Artificial intelligence and expert systems for engineers

310 Pages·1996·15.46 MB·English

by  Krishnamoorthy

A R IIQ A L
INTELLIGENCE and
EXPERT SYSTEMSfer

ARTIFICIA
INTELLIGENCE and
EXPERT SYSTEMSfor
C.S. Krishnamoorthy
S. Rajeev
Indian Institute of Technology
Madras
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PREFACE
The book is aimed at bringing out a comprehensive presentation
of Artificial Intelligence (AI) based methodologies and software tools
wherein, for the first time, the focus is on addressing a wide spectrum
of problems in engineering.
Expert system methodology has been applied in the past to a
number of problems of planning, design, diagnostics etc. However,
the problems of engineering design have not been adequately
addressed, since these problems have to be addressed in an integrated
manner with knowledge from different domains and sources.
Continued research in the last ten years has recently resulted in the
emergence of new methodologies which will enable building of
automated integrated design systems that will have the ability to handle
the entire design process. These methodologies include design
synthesis, design critiquing, case-based reasoning etc., leading to
concurrent engineering. Details of these methodologies and tools are
at present available only in the form of technical papers and reports of
research projects that have been carried out in academic and other
institutions.
Many research and development projects have been carried out
by the authors in the past few years, and prototype systems have been
developed for specific applications to engineering systems. During
this process, the authors have proposed generic frameworks and have
developed efficient software tools to meet the requirements of
engineering design. This intensive work, coupled with the teaching of a
graduate course on Computer-Aided Design, motivated the authors to
write a book on the subject with descriptions of different methods and
a presentation of software tools that meet the requirements of
integrated knowledge-based systems in engineering. The authors hope
that the book will serve as a textbook for students and teachers, and
the software fi-ameworks and tools will provide the requisite resource
material to researchers and professionals who are interested in
developing knowledge-based systems in various disciplines of
engineering.
The book is divided into seven chapters. The first chapter
presents an overview of the developments in the areas of AI and
Knowledge-Based Expert System (KBES) applications to engineering.
The relevance and importance of the use of Al-based methodologies
for solving engineering problems are well brought out in this chapter.
IV Artificial Intelligence and Expert Systems for Engineers
The predominant component of any Al-based program is in the
extensive use of search techniques. Depending on the nature of the
problem being solved and the context, appropriate search techniques
are to be adopted. Chapter 2 presents different search techniques used
in Al-based programs.
KBES is the most popular and successful of the Al-based tools,
that have been evolved to address problems in planning, diagnosis,
classification, monitoring and design. Different knowledge
representation schemes such as rules, semantic nets and frames are
presented in Chapter 3. Inference mechanisms which drive the
knowledge base are also presented with the help of simple engineering
examples. The architecture of an expert system shell, developed by
the authors, called DEKBASE (Development Environment for
Knowledge-Based Systems in Engineering) is presented along with the
examples illustrating the use of DEKBASE to develop production
rule-based expert systems.
Chapter 4 presents the concepts of design synthesis and the
techniques used to generate multiple solutions with predefined
constraints. The domain decomposition-recomposition technique
usefiil for engineering design is explained with examples. The
architecture and framework for design synthesis and computer
implementation of a generic tool, GENSYNT (GENeric SYNthesizing
Tool), are presented and the use of GENSYNT is explained through
examples.
Engineering design process involves use of knowledge sources
from different domains. Any feasible solution generated from the
consideration of one domain has to be evaluated for satisfaction of the
concerns of other domains participating in the process. A
methodology for design critiquing and evaluation of a solution is
presented in Chapter 3. The architecture of GENCRIT (GENeric
CRItiquing Tool) is explained with sample problems.
Another major development in Al-based methodology is the
emergence of Case-Based Reasoning (CBR) which aims at generation
of solutions based on past cases stored in casebases with the
application of appropriate reasoning mechanisms. The requirements
of a CBR-based model for engineering design and a generic frame
work, CASETOOL (CASE-based reasoning TOOL), are presented in
Chapter 6.
Engineering design involves a class of complex generative tasks
whose solutions depend on the cooperative participation of multiple
specialists. In order to develop a knowledge-based system an analysis
Preface
of all the tasks involved has to be performed. Based on the task
analysis the developer has to identify the AI methodologies needed and
propose a process model for the system. The process model should
facilitate horizontal and vertical integration of the tasks involved in the
entire design process. For a better imderstanding of the process
models needed for developing knowledge-based systems for real-life
problems, case studies of typical prototype systems are presented in
chapter 7.
It is felt by the authors that an understanding of Al-based
methodologies, and the generic framework and tools presented in the
book, can be made more effective, if readers get an opportunity to use
these tools on computers and acquire hands-on experience.
Educational versions of the four software tools are provided in the
floppy diskette. The software DEKBASE with a rule base inference
engine and a frame management system provides a platform for
inclusion of other generic tools, GENSYNT, GENCRIT and
CASETOOL. The tools are implemented on PC-based systems under
a DOS environment. The use of the software tools is illustrated in the
Appendices I to III for the examples described in various chapters of
the book.
The authors would like to acknowledge that it was the Indo-US
project under the NSF grant INT 8913816 on KBES for Civil
Engineering Design, in collaboration with Professor Steven J. Fenves
of Camegie-Mellon University, that had significantly contributed to
the development of the software tools, particularly DEKBASE,
presented in this book. The authors would like to express their
gratitude to Professor Steven J. Fenves for his interaction through the
above project which provided the motivation to the authors for the
research and development work in this area.
The four software modules presented in this book are due to the
dedicated efforts of the Indo-US project team and the authors would
like to place on record their deep appreciation and gratitude to the
project officers, affectionately referred to as Indo-Americans, M/s.
C.S. Rao, S. Suresh and H. Shiva Kumar. The authors thank Mr.
Shaikh Karimulla Raja for his contribution to the development of a
few modules of DEKBASE and to a number of graduate students for
testing DEKBASE. The authors would also like to acknowledge Mr.
H. Shiva Kumar and Mr. S. Suresh for their contributions in the
development of two prototype systems SETHU and ODESSY which
are presented as case studies in this book and for their inputs at
various stages of writing this book. The case study dealing with the
VI Artificial Intelligence and Expert Systems for Engineers
design of the shape of the body of a car was based on the project work
carried out by M/s. Harshawardhan Shetty and Biju Baby imder the
direction of Dr. N. Ramesh Babu of the Mechanical Engineering
Department at IIT, Madras, and the authors would like to thank them
for contributing to the development of the system described in Chapter
7.
The authors would like to thank their faculty colleagues Professor
V. Kalyanaraman and Professor N. Rajagopalan for their technical
contribution as co-investigators of the Indo-US project. The
description in Chapter 7 of GENESIS, a prototype system for planimig
and design of steel industrial structures, and of the architecture of the
Integrated Engineering System (lES), is based on the work of Dr. S.
Sakthivel imder the direction of our colleague Professor V.
Kalyanaraman. The authors would like to thank them for making it
possible to include them in this book.
The authors sincerely thank Mr. R. S. Jeevan, Project Associate,
for his excellent support in typesetting and preparation of camera-
ready format for the book and Mr. S. Suresh for assistance at various
stages in the preparation of the manuscript. Thanks are due to Manoj
Thomas and to Muthusamy and Sankari of the Departmental
Computer Facility and Ambika Devi for their help.
The authors would like to thank the authorities of the Indian
Institute of Technology, Madras and particularly acknowledge the CE
Departmental Computer Facility where the software development work
was carried out.
The fillip to write this book came from Professor W.F. Chen of
Purdue University. It was his suggestion that the authors write a book
under a series that he has been editing. The authors would like to thank
Professor Chen for his encouragement and to Mr. Navin Sullivan and
Ms. Felicia Shapiro of CRC Press for their support in the publication
of this book.
C. S. Krishnamoorthy
S. Rajeev
TABLE OF CONTENTS
PREFACE
Chapter ! .......................................................................................... 1
INTRODUCTION. ...................................................................... 1
1.1 General. ............................................................................ 1
1.2 Developments in Artificial Intelligence. ............................ 2
1.3 Developments in Expert Systems ...................................... 5
1.4 Role of AI and Expert Systems in Engineering ................. 6
Chapter 2 .......................................................................................... 11
SEARCH TECHNIQUES. .......................................................... 11
2.1 Introduction ...................................................................... 11
2.2 Problem Definition and Solution Process .......................... 14
2.3 Production Systems. .......................................................... 15
2.4 Search Techniques ............................................................ 16
2.4.1 Breadth-First Search ............................................... 17
2.4.2 Depth-First Search .................................................. 19
2.4.3 Heuristic Search ...................................................... 20
2.4.4 Generate and Test ................................................... 23
2.4.5 Best-First Search ..................................................... 23
2.4.6 Agenda-Driven Search ............................................ 24
2.5 Problem Decomposition and AND-OR Graphs ................. 25
Chapter 3 .......................................................................................... 29
KNOWLEDGE-BASED EXPERT SYSTEM ............................ 29
3.1 Introduction ...................................................................... 29
3.2 What Is KBES ? ............................................................... 30
3.3 Architecture ofKBES ....................................................... 32
3.3.1 Knowledge Base ...................................................... 34
3.3.2 Inference Mechanisms ............................................. 45
3.3.3 Inexact Reasoning ................................................... 53
3.3.4 Non-monotonic Reasoning ...................................... 55
3.3.5 Reasoning Based on Certainty Factors ..................... 56
Chapter 4 .......................................................................................... 89
ENGINEERING DESIGN SYNTHESIS .................................... 89
4.1 Introduction ...................................................................... 89
4.2 Synthesis .......................................................................... 89
4.3 Decomposition Model for Synthesis .................................. 91
4.4 Role of a Synthesiser in KBES Environment... .................. 98
4.5 An Architecture for a Synthesiser-A
Generic Tool .................................................................... 101