Computation of stationary points of distance functions

This paper presents an algorithm for computation of the stationary points of the squared distance functions between two point sets. One point set consists of a single space point, a rational B-spline curve, or a rational B-spline surface. The problem is reformulated in terms of solution of n polynomial equations with n variables expressed in the tensor product Bernstein basis. The solution method is based on subdivision relying on the convex hull property of the n-dimensional Bernstein basis and minimization techniques. We also cover classification of the stationary points of these distance functions, and include a method for tracing curves of stationary points in case the solution set is not zerodimensional. The distance computation problem is shown to be equivalent to the geometrically intuitive problem of computing collinear normal points. Finally, examples illustrate the applicability of the method     

GPU-based parallel solver via the Kantorovich theorem for the nonlinear Bernstein polynomial systems

This paper proposes a parallel solver for the nonlinear systems in Bernstein form based on subdivision and the Newton-Raphson method, where the Kantorovich theorem is employed to identify the existence of a unique root and guarantee the convergence of the Newton-Raphson iterations. Since the Kantorovich theorem accommodates a singular Jacobian at the root, the proposed algorithm performs well in a multiple root case. Moreover, the solver is designed and implemented in parallel on Graphics Processing Unit(GPU) with SIMD architecture; thus, efficiency for solving a large number of systems is improved greatly, an observation validated by our experimental results.     

Tolerances in computer-aided geometric design

In the design of discrete part shapes, the specification of tolerance constraints can have major consequences for product quality and cost. Traditional methods for tolerance analysis and synthesis are timeconsuming, and have limited applicability. This paper presents the results of research into the use of solid modeling technology for the automated solution of tolerancing problems. A linear programming method is presented for the solution of tolerance analysis problems on a worst-case basis. A Monte Carlo method is presented for both worst-case and statistical tolerance analysis. Both methods automatically derive all necessary geometric relationships from a solid model of the assembly. Example problems are solved using the experimental GEOTOL geometric design system.     

Computer aids to the design of integrated manufacturing systems

Building an Integrated Manufacturing System is a complicated and expensive task. There are very few companies anywhere that will deliver turn-key CAD/CAM systems, far less produce a full line of hardware and software products covering every function required. In designing such a system we are faced with the problem of the proper interfacing and coordination of several hundreds of functional sub-systems. It is, therefore, a natural endeavour to use CAD methods in the design of CAD/CAM systems. Brief outlines are given of a highly interactive system having formalized diagrams and alphanumeric information on the input side, and readable system documentation and analysis reports, on the output side - both interacting to widely accepted extant techniques. The structure of a more complex system affording further facilities is also presented.     

Feedback stabilization of homogeneous polynomial systems of odd degree in the plane

In this paper, we give some tools for the construction of homogeneous feedback which stabilizes homogeneous polynomial systems of odd degree in the plane.     

Advanced production systems (APS) — CAD/CAM systems of the future

The CAD/CAM-area is one of the fastest expanding areas in industry of today. In order to support user- as well as vendor-industry, a Norwegian-German project has been started in the field. It consists of a short term project (1982–1984) and a long term project (1982–1991). The paper deals with the results of the cooperative project (APS).     

计算机辅助工程设计在中南铝合金轮毂有限公司的应用

本文介绍计算机辅助工程作为中南铝合金轮毂有限公司ＣＩＭＳ （ＺＮＬ－ＣＩＭＳ）的 分系统在中南铝的实施情况,以及不断地采用先进技术完善该妥系统的应用。使之更加满足公司的经营需要,在市场竞争中保持不败之地,并由此产生的巨大经济效益和社会效益。     

Feature extraction and feature based design approaches in the development of design interface for process planning

The quest for completely automated process planning systems has exposed the lack of techniques capable of automatically understanding the stored CAD models in a manner suitable for process planning. Most current generations of process planning systems have used the ability of humans to translate the part drawing requirements into a form suitable for computer aided process planing. Recently, research advances have been made to improve the understanding of computer stored 3-D part models. The two approaches used are feature recognition and feature based design. This paper presents a state of the art review of feature recognition techniques developed and presents feature based design as an alternative. Process planning systems developed using both approaches are presented.     

The development and application of CAD/CAM workstations in the GDR

For accomplishing low-attended manufacture, step by step, it is necessary that information handling in technological production planning, management and shop control processes is organized economically. This is especially true with respect to computer-aided product development and production planning, faster order throughput, control of production equipment and delivery of information needed for high equipment utilization with a simultaneous increase in the volume of data processed automatically. These complex requirements call for a new type of approach in information handling technology (CAD/CAM) and corresponding layouts of workstations for the designer and manufacturing engineer. Such CAD/CAM facilities should be user-friendly so that they can be adapted to the user's need and not vice versa.     

The introduction of CAD in the shoe industry

A study is presently underway in France concerning the introduction of CAD in the shoe industry. This study involves a manufacturer of men's shoes and the University of Grenoble, with the assistance of ANVAR, the Agence Nationale de Valorisation de la Recherche.     

Adaptive control for output feedback nonlinear systems in the presence of modeling errors

The paper is extending output feedback nonlinear control and backstepping approaches to a class of systems approximately diffeomorphic to output feedback systems that include unknown functions. The unknown functions are addressed via online function approximation, which results in two types of uncertainty. Parametric uncertainty due to online function approximation and non-parametric uncertainty. The non-parametric uncertainty results from the inability of any function approximator to perfectly model an unknown function and from terms unmodeled by the output feedback form. The non-parametric terms are assumed to be bounded by unknown constants. The backstepping procedure is applied to adapt with respect to both parametric uncertainties and the upper bound on the non-parametric uncertainties.     

CAD in the dress-making industry

An action started several years ago in a dress-making factory permitted us to develop the automation of their cutting-out workshop, notably by designing and implementing a method which assumes the automatic research of the garment pieces imbrication over the woven material. In addition, a decision-aid system was developed to determine the medium-term supplying and manufacturing plans.We actually carried out this action within the framework of a project backed by the D.G.R.S.T. (Délégation Générale à la Recherche Scientifique et Technique) to study a computer-aided design system which assists the modelist in the choice of standard elements in function of indicators of costs, cutting-out, making up, assembling and raw material.We analyse, in a first part, the various steps of the design process (from the stylist's sketch to the manufacture ranges) by displaying the computer tools we can associate with them. We then approach the problems linked with the utilized materials, by introducing first, in reference to a library or a trial, the dimensional adjustments to introduce so as to eliminate some deformations which can appear in wearing, and then, by studying the quantify of material required for the manufacture and by verifying that the consequent cost allows to attain the commercial objective that we have defined. In the end of the dialogue, the retained garment prototype responds to a compromise between the production cost and respecting the initial stylist's idea.We at last develop the methodology retained to build and manage the data base which represents the factory savoir-faire, and to integrate the whole graphic and technological information which permits products to continue at each production step.     

Model transformations in the UPES/UPSoC development process for embedded systems

Model-based development (MBD) aims at combining modeling languages with model transformers and code generators. Modeling languages, like profiles of the Unified Modeling Language (UML), are increasingly being adopted for specific domains of interest to alleviate the complexity of platforms and express domain concepts effectively. Moreover, system development processes based on automatic model transformations are widely required to improve the productivity and quality of the developed systems. In this paper, we show how MBD principles and automatic model transformations provide the basis for the unified process for embedded systems (UPES) development process and its unified process for system-on-chip (SoC) (UPSoC) subprocess. They have been defined to foster in a systematic and seamless manner a model-based design methodology based on the UML2 and UML profiles for the C/SystemC programming languages, which we developed to improve the current industrial system design flow in the embedded systems and system-on-chip area. This work is supported in part by the project Model-driven methodologies and techniques for embedded systems design and analysis based on UML, Abstract State Machines, and SystemC at STMicroelectronics, AST R&I of Agrate Brianza (MI), Italy.