2016-10-11 iot presentation v4

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

Pressure StudyGooseberry Island Causeway

David Sprogisdsprogis@gmail.com