360 likes | 450 Views
GDI 2003: status report. Robert Szewczyk Joe Polastre Alan Mainwaring David Culler NEST Retreat, Jan 15, 2004. Outline. GDI Mote design Networking improvements Infrastructure redesign Conclusions. Analysis. Design. Deployment. Scientific motivation: Leach’s Storm Petrel.
E N D
GDI 2003: status report Robert Szewczyk Joe Polastre Alan Mainwaring David Culler NEST Retreat, Jan 15, 2004
Outline • GDI • Mote design • Networking improvements • Infrastructure redesign • Conclusions Analysis Design Deployment
Scientific motivation: Leach’s Storm Petrel • Questions • What environmental factors make for a good nest? How much can they vary? • What are the occupancy patterns during incubation? • What environmental changes occurs in the burrows and their vicinity during the breeding season? • Methodology • Characterize the climate inside and outsize the burrow • Collect detailed occupancy data from a number of occupied and empty nest • Spatial sampling of habitat – sampling rate driven by biologically interesting phenomena, non-uniform patches • Validate a sample of sensor data with a different sensing modality • Augmented the sensor data with deployment notes (e.g. burrow depth, soil consistency, vegetation data) • Try to answer the questions based on analysis of the entire data set
Patch Network Sensor Node Sensor Patch Gateway Transit Network Client Data Browsing and Processing Basestation Base-Remote Link Internet Data Service Application architecture
Sensor node GDI ’02 • Mica platform • Atmel AVR w/ 512kB Flash • 916MHz 40kbps RFM Radio • Range: max 100 ft • Affected by obstacles, RF propogation • 2 AA Batteries, boost converter • Mica weather board – “one size fits all” • Digital Sensor Interface to Mica • Onboard ADC sampling analog photo, humidity and passive IR sensors • Digital temperature and pressure sensors • Designed for Low Power Operation • Individual digital switch for each sensor • Designed to Coexist with Other Sensor Boards • Hardware “enable” protocol to obtain exclusive access to connector resources • Packaging • Conformal sealant + acrylic tube
GDI ’02 population • 43 distinct nodes reporting data between July 13 and November 18 • Heavy daily losses • Between 3 and 5% daily
Redesign directions • Node-level issues that need resolving • Size – motes were too large to fit in many burrows • Application specific packaging; minimize size of burrow package, base the system around mica2dot • Packaging – did not provide adequate protection for electronics or proper conditions for sensors • Waterproof plastic packaging to protect electronics • Design to provide both shielding and exposure to sensors • Node reliability • Power consumption – boost converter not particularly useful • Eliminate boost whenever possible, use stable voltage lithium cells • Data interpretation challenges • Sensor calibration • Occupancy data interpretation – need more sophisticated processing of sensor data and/or ground truth data • Better metadata – sensor location & conditions
Miniature weather station • Sensor suite • Sensirion humidity + temperature sensor • Intersema pressure + temperature sensor • TAOS total solar radiation sensor • Hamamatsu PAR sensor • Radiation sensors measure both direct and diffuse radiation • Power supply • SAFT LiS02 battery, ~1 Ah @ 2.8V • Packaging • HDPE tube with coated sensor boards on both ends of the tube • Additional PVC skirt to provide extra shade and protection against the rain
Burrow occupancy detector • Sensor suite • Sensirion humidity + temperature sensor • Melexis passive IR sensor + conditioning circuitry • Power supply • GreatBatch lithium thionyl chloride 1 Ah battery • Maxim 5V boost converter for Melexis circuitry • Packaging • Sealed HDPE tube, emphasis on small size
Patch network GDI ‘02 • Single hop transmit-only network • 43 nodes, about 25 above ground, the rest in burrows • Repeater network – add an extra hop to improve connectivity into burrows • Ran out of energy before it made any difference • Sampling rates: 1 set of samples from every node every 70 seconds • A compromise between response time (and ease of deployment) and expected power management behavior • Application logic: sense (fix time), send, sleeep(fix time) • Expected that CSMA MAC backoff will effectively desynchronize all nodes
Software architecture advances • Bi-directional communication with low-power listenting • 1% duty cycle • Parameter adjustment and query • Sample rate changes, sensor status queries • Improved power management scheme • Fine granularity through StdControl interface • 10 uA sleep mode, 30 uA with running Timer.
GDI ’03 patch network • Single hop network deployed mid-June • Rationale: Build a simple, reliable network that allows • HW platform evaluation • Low power system evaluation • Comparisons with the GDI ’02 deployment • A set of readings from every mote every 5 minutes • 23 weather station motes, 26 burrow motes • Placement for connectivity • Network diameter 70 meters • Asymmetric, bi-directional communication with low power listening – send data packets with short preambles, receive packets with long preambles • Expected life time – 4+ months • Weather stations perform considerably better than burrow motes – their battery rated for a higher discharge current
GDI ’03 Multihop network • Motivation • Greater spatial reach • Better connectivity into burrows • Implementation • Alec Woo’s generic multihop subsystem • Low power listening: tradeoff channel capacity for average power consumption • Contrast with TASK approach: Alec’s multihop component but with duty cycling on a loosely synchronized network • The network nodes • 44 weather motes deployed July 17 • 48 burrow motes deployed August 6 • Network diameter – 1/5 mile • Duty cycle – 2% to minimize the active time (compromise between receive time and send time) • Reading sent to base station every 20 minutes, route updates every 20 minutes. Expected lifetime: 2.5 months • 2/3 of nodes join within 10 minutes of deployment, remainder within 6 hours. Paths stabilize within 24 hours
GDI ’02 base station: • Requirements • Disconnected operation • Remote management • Automatic restart • Redundancy • Implementation • 2 laptops, each with a direct serial connection to a transit network (via GenericBase) • Asymmetry: one of the laptops acting as a gateway/firewall • Limited inside network • Replicated but independent PostgreSQL servers provide resiliency against laptop crashes • Limited remote admin capability – remote desktop, ssh • How do you reboot a system 3000 miles away • Satellite connection • DirecWay WAN • Uptime: 47%
Web power strip Satellite router WWW power strip DB 4-port VPN router and 16-port Ethernet switch IBM laptop #1 DB Power over LAN midspan IBM laptop #2 Wireless bridge Axis 2130 PTZ South Southern WAP Mica2-EPRB#2 Mica2-EPRB#2 GDI ’03 Base Station • More sophisticated networking structure • Dual laptops with PostgreSQL • Dual base stations (Mica2 + EPRB) • But one logs single hop the other logs multihop • Cross logging of the data • Vastly improved remote access • Remote wakeonlan • Web enabled power strip • Ubiquitous POE • VPN for direct access from authorized networks • Extensible schema to accommodate new sensor modalities and query types, compatibility with TASK • Main stumbling block • Power, power, power • Lack of redundancy on the transit net • Minor HW issues – outdoors is harsh
Wireless bridge Burrow Camera Configuration 12V PoL Active Splitter 12VDC, 0.9A network Axis 2401 Video Server Sensor Patch IR Burrow Camera #5 IR Burrow Camera #1 IR Burrow Camera #6 IR Burrow Camera #2 IR Burrow Camera #7 IR Burrow Camera #3 ) Power over LAN Midspan Ethernet switch IR Burrow Camera #4 IR Burrow Camera #8 110VAC service Northern WAP Occupancy measurements GDI ‘03 • Calibrated ASIC for conditioning and processing the passive IR signal • 0 to 40 deg C range • Corroboration of data • Multiple sensor nodes in occupied burrows • Verification of data • Co-locate a completely different sensing network with motes • IR-illuminated cameras • Ethernet video servers • Wireless connection to the base station • Verification network mimicsthe architecture of the sensornet • Sample a 15 sec video/audio clipevery 5 minutes • ~6 GB worth of data so far…
Occupancy data evaluation status • PIR data from website used for finding occupied burrows • Saturated sensor outputs • Video data analysis underway • Entry/exit events • Automatic video analysis
Analysis from biology side Temperature and humidity distributions
Temperature and humidity in different habitats Weather stations Burrow motes
Climate data Weather stations Burrow motes
Climate data: day-to-day variations,meadow Weather stations Burrow motes
Conclusions • Another iteration on the design, deploy, analyze cycle • 50+ node single hop network, 100+ node multi hop network • 4.5 months of operation – June 8 – October 20 • 436 thousands weather station observations • 234 thousands burrow mote observations • Improvements in the network quality • Longevity, reliability, features, power management, data quality • Room for much more improvement – ease of packaging, robustness • Data analysis • Biologists are engaged • Video analysis for occupancy corroboration under way
Q&A Thank You! http://www.greatduckisland.net
Gateway node design • GDI ’02 implementations • Linux + CerfCube + 802.11b • Generic Base x 2 + omni-directional antenna to receive from patch + directional antenna to xmit to base station • Power requirements: • CerfCube = 30”x30” solar • Mote-based = 6”x6” solar • Reliability • Side effects: transit network transmissions will affect the transmissions in the patch
Gateway node design • GDI ’03 design – keep elements that worked • Keep a mote-based system • Use different frequencies on patch and transit networks to eliminate interference; different frequencies for single and multihop networks • Asymmetrical bi-directional communication on single hop network – exploit low power listening & always-on gateways • Symmetrical bi-directional communication in the multihop network • Storage and processing • Keep it simple • No storage, processing, aggregation, etc. • Big disadvantages – removes a layer that could buffer packets in case of transient failure elsewhere in the system (e.g. base station down)