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DARPA MTO MEMS SMART DUST K. Pister, J. Kahn, B. Boser (UCB) S. Morris (MLB) SMART DUST Goals • Autonomous sensor node (mote) in 1 mm3 • MAV delivery • Thousands of motes • Many interrogators • Demonstrate useful/complex integration in 1 mm3 SMART DUST COTS Dust GOALS: • Create a network of sensors • Explore system design issues • Provide a platform to test Dust components • Use off the shelf components SMART DUST COTS Dust - RF Motes • Atmel Microprocessor • RF Monolithics transceiver • 916MHz, ~20m range, 4800 bps • 1 week fully active, 2 yr @1% N W E S 2 Axis Magnetic Sensor 2 Axis Accelerometer Light Intensity Sensor Humidity Sensor Pressure Sensor Temperature Sensor SMART DUST COTS Dust - Network Simulation Cheap platforms --> Lots of nodes --> Network challenges! SMART DUST Message Diffusion (McLurkin) • 3.5 3 • 2.5 2 1.5 • 1 0.5 Each mote checks all it’s received transmissions for the one with the maximum value The mote then rebroadcasts it with a lower value The result is a gradient pointing towards the signal source. 0 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Number Of Motes=200 Communications Range=.5 SMART DUST Edge Detection using Min/Max • 4.5 4 • 3.5 3 • 2.5 2 1.5 • 1 0.5 0 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 • 1. Ask each or your neighbors how many motes they can see. 2. Find the minimum and maximum of these numbers 3. Share these minimum and maximum numbers with all your neighbors. 4. When all your neighbors have the same min.max info as you, compare your local neighbor count to this info. 5. Turn red if you are lonely Number Of Motes=500 Communications Range=.5 SMART DUST Gradient Directed Communication 6 6 6 5 5 5 4 4 4 3 3 3 2 2 2 1 1 1 1 0 0 0 0 6 5 4 3 2 -1 -1 0 1 2 3 4 -1 0 5 1 2 3 4 -1 5 0 1 2 3 4 5 6 6 5 5 4 4 4 3 3 3 3 2 2 2 2 1 1 1 1 0 0 0 0 6 6 5 5 4 -1 -1 • • • • 0 1 2 3 4 5 -1 0 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5 -1 0 1 2 3 4 5 Number Of Motes=150 These gradients can be used to direct Communications Range=1 transmissions towards a single source Messenger Agents (the light blue dots) transmit themselves to motes with higher message levels This provides the minimum number of hops to get to a central destination SMART DUST Centroid Location • • 5 4 • 3 • 2 Find edges Diffuse pheromone from the edges inward Find the lowest concentration using Min/Max sharing If you have the lowest concentration, turn yellow 1 0 -1 -0.5 0 0.5 1 1.5 2 Number Of Motes=500 Communications Range=.8 2.5 3 3.5 4 4.5 SMART DUST Mote Position Estimation • • • Give GPS receivers to some motes and callthem “BasisMotes”. Ask them to turn gray. Each BasisMote diffuses it’s own pheromone throughout the group The position of any other mote can be estimated from the levels of basis pheromones present. SMART DUST Network Growing • • • Number Of Motes=128 Communications Range=1 Since diffusion directed communication already minimizes number of hops, whatever are we going to optimize? We can use division of labor to optimize power (time) Certain motes are responsible for communications to the hub and others are responsible for sensing SMART DUST COTS Dust - Optical Motes Laser mote • 650nm laser pointer • 2 day life full duty CCR mote • 4 corner cubes • 40% hemisphere SMART DUST CCR Interogator Top View of the Interrogator Filter CCD Camera Polarizing Beamsplitter Quarter-wave Plate Lens 0.25% reflectance on each surface Frequency-Doubled YAG Green Laser Beam Expander 45o mirror SMART DUST Video Semaphore Decoding Diverged beam @ 300m Shadow or full sunlight Diverged beam @ 5.2 km In shadow in evening sun SMART DUST Video Semaphore Decoding Diverged beam @ 300m Shadow or full sunlight Diverged beam @ 5.2 km In shadow in evening sun SMART DUST 1 Mbps CMOS imaging receiver 10mW, 1mrad Optical Filter Collection Lens 64x64 CMOS Imager 10cm 5mm 200m Photosensor CRC Check SIPO Shift Local Bus Driver Register 2 km Field of View of Single Pixel Signal Processing A/D Conversion Off Chip Bus Driver Pixel Array SMART DUST Optical Communication (vs. RF) • Pro: • • • • • • low power small aperture spatial division multiplexing high data rates LPI/LPD baseband coding • Con: • line of sight • atmospheric turbulence SMART DUST Turbulent Channel Physical Origin of Beam Scintillation Maximum-Likelihood Sequence Detection Algorithm 1 4 2 1 3 2 Eddies 1 3 2 1 3 2 1 3 2 2 Communication through Turbulent Atmosphere 3 1 1 3 2 v 1 3 2 1 3 3 1 Laser To Signal Detection Receiver 1 22 33 1 3 2 1 1 3 2 1 1 23 4 1 2 3 0 1 0 Eddies SMART DUST 1 Micro Mote - First Attempt SMART DUST 2D beam scanning AR coated dome lens Steering Mirror laser CMOS ASIC SMART DUST • • • Open loop control Insensitive to disturbance Potentially low power Normalized beam position 6-bit DAC Driving Scanning Mirror 0.8 0.6 0.4 0.2 0 10 20 30 Time (seconds) 40 SMART DUST Power and Energy • Sources • Solar cells • Thermopiles • Storage • Batteries ~1 J/mm3 • Capacitors ~1 mJ/mm3 • Usage • Digital control: nW • Analog circuitry: nJ/sample • Communication: nJ/bit SMART DUST ’01 Goal SMART DUST MAV Delivery Built by MLB Co. • 60 mph • 18 min • 1 mi comm SMART DUST Dust Delivery • Floaters • Autorotators • solar cells • Rockets • thermopiles MOTE • MAVs SMART DUST Micro Flying Insect • • • • ONR MURI/ DARPA funded year 1 of 5 year project Dickinson, Fearing (PI), Liepmann, Majumdar, Pister, Sands, Sastry Heavily leveraged on Smart Dust SMART DUST Applications • DoD • • • • • • Battlefield sensor networks Sensor mine-fields, burrs and fleas Traffic mapping Captured terrain surveillance Bunker mapping ... • Civilian • High speed/low power IRDA • Interactive virtual ballet • ... SMART DUST The (somewhat) Virtual Keyboard SMART DUST Data from ACC-glove SMART DUST Conclusion • Cubic inch motes off-the-shelf, ~$100 • Dec ’99: 100 node network in Soda/Cory • Desperately need intelligent software • Millimeter-scale motes • Dec ’00: first working prototypes • Don’t have a clue what we need in software SMART DUST