Ji Zhou

Intelligent layout for modular design of machine tools

Modular design has played an important role in design and manufacturing of machine tools. With the fast development of modern industry and the appearance of the computer integrated manufacturing system (CIMS), modular design has been developed aiming at the automatic and intelligent design. It is well known that intelligent layout becomes the bottleneck of intelligent design of mechanical products. In this paper, combined with the scheme design, an intelligent layout design methodology is proposed to solve the modular design of machine tools. The authors analyze the properties of modular design, and present the object-oriented representation of layout design knowledge. The techniques of expert system, redesign based on constraints reasoning, parametric solid modeling, and automatic assembly are studied, and the design model, problem-solving strategy, and system architecture are set up. An example is given for the applications.

Vectorization of line drawings via contour matching

A new approach for vectorization of line drawings is proposed. In this paper, contour vectorization is first applied to convert the scanned image of drawings from raster form to vector form. After the operation of contour matching, elements of skeletal vector and sub- shape are obtained. On the basis of the two types of elements, a graph G(V,E) is built up to help analyze the forked joint in line drawings, and the method of curve tracing and splitting is also discussed to fulfill the sub-optimal extraction of line and arc segments. In addition, experimental results are given showing better results than that of the traditional thinning approach.

Intelligent CAD approach for modular design

In this paper, the technology of Artificial Intelligence is introduced into a modular design and manufacturing for machine tools. The authors present a methodology to realize the modular conceptual design combined with traditional CAD, and develop an intelligent machine tools modular conceptual system. The problem-solving strategies are described in detail. The design model and system architecture are set up. Techniques and their incorporation of expert system, case-based reasoning and artificial neural networks are clarified.

Curvature-based shape representation of planar curves

The detection of dominant points is an important problem in shape recognition. In this paper, the dominant point is divided into two kinds of point: corner point and tangent point, and a two stage method to detect the dominant point is proposed. The corner points are first detected based on the curvature smoothed by Gaussian filter, and tangent points are detected based on the curvature accumulation curve with the commonly used splitting method.

Issues on constraint-based design approaches

Design can be viewed as a constraint specification and satisfaction problem. Constraint-based design systems are proven to be more powerful and flexible than the conventional CAD systems. This paper discusses current constraint-based design approaches, together with their strengths and weaknesses. Our research work in constraint-based design is also introduced. Finally, some future development issues in this area are suggested.

Novel algorithm for geometric constraint satisfaction

A new solving method for geometric constraint reasoning is presented in this paper which has been named as maximal-reduction algorithm (MRA). It is the application about constraint network theory, analysis of degree of freedom, sparse matrix, and graph theory. With the MRA, geometric constraint system can be transformed into a series of subsystem which are organized with a forest data structure finally. The strategy enables the time complexity to solve the system separated with the scale of the system. It improves the solving stability and time expenses greatly. An interesting character of the MRA is its generalization which gives itself wide applications including parametric drawing, parametric modeling, kinematics of multibody system and product assembly.

Research and development in feature-based parametric modeling

A feature-centered scheme is presented to represent the feature-based variational part model. Constraint reasoning approach combined with numerical approach is triggered to satisfy the constraints between features. Coassociations between boundary primitives in feature level and part level are maintained to implement a series of feature operations and to implement precision feature modeling for parametric part geometry model. GHCAD, a feature-based parametric modeling system based on these ideas, is developed.

Integral smoothing operation of composite B-spline surfaces

This paper presents a new approach to construct C1 continuous surfaces on N-sided regions of composite B-spline surfaces. For C0 continuous surfaces on the N-sided regions, their smooth surfaces are constructed by the integral smoothing operation with variable integral neighbors, and the final surfaces are C1 continuous with the original surfaces on the N-sided region boundary.

Mechanical product model using STEP

This paper is focused on a mechanical product model for integrated computer aids. With the investigation on product design process and feature techniques, and from viewpoint of STEP (Standard for the exchange of Product Model Data), in this paper, the information model of mechanical product is proposed. The architecture and contents are discussed in detail. Then, a prototype system GHCAD, in which the product model is implemented, is introduced.

Design and realization of a machining process simulator

This paper introduces an NC machining process simulator. It enables NC programmers or machining operators to check the effects on the part of the cutter motions prescribed in an NC program before machining is performed. The device model (both geometry and logic) of a machining center, NC program controller and the stock-fixture model on the pallet can be defined in this system so as to provide a visual simulation circumstance of machining projects. The machining process is driven directly by NC program by means of an NC program interpreter. Not only can the material removal be visualized, but also the possible danger of collision and interference among cutting tool, stocks and fixtures can be detected during the cutting progress. The simulator is suitable for 3 through 5 Axes NC machining, especially milling, drilling and boring of cast box parts.