Energy Harvesting Sensor Systems A Proposed Application for 802.15.4f

1. Energy Harvesting Sensor SystemsA Proposed Application for 802.15.4f Date: 2009-01-21 Authors: Frank Whetten (Boeing)

2. Abstract A new class of sensor and control systems, using the harvesting of ambient energy to power the system are becoming increasingly technologically mature The current market environment for these sensor and control systems is that of proprietary protocol stacks, which intrinsically curtails interoperability A robust standardized protocol stack, designed around extremely low-power devices is needed Frank Whetten (Boeing)

3. Outline • Objectives • Applications • Architectures • Challenges

4. Energy Harvesting Objectives • Reduce weight • Reduce cost of installation • Enable rapid introduction of new features • Enable rapid reconfiguration • With focus on • Low data rate applications • Eliminate “difficult” wires:long runs, span moving joints, difficult access areas, hostile environments

5. 1010 LARGE-SCALE EFFECT 109 108 107 106 105 104 SMALL-SCALE EFFECT 103 102 Power (Watts) 101 INFORMATION TRANSFER 100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 Examples of Power Generation and Consumption Space shuttle at liftoff (11 GW) Typical realm of energy regeneration Boeing 747 at cruise (65 MW) Very large wind turbine (5 MW) Midsize automobile (112 KW) Boeing noise reduction chevrons (2 kW) 150 lb human male running 8 minute mile (280 W) Laptop computer (60 W) Heel-strike energy harvesters (2 W) Cell phone (600 mW) AAA LED flashlight (100 mW) MicroStrain, Inc. wireless sensor (45 mW) Laser in a CD-ROM drive (5 mW) U of W dimmable window (4 mW) Typical realm of energy harvesting EnOcean wireless sensor (24 μ W) Quartz wristwatch (1 μW)

6. Energy Harvesting Power Generation & Utilization Average Power Harvesters Consumers 1W 100 mW 10 mW 1 mW 100 µW 10 µW 1 µW Cell phone Zigbee mesh network node (w/ Rx from wireless sensor) 1 cm2 a-Si PVin sun lit airplane pax window AAA LED flash light Chipcon CC2500 radio (Tx mode) 1 in2 TEG on crease beam Wireless dimming window TEG stringer clip 6 mm2 TEG on hydraulic line TI MSP430 microprocessor (awake) Large inductive vibe harvesters Push button harvester Wireless sensor @ 1 Hz 1 cm2 a-Si PV in blue sky Push button transmitter 1 cm2 a-Si PV in cabin lighting GSE monitoring sensor (log data every 10sec, Tx 2X per day) Small piezo beam vibe harvesters Chipcon CC2500 radio (asleep) TI MSP430 microprocessor (asleep) Sensor @ 2.8 hrs interval

7. Wireless Sensors And Thermoelectric Stringer Clip

8. Sensor Applications • Structural health monitoring • Corrosion • Cracks • Impact damage • Flight Test • Acceleration, strain, temperature, etc. • Troubleshooting

9. Thermoelectric Stringer Clip • Generates several mW from ΔTacross insulation blankets in flight • Cold side: -30ºC (structure) • Warm side: 20ºC (air) • Enables wireless sensors anywhere on fuselage without batteries or wires Patent Pending

10. Thermoelectric Challenges • Power management • Boosting low voltages • Optimizing impedance of boost circuit to support energy storage • Heat sink thermal efficiency versus weight optimization • Thermal interface material optimization OUTPUT INPUT • Boosts to 2.6V • Requires start-up of 0.3 to 0.75 V depending on Output load

11. Wireless Corrosion Sensor And Vibration Harvester

12. Corrosion Issues • Corrosion costs aircraft industry $2.2 billion per year.* • Unpredictable • Difficult to access locations • Current prevention programs rely on scheduled,invasive visual inspections • Causes unnecessary and costly aircraft downtime *Koch, G.H.,“Corrosion Cost and Preventive Strategies in the United States,” 2001.

13. vehicle vibrating structure mechanical energy Self-powered Wireless Corrosion Sensor Accel. PSD frequency corrosion data low power wireless transceiver corrosion sensor index energy harvester time Transmission interval 1200 1200 Pristine sensor reading first transmission 4 Transmission duration Storage Cap Voltage 1000 1000 Sensor placed in Nitric acid solution 3 800 800 Voltage 2 600 600 Corrosion Sensor Resistance [ohms] Test stopped 1 400 400 Regulated Voltage Severe corrosion observed 200 200 0 0 20 40 60 80 100 120 140 160 180 0 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 Time (seconds) Time [hrs] Self-Powered Wireless Sensors Stored voltage builds up to provide short bursts of regulated voltage Simulated corrosion sensor changes resistance when corroded

14. USB Transceiver Wireless Transceivers • Wireless Transceiver • Moteiv Tmote Sky transceiver • Based on UC Berkeley design • TinyOS operating system • Programmed to power on, take a corrosion readingand transmit report to a base station • Conclusions • Was able to detect the onset of corrosion • Wirelessly transmitted corrosion reports every 30 minutes while powered exclusively by characteristic aircraft vibrations

15. Vibration Harvesting Challenges • Need broadband vibration harvestersto support highly variable aircraftvibration spectrum • Need low-power, wide area sensors to detection corrosion or structural damage • Need standardized communications protocol so disparate devices can report through a common communications channel Multi-Frequency Piezoelectric Energy Harvester U.S. Patent No. 6,858,970

16. Simplified Passenger Services System And Finger-Powered Transmitter

17. Traditional Passenger Services System • Traditional system architectures are • Complex • Heavy • Expensive • IFE system required for basic passenger services

18. light switch Traditional Passenger Services System E/E Bay

19. Simplified Passenger Services System Powered Passenger Service Unit mounting rails Finger-powered wireless Passenger Control Units

20. Each seat group / PSU pairform a mini wireless network light switch Simplified Passenger Services System

21. Simplified Passenger Services System BEFORE AFTER

22. Self-Powered Dimming Window And Return Air Grill Thermal Harvesting

23. 787 A330/A340 787 Dimmable Window • 787 Window • 70% larger than competition • “View from every seat” • Re-connect passenger to “magic of flight” • Dimming Window Features • Traditional slider doesn’t fit • Greater control for passenger • Reduced maintenance • Allow cabin crew to operate dimming from central location

24. Dimmable Window for Retrofit Market • Open-circuit memory effect • No power needed to hold state • Power only needed to change state • Low Power Control Circuitry • Low power electronics • Maximize use of sleep modes • Wireless Flight Attendant control Patent Pending

25. Return Air Grill Thermoelectric Device Patent Pending

26. Test Results 55mW @ 3.6 Ohms 30mW @ 160 Ohms

27. Ultra-Low PowerWireless Architectures

28. Hybrid Star/Mesh Sensor Network for Ultra-Low Power Sensors ULPS Node Node Infrastructure Network ULPS ULPS ULPS ULPS ULPS ULPS Gateway ULPS ULPS ULPS ULPS Node ULPS ULPS Sensor-to-Node Node-to-Node Node-to-Gateway Node

29. Proposed (Fuzzy) Requirements • Very low energy requirements • Power consumption should be minimized, but is not key criterion • Layer 1 & 2 security required • Ensure only authorized devices associate with wireless backbone network • Minimal “keep-alive” network traffic required • Network nodes may only transmit once in multiple days • Frame length sufficient for adequate reports • Variable payload size desired • Frequency independent (highly desired) • Specialized or high-criticality applications are unlikely to use unlicensed spectrum Frank Whetten (Boeing)

30. Thank You