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Developing a prototype concurrent design tool for composite topside structures

NAVAL ENGINEERS JOURNAL 1997年第3期109卷 279-290页

作者： Dirlik, S Hambric, S Azarm, S Marquardt, M Hellman, A Bartlett, S Castelli, V Steve Dirlik:began his career at the Naval Surface Warfare Center Carderock Division in 1981 as an aerospace engineer co-op student. He completed his bachelor of science degree in aeropace and ocean engineering from Virginia Polytechnic Institute and State University in 1985 and his master of science degree in aerospace engineering from the University of Maryland in 1990. Mr. Dirlik recently completed a master of science program in applied physics at The Johns Hopins University and currently works in the Radar Cross Section and Target Physics Branch of the Signatures Directorate at the Naval Surface Warfare Center Corderoke Division. He has worked on Navy low observable programs since 1990. Stephen Hambric:is a research associate at the Applied Research Laboratory at The Pennsylvania State University. He received his B. S. and M.S. degree in mechanical engineering from Virginia Polytechnic Institute and State University and his D. Sc. in mechnical engineering from the George Washington University. He has worked on several computer aided multidiscikplinary design and optimization projects over the years including an automated propeller design system and a structural acoustic optimization capability. Dr. Shpour Azarm:is currently working as an associate professor with the Design and Manufacturing Group of the Department of Mechanical Engineering at the University of maryland at College Park. Dr Azarm's expertise is in the areas of optimization-based designed and concurrent design and optimization of multidisciplinary systems. He was a consultant at Black & Decker Corporation (summer 1996) and worked as a Navy senior summer faculty fellow (summer 1995) and a NASA summer faculty fellow (summer 1994). He was a visiting scientist at NASA Langley Research Center for Multidisciplinary Analysis and Applied Structural Optimzatiom at the University of Siegen in Germany (spring 1992) and the Design Institute of the Technical University of Denmark (summer 1990). Dr Azarm was an associate technical editor of the ASME Jour

A prototype concurrent engineering tool has been developed for the preliminary design of composite topside structures for modern navy warships. This tool, named GELS for the Concurrent engineering of Layered Structures, provides designers with an immediate assessment of the impacts of their decisions on several disciplines which are important to the performance of a modern naval topside structure, including electromagnetic interference effects (EMI), radar cross section (RCS), structural integrity, cost, and weight. Preliminary analysis modules in each of these disciplines are integrated to operate from a common set of design variables and a common materials database. Performance in each discipline and an overall fitness function for the concept are then evaluated. A graphical user interface (GUI) is used to define requirements and to display the results from the technical analysis modules. Optimization techniques, including feasible sequential quadratic programming (FSQP) and exhaustive search are used to modify the design variables to satisfy all requirements simultaneously. The development of this tool, the technical modules, and their integration are discussed noting the decisions and compromises required to develop and integrate the modules into a prototype conceptual design tool.

关键词： Warships

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Optimization-based reconstruction of a 3D object from a single freehand line drawing

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computer-AIDED DESIGN 1996年第8期28卷 651-663页

作者： Lipson, H Shpitalni, M Laboratory for Computer Graphics and CAD Faculty of Mechanical Engineering Technion Haifa 32000 Israel

This paper describes an optimization-based algorithm for reconstructing a 3D model from a single, inaccurate, 2D edge-vertex graph. The graph, which serves as input for the reconstruction process, is obtained from an inaccurate freehand sketch of a 3D wireframe object. Compared with traditional reconstruction methods based on line labelling, the proposed approach is more tolerant of faults in handling both inaccurate vertex positioning and sketches with missing entities. Furthermore, the proposed reconstruction method supports a wide scope of general (manifold and non-manifold) objects containing flat and cylindrical faces. Sketches of wireframe models usually include enough information to reconstruct the complete body. The optimization algorithm is discussed, and examples from a working implementation are given. Copyright (C) 1996 Elsevier Science Ltd.

关键词： drawing to model optimization robustness

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Two-stage algorithm for rapid determination of the bending sequence in sheet metal products

Two-stage algorithm for rapid determination of the bending s...

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ASME 1996 Design engineering Technical Conferences and computers in engineering Conference, DETC-CIE 1996

作者： Radin, B. Shpitalni, M. Hartman, I. Laboratory for Computer Graphics and Cad Faculty of Mechanical Engineering Technion - Israel Institute of Technology Haifa32000 Israel

ISBN: (纸本)9780791897591

This paper presents an algorithm for solving the complex and critical problem of bending sequence in sheet metal manufacturing. Finding the bending sequence and required tool assignment presents a large combinatorial problem which is impossible to solve optimally for practical applications within a reasonable period of time. The paper presents a two-stage algorithm. The first stage finds a feasible solution based upon collision avoidance heuristics. The second stage rapidly seeks an alternative feasible sequence with a lower cost without exceeding time limitations. The algorithm is very practical because it reaches a low-cost solution quickly within computer memory limitations. In this paper, the problem is defined, the approach is presented formally, and finally, the power of the algorithm is demonstrated by solving bending sequences for real products. © 1996 American Society of mechanical Engineers (ASME). All rights reserved.

关键词： Sheet metal

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SEPARATION OF DISCONNECTED MACHINING REGIONS ON THE BASIS OF A CSG MODEL

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computer-AIDED DESIGN 1994年第1期26卷 46-58页

作者： SHPITALNI, M FISCHER, A [a]Laboratory for Computer Graphics CAD Faculty of Mechanical Engineering Technion-Israel Institute of Technology Haifa 32000 Israel

The process of converting a given design into the form of a rawstock minus a series of machining features is known as machining-features extraction. One step towards automatic machining-features extraction is the extraction of machining regions. The paper is concerned with the extraction of machining regions from the constructive-solid-geometry representation of a given object. The proposed method for the extraction of machining regions is based on manipulating the original CSG tree, representing the object, evaluating the various machining regions by using octrees, and pruning the CSG tree accordingly. If necessary, an additional stage of compacting follows. As a result, each machining region is represented by a compact CSG tree offering the following advantages. The CSG tree to be analysed is reduced in size, and thus the problem of machining-features extraction is simplified. The information is compact and concise. Moreover, no information is lost (CSG representation is kept rather than boundary representation), and the designer's intensions are conveyed to the process planner more clearly. In the special case in which the machining regions are identical to machining features, the method does offer the automatic extraction of machining features. In addition, the nesting level of the various machining regions is determined when needed.

关键词： FEATURE RECOGNITION CONSTRUCTIVE SOLID GEOMETRY CSG MODELS OCTREES CUTTER-PATH GENERATION

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DESIGN BY INTERPOLATION

DESIGN BY INTERPOLATION

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COMPEURO 93 : computerS IN DESIGN, MANUFACTURING AND PRODUCTION

作者： WEISS, M SHPITALNI, M Laboratory for Computer Graphics CAD Faculty of Mechanical Engineering Technion Haifa Israel

ISBN: (纸本)0818640308

The paper deals with design of shapes by interpolation, that is, cases where the desired shape is somehow "in between" two given shapes. The main issues involved in design by interpolation are: (a) capturing the "nature" (behavior) of the guiding shapes A and B;(b) attaining automatic correspondence between points (i.e., which point in shape A should be associated with which point in shape B);and (c) determining the interpolation method In the paper, new techniques for capturing the "nature" of shapes and for determining automatic correspondence of points are presented. Examples for interpolation of polygons, curves (Bezier and NURBS) and suvaces are included. The possibility of future design based upon extrapolation, rather than interpolation,is also discussed. © 1993 IEEE.

关键词： Bezier cad Interpolation NURBS Shape Design

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CNC interpolators: algorithms and analysis

CNC interpolators: algorithms and analysis

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Proceedings of the 1993 ASME Winter Annual Meeting

作者： Koren, Y. Lo, C.C. Shpitalni, M. Department of Mechanical Engineering University of Michigan Ann Arbor MI United States Laboratory for Computer Graphics and CAD Faculty of Mechanical Engineering Technion Haifa Israel

ISBN: (纸本)0791810291

cad systems today interpolate general curves by dividing each curve into many straight-line segments which are downloaded to the CNC. Determining the number of lines to be transferred from the cad to the CNC poses a conflict between the desired precision of the part and the feedrate fidelity. The current method results in severe variations in the feedrate, leading, in turn, to variations in the surface smoothness and a substantial increase in machining time. These problems are caused by the acceleration/deceleration at the ends of each segment. Moreover, the problems are inherent in the CNC interpolator, as is thoroughly discussed in this paper. These problems can be solved by the development of curve interpolation algorithms for CNC. In this paper, a real-time interpolation algorithm for curves presented in their parametric forms is proposed and compared with the existing cad interpolators. Analysis shows that with this new interpolator, a constant feed is maintained along the cut and the machining time is as expected. In addition, the amount of geometric information transferred from the cad system to the CNC is reduced by orders of magnitude. Moreover, the contour errors caused by the new interpolator are much smaller than those caused by conventional cad interpolators.

关键词： Numerical control systems

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FLEXIBLE AND REDUNDANT ROBOTS

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ROBOTICS AND computer-INTEGRATED MANUFACTURING 1992年第2期9卷 85-86页

作者： JAMSHIDI, MM CHERCHAS, DB COLBAUGH, RD CAD Laboratory for Intelligent and Robotic Systems Department of Electrical Engineering University of New Mexico Albuquerque NM 87131 U.S.A. Department of Mechanical Engineering Computer-Aided Manufacturing and Robotic Laboratory University of British Columbia Vancouver BC V6T 1W5 Canada Department of Mechanical Engineering New Mexico State University Las Cruces NM 88001-0001 U.S.A.

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cad CAM MANUFACTURING OF PROTOTYPE SHIPBOARD COMPONENTS

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NAVAL ENGINEERS JOURNAL 1990年第3期102卷 93-99页

作者： CALVERT, TE RODRIGUEZ, FA SLEBZAK, JS Thomas E. Calvert P.E.: is a senior project engineer with the Propulsion and Auxiliary Systems Department David Taylor Research Center Annapolis Md. His interests include application of computers to all aspects of engineering with particular emphasis on utilization of small computers. Mr. Calvert is a licensed professional engineer in Maryland. He received a BSEE from Drexel University in 1969 and since that time has completed a number of graduate courses related to machinery acoustics. Francisco A. Rodriguez:is an engineer with the Propulsion and Auxiliary Systems Department David Taylor Research Center. He was formerly with the Computer-Aided Design/Interactive Graphics Group of the Division of Engineering and Weapons U.S. Naval Academy. His interests include interfacing the computer aided design to the computer aided manufacturing along with related software and hardware development. Mr. Rodriguez received a BSEEfrom the University of Virginia in 1968. James S. Slebzak:is a mechanical engineering technician with the Propulsion and Auxiliary Systems Department David Taylor Research Center. He received his machinists papers in 1971 after serving his apprenticeship at David Taylor Research Center. He continued his education and became the senior numerical control programmer at the Annapolis Laboratory. He completed his mechanical technology degree from Anne Arundel Community College in 1986. His interests are in the application of numerically controlled manufacturing techniques to prototype machinery components.

The machine shop at the Annapolis laboratory of the David Taylor Research Center (DTRC) provides model making and prototype support to a large variety of naval ship related engineering projects. In order to meet these challenging requirements, computer aided design/computer aided manufacturing (cad/CAM) techniques are being used to produce “one of a kind” prototypes or very low volume production parts. The use of computer aides in these cases is to facilitate the accurate manufacture of a difficult part, rather than to improve manufacturing efficiencies. In addition, the approach provides the flexibility required to support research and development projects. Several examples of prototype shipboard components manufactured using cad/CAM techniques are presented in this paper. The hardware and software that facilitated these projects are discussed. The examples described have met the requirements to produce a wide variety of prototype shipboard machinery components quickly and accurately.

关键词： Ship Equipment

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ADAPTIVE EDGE-FOLLOWING FORCE CONTROL OF AN INDUSTRIAL ROBOT

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ROBOTICS AND computer-INTEGRATED MANUFACTURING 1989年第4期6卷 331-337页

作者： LIOU, JN JAMSHIDI, M STARR, GP CAD Laboratory for Systems/Robotics Department of Electrical and Computer Engineering University of New Mexico Albuquerque NM 87131 United States Robotic Research Laboratory Department of Mechanical Engineering University of New Mexico Albuquerque NM 87131 United States

Control of tool-workpiece interaction force is of vital importance in automated assembly. Using a simple linear continuous model of an edge-following system to predict the appropriate accomodation gains in a force control loop, previous work has shown that force control by accomodation is feasible. Following up this work, this paper describes the analysis, simulation and implementation of an adaptive force control in a two-dimensional edge-following task with a PUMA 560 robot and wrist force sensor. First, a discrete-time model of an edge-following system is developed and then used as the plant; second, a model reference adaptive control (MRAC) scheme is applied to achieve both tracking and regulation purposes. The reference (tracking) model can be determined by experimental reference input and desired model output information; the reference (regulation) model can be obtained by simulation to smooth out the plant output and improve the augmented filtered plant-model error. Study is done on the values of the adaptation gains in the adaptive mechanism, and hence can be adjusted to insure the best plant output performance.

关键词： Robots, Industrial

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Near-Optimum Control of a Robot Manipulator

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IFAC Proceedings Volumes 1987年第5期20卷 271-275页

作者： M. Jamshidi Y.T. Kim M. Shahinpoor CAD Laboratory for Systems/Robotics Electrical & Computer Engineering Department University of New Mexico Aluquerque NM 87131 USA Departmental of Mechanical Engineering University of New Mexico Aluquerque NM 87131 USA

This paper proposes a near-optimum control algorithm for a highly nonlinear robot manipulator model via a parameter sensitivity method. The method uses Pontrvagin's maximum principle and the Riccati formulation of the linear state regulator problem. The effectiveness of the proposed method is verified by simulation results for a two-link planar robot.

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