Sheng Feng Qin

From on-line sketching to 2D and 3D geometry: a system based on fuzzy knowledge

The paper describes the development of a fuzzy knowledge-based prototype system for conceptual design. This real time system is designed to infer users sketching intentions, to segment sketched input and generate corresponding geometric primitives: straight lines, circles; arcs, ellipses, elliptical arcs, and B-spline curves. Topology information (connectivity, unitary constraints and pairwise constraints) is received dynamically from 2D sketched input and primitives. From the 2D topology information, a more accurate 2D geometry can be built up by applying a 2D geometric constraint solver. Subsequently, 3D geometry can be received feature by feature incrementally. Each feature can be recognised by inference knowledge in terms of matching its 2D primitive configurations and connection relationships. The system accepts not only sketched input, working as an automatic design tool, but also accepts user interactive input of both 2D primitives and special positional 3D primitives. This makes it easy and friendly to use. The system has been tested with a number of sketched inputs of 2D and 3D geometry.

A framework of web-based conceptual design

A web-based conceptual design prototype system is presented. The system consists of four parts which interpret on-line sketches as 2D and 3D geometry, extract 3D hierarchical configurations, allow editing of component behaviours, and produce VRML-based behavioural simulations for design verification and web-based application. In the first part, on-line freehand sketched input is interpreted as 2D and 3D geometry, which geometrically represents conceptual design. The system then infers 3D configuration by analysing 3D modelling history. The configuration is described by a parent-child hierarchical relationship and relative positions between two geometric components. The positioning information is computed with respect to the VRML97 specification. In order to verify the conceptual design of a product, the behaviours can be specified interactively on different components. Finally, the system creates VRML97 formatted files for behavioural simulation and collaborative design application over the Internet. The paper gives examples of web-based applications. This work forms a part of a research project into the design and establishing of modular machines for automation manufacture. A consortium of leading automotive companies is collaborating on the research project.

Development of a novel 3D simulation modelling system for distributed manufacturing

This paper describes a novel 3D simulation modelling system for supporting our distributed machine design and control paradigm with respect to simulating and emulating machine behaviour on the Internet. The system has been designed and implemented using Java2D and Java3D. An easy assembly concept of drag-and-drop assembly has been realised and implemented by the introduction of new connection features (unified interface assembly features) between two assembly components (modules). The system comprises a hierarchical geometric modeller, a behavioural editor, and two assemblers. During modelling, designers can combine basic modelling primitives with general extrusions and integrate CAD geometric models into simulation models. Each simulation component (module) model can be visualised and animated in VRML browsers. It is reusable. This makes machine design re-configurable and flexible. A case study example is given to support our conclusions.

Development of a design performance measurement matrix for improving collaborative design during a design process

Purpose of this paper: the purpose of this paper is to investigate how to measure collaborative design performance and, in turn, improve the final design output during a design process, with a clear objective to develop a Design Performance Measurement (DPM) matrix to measure design project team members¹ design collaboration performances. Design/methodology/approach: the methodology adopted in this research uses critical literature reviews, in-depth focus groups interviews and a questionnaire survey. Findings: the main finding of this study is a DPM matrix that addresses five DPM indicators: efficiency, effectiveness, collaboration, management skill, and innovation, and 25 detailed DPM criteria. It was found that decision-making efficiency is the most important DPM criteria for collaborative design efficiency; plus delivering to the brief for effectiveness; clear team goal/objectives for collaboration; decision-making ability for management skill; and competitive advantage for innovation. Research limitations/implications: as the present study was focused on exploring DPM during a design process, some key DPM criteria, which are not measurable during a design development process, were not included in this study. The proposed multi-feedback approach for DPM matrix implementation needs to be validated in future research. Practical implications: the DPM matrix can be applied to support a design manager in measuring and improving collaborative design performance during a design process, by reviewing and modifying collaborative design development, identifying the design team strengths and weaknesses, improving team communication, and suggesting suitable responsive actions. Original/values: the major contribution of this study is the investigation and development of a DPM matrix to measure collaborative design performance during a design process

Freehand drawing system using a fuzzy logic concept

Chen and Xie reported the development of a pen-based Fuzzy Freehand Drawing System (FFDS) that uses a Limiting multiplier to reconstruct ellipses from scattered data. The purpose of the present work is to show that although Chen and Xies method is of interest, two of their equations (Eqs. 11 and 12) are correct only for a special case and not in general.

A sketch-based gesture interface for rough 3D stick figure animation

This paper introduces a novel gesture interface for sketching out rough 3D stick figure animation. This interface can allow users to draw stick figures with the system automatic assistance in figure proportion control. Given a 2D hand-drawn stick figure under a parallel view, there is a challenge to reconstruct a unique 3D pose from a set of candidates. Our system utilizes figure perspective rendering, and introduces the concept of ‘thickness contrast’ as a sketch gesture combined with some other constraints/assumptions for pose recovery. The resulting pose can be further corrected, based on physical constraints of human body. Once obtaining a series of 3D stick figure poses, user can easily sketch out motion paths and timing, and add their preferable sound/background. The resulting 3D animation can be automatically synthesized in VRML. This system has been tested on a variety of input devices: electric whiteboard, tablet PC, as well as a standard mouse.

Intelligent Classification of Sketch Strokes

This paper presents an intelligent method for classifying pen strokes in an on-line sketching system. The method, based on adaptive threshold and fuzzy knowledge with respect to curves linearity and convexity, can identify sketch strokes (curves) into lines, circles, arcs, ellipses, elliptical arcs, loop lines, spring lines and free-form B-spline curves. The proposed method has proven to be fast, suitable for real-time classification and identification

A novel method for early formal developments using computer aided design and rapid prototyping technology

Abstract The paper describes a novel method for updating computer aided design (CAD) models with information taken from physical models in the early stages of design. The new approach is an image mapping based method in which an initial. CAD model is transferred to a soft rapid prototype model (RPM) made by a three-dimensional printer and sculpted in order to carry out formal developments. The RPM has a built-in contrasting three-dimensional grid composed of parallel orthogonal planes, and the initial CAD model is represented by cross-section curves corresponding to the RPM grid. The initial CAD geometry is then updated from images of the developed RPM by matching the differences between the initial CAD model and the modified RPM, making use of identical perspective transformations and viewpoints for the initial CAD model and an RPM image. Examples studied varied from a small depression on a cube face to general freeform surfaces. Compared with typical reverse engineering (RE) processes, the present approach is simpler and more direct. It is not necessary to use three-dimensional scanning or coordinate measuring devices for updating existing initial geometrical CAD models with data obtained from physical models.

Geometric error model and measuring method based on worktable for five-axis machine tools

This article presents a new integrated geometric model that takes worktable as reference for five-axis machine tools. It could simplify the description of different machine kinetic structures and uniform the measurement coordinate system and machining coordinate system. Based on this model, a new method of measuring geometric errors with conventional instruments is proposed. It could break through some existing limitations, such as special instrument, specific machine kinetic structures, or errors incompletion. In addition, some deviation errors in measuring process could be eliminated to improve accuracy further. Finally, a series of experiments are conducted on a five-axis machine tool with rotary worktable and tilting head. The results show that the error model and measuring method are effective and applicable.

A novel form design and CAD modelling approach

This paper presents a novel form design and CAD modelling approach to simultaneously support intuitive physical model development such as 3D sculpting, and CAD surface modelling for effective design communication, evaluation and collaboration. The concept of creation of 3D form profiles by simply projecting a set of 2D drawing on a physical model is utilised for generating 3D constraints and converting a single perspective image of the physical model captured by a web camera to a CAD surface model. This method has been implemented and tested in our prototype design desktop system.