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APPROACHES TO IMPROVE ENGINEE RING D E S I ON 1 3: THE NATIONAl ACADEMIES PRESS Washington, D.C. www.nap.edu q
THE NATIONAL ACADEMIES PRESS 500 Fifth Street, N.W. Washington, DC 20001 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. The report is available from the National Academies Press, http://www.nap.edu Copyright 2001 by the National Academy of Sciences. All rights reserved. Printed in the United States of America 5
THE NATIONAL ACADEMIES Advisers to the Nation on Science, Engineering, and Medirine The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Wm. A. Wulf is president of the National Academy of ~ . . tnglneermg. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. Wm. A. Wulf are chair and vice chair, respectively, of the National Research Council www.national-academies~org 5 A ,
PREFACE Design is a process by which human intellect, creativity, and passion are translated into useful artifacts. The practice of engineering design involves not only pure and applied sciences, behavioral and social sciences, and economics but also many aspects of business and law. A designer must work effectively with a team composed of members of different disciplines and make tens or even hundreds of decisions for simple products and thousands of decisions for complex products. Tools to aid designers extend from design guides and rules of thumb that capture experience to synthetic environments that allow the designer to fly through virtual models. Both engineering design and the ability to teach it have been the subject of many meetings, publications, and organizations as well as any number of spirited discussions. Without doubt, the various aspects of this issue can admirably engage both sides of our brains. The authors of this report set out to examine the theories and techniques for decision making under conditions of risk, uncertainty, and conflicting human values. This report attempts not only to analyze existing tools but also to identify opportunities to establish a more rigorous fundamental basis for decision . . . . . making In engineering c ensign. Decision-making tools can be useful design aids when appropriately applied. However, because the knowledge embodied in a designer or design team to synthesize and create is uniquely human, design cannot ever be totally automated. Decision tools and many other methods can aid the design process by organizing knowledge and providing systematic frameworks to enable the designer to generate new options and make intelligent choices to realize a product. The design community can make progress only when engineering design decisions are understood from the perspective of stakeholders in manufacturing enterprises and society. Time, effort, and resources must be invested in understanding engineering design as it is practiced, in creating a taxonomy to facilitate communication among the stakeholders and participants, and finally in identifying what needs to be done to move forward. The authors reviewed previous studies about decision making in engineering design and consulted with a cross section of engineering design leaders in industry and academia. In conducting the data gathering and analysis and in formulating findings and recommendations, the authors brought wide-ranging expertise in economics, decision theory, academic research, and industrial practice. This diversity was valuable in deliberations and instructive in the difficulties of communicating across disciplinary areas, especially in the study of decision analysis for . . . englneerlng c .eslgn. Robert J. Eagan, Sandia National Laboratories, Albuquerque, New Mexico Chair Beth E. Allen, University of Minnesota, Minneapolis Corbett D. Caudill, GE Aircraft Engines, Cincinnati, Ohio Ronald A. Howard, Stanford University, Palo Alto, California J. Stuart Hunter, Princeton University, Princeton, New Jersey Christopher L. Magee, Ford Motor Company, Dearborn, Michigan Simon Ostrach, Case Western Reserve University, Cleveland, Ohio William B. Rouse, Enterprise Support Systems, Norcross, Georgia v
ACKNOWLED GMENTS The authors would like to thank the following individuals for their presentations: Wm A. Wulf, National Academy of Engineering, on Engineering Education Reform; Steve Barrager, independent consultant on Design of the Corvette; David Halstead, GE Aircraft Engines on Jet Engine Design; John Taylor, NASA, on Design in Space Exploration; and Greg Wyss, Sandia National Laboratories, on Risk Assessment Analysis. In addition, the authors acknowledge Karen Padilla, Sandia National Laboratories, for typing several editions of the manuscript. This report has been reviewed by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the National Research Council's (NRC's) Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the authors and the NRC in making the published report as sound as possible and to ensure that the report meets the institutional standards for objectivity, evidence, and responsiveness to the study charge. The content of the review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their participation in the review of this report: Ernest R. Blood, Caterpillar Inc.; Clive L. Dym, Harvey Mudd College; Jay Lee, University of Wisconsin at Milwaukee; Steven C. Lu, University of Southern California; Farrok Mistree, Georgia Institute of Technology; and David J. Vander Veen, General Motors. Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations, nor did they see the final draft of the report before its release. The review of the report was overseen by George Dieter, University of Maryland, appointed by the Division on Engineering and Physical Sciences, who was responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authors and the institution. 5 . . V11
CONTENTS 1 OVERVIEW 1 PRIOR STUDIES 1 THE CHANGING NATURE OF ENGINEERING DESIGN 2 2 DECISION MAILING IN ENGINEERING DESIGN 5 3 BASIC TOOLS FOR APPLIED DECISION THEORY -- THE DECISION BASIS ......................................................................................................................... FRAMING 12 SENSITIVITY ANALYSIS.......................................................................................................................... 4 METHODS, THEORIES, AND TOOLS 17 CONCURRENT ENGINEERING 17 TOOLS TO OBTAIN STAI<EHOLDER INPUT 19 The Pugh Method, 19 Quality Function Deployment,20 Decision Matrix Techniques,21 Analytic Hierarchy Process, 23 METHODS AND TOOLS TO ADDRESS VARIABILIltY, QUALITY, AND UNCERTAINI-Y Projected Latent Structure, 26 .9 10 25 Taguchi Methodt,27 Six Sigma, 27 METHODS AND TOOLS FOR GENERATING ALTERNATIVES 28 Design Information Systems, Support Systems, And Environments,28 Triz,29 FORMAL METHODS FOR REPRESENTING DESIGN PROBLEMS 30 Engineering Design: A Synthesis Of Views, 30 Suh's Axiomatic Design,31 Yoshikawa's General Design Theory,32 A Mathematical Framework For Engineering Design, 32 DECISION MAILING IN MANAGEMENT SCIENCE AND ECONOMIC FIELDS 34 Decision Making In Economics,35 Game Theory,36 SUMMARY OF METHODS, THEORIES, AND TOOLS 36 5 IMPLICATIONS FOR ENGINEERING DESIGN EDUCATION AND RESEARCH 39 REFERENCES 43 APPENDIXES A ACCREDITATION BOARD FOR ENGINEERING AND TECHNOLOGY 2000 47 B THE AUTHORS C FORD USAGE. q ix i
FIGURES FIGURES AND TABLES 2-1 Decision process in the context of business and environment 2-2 Decisions framed in relevant context ~ 1 The ~llOli - T m(O A~ricinn 10 3-2 The problem space for characterization and decision-making 11 3-3 The decision hierarchy 2_A The Amrici^m cc 3-5 Decision diagram..................................................................................................................... 3-6 Decision diagram for design of a dual-sport motorcycle 14 3-7 Tornado diagram 14 3-8 The decision quality spider 4-1 The House of Quality............................................................ 4-2 A cascade of evaluation matrices 4-3 General format of the decision matrix 22 4-4 Decision matrix for access door attachment 4-5 Decision making in the context of variation. 4-6 Scope of artificial intelligence in design 3; TABLES 2-1 Framing a Decision in the Relevant Context 26 29 7 4-1 Comparison Between Concurrent Versus Linear (Serial) Engineering 18 4-2 Summary of Tools and Applications Examined 37 q x