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Table 2 - Specifications of the used air pollutants measuring sensors
Used sensors
MQ2
MQ7
MQ135
Methodology
Modeling Drone: In this section, the required steps to construct
the drone are discussed in detail. Since a GPS module in the
drone has been used in this work, it is essential to choose a path
for the drone called mapping so that it can fly over an area and
take data for that specified region. It means the defined area
where we want to monitor the air quality before the drone's
flight is fixed. The vital part of the project is taking data from
the air in a stable and efficient way.
In this work, a DJI F450 frame, composed of very strong ultra-strength
material, is chosen to construct the drone to avoid
damage in case of hard landings. Because of the frame's high
assembly space, it can easily carry the load. A 2200 mAh 11.1 V
LiPo battery is used to power the drone, and it can deliver 2.2 A
current for approximately 1 h. The battery provides a 16-17 min
lifetime, but practically, it varies from 12-14 min depending on
the weather, airflow, and load. Four 920 kV brushless motors
are used, which take power from the battery and help the drone
operate. Each motor draws 2 A while hovering; consequently,
four motors draw 8 A for drifting in the air. A highly sensitive
GPS-Neo-7 module is used to navigate specific locations. Also,
an electronic speed controller (ESC) and a flight controller
APM-2.8 are used to control the drone's flight efficiently.
After successfully assembling and constructing the drone,
it is programmed to operate and collect data from the site. The
LPG (CO2, O3, SO2
CO
NOx
Detecting gas particles
)
Measurement range
(ppm)
300 - 10,000
200 - 2,000
10 - 1,000
Approximate cost (USD)
1.30
1.95
1.65
transmitter to the receiver communicates via a 2.4 GHz frequency.
In this research, we use the open-source applications
'Mission Planner' from the laptop or 'DroidPlanner' from mobile
to select the specific path for the proposed drone. But in
case of an error, we alternatively employ a joystick remote to
control the drone. Initially, the input is given from a laptop
or smartphone, and then the drone flies accordingly and returns
to the same place. Theoretically, the range of our drone
is 1 km, but practically it varies from 600-800 m depending on
the weather.
External Set-up of Various Sensors: Various sensors are the
primary external circuit that are integrated with the constructed
unmanned aircraft system to detect pollutants from
the air. In this research, MQ2, MQ7, and MQ135 gas sensors are
employed to detect LPG (CO2,
O3, SO2), CO and NOx concentrations,
respectively, and a particulate matter (PM) detector
is used to monitor dust pollutants. Specifications of the used
air pollutants estimating sensors are listed in Table 2. This research
employs these low-cost and readily available sensors
because they have been used effectively in many published
manuscripts [5]-[7].
Fig. 1 demonstrates the project's primary circuit, designed
in the EasyEDA software tool, and the final external components,
which are connected to the drone and detect various
contaminants in the air. As the nodeMCU comprises only one
Fig. 1. (a) Circuit diagram of project's primary circuit. (b) External IoT device after building.
December 2022
IEEE Instrumentation & Measurement Magazine
55

Instrumentation & Measurement Magazine 25-9

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