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Softwalls: Preventing Aircraft from Entering Unauthorized Airspace . Adam Cataldo Prof. Edward Lee Ian Mitchell Prof. Shankar Sastry. CHESS Review May 8, 2003 Oakland, CA. Outline. Introduction to Softwalls Objections Control system progress Future challenges Conclusions.
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Softwalls: Preventing Aircraft from Entering Unauthorized Airspace Adam Cataldo Prof. Edward Lee Ian Mitchell Prof. Shankar Sastry CHESS Review May 8, 2003 Oakland, CA
Outline • Introduction to Softwalls • Objections • Control system progress • Future challenges • Conclusions
Introduction—Avionics Application • On-board database with “no-fly-zones” • Enforce no-fly zones using on-board avionics • Non-networked, non-hackable
Autonomous control Pilot Aircraft Autonomous controller
Softwalls is not autonomous control Pilot Aircraft + bias pilot control Softwalls
Relation to Unmanned Aircraft • Not an unmanned strategy • pilot authority • Collision avoidance
A deadly weapon? • Project started September 11, 2001
Design Objectives Maximize Pilot Authority!
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
Objections • Reducing pilot control is dangerous • reduces ability to respond to emergencies
Objections • Reducing pilot control is dangerous • reduces ability to respond to emergencies • There is no override • switch in the cockpit
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
Localization Backup • Inertial navigation • Integrator drift limits accuracy range
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?
Deployment • Fly-by-wire aircraft • a software change • Older aircraft • autopilot level • Phase in • prioritize airports
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
Not Like Air Traffic Control • Much Simpler • No need for air traffic controller certification
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
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
Reachable Set set of all points reachable with some control input reachable set starting at a point in the state space
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
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
Implicit Surface Functions implicit surface function for no-fly zone implicit surface function for backwards reachable set No-fly zone Backwards Reachable Set
Analytic Solution • Hamilton-Jacobi-Isaacs PDE backwards reachable set implicit surface function no-fly zone implicit surface function • Evans & Souganidis--1984 v dynamics
Control from Implicit Surface Function Control decreases to zero Safe States Safe States Control at boundary Backwards Reachable Set
Numerical Solution • Mitchell--2001 computations & storage 1 2 3 4 states
Get Real • Control algorithm • model predictive control Richard Murray DARPA SEC Program Software Enabled Control
Conclusions • Embedded control system challenge • Control theory identified • Future implementation challenges identified
Acknowledgements • Iman Ahmadi • Zhongning Chen • Xiaojun Liu • Steve Neuendorffer • Claire Tomlin