medito a logic based meta diagnosis...
TRANSCRIPT
MEDITOa logic‐based meta‐diagnosis tool
Nuno [email protected]
Yannick Pencolé[email protected]
Michel [email protected]
1. Can we trust model‐based diagnosis?
2. A theory of meta‐diagnosis
3. Some diagnostic system’s potential abnormalities
4. MEDITO: a logic‐based meta‐diagnosis tool
5. Meta‐diagnosing an Airbus Landing Gear Extraction and Retraction System (LGERS)
6. Conclusions
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Can we trust model‐based diagnosis (MBD)?
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Structure of information (Ψ)
Real system
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Structure of information (Ψ)
Real system
SystemDescription (SD)
Definition (Believed System) A believedsystem is a pair (DS,COMPS) where:1. SD, the system description is a set offirst order sentences.2. COMPS, is a finite set of constantsrepresenting the real‐world systemphysical units to diagnose.
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Structure of information (Ψ)
Real system
SystemDescription (SD)
Observations(OBS)
Definition (Believed System) A believedsystem is a pair (DS,COMPS) where:1. SD, the system description is a set offirst order sentences.2. COMPS, is a finite set of constantsrepresenting the real‐world systemphysical units to diagnose.
Definition (Observations) The set ofobservations, OBS, is a set of finite firstorder sentences.
11/3/2011 7MEDITO: a logic‐based meta‐diagnosis tool
Structure of information (Ψ)
Real system
SystemDescription (SD)
Observations(OBS)
Definition (Believed System) A believedsystem is a pair (DS,COMPS) where:1. SD, the system description is a set offirst order sentences.2. COMPS, is a finite set of constantsrepresenting the real‐world systemphysical units to diagnose.
Definition (Observations) The set ofobservations, OBS, is a set of finite firstorder sentences.
Definition (Health state) Let Δ be a setof components considered abnormal.The health state of a believed system,σ(Δ,COMPS\ Δ), is:
/\ c €Δ Ab(c) /\ c €(COMPS\Δ) ¬Ab(c)
11/3/2011 8MEDITO: a logic‐based meta‐diagnosis tool
Structure of information (Ψ)
Real system
SystemDescription (SD)
DiagnosticAlgorithm (A )
Observations(OBS)
Definition (Believed System) A believedsystem is a pair (DS,COMPS) where:1. SD, the system description is a set offirst order sentences.2. COMPS, is a finite set of constantsrepresenting the real‐world systemphysical units to diagnose.
Definition (Observations) The set ofobservations, OBS, is a set of finite firstorder sentences.
Definition (Health state) Let Δ be a setof components considered abnormal.The health state of a believed system,σ(Δ,COMPS\ Δ), is:
/\ c €Δ Ab(c) /\ c €(COMPS\Δ) ¬Ab(c)
Definition (Diagnosis) A diagnosis D, forthe diagnostic problem (DS,COMPS,OBS)is the set of all diagnosis hypotheses σsuch that:
SD ∪ OBS ∪ σIs satisfiable.
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Structure of information (Ψ)
Real system
SystemDescription (SD)
DiagnosticAlgorithm (A )
Observations(OBS)
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Structure of information (Ψ)
Real system
SystemDescription (SD)
DiagnosticAlgorithm (A )
Observations(OBS)
PossibleAbnormalities
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Real
M1desc: ¬Ab(M1) => (v(x) = (v(a) +1) * v(c))
M2desc: ¬Ab(M2) => (v(y) = v(b) * v(d))
M3desc: ¬Ab(M3) => (v(z) = v(c) * v(e))
A1desc: ¬Ab(A1) => (v(f) = v(x) + v(y))A2desc: ¬Ab(A2) => (v(g) = v(y) + v(z))
SD
Ob1: v(a) = 1 /\ v(b) = 2 /\
v(c)= 3 /\ v(d) = 4 /\ v(e) = 5 /\
v(f) = 11 /\ v(g) = 22
OBS
A : {A1} , {M3} , {M1,M2} , {A1,M2}
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A theory of meta‐diagnosis
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Diagnostic System: (SD,COMPS,OBS,A)
DiagnosticAlgorithm (A )
Observations(OBS) System
Description (SD)
Structure of information (Ψ)
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Diagnostic System: (SD,COMPS,OBS,A)
DiagnosticAlgorithm (A )
Observations(OBS) System
Description (SD)
Structure of information (Ψ)
Meta‐systemdescription(M‐SD)
Definition (Meta‐System Description)The meta‐system description is a pair(M‐SD,M‐COMPS) where:1. M‐SD, the meta‐system description, isa set of first order sentences.2. M‐COMPS, is a finite set of constantsrepresenting the meta‐components ofthe diagnostic system.
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Diagnostic System: (SD,COMPS,OBS,A)
DiagnosticAlgorithm (A )
Observations(OBS) System
Description (SD)
Structure of information (Ψ)
Meta‐systemdescription(M‐SD)
Meta‐observations(M‐OBS)
Definition (Meta‐System Description)The meta‐system description is a pair(M‐SD,M‐COMPS) where:1. M‐SD, the meta‐system description, isa set of first order sentences.2. M‐COMPS, is a finite set of constantsrepresenting the meta‐components ofthe diagnostic system.
Definition (Meta‐Observations)The set of meta‐observations, M‐OBS, isa finite set of first order sentences.
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Diagnostic System: (SD,COMPS,OBS,A)
DiagnosticAlgorithm (A )
Observations(OBS) System
Description (SD)
Structure of information (Ψ)
Meta‐systemdescription(M‐SD)
Meta‐observations(M‐OBS)
Definition (Meta‐System Description)The meta‐system description is a pair(M‐SD,M‐COMPS) where:1. M‐SD, the meta‐system description, isa set of first order sentences.2. M‐COMPS, is a finite set of constantsrepresenting the meta‐components ofthe diagnostic system.
Definition (Meta‐Observations)The set of meta‐observations, M‐OBS, isa finite set of first order sentences.
Definition (Meta‐health state) Let Φ bea set of meta‐components consideredabnormal. The meta‐health state π(Φ,M‐COMPS\Φ) is the conjunction:
/\ mc € Φ M‐Ab(mc) /\ mc € (M‐COMPS\ Φ)¬M‐Ab(mc)
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Diagnostic System: (SD,COMPS,OBS,A)
DiagnosticAlgorithm (A )
Observations(OBS) System
Description (SD)
Structure of information (Ψ)
Meta‐systemdescription(M‐SD)
Meta‐observations(M‐OBS)
Meta‐diagnosticAlgorithm (M‐A )
Definition (Meta‐System Description)The meta‐system description is a pair(M‐SD,M‐COMPS) where:1. M‐SD, the meta‐system description, isa set of first order sentences.2. M‐COMPS, is a finite set of constantsrepresenting the meta‐components ofthe diagnostic system.
Definition (Meta‐Observations)The set of meta‐observations, M‐OBS, isa finite set of first order sentences.
Definition (Meta‐health state) Let Φ bea set of meta‐components consideredabnormal. The meta‐health state π(Φ,M‐COMPS\Φ) is the conjunction:
/\ mc € Φ M‐Ab(mc) /\ mc € (M‐COMPS\ Φ)¬M‐Ab(mc)
Definition (Meta‐Diagnosis) A meta‐diagnosis, M‐D, for the meta‐diagnosticproblem (M‐SD,M‐COMPS,M‐OBS) is theset of all meta‐diagnosis hypotheses πsuch that:
M‐SD ∪M‐OBS ∪ πIs satisfiable.
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Real
¬M‐Ab(M1desc) => [¬Ab(M1)=>(v(x)=(v(a)+1)*v(c))]
¬M‐Ab(M2desc) => [¬Ab(M2) => (v(y) = v(b) * v(d))]
¬M‐Ab(M3desc) => [¬Ab(M3) => (v(z) = v(c) * v(e))]
¬M‐Ab(A1desc) => [¬Ab(A1) => (v(f) = v(x) + v(y))]¬M‐Ab(A2desc) => [¬Ab(A2) => (v(g) = v(y) + v(z))]
M‐SD
v(a)=1 /\ v(b)=2 /\ v(c)= 3 /\ v(d)=4
/\ v(e)=5 /\ v(f)=11 /\ v(g)=22
¬Ab(M1) /\ ¬Ab(M2) /\ ¬Ab(M3) /\
¬Ab(A1) /\ Ab(A2)
M‐OBS
M‐A: {M1desc} , {M2desc} , {A1desc}
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Information (Ψ)
SD
A
OBS
AOBS SD
Information (Ψ)
M‐SDM‐OBS
M-A
Meta‐DiagnosisDiagnosis
Diagnosis and Meta‐Diagnosis are semantically different, butsyntactically the same. Therefore, diagnostic‐worldtechniques, algorithms and tools can be directly used inmeta‐diagnosis.
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Some diagnostic systems’ potential abnormalities
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of observations (Tarski, 1936)
Definition (Truth): Let Ω be the set of allstructures and Ψ e Ω the structure of rawinformation about the reality. Theobservations OBS are an ontological truth iff‘
s€Mod(OBS) t€Ω: (s t)/\(t<‐>Ψ).E E U|
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of observations (Tarski, 1936)
Definition (Truth): Let Ω be the set of allstructures and Ψ e Ω the structure of rawinformation about the reality. Theobservations OBS are an ontological truth iff‘
s€Mod(OBS) t€Ω: (s t)/\(t<‐>Ψ).E E U|
of system description (Tarski, 1936)Definition (truth): Let Ω be the set of allstructures and Ψ e Ω the structure of rawinformation about the reality. A believedsystem is an ontological truth iff, for allontologically true OBS,
s€Mod(OBSUSD) t€Ω: (s t)/\(t<->Ψ).E E U|
of diagnoses
Definition (validity): Let σreal be the believedsystem health state such that for everyc€COMPS, if c is the image of r€R, 1) if r isnormal, σreal => ¬Ab(c), and 2) if r isabnormal σreal => Ab(c).A diagnosis, D, is valid iff σreal€D.
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of observations (Tarski, 1936)
Definition (Truth): Let Ω be the set of allstructures and Ψ e Ω the structure of rawinformation about the reality. Theobservations OBS are an ontological truth iff‘
s€Mod(OBS) t€Ω: (s t)/\(t<‐>Ψ).E E U|
of system description (Tarski, 1936)Definition (truth): Let Ω be the set of allstructures and Ψ e Ω the structure of rawinformation about the reality. A believedsystem is an ontological truth iff, for allontologically true OBS,
s€Mod(OBSUSD) t€Ω: (s t)/\(t<->Ψ).E E U|
Theorem: If (SD,COMPS) is an ontologically true believedsysyem, then for every diagnostic problem (SD,COMPS,OBS) with ontologically true observations, everydiagnosis D is valid.
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MEDITO: a logic‐based meta‐diagnosis tool
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GUI
Database Management
Tool
Database
Meta-diagnoser
Core Algorithms
Parsing Tool
Model Tool
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Data injection
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1
Data injection
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1
Data injection
2
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Data exploitation
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Data exploitation
1
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Data exploitation
1Parsing of user‐input text SD and M‐OBS into java objects.
2
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Data exploitation
1Parsing of user‐input text SD and M‐OBS into java objects.
2
Creation of CHOCO model depending on user‐input
hypotheses.(Choco Team, 2010)
3
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Data exploitation
1Parsing of user‐input text SD and M‐OBS into java objects.
2
Creation of CHOCO model depending on user‐input
hypotheses.(Choco Team, 2010)
3
Running of Zhao and Ouyang diagnostic
algorithms using CHOCO for consistency checking.(Zhao & Ouyang, 2006)(Zhao & Ouyang, 2007)
4
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Data exploitation
1Parsing of user‐input text SD and M‐OBS into java objects.
2
Creation of CHOCO model depending on user‐input
hypotheses.(Choco Team, 2010)
3
Running of Zhao and Ouyang diagnostic
algorithms using CHOCO for consistency checking.(Zhao & Ouyang, 2006)(Zhao & Ouyang, 2007)
4
5
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Meta‐diagnosing an Airbus LGERS
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Side 1 Side 2
CPIOM Z
CPIOM Y
CPIOM X
CPIOM W
RDCB
RDCA
RDCC
RDCD
Sensors
NLG / WLG / BLGActuators
EPDC 1 EPDC 2
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Warn
ings
Main
tenance
Com
ponen
ts
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For confidentiality issues, thebelieved system (BS) in thisslide is not a perfect copy ofAirbus’ LGERS BS (roughly with6000 nodes)
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For confidentiality issues, thesituations presented in thisslide, although representative,are not Airbus’ real‐lifesituations.
Situation 1
CMSLGERSCTL1+2FAULT =
LGERSCTL1FAULT =
LGERSCTL2FAULT =
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For confidentiality issues, thesituations presented in thisslide, although representative,are not Airbus’ real‐lifesituations.
T
T
T
Situation 1
CMSLGERSCTL1+2FAULT =
LGERSCTL1FAULT =
LGERSCTL2FAULT =
Line mechanic
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For confidentiality issues, thesituations presented in thisslide, although representative,are not Airbus’ real‐lifesituations.
T
T
T
Situation 1
CMSLGERSCTL1+2FAULT =
LGERSCTL1FAULT =
LGERSCTL2FAULT =
Line mechanic
Ab(CPIOMW)
¬Ab(CPIOMX)
¬Ab(CPIOMZ)
¬Ab(SoftCPIOMXCOM)
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For confidentiality issues, thesituations presented in thisslide, although representative,are not Airbus’ real‐lifesituations.
T
T
T
T
Situation 1
CMSLGERSCTL1+2FAULT =
LGERSCTL1FAULT =
LGERSCTL2FAULT =
Situation 2
LOSSCOM1XtoW =
Line mechanic
Ab(CPIOMW)
¬Ab(CPIOMX)
¬Ab(CPIOMZ)
¬Ab(SoftCPIOMXCOM)
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For confidentiality issues, thesituations presented in thisslide, although representative,are not Airbus’ real‐lifesituations.
T
T
T
T
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Where SD‐sentence4 is:
Ab(CPIOMX) v Ab(SoftCPIOMXCOM) <=> [LossCOM1AFDXDataFromXtoW=T]
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Where SD‐sentence4 is:
Ab(CPIOMX) v Ab(SoftCPIOMXCOM) <=> [LossCOM1AFDXDataFromXtoW=T]
L/G CTL 1+2Fault
L/G CTL 1Fault
L/G CTL 2Fault
Loss of COM1 AFDX data from
CPIOM X to CPIOM W
AND
OR
Loss of CPIOM Y
Loss of CPIOM Z
OR
CPIOM X Fault
Soft. CPIOM X COM Fault
CPIOM Y Fault
CPIOM Z Fault
OR
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Where SD‐sentence4 is:
Ab(CPIOMX) v Ab(SoftCPIOMXCOM) <=> [LossCOM1AFDXDataFromXtoW=T]
L/G CTL 1+2Fault
L/G CTL 1Fault
L/G CTL 2Fault
Loss of COM1 AFDX data from
CPIOM X to CPIOM W
AND
OR
Loss of CPIOM Y
Loss of CPIOM Z
OR
CPIOM X Fault
Soft. CPIOM X COM Fault
CPIOM Y Fault
CPIOM Z Fault
OR
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Engineers later determined that lack ofpreconditions Ab(CPIOMW) vAb(SoftCPIOMWCOM) explained theSD‐sentence 4 abnormality
Conclusions
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1. The theory of meta‐diagnosis provides a formal frameworkfor detecting and isolating abnormalities in diagnosticsystems.
2. MEDITO provides empirical proof supporting meta‐diagnosisclaim that any sound and complete diagnostic algorithm canbe used to solve a meta‐diagnostic problem.
3. The usage of MEDITO for treating an Airbus problem supportsthe usage of meta‐diagnosis in real‐world problems.
4. Meta‐diagnosis inherits from diagnosis complexity problems.This is why we plan, in future works, on using classical Model‐Based Diagnosis complexity management techniques such ashierarchical approaches.
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Thank you for your attention
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