Tamotsu Murakami

Direct and intuitive input device for 3-D shape deformation

Standard input devices such as a mouse and a keyboard in present computer-aided design systems do not provide users with direct and intuitive facilities for highly 3-D shape manipulation. To solve the problem, this paper proposes a new interface system for 3-D shape manipulation by adopting a real elastic object as an input device. By deforming the device with bare hands with a tactile feedback, users can manipulate a 3-D shape modeled and displayed on a computer screen quite directly and intuitively. A prototype with a cubical input device made of electrically conductive polyurethane foam is also presented.

Mechanism concept retrieval using configuration space

When designing mechanisms, making use of examples in past designs and handbooks should lead to cost reduction by promoting the sharing of parts and subassemblies among the products as well as reduction of time and effort. At present, however, the process of surveying design examples is left almost entirely to human designers and little computerised aid has been developed. We propose a computerised method of retrieving mechanism concepts from a library by specifying a required behaviour using qualitative configuration space as a retrieval index. First, mechanism concepts and their kinematics characteristics are described and stored in a computerised library using qualitative configuration spaces accompanined by additional information such as motion type and motion transmission direction. To retrieve mechanism concepts which realise specific kinematic behaviour, designers specify the required behaviour as timing charts of given input and intended output motions. Motion types, motion transmission direction, and motion speed dependence of the input and output motions can also be specified. Computer programs translate the required timing charts into required locus patterns in motion parameter space, and then available mechanism concepts to realise the behaviour are retrieved based on pattern matching between the qualitative configuration spaces and the locus patterns. The method is implemented as an experimental computer program written in Prolog and applied to simple mechanism design problems as examples to confirm the effectiveness of the approach.

DO-IT : Deformable Object as Input Tool for 3-D Geometric Operation

In this paper, a new concept of an interface system for 3-D geometric operation using a deformable real object as an input tool is proposed. By deforming the tool with bare hands by tactile feedback, users can deform a 3-D shape modeled and displayed on a computer screen directly and intuitively. By adopting a free form deformation-oriented approach, the interface enables various types of 3-D shape operations using a rather simple input tool. A prototype of the deformable object as input tool (DO-IT) interface system using a cubic input tool made of foam rubber and strain gauges demonstrates the effectiveness and potential of the concept.

DO-IT: deformable objects as input tools

Standard input tools such as the mouse and keyboard do not provide users with a direct and intuitive means of 3-D shape manipulation. This study proposes a new concept of interface system for 3-D shape deformation using a deformable real object as an input tool. By deforming the tool with bare hands with a tactile feedback, users can manipulate a 3-D shape modeled and displayed on a computer screen directly and intuitively. A PC-based prototype system with a cubical input tool made of electrically conductive polyurethane foam demonstrates the effectiveness and promise of the concept.

Knowledge Management for Fault Tree Analysis Based on Quantity Dimension Indexing

In this paper, the authors propose computerized support for fault tree analysis (FTA) based on a new design knowledge management approach called quantity dimension indexing. FTA is a method of analyzing and visualizing the causes of fault events by expanding a fault event hierarchically to its possible cause events and constructing a tree diagram representing the entire structure of the problem. When a designer finds or encounters a problem during a product design and development process, an effective way of ensuring the security and safety of the product is to identify all the possible causes of the problem by FTA and fix them. Although FTA is an effective method, it is not easy for a designer to construct a complete fault tree without any misunderstanding or oversight. A promising approach for supporting FTA is to utilize a computerized knowledge management method. Although many knowledge management techniques for literal expression have been developed, they are not necessarily suitable for managing the engineering design knowledge of physical phenomena. To solve this problem, the authors propose a new design knowledge management approach called quantity dimension indexing and computerized support for FTA such as the verification of consistency of a fault tree and fault tree construction advice. By analyzing fault tree examples based on actual design activities in a company, the possible feasibility and future promise of the proposed approach are indicated.Copyright

Positive direct-mask stereolithography with multiple-layer exposure: layered fabrication with stair step reduction

In this paper, we explain a new stereolithography involving the separate use of liquid photoinitiator and a base resin (photopolymer resin without photoinitiator). First, the base resin is supplied as a layer, and then a mask pattern is drawn onto the surface with photoinitiator by inkjet printing. When the surface is exposed to a UV lamp, only the pattern drawn with the photoinitiator is cured. In this process, the photoinitiator acts as a positive mask. Also, the idea of multiple-layer exposure, which may enable stair step reduction and fabrication time reduction, is introduced. The proposed idea and method are implemented in an experimental stereolithography system and some experiments are conducted using the system. As a result, the effectiveness and feasibility of the idea and method are confirmed.

Method of Computer-Aided Fault Tree Analysis for High-Reliable and Safety Design

Fault tree analysis (FTA) is a method of analyzing and visualizing the causes of a fault using a fault tree diagram (FT diagram), which has a tree structure with logical steps. Design engineers developing a new product generally use FTA to analyze many fault events, calculate their probability, and include redundancy systems in the design process. Furthermore, FTA has been used to analyze problems with products and to prevent the occurrence of problems in the design phase. In particular, it is necessary for design engineers to analyze the events after a failure to determine the root causes of the failure of the redundancy systems. However, it is not easy for design engineers to produce an accurate FT diagram in the actual design process. We have developed a computer-aided knowledge management system for creating FT diagrams (FTAid) as part of a collaborative group (The University of Tokyo, National Institute of Advanced Industrial Science and Technology (AIST), and Jatco Ltd.). This system has been verified by the design engineers of Jatco Ltd. in actual product development. We report its effectiveness for predicting mechanical, electrical, and heat transfer failure, the verification of the system, and its validation in an actual design process. We conclude that the system can help design engineers to effectively and efficiently create FT diagrams in reliability engineering, although some existing ability in FTA and engineering is required. We also describe some outstanding issues regarding the improvement of FTAid, engineering education, and ensuring reliability.

Factors Affecting Viewpoint Shifts When Evaluating Shape Aesthetics: Towards Extracting Customer’s Latent Needs of Emotional Quality

There are three main issues when trying to capture the customer’s need for a product’s emotional quality such as its aesthetics. The first is that customers have difficulty externalizing their emotional needs even if they have a clear mental image of those needs. The second is that people have different sensitivities when perceiving emotional qualities. The third is that customers have a latent sensitivity of which they are unaware. Evoking such latent sensitivity is effective when extracting the customer’s potential needs. Latent sensitivity may be evoked by shifting a fixed viewpoint for evaluating an emotional quality [1]. In this paper, we focus on the third issue, which has not been dealt with in conventional studies. The authors address the question of how to provide information that can shift the customer’s fixed viewpoint and evoke his/her latent sensitivities on a product’s emotional quality. To determine what factors are involved in such information, we conduct an experiment in which the subjects exchange and mutually evaluate their shape solutions for an emotional image and the associated viewpoints. Because people have different sensitivities, customers have different viewpoints and images toward an emotional design concept as expressed by a subjective word. We assume that different viewpoints and images may contain information that can evoke the latent sensitivity of a customer. To help the subjects to externalize their images for a given emotional concept, which is the first issue, we developed an interactive shape generation system in which the customer as non-designer can easily shape his/her image. The system generates design samples, which the user synthesizes using genetic operation. From the experiment, we observed different types of subjects and different patterns of effective viewpoints that can shift one’s fixed viewpoint.Copyright

Quantity Dimension Indexing for Design Knowledge Management

Although many knowledge management techniques based on text expression have been developed, they are not necessarily sufficient for managing engineering design knowledge. In this paper, we propose quantity dimension indexing of design knowledge as a fundamental method for design knowledge management. Physical quantities describing physical phenomena can be represented as vectors in a seven-dimensional space where the orthogonal axes are the seven base units of the SI (The International System of Units). Because of the generality, objectivity and universality of the SI, this space covers all physical quantities that appear in the past, present and future design knowledge and design problems, and the same quantities are represented as the same vectors regardless of the differences in people, products, domains, organizations, nations and languages. We assume that the similarities of physical phenomena lead to similarities in the dimensions of quantities describing the phenomena, and propose to use this seven-dimensional vector for estimating the similarity of design knowledge from the viewpoint of physical phenomena. Based on this basic idea, we mathematically define similarity between two quantities using quantity dimensions. We prepared design knowledge examples and retrieval keys and conducted design knowledge retrieval and design knowledge similarity estimation by quantity dimension indexing and confirmed that we obtained adequate results without using a concept dictionary or thesaurus elaborated in advance, which are indispensable in the text approach.Copyright

A Proposal of Kansei Database Framework and Kansei Modelling Methodology for the Delight Design Platform

The delight design platform (DDP) is a vision of a new integrated design environment that would enable design engineers to consistently design delightful products. Such delightful products satisfy an attractive quality as well as the performance and must-have qualities of the Kano model. The attractive quality depends on a customer’s subjective evaluation involving emotion. To implement DDP, we aim to develop a model-based design (MBD) environment that can simulate a customer’s affective responses toward digital design models. With this environment, a designer can test their ideas in the early-design phase. In this article, we propose a Kansei database framework as an essential component of the DDP. The Kansei database stores functions that estimate the customer’s emotional responses to the design model. Firstly, we propose a Kansei database structure including two indexes, perception and delight, with a delight map as a visualization scheme. Secondly, we propose a cyclic Kansei model of product experience. Based on the model, we propose a methodology to model the user’s cognitive structure while interacting with a product, and create the indexes. Furthermore, we discuss the effect of scene-transition expectations on the user’s response to a delightful experience.