Fred J.A.M. van Houten

Recent and future trends in cost estimation

Increasingly keen competition and the demand for shorter times to market are driving innovative approaches within the product creation process. When considering the factors that decide the success of a product in the market today, it becomes clear that cost is as crucial as quality and functionality. This paper gives an overview of the state of the art and future trends in the field of cost estimation. First, a short overview of the relevant terms from the field of cost accounting is given. The impact of product development on costs is elaborated and the requirements for a cost calculation model are outlined. The currently prevailing methodological approaches for cost estimation in the product development process are set out and classified in the scientific context with a schema being introduced to reduce the vast number of methods to a single basic structure. Finally, various methods for cost estimation are set out and their shortcomings summarized. This paper aims at building a foundation for future research in the field of cost estimation and ends with a look at future work.

Current Status of CAT Systems

The paper discusses the current status of and research behind some of the major computer aided tolerancing (CAT) systems that are now commercially available. The focus is directed to computer aided toler- ancing systems which serve as an aid in the support of the design process and which are suitable for both 2D and 3D purposes. Other focal points are the theoretical backgrounds as well as the usefulness of the currently available systems in design practice. Some new research developments are identified that will influence future CAT systems. In addition, shortcomings of currently available CAT systems are discussed. Finally, resulting from the identified shortcomings and new research efforts, future research objectives are identified in order to arrive at improved future CAT systems.

Use of models in conceptual design

This article investigates the use of product models by conceptual designers. After a short introduction, abstraction applied in conceptual design is described. A model that places conceptual design in a three-dimensional space is used. Applications of conceptual design from the literature are used to identify several product models used by conceptual designers to handle the complex problems. Next, the models available in four conceptual design support tools are listed. In order to investigate the current use of models by conceptual designers, a questionnaire has been designed and issued. The design and results of this questionnaire are described and analysed. The results have been discussed with conceptual designers. It is concluded that several types of models are needed for conceptual designers to cope with and structure the large amount of information. In particular, budgets are used in the very early stages of the design process. Following that, mathematical models, physical models, block diagrams, specifications, and sketches are used. computer-aided design tools are used to implement the design. Finally, steps for further research are given.This article investigates the use of product models by conceptual designers. After a short introduction, abstraction applied in conceptual design is described. A model that places conceptual design in a three-dimensional space is used. Applications of conceptual design from the literature are used to identify several product models used by conceptual designers to handle the complex problems. Next, the models available in four conceptual design support tools are listed. In order to investigate the current use of models by conceptual designers, a questionnaire has been designed and issued. The design and results of this questionnaire are described and analysed. The results have been discussed with conceptual designers. It is concluded that several types of models are needed for conceptual designers to cope with and structure the large amount of information. In particular, budgets are used in the very early stages of the design process. Following that, mathematical models, physical models, block diagrams, specifications, and sketches are used. computer-aided design tools are used to implement the design. Finally, steps for further research are given.

A knowledge acquisition method to model parametric engineering design processes

This paper proposes an interview-style method to create models of engineering design processes intended for design automation. Development of design automation tools often requires a model of the design artefact, design process or design knowledge. However, the knowledge about product development often resides tacitly inside the mind of designers and is difficult to make explicit. The lack of explicit process models creates a challenge for organisations to improve their design processes. A method is proposed to create explicit models of tacit design knowledge of structured design problems. A standardised model of the design process is used to classify sets of information and processes. The content of the model is filled step-by-step through a series of questions. A prescriptive modelling method reduces the required effort for knowledge modelling and allows design processes to be supported more effectively. The method is demonstrated for a design case with tacit knowledge and a further nine cases are used to demonstrate scalability and comparison between design knowledge of mechanical components and complex product systems.

Haptic virtual prototyping for design and assessment of gear-shifts

Traditionally, a designer forms the link between the customer and the final product by interpreting customer demands and desires and translating them into geometry. By combining 3D CAD systems and software tools for analysis, a designer is able to examine whether the created geometry complies with these customer demands and desires. However, in the process of translation and examination, a measure of subjectivity is added to the design. A virtual prototyping environment (VPE) can be created by utilizing Virtual Reality technology, in which the customer is able to specify the Product’s behavior in a direct way, i.e. without designer interference. In this way, not only is the design process is made more objective, but also significant amounts of time and money are saved since less physical prototypes are required. This paper describes the design and evaluation of a VPE for manually operated gearboxes in passenger cars. Based on measurements taken of the gearlever on a test vehicle, an application is designed that simulates its gearshift feel. This application incorporates a commercially available haptic device. In order to determine whether the virtual gearshift feel conforms with the real gearshift feel, a usability test is performed. The test group considered the feel of the simulated “virtual” gearshift to be quite similar to the “real” gearshift feel of a test vehicle. By further developing this VPE, it should become possible to define gearshift feel by customer assessment through haptic simulation, after which the physical gearbox is designed in such a way that it matches the preferred shifting behavior.

Conceptual design in a high-tech environment

This article will give an overview over design process models before concentrating on the main subject: Conceptual Design, which has had less academic attention than the detail design phases. In high-tech environments specific conditions apply. This article will deal with these conditions. Some views on design in general are treated and attention is paid to the conditions and steps and to the level of abstraction, goals, people and skills. The paper identifies the crucial role of the systems engineer in the conceptual design phase. The conceptual design tasks and their results will be treated. As the conceptual designer is best aware of the overall functionality of the system and the interrelations, he is able to safeguard the concepts in later design phases and to make a good decomposition into subsystems. The paper ends with conclusions and directions for Future Work.

Reducing design complexity of multidisciplinary domain integrated products: a case study

Multidisciplinary product development is well known for the complexity of its design process. It is commonly addressed by domain integration and a modular design approach. The former, often resulting in smaller products and integrated functions, is characterized by a complex non-linear design process. The latter, which may not result in such integrated functions, has a simpler —usually linear— design process, resulting in novel solutions. This paper presents a method for reducing design complexity of Multidisciplinary Domain Integrated Products by decomposing the problem into modular structures. Computational synthesis techniques are used to solve the resulting modules. Printed Circuit Board design is used as case study, as it is well known for its complexity and highly integrated product functionalities.

APPLYING UNIVERSAL LINKING OF ENGINEERING OBJECTS IN THE AUTOMOTIVE INDUSTRY - PRACTICAL ASPECTS, BENEFITS, AND PROTOTYPES

The bi-directional communication of CAD programs with subsequent applications such as process planning remains a key challenge in design-for-the-lifecycle. While it seems sensible that individual applications use their own collection of feature types and thereby allow users to have their specific perspective of the product, it is still difficult to automatically close the gap between the variety of applications. Universal Linking of Engineering Objects (ULEO) targets this concern. It is general enough to facilitate informational integration of the applications along the process chain. This paper examines a number of scenarios for exploiting ULEO’s benefits in the field of automotive development and reports on the associated prototypical software implementations. Principle alternatives and technical aspects relevant for applying ULEO are discussed in some detail beforehand.Copyright

A Development Methodology for Parametric Synthesis Tools

Software to support the solution generation phase of the engineering design process has been developed in academia for decades. Computational synthesis software enables generation of solutions on both conceptual and embodiment level. This paper focuses on the class of parametric design, such as documented in mechanical engineering handbooks. Examples include machine elements such as bearings, springs, fasteners, transmissions, etc. A parametric synthesis tool automates the engineering design process from functional requirements to quantified solutions, for a single machine element. Since the amount of machine elements is vast and software development time should be low, a generic methodology is helpful to speed up this process. This paper discusses such a methodology to develop synthesis tools for the class of parametric designs. It includes an analysis-oriented approach to formalize the design process’ parameters in terms of embodiment, performance and scenario. Mathematical constraint solving techniques are used to generate candidate solutions. Graphical presentation and exploration of the solution space is done with interactive plots. A standardized layout for the graphical user interface is suggested to allow uniform and intuitive use. A demonstrator is developed using the described methodology and several challenges are discussed for improved constraint solving techniques, more advanced visualization and handling problems with higher complexity. Although small in size, parametric design processes are time consuming due to their reoccurring nature. Developing synthesis tools for these designs will allow engineers to save time and improve design quality.Copyright

‘What-if’ Design as an Integrative Method in Product Design

In product development, many different aspects simultaneously influence the advancement of the process. Many specialists contribute to the specification of products, whilst in the meantime the consistency and mutual dependencies have to be preserved. Consequently, much effort is spent on mere routine tasks, which primarily distract members of the development team of their main task of creating the best solution for the design problem at hand. Many of these routine tasks can be translated into problems with a more or less tangible structure; often they are in fact an attempt to assess the consequences of a certain design decision on the rest of the product definition. Therefore, such questions can be formulated as: “what happens if....”. The question is subsequently translated into a need for evolution of the information content determining the product definition. Based on this need for information, immediate workflow management processes can be triggered. This results in a ‘train’ of design and engineering processes that are carried out, leading to a viable answer to the question. As the structure of a ‘what-if’ question is independent of the domain under consideration, the ‘what-if’ questions can relate to any aspect in the information content at any level of aggregation. Consequently ‘what-if’ questions can range from anything between ‘What if another machine tool is used’ to ‘What does this product look like if it is made from sheet metal’. Such a way of looking at products under development obviously strongly binds different domains and downstream processes under consideration, thus enabling a more integrated approach of the design process.