Karaburan

Project Karaburan
Monitoring water quality
Status	In progress
Contact	bertrik
Last Update	2024-10-30

Next steps

• engage with PX4 community on getting a feel if this is useful to use and if so, how to get started
• figure out how to duplicate an MQTT stream
• write python scripts
  • arduino turbidity
  • turbidity-to-mqtt
  • HID-to-mqtt
  • position/velocity listener script: latitude, longitude, altitude, heading/bearing/track/whatever, velocity
• hook things into systemd / udev
• analoog in op de pi:
  • https://elektronicavoorjou.nl/product/adc-pi/
  • https://www.123materialen.com/products/zeer-nauwkeurige-ads1256-dac8552-ad-da-board-voor-raspberry-pi_1676153
  • FreeJoy project
• UPS voor pi: https://elektronicavoorjou.nl/product/raspberry-pi-ups-hat/
• 1-wire stuff:
  • 1-wire adapter emulation on an stm32: https://github.com/alitekin2fx/stm32_ds2480_emu
  • owfs.org for easy interfacing with multiple 1-wire devices in a hierarchical way on linux

Check:

• https://www.rtvnoord.nl/natuur/1215705/vuilrobot-maakt-jachthaven-winschoten-schoon-beter-dan-met-een-schepnet

USB HID as analog input

An stm32 based bluepill board can be flashed with firmware to allow its analog inputs to be exposed as USB HID sliders.

Flashing the bluepill with openocd to the freejoy firmware:

• install openocd

 sudo apt install openocd

• connect an stlinkv2 to an stm32 bluepill, connect the stlinkv2 to USB
• flash the freejoy firmware as follows:
  • download the firmware from https://github.com/FreeJoy-Team/FreeJoy
  • create a symlink to the hex file called firmware.hex
  • flash the firmware from the command line

 openocd -s /usr/share/openocd/scripts -f interface/stlink.cfg -f target/stm32f1x.cfg -c init -c "program firmware.hex verify reset exit"

• watch the kernel logs

 sudo dmesg -w

• connect the stm32 using a USB cable
• download the freejoy configurator from https://github.com/FreeJoy-Team/FreeJoyConfiguratorQt
• start the configurator and load the karaburan.cfg setting
• Write config to device -> it should reboot now and come up with the new settings

Verify that it works:

• install the evtest package
• run

 evtest /dev/input/by-id/usb-FreeJoy_FreeJoy_v1.7.1-event-if00

See also https://github.com/vostrenkov/EazyJoy

influxdb

See https://hub.docker.com/_/influxdb

See https://github.com/bertrik/karaburan/tree/master/influxdb

Introduction

Topics:

• air quality sensors
  • ammonia
  • NOx
• water chemical analysis
  • nitrates
  • ammonia
  • dissolved oxygen
  • sulfide/sulfate
  • phosphates?
  • salinity (chlorides?)
• water physical analysis
  • temperature
  • clarity/turbidity -> investigate standard ways of measuring/expressing this
  • conductivity/total dissolved solids
  • water properties by light reflection, hyperspectral/polarity
  • depth?
• boat control
  • trajectory -> steering
  • idea: interface with the remote control, not with the boat
  • idea: find a boat with easily hackable remote control protocol
  • idea: can we get sensor data over this link too, e.g. GPS?
• camera control
• post-processing
  • data presentation
    • video/photo stitching
    • time lapse view
    • map view of properties
• use cases
  • verify with domain experts, how to engage?
  • slootview, under/above water
  • minimum viable prototype
  • high-res measurement by location, by time
• materials
  • boat selection
  • processing platform selection
  • communication platform selection

Investigate RTK GPS

Goal: figure out if it is practically possible to achieve cm resolution with a 200-euro GPS and a free correction service: YES

• https://www.nsgi.nl/referentiepunten-en-gnss-data/gnss-data/real-time-streams public correction data service
• https://www.ardusimple.nl/rtk-in-5-minutes/
• RTK in action https://www.youtube.com/watch?v=Oc1LBFDj2MA
• Use with Linux / gpsd: https://stackoverflow.com/questions/77314115/drotek-gpsd-and-ntrip-correction-data-for-precise-positioning ?
• Chipsets
  • Quectel LC29H (default: 115200 bps)
    • review: see https://rtklibexplorer.wordpress.com/2024/04/28/dual-frequency-rtk-for-less-than-60-with-the-quectel-lc29hea/
    • configuration: https://rtklibexplorer.wordpress.com/2024/05/06/configuring-the-quectel-lc29hea-receiver-for-real-time-rtk-solutions/
  • uBLOX ZED-F9P
• Boards
  • UM980 / UM982

Edit /etc/default/gpsd, set GPSD_OPTIONS:

 GPSD_OPTIONS="-Gn ntrip://user:pass@ntrip.kadaster.nl:2101/CBW100NLD0"

Option -G exposes the control socket on all network interfaces, option -n keeps the GPS active if there is no one currently connected.

Plotting live location on a map:

• Configure gpsd to expose its socket to the outside world: last section of https://gpsd.gitlab.io/gpsd/troubleshooting.html
• In QGIS, press ctrl+0 to show the GPS information tab, enter the name of the remote gpsd (port 2947)

Station at Stolwijk (close to Gouda): https://gnss1.tudelft.nl/dpga/station/Stolwijk.html#STWK ?

Starting from the command line:

• stop gpsd.socket

 sudo systemctl stop gpsd.socket

• run from command line

 sudo /usr/sbin/gpsd -Gn -D 1 -N /dev/ttyUSB0 .... (not sure yet)

Validation

How to show that RTK GPS is actually accurate?

• Relative positioning: with an "fix RTK" solution, place the antenna at 4 points 25cm apart, each point for 20 seconds or so -> you see 4 distinct clusters of points
• Positioning over short time: put it in a fixed location, make sure that it has "fix RTK" solution, take 100 measurements or so -> determine the radius of the circle that contains 90% of the points
• Positioning over longer time: do this for (say) an hour
• Absolute positioning: look up a national reference point, for example "RD-punt 389346", located on the Sluisdijk between Gouda and Moordrecht. Technical data: https://www.nsgi.nl/iv-api/rdinfo/rdpoint/389346
  • see https://www.nsgi.nl/referentiepunten-en-gnss-data/informatie-referentiepunten/rdinfo and enter 389346
  • latitude: 51° 59' 49,64048" , longitude: 4° 41' 19,90765", or 51.99712236/4.68886324

Comparison with reference coordinate

On october 4th, we took the RTK GPS to a kernnet reference point at 51.99712236/4.68886324, results below:

Differences between the reference point and the measurements are calculated to easting ('X') and northing ('Y'), unit meter. To calculate distance in meters, we use a linear approximation:

• For dy: 40075km/360 = 111,319 m/deg
• For dx: dy * cos(latitude) = 68,549 m/deg

Measurements + deviations

Name	Latitude	Longitude	dx (m)	dy (m)	absolute (m)	Remark
Reference	51.99712236	4.68886324	-	-	0	by definition
Screenshot 1	51.99712217	4.68886567	0.167	-0.021	0.168	-
Screenshot 2	51.99712200	4.68886533	0.143	-0.040	0.149	-
Meting 1	51.9971220	4.6888663	0.210	-0.040	0.214	-
Meting 2	51.9971222	4.6888660	0.189	-0.018	0.190	-
Average	-	-	0.177	-0.030	0.180	-

According to this page, the rate of movement is about 15.75mm/year to the north and 17.45 mm/year to the east (ITRF2020 model). Over 12 years, that amounts to 0.189m north and 0.209m east.

Air quality sensors

Nitrogen compounds in air

According to https://www.rivm.nl/stikstof/monitoren-advies-onderzoek/overzicht-stikstofmetingen/metingen-stikstof-in-de-lucht average (typical?) values of

• Ammonia (NH3): 6.7 ug/m3 (9.6 ppb)
• NOx: 27.3 ug/m3
• NO2: 18.6 ug/m3 (9.9 ppb)

(ppb-conversion using https://www.breeze-technologies.de/blog/air-pollution-how-to-convert-between-mgm3-%C2%B5gm3-ppm-ppb/ )

RIVM report on inexpensive nitrogen-in-air sensors: https://www.samenmeten.nl/sensoren-voor-no2 Conclusion: most sensors are not sensitive enough to be used in typical outdoor conditions, with perhaps one exception: alphasense NO2-B43F

Water physical analysis

Turbidity / clarity

See https://en.wikipedia.org/wiki/Turbidity

Aliexpress sensor TS-300B: https://nl.aliexpress.com/item/1005006732956937.html Has a range 0 ~ 1000 ± 30 NTU

Order of magnitude for turbidity:

• Drinking water upper limit: 4 NTU (European turbidity standard for drinking water)
• Ambient water: 10-150 NTU. The US state of Washington use a "background" value of 50 NTU as reference.

(see https://en.wikipedia.org/wiki/Turbidity#Standards_and_test_methods )

So the Aliexpress sensor is suited only for "dirty" water.

Boat control

Typically the wireless link looks like this:

• 2.4 GHz working frequency
• 500m range

Interesting links:

• Flytec-2011 remote control https://nl.aliexpress.com/item/1005002984723718.html
• Replacement board for various boats with "18" in their type number: https://nl.aliexpress.com/item/1005006115484716.html
• DIY Multi-protocol module: https://github.com/pascallanger/DIY-Multiprotocol-TX-Module

remote control

Image of remote control RF chip: [...]

Parts:

• 12.000 MHz crystal/oscillator
• 16-pin control chip: 20_CL6L071
• 6-pin RF chip: 1110 / VKA3, could be an rx/tx switch, amplifier or filter circuit

See also: https://www.open-tx.org/

Next steps:

• map out the connections between the mainboard and the rf board, expected: VCC, GND, spi ?

Use cases

material:

• https://www.youtube.com/watch?v=cMk0bGvIU1E
• https://iplo.nl/thema/water/oppervlaktewater/kaderrichtlijn-water
• kaartje: https://krw-nutrend.netlify.app/ -> 2 meetpunten op de reeuwijkse plassen, tijdresolutie is 1 jaar?

Useful distinction, typically used in documents/guidelines:

• chemical quality, what substances are present in the water?
• biological / ecology quality, what kind of living organisms live in the water?

Reeuwijkse plassen

See

• https://www.rijnland.net/wat-doet-rijnland/in-uw-buurt/reeuwijkse-plassen/ their stated goal: CLEAR WATER
• https://www.rijnland.net/regels-op-een-rij/subsidies-en-andere-financi%C3%ABle-bijdragen/

potential applications:

• inspect water sides (oever) over time
• underwater camera: detect invasive cray fish
• sample water properties at high spatial resolution, high time resolution
• early detection of indicators for cyanobacteria: temperature and nutrients

Detect/find pollution source

• ...

Implementation

reading temperature sensor

The idea is to to use a DB18B20 temperature sensor, read it using an arduino nano board acting as a 1-wire adapter. Use openwire-fs as user-side openwire software http://owfs.org

Preparation:

• Add the regular user to the 'dialout' group, so it can access serial ports

 sudo adduser <name> dialout

Setting up the hardware:

• connect the DS18B20 to the connector board with the pull-ups
• wire the connector board to the arduino nano, see ...
• plug the arduino nano in the pi

Setting up the software:

• Install openwire fs

 sudo apt install owfs

• Create the openwire fs mountpoint

 sudo mkdir /mnt/1wire

• Configure owfs, edit /etc/owfs.conf

 server: device = /dev/ttyUSB0
 mountpoint = /mnt/1wire
 allow_other
 (comment out the line with the FAKE devices)

• Configure systemd services

 sudo systemctl enable owserver owhttpd
 sudo systemctl disable owftpd

• Start the systemd service

 sudo systemctl start owserver owhttpd

• Check the logs

 sudo journalctl -xeu owserver -f

• Open a browser to view the web interface

 http://localhost:2121 or
 http://raspberrypi.local:2121