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NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS EXPERT SYSTEMS DEVELOPMENT UTILIZING HEURISTIC METHODS by John N. Lewis June 1996 Thesis Advisor: Hemant Bhargava Approved for public release; distribution is unlimited. DUDLEY KNGX LIBRARY SCHOOL N^/at POSTGRADUATE MONTEREY CA 93943-5101 REPORT DOCUMENTATION PAGE FormApprovedOMBNo.0704-01i Publicreportingburdenforthiscollectionofinformationisestimatedtoaverage 1 hourperresponse,includingthetimeforreviewinginstruction,searchingexistingdata sources,gatheringandmaintainingthedataneeded,andcompletingandreviewingthecollectionofinformation.Sendcommentsregardingthisburdenestimateorany otheraspectofthiscollectionofinformation,includingsuggestionsforreducingthisburden,toWashingtonHeadquartersServices,DirectorateforInformation OperationsandReports. 1215JeffersonDavisHighway,Suite 1204,Arlington.VA22202-4302,andtotheOfficeofManagementandBudget,PaperworkReduction Project(0704-0188)WashingtonDC20503. 1. AGENCY USEONLY (Leaveblank) 2. REPORTDATE 3. REPORTTYPE AND DATES COVERED June 1996 Master's Thesis TITLE AND SUBTITLE: Expert Systems Development Utilizing 5. FUNDING NUMBERS Heuristic Methods 6. AUTHOR(S) LT John N. Lewis, USNR PERFORMINGORGANIZATION NAME(S) AND ADDRESS(ES) PERFORMING 7. Naval Postgraduate School ORGANIZATION Monterey CA 93943-5000 REPORTNUMBER SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSORING/MONITORING 10. AGENCY REPORTNUMBER 11. SUPPLEMENTARY NOTES The views expressed in this thesis are those ofthe author and do not reflect the official policy or position ofthe Department ofDefense or the U.S. Government. 12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTIONCODE Approved for public release; distribution is unlimited. 13. ABSTRACT(maximum 200words) This thesis analyzes the diagnostic domain and isolates the heuristics employed by experts to arrive at diagnostic solutions. These heuristic methods are then generalized in order to arrive at a series of heuristic rules that can be applied to a wide range of diagnostic processes independent of there respective domain. To test the validity of the generalized heuristics, a prototype expert system was created targeting the heuristics employed by avionics repair technicians in repair of the APS-1 15 radar system on the P-3C Orion. 14. SUBJECTTERMS Expert System, Prototype, Knowledge Acquisition, Heuristic 15. NUMBEROF PAGES 82 Development, Heuristic, P-3C Orion, Avionics Maintenance, Diagnostics, Troubleshooting 16. PRICECODE 17. SECURITY CLASSIFI- SECURITY CLASSIFI- 19. SECURITY CLASSIFICA- 20. LIMITATION OF CATION OFREPORT CATIONOFTHIS PAGE TIONOFABSTRACT ABSTRACT UL Unclassified Unclassified Unclassified NSN 7540-01-280-5500 Standard Form298 (Rev. 2-89) PrescribedbyANSIStd.239-18298-102 11 Approved for public release; distribution is unlimited. EXPERT SYSTEMS DEVELOPMENT UTILIZING HEURISTIC METHODS John N. Lewis Lieutenant, United States Navy Reserve B.A., California State University, Sacramento, 1984 Submitted in partial fulfillment ofthe requirements for the degree of MASTER OF SCIENCE IN INFORMATION TECHNOLOGY MANAGEMENT from the NAVAL POSTGRADUATE SCHOOL June 1996 DUBLEY KNOX LIBRARY NAM&L POSTGRADUATE SCHOOL MONTEREY CA 93943-5101 ABSTRACT This thesis analyzes the diagnostic domain and isolates the heuristics employed by experts to arrive at diagnostic solutions. These heuristic methods are then generalized in order to arrive at a series ofheuristic rules that can be applied to a wide range of diagnostic processes independent of there respective domain. To test the validity of the generalized heuristics, a prototype expert system was created targeting the heuristics employed by avionics repair technicians in repair of the APS-1 15 radar system on the P-3C Orion. VI ... TABLE OF CONTENTS INTRODUCTION I. 1 BACKGROUND A. 1 OBJECTIVES B. 1 THE RESEARCH QUESTIONS C. 1 SCOPE D. 2 METHODOLOGY E. 2 F. THESIS ORGANIZATION 3 BACKGROUND n. 5 A. THE AVIATION MAINTENANCE SYSTEM 5 1 Levels ofmaintenance 5 a. Organizational Level Maintenance 5 b. Intermediate Level Maintenance 6 c. Depot Level Maintenance 7 d. Other Technical Support 7 2. Maintenance Scenario 8 3. The A-799 Rate 9 EXPERT SYSTEM B. 9 DOMAIN SELECTION C. 11 D. THE APS 115 RADAR SYSTEM 12 m. EXPERT SYSTEM SOLUTIONS 13 DIAGNOSTICS A. 13 EXPERT SYSTEMS IMPLEMENTATIONS B. 13 1. GTE COMPASS System 14 2. MK-92 Maintenance Advisor System 15 3. The Interactive Fault Diagnosis System 16 4. Automotive Engine Troubleshooter 17 MYCIN 5. 17 SEPARATING DIAGNOSTICS FROM THE DOMAIN C. 18 IV. HEURISTIC DEVELOPMENT FOR DIAGNOSTIC SYSTEMS 21 A. HEURISTIC DEFINITION 21 1 Heuristic Example 21 2. Benefits OfGeneralization 22 3. Heuristic Representation 23 - > B. HEURISTIC GENERATION 23 Abduction 24 1 a. Pseudo-code Representation 25 2. Commonality 25 a. Pseudo-code Representation 26 vn ... 3. Cross Commonality 27 a. Pseudo-code Representation 27 4. Complexity 28 a. Pseudo-code Representation 28 C. PROTOTYPE KNOWLEDGE ACQUISITION 29 1 Initial Steps 30 2. The Expert 31 IMPLEMENTATION D. 31 E. PROTOTYPE DESIGN 32 V. TEST AND VALIDATION 33 A. PROTOTYPE TESTING 33 1 Initial Prototype Improvements 33 2. Subsequent Improvements 34 3. Knowledge Acquisition Issues 35 B. HEURISTIC TESTING 35 Abduction 36 1 2. Commonality 36 3. Cross-Commonality 37 4. Complexity 37 C. FINAL TEST 38 VI. LESSONS LEARNED 39 A. KNOWLEDGE ACQUISITION 39 B. KNOWLEDGE REPRESENTATION 40 C. IMPLEMENTATION 40 D. CLIPS INTERFACE 41 CONCLUSION E. 41 APPENDIX A. PROTOTYPE SYSTEM CODE 43 APPENDIX B. APS 115 RADAR SYTEM 65 LIST OF REFERENCES 71 INITIAL DISTRIBUTION LIST 73 Vlll