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Soft Walls: Algorithms to Enforce Aviation Security

Soft Walls: Algorithms to Enforce Aviation Security . Adam Cataldo Prof. Edward Lee Prof. Shankar Sastry. Center for Hybrid and Embedded Software Systems. August 24, 2004 Berkeley, CA. Outline. The Soft Walls system Objections Control system design Current research Conclusions.

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Soft Walls: Algorithms to Enforce Aviation Security

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  1. Soft Walls: Algorithms to Enforce Aviation Security Adam Cataldo Prof. Edward Lee Prof. Shankar Sastry Center for Hybrid and Embedded Software Systems August 24, 2004 Berkeley, CA

  2. Outline • The Soft Walls system • Objections • Control system design • Current research • Conclusions

  3. A Deadly Weapon? • Project started September 11, 2001

  4. Introduction • On-board database with “no-fly-zones” • Enforce no-fly zones through avionics

  5. Early Prototype UsingStanford DragonFly UAVs Dragonfly 2 Dragonfly 3 [Claire Tomlin,Jung Soon Jang, Rodney Teo] Ground Station

  6. Flight Test Result Nov 19th, 2003 Moffett Federal Air Field

  7. Another Early Prototype, Demo’d byHoneywell on National TV, Dec., 2003 • Based on advanced ground avoidance system • Issues a warning when approaching terrain or a no-fly zone • Takes over control from the pilot when approach is too close • Returns control to thepilot after diverting • Demonstrated on ABCWorld News TonightDec. 30, 2003 Honeywell pilot on ABC World News Tonight with Peter Jennings, Dec. 30, 2003.

  8. Both Prototypes useAutonomous Control Pilot orPath PlanningController Aircraft Soft Walls controller

  9. Our End Objective is Not Autonomous Control but a Blending Controller Pilot Aircraft + bias pilot control asneeded Soft Walls

  10. Our End Objective Maximize Pilot Authority, but keep outside forbidden airspace

  11. Unsaturated Control Pilot remains neutral Pilot aims for no-fly zone Pilot turns away from no-fly zone No-fly zone Control applied

  12. In the News • ABC World News Tonight with Peter Jennings • Dec. 30, 2003 • Radio Interviews • Voice of America, Dec. 6, 2003. • NPR Marketplace • WTOP, Washington DC, July 14, 2003 • As It Happens, CBC, July 9, 2003 • Magazines • New Scientist, July 2, 2003 • Salon, December 13, 2001 • Slashdot, July 3, 2003 • Slashdot, Jan 3, 2004 • Newspapers • New York Times, April 11, 2002 • Toronto Globe and Mail • The Washington Times • The Orlando Sentinel • The Straits Times (Singapore) • The Times of India • The Star (South Africa) • The Age (Australia) • Reuters, July 2, 2003 Graphic on ABC World News Tonight with Peter Jennings, Dec. 30, 2003.

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

  14. There is No Emergency That Justifies Attempting to Land on Fifth Ave. • Flying in certian regions of space is unacceptable • Regulatory bodies must not overconstrain the air space • A pilot flying over restricted airspace risks the aircraft being shot down

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

  16. No override switch enables transit through here • Terrain imposes “hard wall” constraints on airspace • Soft Walls impose more gentle contraints on airspace • Again, regulatory bodies should not overconstrain the airspace

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

  18. Localization Backup • Radio beacons • Inertial navigation • drift limits accuracy • affects the geometry of no-fly zones

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

  20. Deployment • Fly-by-wire aircraft • a software change • which is of course extremely costly • Older aircraft • autopilot level? • Honeywell prototype? • Phase in • prioritize airports

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

  22. Not As Complex as Air Traffic Control • Self-contained avionics system (not multi-vehicle) • Human factors is an issue: • pilot training? • air traffic controller training?

  23. Objections • Reducing pilot control is dangerous • reduces ability to respond to emergencies • There is no override • pilots want a 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

  24. 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? • Requires radio communication • hackable • jammable

  25. Relationship to Flight Envelope Protection • With flight envelope protection, the limits on pilot-induced maneuvers are known • Knowing these limits enables tighter tolerances, and hence tighter geometries for no-fly zones. see http://softwalls.eecs.berkeley.edufor FAQ

  26. Here’s How It Works

  27. Safe Control Design Backwards reachable set No-fly zone At some points, the pilot can fly into the no-fly zone even with Soft Walls bias Can prevent aircraft from entering the backwards reachable set: This set is avoidable

  28. Control Design Components • Make controller push aircraft away from no-fly zone (easy) • Find avoidable set containing no-fly zone (hard) • Apply control only when aircraft gets near avoidable set No-fly zone Avoidable Set

  29. Numerical Aproach(Mitchell, Tomlin, …) • Approximate the “optimal” backwards reachable set and corresponding controller numerically • Store this information in a look-up table • Storage requirements are prohibitive No-fly zone Backwards Reachable Set

  30. The Backwards Reachable Set for the Stanford no-fly Ellipse Theorem [Computing ]: where is the unique viscosity solution to:

  31. Analytic Methods(Leitmann, Skowronski, …) • Calculate a controller and avoidable set analytically • This tends to give simple control laws • This is hard when the model is complex Example No-fly zone Pilot always turns into the no-fly zone

  32. The Research Goal • Find an easy-to-implement method which: • Guarantees safety • Includes the corresponding avoidable set

  33. The Soft Walls Goal • Increase security of the airspace • Maintain as much pilot authority as possible

  34. Acknowledgements • Ian Mitchell • Aaron Ames • George Pappas • Xiaojun Liu • Steve Neuendorffer • Claire Tomlin

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