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A Knowledge-Rich Approach to Understanding Text about Aircraft Systems

A Knowledge-Rich Approach to Understanding Text about Aircraft Systems Peter Clark Lisbeth Duncan Heather Holmback Tom Jenkins John Thompson Boeing Engineering and Information Technology Overview

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A Knowledge-Rich Approach to Understanding Text about Aircraft Systems

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  1. A Knowledge-Rich Approach to Understanding Text about Aircraft Systems Peter Clark Lisbeth Duncan Heather Holmback Tom Jenkins John Thompson Boeing Engineering and Information Technology

  2. Overview • Situation: Using a hand-built, airplane knowledge-base (KB) at Boeing (e.g., for concept-based search) • Goal: Extend this KB by processing text: • from airplane training manuals • directly from an aerospace engineer • Target: airplane parts, connections, and behaviors

  3. Airplane Powered-System source Script sink behavior Hydraulic System Rudder “The hydraulic system supplies power to the rudder.” Consume Transmit Supply Conduit Power Challenge • Interpretation of text requires background knowledge • author trying to convey a model to the reader • only some parts of this are explicitly stated in text • rest is assumed to be already known to the reader

  4. Approach • Use an aerospace knowledge base (KB): • Taken from an earlier project and extended • Contains general models about what might be said • Contains general knowledge of aircraft and systems • Doesn’t know details of specific aircraft • Text interpretation = specializing and refining this background knowledge

  5. Constraints on the Scope • Working with restricted sublanguage of English • Simple, declarative sentences • Regular, “boring” style “The hydraulic system supplies power to the rudder.” “A ripple damper smooths the pump pressure output.” “The EDP is on the left side of the engine main gearbox.” “The gearbox turns the EDP when the engine turns.” • Constrained domain (aircraft systems) • Reduces vocabulary, background KB • Domain of mechanical artifacts • Simple statements about structure and behavior

  6. Approach Initial (general) representation of airplane built. Text is provided. 777-200-Airplane purpose parts systems Wing Tail Fuselage parts Vertical Stabilizer Powered System “The hydraulic system supplies power to the rudder.” Flap connects sink source parts script Power Source Rudder recipient agent Supplying KB User specifies topic (eg. “777-200-Airplane”)

  7. Approach Hydraulic System Rudder recipient agent Supplying Stage 1 object Power KB • Then: • Text  NLP structure 777-200-Airplane purpose parts systems Wing Tail Fuselage parts Vertical Stabilizer Powered System “The hydraulic system supplies power to the rudder.” Flap connects sink source parts script Power Source Rudder recipient agent Supplying

  8. Approach KB • Then: • Text  NLP structure • Match NLP structure with airplane repn. 777-200-Airplane purpose parts systems Wing Tail Fuselage parts Hydraulic System Rudder Vertical Stabilizer Powered System “The hydraulic system supplies power to the rudder.” Flap recipient agent connects sink source parts script Supplying Stage 1 Stage 2 Power Source object Rudder Power recipient agent ? Supplying

  9. KB Approach Then: • Text  NLP structure • Match NLP structure with airplane repn. Unify the matching structures. 777-200-Airplane purpose parts systems Wing Tail Fuselage parts Hydraulic System Rudder Vertical Stabilizer Powered System “The hydraulic system supplies power to the rudder.” Flap recipient agent connects sink source parts script Supplying Stage 1 Stage 2 Hydraulic System object Rudder Power Supplying Power

  10. KB The Knowledge Base 777-200-Airplane purpose parts systems Wing Tail Fuselage parts Hydraulic System Rudder Vertical Stabilizer Powered System “The hydraulic system supplies power to the rudder.” Flap recipient agent connects sink source parts script Supplying Stage 1 Stage 2 Power Source object Rudder Power recipient agent Supplying

  11. Axiom:“Every airplane has a fuselage, and a tail connected to the fuselage.” Prototype (sketch) Airplane parts (every Airplane has (parts ((a Fuselage) (a Tail with (connected-to (the Fuselage parts of Self)))) Fuselage Tail connected-to The Knowledge Base • ~500 concepts, ~1500 axioms • Mainly airplane parts, behaviors, and connections • Axioms converted to prototypes (graph structures)

  12. parts Fuselage Tail connected-to parts behavior Vertical Stabilizer Horizontal Stabilizer Flight subevents Takeoff Cruise Land Inference: Building the Initial Airplane Representation Axioms in KB: Airplane representation: Airplane 777-200-Airplane behavior parts Fuselage Tail Flight Tail parts Vertical Stabilizer Horizontal Stabilizer Flight Takeoff Cruise Land

  13. Stage 1:Text to NLP Structure 777-200-Airplane purpose parts systems Wing Tail Fuselage parts Vertical Stabilizer Powered System “The hydraulic system supplies power to the rudder.” Flap connects sink source parts script Power Source Rudder recipient agent Supplying KB

  14. KB Stage 1:Text to NLP Structure 777-200-Airplane purpose parts systems Wing Tail Fuselage parts Hydraulic System Rudder Vertical Stabilizer Powered System “The hydraulic system supplies power to the rudder.” Flap recipient agent connects sink source parts script Supplying Stage 1 Power Source object Rudder Power recipient agent Supplying

  15. Supply_1 [sing,pres,3S] object recipient Hydraulic System Rudder causer Power_1 [sing,mass] To_5 recipient agent range Hydraulic System_1 [sing,N] Parse & semantic analysis Supplying Rudder_1 [sing,N] Abstract & rewrite object delim delim Power The_1 [det] The_1 [det] Stage 1: Text to NLP Structure • Superficial linguistic variations normalized • Add initial semantic interpretation “The hydraulic system supplies power to the rudder.” • Commits to: overall parse/syntactic configuration, word senses • May underspecify: some semantic relationships (e.g., modifiers)

  16. KB 777-200-Airplane purpose parts systems Wing Tail Fuselage parts Hydraulic System Rudder Vertical Stabilizer Powered System “The hydraulic system supplies power to the rudder.” Flap recipient agent connects sink source parts script Supplying Stage 1 Power Source object Rudder Power recipient agent Supplying

  17. Stage 2: Match NLP Structure with Airplane Representation KB 777-200-Airplane purpose parts systems Wing Tail Fuselage parts Hydraulic System Rudder Vertical Stabilizer Powered System “The hydraulic system supplies power to the rudder.” Flap recipient agent connects sink source parts script Supplying Stage 1 Stage 2 Power Source object Rudder Power recipient agent ? Supplying

  18. … … … Hydraulic System Rudder Power Source Rudder recipient agent recipient agent Supplying Supplying object Power Text KB (Topic airplane representation) Stage 2: Match with Airplane Representation • Goal: Integrate text into airplane representation • Approach: find matching (subsuming) structure(s)

  19. … … … Hydraulic System Rudder Power Source Rudder recipient agent recipient agent Supplying Supplying object Power Text KB (Topic airplane representation) Stage 2: Match with Airplane Representation • Goal: Integrate text into airplane representation • Approach: find matching (subsuming) structure(s) • If match found, unify thetwo structures together

  20. … … … Hydraulic System Rudder recipient agent Supplying object Power Stage 2: Match with Airplane Representation • Goal: Integrate text into airplane representation • Approach: find matching (subsuming) structure(s) • If match found, unify thetwo structures together … … … Hydraulic System Rudder Power Source Rudder recipient agent recipient agent Supplying Supplying object Power

  21. Matching Problem 1:Linguistic Variation But text may deviate with: 1. Synonyms Providing Power “The hydraulic system provides power to the rudder.” Hydraulic System Rudder 2. Contractions Powering “The hydraulic system powers the rudder.” Hydraulic System Rudder 3. Roles Be “The hydraulic system is the supplier of power for the rudder.” Supplier Hydraulic System Power Rudder KB expects: Supplying Power “The hydraulic system supplies power to the rudder.” Power Source Rudder 4. …

  22. synonym Providing Power Supplying Power Hydraulic System Rudder Hydraulic System Rudder role contraction/ expansion Be Supplier Hydraulic System Powering Power Rudder Hydraulic System Rudder Matching Problem 1:Linguistic Variation • Use simple transformation rules to modify NLP structure • No match  transform and re-search for a match

  23. Explicit facts: Rudder Control System agent object behavior Pilot Script Rudder agent object subevents Press Pull Move agent object Pedal Cable Matching Problem 2:Expression of Implied Facts • Problem: • Not all airplane facts are explicit in the KB structures • If user refers to an implied fact, matcher will not find it

  24. Matching Problem 2:Expression of Implied Facts • Problem: • Not all airplane facts are explicit in the KB structures • If user refers to an implied fact, matcher will not find it Explicit facts: Rudder Control System “The pilot presses the pedal.” agent object behavior Pilot Script Rudder agent object subevents Press Pull Move agent object Pedal Cable

  25. Matching Problem 2:Expression of Implied Facts • Problem: • Not all airplane facts are explicit in the KB structures • If user refers to an implied fact, matcher will not find it Explicit facts: Rudder Control System “The pilot presses the pedal.” “The pedal pulls a cable.” agent object behavior Pilot Script Rudder agent object subevents Press Pull Move agent object Pedal Cable

  26. Matching Problem 2:Expression of Implied Facts • Problem: • Not all airplane facts are explicit in the KB structures • If user refers to an implied fact, matcher will not find it Explicit facts: Rudder Control System “The pilot presses the pedal.” “The pedal pulls a cable.” “The cable moves the rudder.” agent object behavior Pilot Script Rudder agent object subevents Press Pull Move agent object Pedal Cable

  27. Matching Problem 2:Expression of Implied Facts • Problem: • Not all airplane facts are explicit in the KB structures • If user refers to an implied fact, matcher will not find it Explicit facts: Rudder Control System “The pilot presses the pedal.” “The pedal pulls a cable.” “The cable moves the rudder.” agent object behavior Pilot Script Rudder agent object subevents Press Pull Move Inference Rule: If A does X, and X causes Y then add A does Y. agent object Pedal Cable

  28. Matching Problem 2:Expression of Implied Facts • Problem: • Not all airplane facts are explicit in the KB structures • If user refers to an implied fact, matcher will not find it Implied facts: Rudder Control System “The pilot presses the pedal.” “The pedal pulls a cable.” “The cable moves the rudder.” agent object behavior Pilot Script Rudder agent object subevents “The pilot moves the rudder using the pedal.” Press Pull Move object agent object instr- ument. agent Move Pedal Cable

  29. Matching Problem 2:Expression of Implied Facts • Problem: • Not all airplane facts are explicit in the KB structures • If user refers to an implied fact, matcher will not find it Implied facts: Rudder Control System “The pilot presses the pedal.” “The pedal pulls a cable.” “The cable moves the rudder.” agent object behavior Pilot Script Rudder agent object subevents “The pilot moves the rudder using the pedal.” Press Pull Move object agent object instr- ument. “The pedal moves the rudder using the cable.” agent Move Pedal Cable object instrument agent Move

  30. Matching Problem 2:Expression of Implied Facts • Problem: • Not all airplane facts are explicit in the KB structures • If user refers to an implied fact, matcher will not find it • Approach: • Match text against an extended version of the KB • Extensions generated on demand Airplane representation: Explicit facts Implied facts

  31. Status and Assumptions • While some components are mature, only complete throughput for a small number of sentences • Relies on strong expectations from the KB • Everything that might be said is encompassed by KB • Assumes stage 1 output is correct • Assumes a single model of the airplane is described

  32. Challenges… • Inaccurate knowledge • “The pump supplies a source of power to the rudder.” • Simplifications/multiple models • “There are three hydraulic systems in the 777-200.” • “The flight control surfaces steer the airplane.” • Fluctuating (“fuzzy”) concept boundaries • “hydraulic system” includes controlled devices (eg rudder)? • Ambiguities not locally resolvable • “The EDP is attached to the airplane’s engine.”

  33. Summary • Goal: extend an airplane KB from text • Use of background knowledge can help: • constrains possible interpretations • provide the surrounding context • Presented a simple model of how this can be done: • text interpretation = iterative refinement of a representation • use of graph matching and unification

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