Traditional Computer-aided Design Systems Research Articles

Constructing assembly design model capable of capturing and sharing semantic dynamic motion information in heterogeneous CAD systems

Over the last decades, collaborative assembly design has received much attention, which has provided fruitful results in terms of data models, knowledge-based, and top-down geometric modeling approaches, to name a few. Particularly, researchers have focused their efforts towards assembly relationships within product models, but have limited the scope to static assembly geometric description as currently stated in computer-aided design (CAD) systems. A disruptive vision is assumed in this research work, arguing that the assembly design itself presents a dynamic nature via, especially, dynamic motion. Such a paradigm shift requires an appropriate logical and semantic foundation to augment current CAD systems and data models’ capabilities with the capture of dynamic phenomena such as assembly motions and kinematic behaviors. Traditional CAD systems nowadays can handle the kinematics-related motion-related information; however, the interoperation of this motion-related information from one CAD system to the other is still a limitation of the interoperability standards. To tackle this research challenge, this paper aims at defining an original framework built upon a formal ontology to capture and share dynamic assembly motion among heterogeneous CAD systems. The formal ontology uses spatiotemporal mereotopology, which serves as a theoretical backbone to qualitatively describe the dynamic behavior of a product. This theory addresses the qualitative description of the temporal dimension over the spatial dimension of 3D objects. The proposed ontology is then enhanced to maintain semantic continuity of the spatial and temporal aspects embedded in assembly design ontology models. Built with a Web Ontology Language (OWL) data structure to interact with a CAD system and a motion visualization application, the ontology ensures the dynamic motion information capturing and sharing. SWRL (Semantic Web Rule Language) is utilized to show the semantic reasoning among the moving and non-moving parts of the product assembly. As a result, a semantic articulation ensuring flexibility and interoperability as a competitive industrial edge is demonstrated with proof of concept to be effective in a collaborative assembly design environment.

BandWeavy: Interactive Modeling for Craft Band Design.

Traditional computer-aided design systems are mainly intended for expert users, but research involving systems incorporating computer graphics and interactive techniques that are easy to use by novices is also active. In this paper, we describe a design support system, BandWeavy, that can be used by a novice to easily design a craft band artwork using his or her desired pattern. We propose an algorithm that can automatically calculate cuboid and cylinder shapes according to the sizes desired by the users.

The effect of sub-threshold forces on human performance in multi-modal computer-aided design

In traditional CAD (computer-aided design) systems, the manipulation of points and lines is often difficult because designers manipulate virtual objects through their vision system. Nowadays, designers can explore and manipulate virtual objects in haptic-enabled CAD systems using haptic devices. Haptic devices can present force feedbacks to pull or push the users’ hands into desirable targets. Of course the intent is for the user to experience the same sensations in the virtual realm as they would in the real world. Thus, sub-threshold forces, which cannot be perceived by users, should be incorporated in the control of users’ movements. As a result, our attention is directed to study the effect of sub-threshold forces on the accuracy of movement in a haptic-enabled virtual reality (VR) system. In this study, our goal is to manipulate users’ hands using controlled forces such that users cannot notice the forces. With this in mind, we have constructed a haptic-enabled virtual environment (VE) to carry out a multi-modal Fitts’ type task. In the task, subjects could see the position of the haptic probe in the VE where forces were applied on their hands. Basically, the accuracy of subjects was measured using a performance index when the intensity and direction of forces changed. A psychophysical method was utilized to ensure that the forces were below the force threshold of the human force perception. Results indicate that the accuracy is affected by the intensity and direction of sub-threshold forces even when users are allowed to control their actions through visual feedbacks.

Special Issue on Collaborative Engineering

Special Issue on Collaborative Engineering

Evolutionary design and re-design using design parameters and goals

Design parameters and goals play important roles in design. Design goals are the required functions of the design elements and are explicitly expressed by design parameters. Design parameters also indicate the relations among design elements, by which a constraint network can be constructed and some useful information can be induced. In this study, the mechanical design process is viewed to be the assignment of design goals and their realization through the evolutionary refinement of the design parameters. The design activities are processed on traditional computer-aided design systems by specifying the shapes of the design elements. Thus, an integrated design system based on the computer-aided design system is proposed to assign the design goals and refine the values of the design parameters along the design process. The proposed design system also provides some useful facilities to a designer such as the construction of a constraint network, an evolutionary design method and a re-design plan.