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I have built a prototype of a remote controlled vessel, the LoRa Marine Environmental Ranger (LoRa MER) that gathers environmental data and relays it to a shore based station using Arduino MKR WAN 1300 LoRa boards. This post is the ninth and final post in the series, and demonstrates how the prototype works and how it can be used as an educational tool and for citizen science.
Implementation Status
A number of modifications were made to the electronics / sensors to better secure them and improve readings. The LoRa antenna was moved outside the cockpit. A new sea trial was undertaken and experiments were performed on water turbidity and environmental temperatures. Changes from last week are in red bold
Boat
- RC control inspected and retested
- MKR WAN 1300 firmware tested
- MKR WAN 1300 Antenna moved outside cockpit
- Following sensors / hardware more modified
- ST3775 TFT Display
- ICP10100 Atmospheric Pressure / Temperature
- NEO-6M-0-001 GPS
- Thermistor Water Temperature
- Thermistor Air Temperature
- KX224-I2C 3 axis Accelerometer
- RPR-0521RSLight Sensor
- TSW-10 Turbidity Sensor
- Sea Trials and Experiments Performed
Shore base:
- Enclosure completed
- TFT screen fitted
- Firmware has LoRa reception (polls) and responds with RSSI
- MKR WAN 1300 connected to Raspberry Pi by USB serial
- Python script sends data over internet to adafruit.io
- Dashboard implemented on adafruit.io
- Fitted a DIY dipole antenna
- Tested TTGO LoRa32 with MKRWAN 1300
Boat Modifications
The instrument attachment in the cockpit was modified so that the LoRa antenna, air temperature probe, and light sensor could be moved to the top of the cabin. Many of the connections are still being made with duPont connectors but in a final version everything needs to be soldered or fitted with more robust connectors. The propulsion and radio control was checked one more time - no issues have occurred in the last couple of tests.
The LoRa antenna was placed horizontally on top of the cabin due to mechanical considerations and the length of the coax cable. While an improvement over locating it inside the cockpit, it would ideally be placed vertically and as high as possible. The light sensor was covered with a plastic bottle cap for diffusion and to protect from the elements - it has not been calibrated. All temperature sensors, GPS, and turbidity sensor appear to work fine. Everything was tidied up and made ready to go.
Note the fancy element14 livery! The stickers look like they were made for this project. The boat looks fast even when it is standing still!
| {gallery} Boat Modifications |
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Concept Demonstration
On the way to the duck pond my 7 year old grandson and I discussed the scientific method and how we might use the LoRa Mer for experimentation. An outline of our experiment follows:
Problem / Question: How does the water temperature and turbidity vary from the inlet of the duck pond to the outlet?
Hypothesis: I hypothesized that cooler water coming in would be warmed up by the sun as it slowly moved through the pond. My grandson hypothesized that it would cool down because "the water is deeper". We both thought the turbidity would be higher at the inlet due to mixing in the fast moving creek followed by settling in the pond.
Experiment: The boat was maneuvered close to the inlet and then allowed to drift. Data was recorded by photographing the readings on the base station.
Example data: (close to inlet and then outlet) is shown below.
Analysis: The limited readings taken showed minimal water temperature and turbidity differences from the inlet to the outlet of the pond.
Conclusion: The data did not show meaningful variation in the limited data recorded. The outcome might be different in different seasons or with higher or lower water flow rates.
Notes: During these tests the light sensor was not working - it was subsequently discovered the duPont connection was not good. The accelerometer was not perfectly aligned and the board was such that the Y axis was down.
Video Demonstration
Photograph showing the launching of the boat and water clarity...
The initial data sampling run...
You need to have a bit of fun while doing this :-)
Next Steps
While we plan to continue working on the project, this is the final post for the Build a Smarter World challenge from element14 and Arduino. For a concise summary and links to the chronological development of the project see the landing page.
Links
MKR WAN 1300: Marine Environmental Ranger
Week 3: Building a Shore Station and Starting the Boat
Week 3.5: Testing Turbidity and Posting to the Internet
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