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“ Fly-By-Wireless ”. Wireless Network for Aircraft Control and Monitoring. Chris Dimoulis CS 441 Fall 2013. Introduction. Aircraft Systems (Current) Benefits of Wireless System Characteristics and Obstacles Proposed Solutions. Aircraft Systems: Flight Control. Cables and Pulleys
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“Fly-By-Wireless” Wireless Network for Aircraft Control and Monitoring Chris Dimoulis CS 441 Fall 2013
Introduction • Aircraft Systems (Current) • Benefits of Wireless System • Characteristics and Obstacles • Proposed Solutions
Aircraft Systems: Flight Control • Cables and Pulleys • Direct connection from flight controls to control surface • Hydraulic • Direct manipulation of hydraulic actuators in flight controls • Fly-By-Wire • Avionics Full Duplex Switched Ethernet (AFDX) used to send data from controls to actuators
Aircraft Systems: Avionics • View and manipulate flight and engine data\ • Old Systems • Pressure systems for altitude and airspeed • Mechanical linkages for engine data (tachometer and manifold pressure) • New Systems • Full Authority Digital Engine Control (FADEC) • Automatically controls engine parameters, sends data to pilots through AFDX
Benefits of Wireless System • Cost from Weight Reduction • Cable costs: A320: $14M B787: $50M [1] • A380: 300 miles (500 km) of wire [2] • Weight reduction means better fuel efficiency and increased space for revenue weight
Benefits of Wireless System • Improved Safety and Less Maintenance • Less Wire degradation • U.S. Navy: 78 aircraft made non-mission capable due to wiring, 1000 aborts from wiring faults [2] • Wired interconnects and potential fires • B 747 tank explosion due to arcing between fuel sensor wiring [3]
Characteristics and Obstacles • Real-Time and Deterministic [1] • Aircraft Network must behave in a predictable way • Current system provides 100Mbps • Latencies must be bounded and deadline constraints respected
Characteristics and Obstacles • Reliability and Availability • Probability of failure needs to be 10-9 per flight hour [1] • Fault Detection • Long lifetime: Avionics system lifetime can be 20 – 30 years [1]
Characteristics and Obstacles • Security [1] • Data confidentiality to prevent passive eavesdropping • Data integrity to guarantee data is not altered in transit • Prevent unauthorized access to network
Characteristics and Obstacles • Electromagnetic Compatibility[1] • Deployment is in a harsh physical environment • Large temperature and humidity changes along with vibrations • Intense radio frequency noise
Characteristics and Obstacles Table reproduced from [1]
Proposed Solutions • 802.11n • Adequate Data rate • Uses Point Coordination Function for contention free mode • Reliability: Automatic Retransmission ReQuest (ARQ ) • Not adapted for multicast[1] • High possibility of interference from common devices[1]
Proposed Solutions • ECMA-368 High Rate Ultra WideBand • Adequate Data rate and ranges • Distributed Reservation Protocol • TDMA (Contention free) • More secure from “man-in-middle” than 802.11
Proposed Solutions • Begin with a hybrid system • Full Duplex Ethernet Switch to connect clusters Image reproduced from [1]
Proposed Solutions • MAC Protocol Proposals • Need predictable behavior under real-time constraints • Synchronization protocol for TDMA • Reliability Mechanism for sending/receiving data • Probability of failure to be 10-9 per flight hour
Proposed Solutions • Synchronization Protocol • IEEE1588 Wired network synchronization have been implemented within few nanoseconds precision • IEEE1558 has reached less than 200 nanosecond precision for wireless network synchronization, however too many messages • Proposed enhanced IEEE1588
Proposed Solutions • Synchronization Protocol • Master/Slave/Passivenode • If slave node failspassive node canfill in Image reproduced from [1]
Proposed Solutions • Reliability Mechanism • Need adequate acknowledgement and retransmission mechanism • Communication is multicast • Multiple ACKs colliding? • Overhead from sender needing to receive all ACKs
Proposed Solutions • Reliability Mechanism • Designated “leader” of cluster • ACK from leader, NACK from rest • If sender hears NACK or nothing (due to ACK/NACK collision) then it will retransmit Image reproduced from [1]
Conclusion • ECMA-368 can provide adequate data rate, contention free, and security properties • Needs predictable real-time behavior • Enhanced IEEE1588 synchronization • Reliable data reception • Cluster leaders with ACK/NACK messages
Sources [1] D. Dang, A. Mifdaoui,and T. Gayraund, “Fly-By-Wireless for Next Generation Aircraft: Challenges and Potential solutions.” (In Press: 2012) In: Wireless days conference, 21-23 Nov 2012, Dublin, Ireland [2] R. K. Yedavalli, R. K. Belapurkar, “Application of Wireless Sensor Networks to Aircraft Control and Health Management.”Journal of control Theory & Applications. February 2011; 9(1):28. [3] M. Panitz, D. Hope, W. Crowther, et al. “The opportunities and challenges associated with wireless interconnects in aircraft.”Proceedings Of The Institution Of Mechanical Engineers -- Part G -- Journal Of Aerospace Engineering (Sage Publications, Ltd.) [serial online]. April 2010;224(4):459.