Chih-Hsing Chu

Developable Bézier patches: properties and design

Geometric design of quadratic and cubic developable Bezier patches from two boundary curves is studied in this paper. The conditions for developability are derived geometrically from the de Casteljau algorithm and expressed as a set of equations that must be fulfilled by the Bezier control points. This set of equations allows us to infer important properties of developable Bezier patches that provide useful parameters and simplify the solution process for the patch design. With one boundary curve freely specified, five more degrees of freedom are available for a second boundary curve of the same degree. Various methods are introduced that fully utilize these five degrees of freedom for the design of general quadratic and cubic developable Bezier patches in 3D space. A more restricted generalized conical model or cylindrical model provides simple solutions for higher-order developable patches.

Economical green product design based on simplified computer-aided product structure variation

Environmental issues have become an imperative concern for most companies in relation to modern product development. Special procedures have to be taken during the product development process to comply with recent green directives. Product structure is recognized as a critical factor that provides effective means for reducing environmental impact in product end-of-life. However, most previous studies failed to leverage the vast latitude at the design stage due to the assumption of a fixed product structure. To overcome this deficiency, we propose a CAD-based approach that allows automatic variation of 3D product structure by means of changing the combination of parts, selecting the assembly method, and rearranging the assembly sequence. A computing scheme uses Genetic Algorithm (GA) techniques to produce an optimal product structure from the design alternatives generated by the approach. This corresponds to lower assembly/disassembly costs, while complying with specified recycling and recovering rates. The scheme also chooses a smaller set of parts that needs to be disassembled and determines an economical disassembly process. Implemented in a commercial CAD system, the test results demonstrated the effectiveness of this scheme in green product design in a cost-effective manner.

Applications of the Web-based collaborative visualization in distributed product development

This paper illustrates applications of the Web-based collaborative visualization (WCV) in distributed product development. Three software prototypes were developed using the WCV technologies. The first one enables the end users to configure individual parts of 3D assembly in a regular browser, and thus provides an effective tool to collect the customers voices in e-commerce. The second system realizes mass customization for car interior design. Online ergonomic evaluation is conducted based on the interactions between a digital human mimicking the user and the design model. Finally, an Internet-based design review system is implemented. It enables synchronous communications between a designer and people involved in the change process with no access to CAD. These prototypes demonstrate the practicality, flexibility, and versatility of the WCV in integration with other proprietary software tools using a variety of platforms like ASP framework, Java-based technology, and Windows C/C++ applications. This work shows that the WCV is an interfacing technology, which facilitates 3D information sharing for most product-centric activities in a simple and cost-effective manner.

Computer aided parametric design for 3D tire mold production

This paper presents a parametric design system for 3D tire mold production. Tire grooves commonly used in the current industry are classified according to their modeling procedures, and the design parameters for each groove type are characterized. The result serves as a foundation for standardization of the tire mold design. The presented system simplifies the construction of 3D groove surfaces by reducing the number of interactive modeling operations. The resultant surface model is parameterized, and thus, allows for rapid creation of other grooves with simple design tables. In addition, a set of geometric algorithms is proposed that first detects undesired groove geometries arising in the design process, and then corrects them automatically. In this manner, 3D mold models are created with minimal user interactions. This work is implemented in an integrated CAD/CAM system for actual mold production. Test examples demonstrate that it provides an effective approach to reducing the time yet improving the quality of tire mold development.

An online ergonomic evaluator for 3D product design

This paper presents an online ergonomic evaluation system for 3D product development with car interior design as an example, which consists of a 3D viewer, a digital human model, an ergonomic engine, and the web-based GUIs. The digital human is constructed with a number of templates based on anthropometry database that represent various levels of body size and shape for the end-user. The interactions between the human and a product model are captured by the viewer, and thus, simulate the user operation of the product. According to the Chaffins biomechanical model, the ergonomic engine then computes the physical loads of body joints with the captured information. The result enables online evaluation of the product design from the ergonomic aspects. It also serves as a base of interactive product customization. This research is the first study that realizes the web-based ergonomic evaluation for 3D car interior design with no needs of high-end CAD systems or complex VR environment. In this manner, the human factor issues can be effectively taken into account at the early design phase and the costs of ergonomic evaluation will be significantly reduced.

Exemplar-based statistical model for semantic parametric design of human body

This paper presents an exemplar-based method to provide intuitive way for users to generate 3D human body shape from semantic parameters. In our approach, human models and their semantic parameters are correlated as a single linear system of equations. When users input a new set of semantic parameters, a new 3D human body will be synthesized from the exemplar human bodies in the database. This approach involves simpler computation compared to non-linear methods while maintaining quality outputs. A semantic parametric design in interactive speed can be implemented easily. Furthermore, a new method is developed to quickly predict whether the parameter values is reasonable or not, with the training models in the human body database. The reconstructed human bodies in this way will all have the same topology (i.e., mesh connectivity), which facilitates the freeform design automation of human-centric products.

Data management of green product development with generic modularized product architecture

Many manufacturers are facing a complex situation in the mixed production environment, in which green and non-green products are fabricated simultaneously. They are losing competitiveness as a downstream supplier due to lacking of a cost-effective approach to managing product variations compliant with different green directives. This paper presents a methodology based on generic modularized product architecture that facilitates data management of green product development. The four-level architecture allows one unified representation for multiple product models. An option control mechanism enables a quick generation of their BOMs (bills of material). A procedure consisting of seven steps is proposed to accomplish this. PDM functions are implemented to demonstrate the effectiveness of the methodology using a real LCD TV family as an example. This work complements the past studies on green product development, which mainly tackled the problem from design, process, and supply chain improvement. In contrast, from a management perspective, the proposed methodology provides a simple but useful tool for small-to-medium-sized enterprises (SMEs) to perform green product development in an economical manner.

Mass customization in the product life cycle

This study presents an introduction to mass customization in the product life cycle—the goal of mass customization, mass customization configurations, and new customer integration techniques, modular design techniques, flexible manufacturing systems (FMSs), and supply chain management methods. The study reviews three selected books and twenty-one selected papers—early papers that describe the goal of mass customization, early papers that describe mass customization configurations, and recent papers that describe new customer integration techniques, modular design techniques, FMSs, and supply chain management methods. The study shows that the goal of mass customization is to create individually customized products, with mass production volume, cost, and efficiency, that most companies use ‘assemble-to-order’ configurations to create standardized products, and that more work is needed on interactive customer integration techniques, collaborative modular design techniques, reconfigurable manufacturing systems, and integrated supply chain management methods to achieve the goal of mass customization.

Empirical Studies on Inter-Organizational Collaborative Product Development

Collaborative product development (CPD) has become an imperative for companies to strengthen their niche values and remain competitive in the global market. However, most scholars may lack knowledge of deploying CPD in current industrial settings, and their research efforts may thus fail to fulfill practical needs. This paper presents a series of empirical case studies on distributed product development in Asia-Pacific Region. Engineering collaborations among brand-owner, manufacturer, and supplier in six product design chains (desktop PC, IC substrate, LCD monitor, bicycle, mold design, and CPU cooler) are under investigation. A systematic approach is developed that categorizes CPD into three modes based on the number of engineering BOM items and the difficulty of modularization in product design. It provides a preliminary but structured template for CPD deployment by characterizing the implications and software features of each mode. The cases also reveal values which CPD creates for the downstream supplier of a global value chain and new IT technologies enabling the collaboration process. This work is one of the early studies that analyze collaborative product development from the perspective of a manufacturer. The findings complement and corroborate theoretical studies in related research.

Tool-path verification in five-axis machining of sculptured surfaces

This paper presents a systematic scheme for the verification of tool paths in five-axis machining of sculptured surfaces. The criterion of interference detection is developed for a general APT cutter. Tool interference problems which occur across multiple surfaces can be dealt with. In this work, sculptured surfaces are subdivided into discrete sample points for interference detection. The undetected interference error introduced in the surface subdivision process is ensured within a user-specified tolerance. Simulation results of test examples are included to demonstrate the feasibility of the proposed scheme.