Stack

Architecture

The project is split into four relevant sections:

1. Hardware: a laser dust detection sensor, used for continuos and real-time detection of dust in the air was connected to a ESP32 board which includes a GPS sensor.
2. Network: the board communicates with the Low Powered Wide Area Network (LPWAN) LoRa, due to its range of 15Km (5km in urban scenarios) and low power consumption. Data from the device is received by the multiple public gateway available in The Things Network.
3. Backend: Information is sent from the TTN to our Node-Red backend, where the data is processed and displayed to the user.
4. Frontend a dashboard split into two views generic and detailed.

Dashboard

The generic dashboard allows the user to:

• Track the position of all the available devices through the map
• Observe the devices currently deployed and their metadata (Status, Name, Uptime, Position and Battery Level)
• An evolution of the multiple Particle Matters (PM) over the last 28 days (subtracting the average of the last 28 days with the average of the current day)
• The gauges display the Average, Minimum and Maximum values for the PM chosen over the period of days also selected by the user
• Lastly, line graphs that display the average values (Avg, Min, Max) for the last hour for all of the devices

It is also possible to keep up with the devices individually, allowing us too see:

• Path taken during operation
• Real time temperature levels
• Device metadata
• Real time measurements of the different particles tracked (PM 1.0, 2.5 and 10)
• All the information received for the particles during the last 24 hours, in 5 minute increments

Dashboard updates

Each dashboard is updated in a different manner. The home dashboard, which includes only aggregated information over multiple days does not require real time information, as such, data is updated through Polling with a periodicity of 1 hour or every time the user refreshes the page.

On the other hand, as the user requires real time information when tracking individual devices a Publish/Subscribe broker was introduced, this way every time new information is received from the gateways a notification is sent to the dashboards and data is updated in realtime.

A subscription was created for the device, that notifies every time something changers such as battery level or location. And a second subscription dedicated to the air quality observed.