DETC2005-84662 A STUDY OF MODEL REPRESENTATIONS FOR SHAPE CONCEPTUALIZATION

ABSTRACT Shape conceptualization is considered as an iterative search process with the goal to gather, generate, represent, transform, manipulate, and communicate information and knowledge related to various kinds of shape concepts. The search for shape concepts is not focused on finding a specific solution, but on exploring, analyzing and comparing various alternatives. This search is vague because shape concepts and mental models are abstract, uncertain, and incomplete. They gradually become concrete, definite, and complete as the design process advances. Therefore, the main challenges for model representation of shape design concepts are (a) facilitation of capturing, transforming and manipulating uncertain, incomplete, and abstract mental images by computer, and (b) handling coexistence of shape alternatives. Due to these features, the development of computer aided conceptual design systems for shape conceptualization applications is not without problems. Intensive research is carried on to solve the problems and to propose solutions. Due to the wide horizon of research and the lack of papers surveying the progress and the open issues, there is no comprehensive picture on the state of the art. Starting out from the methods and tools developed for shape modeling, this study investigates the means for shape conceptualization. First, a reasoning scheme is introduced to make the investigation systematic. From the point of view of information captured in a representation on a shape, simplified, nominal, and expanded shape modeling methods have been found and investigated. The paper concludes about an optimum modeling approach, which melt the advantages of the present techniques and extends it with new features. KEYWORDS Computer aided conceptual design, shape conceptualization, simplified shape modeling, nominal shape modeling, expanded shape modeling. INTRODUCTION Commercial computer aided design and engineering systems have reached a remarkable level of sophistication and comprehensiveness in terms of functionality. Relying on advanced geometric modeling kernels, they support part modeling, assembly modeling, analysis, simulation, data management, technological process planning, numerical control, reverse engineering and other downstream design and engineering activities. In order to provide even more support to product development, current research addresses the issues related to the computer involvement in conceptual design. It involves not only modeling the conceptual geometry, but also modeling the operation of the conceptualized artifact. New challenges emerge and the system developers need new theories, methods, and algorithms that enable them to offer solutions for conceptual design problems. The shape of product concepts always had a central role in conceptual design. For instance, the mechanical function of a product typically operates based on the global shapes and the contact surfaces of the components in an assembly. Nevertheless, the shape of the product has also primary importance from the aspect of ergonomics, production, appearance, and aesthetics. Therefore, this paper will focus representation of geometry in shape conceptualization. Shape conceptualization is considered as an iterative search process with the goal to gather, generate, represent

SIMULATING THE USE OF PRODUCTS: APPLYING THE NUCLEUS PARADIGM TO RESOURCE-INTEGRATED VIRTUAL INTERACTION MODELS

{i.horvath, z.rusak} @ tudelft.nl We introduce a methodology for modelling and simulating fully virtual human-artefact systems, aiming to resolve two issues in virtual prototyping: (i) integration of distinct modelling and simulation approaches, and (ii) extending the deployability of simulations towards conceptual design. We are going to offer designers a new way of investigating the use of a product, by integrating scenarios of expected humanartefact interaction and simulations of artefact behaviour into a unified framework. Since recruitment and employment of human subjects for physical and virtual testing is problematic, we propose a fully virtual simulation method based on resource-integrated models. The models incorporate both the logical and the physical aspects of the behaviours of humans and artefacts. This paper elaborates on a pilot implementation, in particular on realizing the implementation of the physical modelling and simulation elements based on commercially available software packages. Within limitations imposed by the software we used, the applicability testing by carrying out simulations of virtual human-product interaction during the use of a product proved that human-artefact interaction could be simulated with sufficient fidelity based on resource-integrated models,. It also provided useful knowledge on the improvements needed to develop a full-fledged dedicated simulation package. KEYWORDS Product design, virtual prototyping, hybrid simulation, use process, nucleus-based modelling, scenarios, grasping simulation. 1

Methodology for Controlling Contact Forces in Interactive Grasping Simulation

International audienceThe paper proposes a new methodology to interactively simulate grasping of virtual product prototypes with the goal to evaluate the contact forces between the grasping hand and product as well as the load on the human arm. Interaction between product concepts and the users happens in a virtual environment, in which the user controls a virtual hand interactively. The contact between the virtual hand and the grasped product is simulated and visual feedback is provided to the user. Controlling the virtual hand interactively in real time holds many challenges. One of the challenges is mapping the motion of the user to contact forces, which then results in stable grasping of objects. In this paper we present a new methodology to convert and map the measured position of the real hand into contact forces so that the contact between the virtual hand and the object remains stable. Our approach applies a multi-objective optimization that takes into account the posture and anthropometric properties of grasping hand, as well as the penetration of the hand in the grasped virtual object in order to find the optimal arrangement of contact forces. The paper reports on the principle of our grasping control methodology as well as presents some test cases to show the advantages and disadvantages of the proposed approach

PHYSICALLY-BASED OPERATORS FOR VIRTUAL CLAY MODELING IN A COLLABORATIVE VIRTUAL DESIGN ENVIRONMENT

Virtual claying has become a preferred method of computer aided shape conceptualization. Nevertheless, the current implementations do not support collaborative design by remote participants. This paper reports on an implementation of virtual claying in a collaborative virtual design environment where ideas and actions of the stylists and the designers are converted to a model by physically-based operators. The basis of the model is a vague discrete modeling kernel. Physical operators are implemented on class and instance levels. The classes contain the generic support constraints and external forces, which can be combined to deform the shape. The instances of a physical operator class are able to model specific effects by various load-support arrangements. The fix, hinge, roller, and slide support operators represent typical mechanical supports. We defined concentrated and distributed forces, both static and dynamic, based on the principles of the Newtonian physics. We implemented the stretch, squash, bend and torque operators as the instances of the generic deformation operator. This paper presents the definitions and implementation of the operators, together with a comprehensive application example, which shows the capabilities of physically-based operators