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Softwalls: Preventing Aircraft from Entering Unauthorized Airspace

Softwalls: Preventing Aircraft from Entering Unauthorized Airspace. Adam Cataldo Prof. Edward Lee Prof. Ian Mitchell, UBC Prof. Shankar Sastry. NASA JUP Sep 26, 2003 Los Angeles, CA. Outline. Introduction to Softwalls Objections Control system progress Future challenges Conclusions.

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Softwalls: Preventing Aircraft from Entering Unauthorized Airspace

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  1. Softwalls: Preventing Aircraft from Entering Unauthorized Airspace Adam Cataldo Prof. Edward Lee Prof. Ian Mitchell, UBC Prof. Shankar Sastry NASA JUP Sep 26, 2003 Los Angeles, CA

  2. Outline • Introduction to Softwalls • Objections • Control system progress • Future challenges • Conclusions

  3. Introduction • On-board database with “no-fly-zones” • Enforce no-fly zones using on-board avionics • Non-networked, non-hackable

  4. Autonomous control Pilot Aircraft Autonomous controller

  5. Softwalls is not autonomous control Pilot Aircraft + bias pilot control Softwalls

  6. Relation to Unmanned Aircraft • Not an unmanned strategy • pilot authority • Collision avoidance

  7. A deadly weapon? • Project started September 11, 2001

  8. Design Objectives Maximize Pilot Authority!

  9. Unsaturated Control Pilot lets off controls Pilot tries to fly into no-fly zone Pilot turns away from no-fly zone No-fly zone Control applied

  10. Objections • Reducing pilot control is dangerous • reduces ability to respond to emergencies

  11. There is No Emergency That Justifies Landing Here

  12. Objections • Reducing pilot control is dangerous • reduces ability to respond to emergencies • There is no override • switch in the cockpit

  13. Hardwall

  14. Objections • Reducing pilot control is dangerous • reduces ability to respond to emergencies • There is no override • switch in the cockpit • Localization technology could fail • GPS can be jammed

  15. Localization Backup • Inertial navigation • Integrator drift limits accuracy range

  16. Objections • Reducing pilot control is dangerous • reduces ability to respond to emergencies • There is no override • switch in the cockpit • Localization technology could fail • GPS can be jammed • Deployment could be costly • Software certification? Retrofit older aircraft?

  17. Deployment • Fly-by-wire aircraft • a software change • Older aircraft • autopilot level • Phase in • prioritize airports

  18. Objections • Reducing pilot control is dangerous • reduces ability to respond to emergencies • There is no override • switch in the cockpit • Localization technology could fail • GPS can be jammed • Deployment could be costly • how to retrofit older aircraft? • Complexity • software certification

  19. Not Like Air Traffic Control • Much Simpler • No need for air traffic controller certification

  20. Objections • Reducing pilot control is dangerous • reduces ability to respond to emergencies • There is no override • switch in the cockpit • Localization technology could fail • GPS can be jammed • Deployment could be costly • how to retrofit older aircraft? • Deployment could take too long • software certification • Fully automatic flight control is possible • throw a switch on the ground, take over plane

  21. Potential Problems with Ground Control • Human-in-the-loop delay on the ground • authorization for takeover • delay recognizing the threat • Security problem on the ground • hijacking from the ground? • takeover of entire fleet at once? • coup d’etat? • Requires radio communication • hackable • jammable

  22. Here’s How It Works

  23. Reachable Set set of all points reachable with some control input reachable set starting at a point in the state space

  24. Backwards Reachable Set set of all states that can reach the final point for some control input backwards reachable set given a final point in the state space

  25. Backwards Reachable Set Backwards reachable set No-fly zone States that can reach the no-fly zone when control is applied Can prevent aircraft from entering no-fly zone Safe States

  26. Implicit Surface Functions implicit surface function for no-fly zone implicit surface function for backwards reachable set No-fly zone Backwards Reachable Set

  27. Analytic Solution • Hamilton-Jacobi-Isaacs PDE backwards reachable set implicit surface function no-fly zone implicit surface function • Tomlin, Lygeros, Sastry v dynamics

  28. Control from Implicit Surface Function Control decreases to zero Safe States Safe States Control at boundary Backwards Reachable Set

  29. Numerical Solution • Mitchell computations & storage 1 2 3 4 states

  30. Assumptions for Verification • The pilot and control inputs could be any bounded, measurable functions

  31. In Fly-By-Wire Aircraft • The pilot and control inputs will be piecewise constant, bounded functions which can change only every T milliseconds T

  32. Fly-By-Wire Aircraft • How do we verify this?

  33. In the News • ABC News • NPR Market Place • CBC As It Happens • Slashdot • Reuters…

  34. Conclusions • Embedded control system challenge • Control theory identified • Future challenges identified

  35. Acknowledgements • Xiaojun Liu • Steve Neuendorffer • Claire Tomlin

  36. Backup • Discrete-Time Modified HJI PDE

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