# Applications of the Open-Source Hardware Arduino Platform in the Mining Industry: A Review
## 5 Discussion
This is because the Arduino can be easily connected to various sensors and can record and transmit the values obtained from the sensors. The statistics of the sensor types in the reviewed papers are summarized in Table 10. Gas, temperature, and humidity sensors are frequently used as atmospheric monitoring is the most common topic. In addition, it can be seen that various sensors suitable for the research purpose(s) were used. The information acquired through monitoring is often transmitted through various communication technologies that can be combined with Arduino. Table 11 shows the statistics of the applied communication techniques. ZigBee, which makes it easy to build WSNs, was used the most frequently (18 papers), and technologies such as GSM, Wi-Fi, and Bluetooth were used according to each need and purpose. In addition, actuators such as buzzers, LCDs, and LEDs were used to promptly respond to monitoring results. In another example, in autonomous systems, the actuators related to the control of the machine were important. Table 12 summarizes the actuators in the reviewed papers. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Mine Type**} & **Field Monitoring** & **Wearable** & **Autonomous** & **Sum** \\  & **Systems** & **Systems** & **Mine Systems** & **(Percentage)** \\ \hline Underground & 18 (37.5\%) & 11 (22.9\%) & 7 (14.6\%) & 36 (75.0\%) \\ \hline Open-pit & 5 (10.4\%) & 0 (0.0\%) & 2 (4.2\%) & 7 (14.6\%) \\ \hline Polluted area & 2 (4.2\%) & 0 (0.0\%) & 1 (2.1\%) & 3 (6.2\%) \\ \hline Undefined & 0 (0.0\%) & 0 (0.0\%) & 2 (4.2\%) & 2 (4.2\%) \\ \hline
**Sum (Percentage)** & 25 (52.1\%) & 11 (22.9\%) & 12 (25.0\%) & 48 (100.0\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Reviewed literature classified by mine type. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sensor**} & \multicolumn{2}{c}{**Field Monitoring Systems**} & \multirow{2}{*}{**Wearable Systems**} & \multirow{2}{*}{**Autonomous Mine Systems**} & \multirow{2}{*}{**Sum (Percentage)**} \\ \hline Gas & 17 (15.9\%) & 9 (8.4\%) & 4 (3.7\%) & 30 (28.0\%) \\ \hline Temperature & 9 (8.4\%) & 8 (7.5\%) & 4 (3.7\%) & 21 (19.6\%) \\ \hline Humidity & 5 (4.7\%) & 7 (6.5\%) & 3 (2.8\%) & 15 (14.0\%) \\ \hline Heart beat & 1 (0.9\%) & 6 (5.6\%) & 0 (0.0\%) & 7 (6.5\%) \\ \hline Accelerometer or vibration & 2 (1.9\%) & 1 (0.9\%) & 2 (1.9\%) & 5 (4.7\%) \\ \hline Pressure & 1 (0.9\%) & 1 (0.9\%) & 1 (0.9\%) & 3 (2.8\%) \\ \hline LiDAR & 1 (0.9\%) & 0 (0.0\%) & 3 (2.8\%) & 4 (3.7\%) \\ \hline IR & 0 (0.0\%) & 2 (1.9\%) & 1 (0.9\%) & 3 (2.8\%) \\ \hline TDR & 3 (2.8\%) & 0 (0.0\%) & 0 (0.0\%) & 3 (2.8\%) \\ \hline Air flow or density & 1 (0.9\%) & 1 (0.9\%) & 0 (0.0\%) & 2 (1.9\%) \\ \hline Ultrasonic & 1 (0.9\%) & 1 (0.9\%) & 1 (0.9\%) & 3 (2.8\%) \\ \hline GPS & 0 (0.0\%) & 1 (0.9\%) & 2 (1.9\%) & 3 (2.8\%) \\ \hline Gyroscope & 0 (0.0\%) & 0 (0.0\%) & 1 (0.9\%) & 1 (0.9\%) \\ \hline Etc. & 1 (0.9\%) & 1 (0.9\%) & 5 (4.7\%) & 7 (6.5\%) \\ \hline
**Sum** & 42 (39.3\%) & 38 (35.5\%) & 27 (25.2\%) & 107 (100.0\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Reviewed literature classified by sensor.