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OXYBUOY Constructing a Real-Time Inexpensive Hypoxia Monitoring Platform

OXYBUOY Constructing a Real-Time Inexpensive Hypoxia Monitoring Platform. Rizal Mohd Nor Mikhail Nesterenko Peter Lavrentyev. ASIT 2009. Hypoxia Description. Hypoxia – dissolved oxygen depletion in the lower part of the water column an emerging global problem

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OXYBUOY Constructing a Real-Time Inexpensive Hypoxia Monitoring Platform

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  1. OXYBUOYConstructing a Real-Time Inexpensive Hypoxia Monitoring Platform Rizal Mohd Nor Mikhail Nesterenko Peter Lavrentyev ASIT 2009

  2. Hypoxia Description • Hypoxia – dissolved oxygen depletion in the lower part of the water column • an emerging global problem • negatively affects biological resources: fish and commercial invertebrate species • anthropogenic causes • hypoxia dimensions - affects a large areas in coastal waters over the summer • up to 20,000 km2, up to 50 meters in depth, 10-40 miles off shore • active up to 4 months • poorly understood – no accurate models to describe phenomenon, needs empirical measurements • measurements techniques • research vessels – vessels can be sent to collect water samples or trawl sensors • expensive and insufficient data density • satellite images • no biological markers • does not occur at surface • unattended sensor buoys

  3. Why Build a New Buoy • commercial offerings • market too small – tend to make them generic and expensive • COTS components enable scientific multi-parameter sensors to construct buoys • we propose Oxybouy • inexpensive • COTS components • easy to assemble • allows long term deployment

  4. Outline • Oxybuoy description • components • component cost • architecture • programming and operation • electric power design • experiments • lab experiment • Bath lake deployment • power consumption study • future work

  5. Oxybuoy Components • processor • Gumstix embedded computer • Xscale PXA270 processor • PIC16F86 Microcontroller • Nalresearch 9601-D-N satellite modem via RS232 • ZebraNet D-Opto DO sensor via SDI-12 • more robust than membrane based DO sensor • Vegetronix RS232 to SDI-12 converter • 802.11(b and g) wireless card • Dimension Engineering 5V 1A switching voltage regulator • 2 Gig Flash Micro SD card • 12 volts 7Ahr seal acid battery

  6. Component Cost

  7. Oxybuoy Architecture

  8. Gumstix Programming and Operation • data sampling • receive power level from the PIC processor • sample DO sensor • requests satellite modem to transmit the data • data transmission and saving • checks the signal strength indicator. • If it is too low, the data is saved to flash card and transmitted next time • check for change in sampling rate request from data center • system power down • send command to PIC to set sleep interval • check WiFi for connection, remain awake if exists • send power down signal to PIC

  9. Electric Power Design • managed by PIC • two operating modes • active sampling mode: • draws 350 mA • turns on for every sampling period • has 1024-bit ADC connection to the battery to read voltage level • PIC operation • sends the current battery voltage level to the Gumstix • waits for a 2-bit signal from Gumstix to indicate the sleep duration • when signal received, switches to sleep mode (power down the remainder of the system) • power saving sleep mode: • draws 11 mA • only PIC remains powered • PIC operation • keeps track of the clock cycle for the next sampling time • turns system on for the active sampling mode

  10. Lab Experiment • Objective: test the operation of the electronics in controlled environment • used a water tank in a fish physiology laboratory at the AkronU equipped for hypoxia experiments • DO concentration in the tank was maintained at specific level • tank had external thermometer and YSI DO meter • minimal protective packaging for the electronic components • only the DO sensor was submerged • configured Oxybuoy to use the wireless card to report the measurements every 20 minutes to the wireless bridge and on to the data center located at KSU

  11. Lab Experiment Results, Temperature

  12. Lab Experiment Results, DO

  13. Bath Lake Deployment • Objective: test the complete operation of Oxybuoy in target environment • deployed buoy in Bath Lake, a small eutrophuc lake within the Bath Nature Preserve near Akron, Ohio for 7 days • did not use power saving mode • during the deployment, Oxybuoy reported DO measurements 6 times per hour • Oxybuoy remained operational and reported data for over 18 hours

  14. Bath Lake Results, Temperature

  15. Bath Lake Results, DO

  16. Power Consumption Study • Objective: to estimate the lifetime of the buoy in multi-mode operation • ran the electronics of the buoy in the simulated deployment • electronics were configured to switch to data acquisition mode once an hour • PIC recorded battery power output and relayed it to Gumstix • stopped experiment when battery power > 8 Volts (required by the DO operation) • results: Oxybuoy produced 155 samples. • For four 4 months operation required battery: • 1 hour duty cycle, 160 Ah battery • 6 hour duty cycle , 28 Ah battery

  17. Conclusion and Future Work • demonstrated Oxybuoy viability • plan on building extended prototypes and array of buoys

  18. OXYBUOYConstructing a Real-Time Inexpensive Hypoxia Monitoring Platform Rizal Mohd Nor Mikhail Nesterenko Peter Lavrentyev Thank you! Questions? ASIT 2009

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