麻省理工学院：《自制决策制造原则》英文版 Model-based Diagnosis

Model-based Diagnosis Brian c。 WIllams 1641013 November 3rd 5th 2003 CourtesyNasa/Jpl-calTech.http://www.jplnasgov

10/03/03 copyright Brian Williams, 2003 1 Courtesy NASA/JPL-Caltech. http://www.jpl.nas.gov. Model-based Diagnosis Brian C. Williams 16.410-13 November 3rd & 5th 2003 Brian C. Williams, copyright 2000

Assignment Reading Model-based Diagnosis -Lecture notes Propositional Logic AlMA Chapter 6 Problem set Model-based Diagnosis implementation Propositional Logic 16.413: Hello World implementation Due Monday, November 17th 10/03/03 copyright Brian Williams, 2003

10/03/03 copyright Brian Williams, 2003 2 Assignment ƒ Reading ƒ Model-based Diagnosis – Lecture notes ƒ Propositional Logic AIMA Chapter 6 ƒ Problem Set ƒ Model-based Diagnosis implementation ƒ Propositional Logic ƒ 16.413: Hello World implementation ƒ Due Monday, November 17th

WORLD observations Plant actions sense act Diagnostic Agent AGENT Monitors diagnoses Repairs avoids Probes and tests Symptom-directed 10/03/03 copyright Brian Williams, 2003

10/03/03 copyright Brian Williams, 2003 3 sense P(s) WORLD observations actions AGENT Diagnostic Agent: • Monitors & Diagnoses • Repairs & Avoids • Probes and Tests Plant act Symptom-directed

Out line Model-based diagnosis Accounting for failures Explaining failures Handling unknown failures 10/03/03 copyright Brian Williams, 2003

10/03/03 copyright Brian Williams, 2003 4 Outline ƒ Model-based diagnosis ƒ Accounting for failures ƒ Explaining failures ƒ Handling unknown failures

Hidden Failures Require Reasoning ftom a Model Symptons. s e a STS-93 Engine p sensor high LOX le low GN&C det low thrust H2 level poss ly low Problem: Liquid hydrogen leak u5真 Effect: LH2 used to cool engine Engine runs hot Consumes more lOX ImagetakenfromNasa'swebsitehttp://www.nasa.gov

10/03/03 copyright Brian Williams, 2003 5 H i d d e n F a i l u r e s R e q u i r e R e a s o n i n g f r o m a M o d e l : S T S - 9 3 Symptoms: • Engine temp sensor high • LOX level low • GN&C detects low thrust • H2 level possibly low Problem: Liquid hydrogen leak Effect: • LH2 used to cool engine • Engine runs hot • Consumes more LOX Image taken from NASA’s web site: http://www.nasa.gov

Model-based Diagnosis Given a system with symptomatic behavior and a model of the system, find diagnoses that account for symptoms 6 2、 Symptom MI Ⅹ B 6 Al M2 A2 G12 6 E M3 10/03/03 copyright Brian Williams, 2003

10/03/03 copyright Brian Williams, 2003 6 Model-based Diagnosis Given a system with symptomatic behavior and a model of the system, find diagnoses that account for symptoms. 6 12 Symptom 6 O1 M2 M3 A1 A2 A B C D E F G X Y Z 3 2 2 3 3 10 12 M1 6 12

Model-based Diagnosis Given a system with symptomatic behavior and a model of the system, find diagnoses that account for symptoms 6小 2、 Symptom MI B 6 Al M2 A2 G12 6 E M3 10/03/03 copyright Brian Williams, 2003 7

10/03/03 copyright Brian Williams, 2003 7 Model-based Diagnosis Given a system with symptomatic behavior and a model of the system, find diagnoses that account for symptoms. 6 12 Symptom 6 M1 M2 M3 A1 A2 A B C D E F G X Y Z 3 2 2 3 3 10 12 6 12

Diagnosis as Hypothesis Testing 1. Generate candidates, given symptoms 2. Test if candidates account for all symptoms Set of diagnoses should be complete Set of diagnoses should consider all available information 10/03/03 copyright Brian Williams, 2003

10/03/03 copyright Brian Williams, 2003 8 Diagnosis as Hypothesis Testing 1. Generate candidates, given symptoms. 2. Test if candidates account for all symptoms. • Set of diagnoses should be complete. • Set of diagnoses should consider all available information

Out line Model-based diagnosis Accounting for failures Explaining failures Handling unknown failures 10/03/03 copyright Brian Williams, 2003

10/03/03 copyright Brian Williams, 2003 9 Outline ƒ Model-based diagnosis ƒ Accounting for failures ƒ Explaining failures ƒ Handling unknown failures

How Should Diagnoses Account for Symptoms? Abductive Diagnosis: Given symptoms, find diagnoses that predict observations 12、 Symptom MI B Al M2 A2 12 EM3 Assume Exhaustive Fault models 10/03/03 copyright Brian Williams, 2003 10

10/03/03 copyright Brian Williams, 2003 10 How Should Diagnoses Account for Symptoms? Abductive Diagnosis: Given symptoms, find diagnoses that predict observations. 6 6 12 Symptom M1 M2 M3 A1 A2 A B C D E 3 2 2 3 3 F G X Y Z 10 12 Assume Exhaustive Fault Models: