1
OXYBUOYConstructing a Real-Time
Inexpensive Hypoxia Monitoring Platform
Rizal Mohd NorMikhail NesterenkoPeter 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 NorMikhail NesterenkoPeter Lavrentyev
ASIT 2009
Thank you!Questions?
Top Related