2016-10-11 iot presentation v4
TRANSCRIPT
Pressure StudyGooseberry Island Causeway
An IoT Research Project(sort of)
Agenda• Problem Statement
– Video of the area• Thesis• Objective• Approach
– Hardware– Software– Bug Fixes & Enhancements– Physical Issues
• Tests• Issues and Fixes• Experiment Results• Conclusion
• Observations and Opportunities
Problems
Sandbars Algae Blooms Beach Stones
Video
https://vimeo.com/186511839
What’s New?
Gooseberry Island Causeway
Tower
Currents and wave action that once flowed over the tombolo …
… began circulating in an eddy.
BEFORE
AFTER
Thesis: The Change
Thesis: The ResultSand is transported toward the harbor by new Westerly current
Sand is deposited in the harbor
Nitrogen comes out of the river with every tide but circulates back in
Thesis: The FixEquilibrium is restored and sand begins accumulating again
The harbor is no longer threatened by sandbars
Nitrogen flushes more thoroughly with each tide cycle
Remove the causeway
Eddy currents are the result ofa textbook “groyne”
GROY
NE
GROY
NE
Source: Yossef 2005
Opposition
In 1997, the Department of Environmental Management commissioned a study that concluded
the causeway has no appreciable environmental impact.
Objective
Cast doubt on the 1997 study and compel the Department of Environmental Management to re-examine impact of the causeway.
Objective
Would water flow if there was no causeway?
- in other words -
Is the water level higher on one side than the other creating the potential for flow?
Height West Height East
ApproachUsing survey tools, physically measure the height of the two sides and calculate the difference.
Impractical to collect measurements over days and difficult at night.
Approach
A sensor could measure up from the bottom … but how?
Water pressure
ApproachBut the bottom is not the same on both sides, one side is going to be lower than the other. How would we know the offset?
Combine approaches?
ApproachCollect data from sensors over time.
ApproachNormalize by the drop initial depth
ApproachUse a single reading at a recorded date/time to align signals
Device Requirements
• Read Pressure up to 25 feet under water• Accurate to less than 1 inch• Submersible• Runs on battery for several days• Inexpensive• Small
COTS Hardware ComponentsBMP180Pressure range: 300 ... 1100hPa (-34 feet below sea level, salt water)Low power: 5µA at 1 sample / sec. in standard modeLow noise: 0.02hPa (0.17m) advanced resolution mode
DS3231 Real Time ClockAccurate to within 1 second per yearButton battery maintains time between usesLow power
32u4 AdaloggerATmega32u4 @ 8MHz2K RAMMicroSD card holder Built in 100mA lipoly charger
Wiring
AdaFruit “Feather” “Wing” bus
Power I2C Data
Prototype
Software• Include Libraries
– #include <SD.h>– #include "RTClib.h"– #include <Adafruit_Sensor.h>– #include <Adafruit_BMP085_U.h>
• Set-up– Initialize pressure sensor– Initialize SD card– Confirm clock working– Create log file
• Loop– Read Sensor– Read time– Write entry– Sleep 60 seconds (minus a few instruction cycles)
Code: https://github.com/dsprogis/Pressure-Sensor-1.0-build-4
Triple Bagged, Weighted Bucket
Test 1: Does it work?{"date": "2016-07-15T22:19:29", "pressure_hPa": "1013.78", "temperature_C": "28.00", "altitude_meters": "-4.41"}{"date": "2016-07-15T22:20:29", "pressure_hPa": "1013.75", "temperature_C": "28.00", "altitude_meters": "-4.16"}{"date": "2016-07-15T22:21:29", "pressure_hPa": "1014.84", "temperature_C": "27.90", "altitude_meters": "-13.23"}{"date": "2016-07-15T22:22:29", "pressure_hPa": "1151.47", "temperature_C": "27.90", "altitude_meters": "-1092.00"}{"date": "2016-07-15T22:23:30", "pressure_hPa": "1151.21", "temperature_C": "27.80", "altitude_meters": "-1090.05"}{"date": "2016-07-15T22:24:30", "pressure_hPa": "1150.85", "temperature_C": "27.70", "altitude_meters": "-1087.34"}...
Yes
For how long?
7/16/16 0:00 7/17/16 0:00 7/18/16 0:00 7/19/16 0:00 7/20/16 0:00 7/21/16 0:00 7/22/16 0:00 7/23/16 0:00 7/24/16 0:000
20
40
60
80
100
120
140
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
Temp (F) Depth (ft)
About a week
Device Calibration?
10 390 770 115015301910229026703050343038104190457049505330571060906470685072307610799083708750913095101150
1170
1190
1210
1230
1250
1270
1290
hPa 1hPa 2hPa 3
Readings deviate by 0.002-0.004 inches
(salt water)
Readings deviate by ~0.5C
Aligned
Requirements (review)
Read Pressure up to 25 feet under waterAccurate to less than 1 inchSubmersibleRuns on battery for several daysInexpensiveSmallUnits are calibrated
IssuesOne device went bad – not sure why.
Spider Crab found in one container – outer bag was punctured
Units are not reporting on exactly same interval –adjusted in Excel but very time consuming!
time
Software/Hardware Enhancement
• Fix time drift– Hardware:
• Jump 1Hz Square Wave Signal to readable pin (yellow cable, SQW to A2)
– Software:• Decrement counter on rising signal (A2)• Log data when counter = 0
– Reset counter to 60 (or whatever I want)
A2 = I Hz
A2
Additional Software Enhancements
• Switch from JSON to CSV – more convenient for Excel
• Added Device ID to filename – easier to keep track
• Added Date to file in OS – easier for managing archive
Deployed Devices at Causeway
Gooseberry Test Results
2016-07-30T10:56:00 2016-07-31T16:38:00 2016-08-01T22:20:00 2016-08-03T04:02:00 2016-08-04T09:44:00 2016-08-05T15:26:000.00
1.00
2.00
3.00
4.00
5.00
6.00
Relative Tide Heights
Unit 01 (West)Unit 03 (East)Unit 04 (East)
What’s the differential?
Differential Readings
2016-07-30T10:56:00 2016-07-31T09:08:00 2016-08-01T07:20:00 2016-08-02T05:32:00 2016-08-03T03:44:00 2016-08-04T01:56:00 2016-08-05T00:08:00
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
1.20
Differential from Unit 1 to Unit 2 Differential from Unit 1 to Unit 3
Conclusion• West side averages 6” higher than East side• Peaks about 12” per tide cycle• Is level or slightly below per tide cycle
• Causeway holding back 6” inches of water across a 900 feet.• Holding back or redirecting this much potential energy is certain to have an
appreciable environmental impact.
QED
Objective
The 1997 study is wrong.The causeway DOES HAVE an
appreciable environmental impact.
Additional Observationsand
Opportunities
Tide/Temp Offset
Water temp reached it’s low 90 min after tide reached low and began coming in.Why?How can we use this information?
Cool Water
Warm Water
What’s going on with this double hump?First it gets warmer, then cooler, then warmer again?
2016-07-30T10:56:00 2016-07-31T17:14:00 2016-08-01T23:32:00 2016-08-03T05:50:00 2016-08-04T12:08:00 68.00
70.00
72.00
74.00
76.00
78.00
80.00
Temperature Analysis
Unit 1 Temp FUnit 3 Temp F
Temperature Across Causeway
