Design for all’ embraces the concept of designing products and workplaces so as not to exclude significant sections of the total user population. In particular, the needs of old and disabled people are to be considered alongside the younger and able-bodied population to ensure that products that are equally appropriate for all users. This is to be contrasted with a ‘design for the disabled’ approach where the special needs of disabled people are considered in order to provide products that may only be appropriate for that section of society. Fitting trials are an established technique in ergonomics where a product or workplace is evaluated by trials (perhaps on a mock-up or prototype) using a carefully selected user group that is representative of the total target population. Typically, subject selection would be based on age, gender, size, etc., and total sample sizes limited to perhaps a few dozen. A percentage of the population accommodated by the design can then be determined by reference to a set of elemental tasks such as reaching to controls. In this research, the fitting trials are virtual in that computer modelling techniques are used to create a three-dimensional geometric model of the workplace/product and evaluation is achieved using a human model that can be varied to represent the individuals within the sample. There is a lack of anthropometric and biomechanical data relating to older and disabled people so a small-scale survey is being undertaken so that an appropriate population of computer human models can be created. Methods are being developed to allow the percentage accommodated by a design to be determined in relation to a description of tasks to be carried out. Currently, an ATM (automated teller machine) design is being used as a case study to develop these techniques. Further research will eventually be undertaken to extend the data, generalise the percentage accommodation evaluation and optimise the design in terms of percentage accommodation.

A methodology for best practice knowledge management

Abstract Capturing and reusing knowledge of best practices has been identified as one of the requirements for next-generation product development. Knowledge identification is therefore already being done to some degree in many organizations, through instruction manuals or ‘how to’ guidelines. However, this is only a first step, as to fully exploit valuable knowledge, best practices must be identified and shared. A detailed review of previous research in best practice knowledge management shows that the method of modelling best practice knowledge and the resulting model structure are critically important for the successful reuse of best practice knowledge. Yet, to date, only limited research has been focused on these aspects. This paper therefore presents research into a methodology to determine ways for better communication, sharing, and reuse of best/good practice knowledge. The proposed methodology has been divided into two parts: firstly, the identification of best practices for product development, and secondly, the structuring of best practice knowledge for effective sharing and reuse. This methodology encourages the adoption of best practices by providing knowledge about both process and implementation elements. This makes the explicit knowledge easier to find and reuse. Once a best practice is found to suit current requirements and circumstances, an expert who has identified and used the best practice can also be contacted to gain additional knowledge/information. This helps to address the challenges posed by ‘tacit’ knowledge, which cannot easily be shared within the knowledge base.

Using HADRIAN for eliciting virtual user feedback in 'design for all'

Abstract ‘Design for all’ is an approach to product, environment or service design that aims to maximize the usability of a particular design. However, a key concept of this approach is not to tailor designs to the user in a bespoke fashion, but rather to provide a single solution that accommodates the needs of all users, including those who are older or are disabled. In order to support the designer/design team in ‘design for all’ a computer aided design and analysis tool has been developed. The tool, known as HADRIAN, has been developed to address two critical factors. The first factor is the provision of accurate and applicable data on the target users, including a broad spectrum of size, shape, age and ability. The second factor is an efficient and effective means of utilizing the data for ergonomics evaluations during the concept stages of design. HADRIANs database and task analysis tool work in combination with the existing human modelling system SAMMIE. The system as a whole allows assessment of a design against the population in the database, providing a means to elicit some of the feedback that might be gained by real user trials at a stage in the design process when physical mock-ups and user group selection would be prohibitively time consuming and expensive.