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Coal Mining Robot – Electronics For You

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This project is to design a robot to detect toxic gases emitted from the coal mine. It is used to detect the level of temperature and humidity inside the coal mine and it is also to detect the fire inside the coal mine and extinguish it.

Coal mines are more prone to fires, this is due to fact that coal itself is a combustible matter. Coal fires can be severe that mining operations may have to cease. The severe consequences of fires may be coal dust explosion and burning of coal seams. The need for designing, and implementing safety measures and systems to prevent and mitigate the impact of fires is of utmost importance.

This report elucidates the causes of fires in coal mines, the detection methods, the prevention methods, fire suppression methods, alerting and evacuation during fires, latest
technological trends. The conclusion will give a brief discussion on the new technology that
will enhance and effectively monitor the environmental conditions of coal mines.

We design a robot to detect toxic gases emitted from the coal mine. It is used to detect the level of temperature and humidity inside the coal mine and it is also to detect the fire inside the coal mine and extinguish it.

Our Project works as in the following block diagram

Block DIagram
Block DIagram

It consists of the following components

  • Microcontroller
  • Battery
  • Temperature Sensor
  • Gas Sensor
  • Humidity Sensor
  • LCD
  • Relay
  • Motor
  • Zigbee Tx and Rx
  • Pump and Computer System.

Here we use

Arduino Uno

Arduino is an open-source electronics platform based on easy-to-use hardware and
software. Arduino boards can read inputs-light on a sensor, a finger on a button, or a Twitter message and turn it into an output-activating a motor, turning on an LED, or publishing something online. Arduino boards are completely open-source, empowering users to build them independently, and eventually adapt them to their particular needs. The software, too, is open-source and extensible. Arduino boards are relatively inexpensive compared to other microcontroller platforms. It provides a simple, clear programming environment. The Arduino board is easy to handle and compatible.


Zigbee is a wireless technology developed as an open global standard to address the
unique needs of low-cost, low-power wireless IoT networks. The Zigbee standard operates on the IEEE 802.15.4 physical radio specification and operates in unlicensed bands including 2.4 GHz, 900 MHz and 868 MHz.

Temperature Sensor

LM35 is a temperature sensor that outputs an analog signal which is proportional to
the instantaneous temperature. The output voltage can easily be interpreted to obtain a
temperature reading in Celsius. The advantage of lm35 over thermistor is it does not require any external calibration. The coating also protects it from self-heating. Low cost
(approximately $0.95) and greater accuracy make it popular among hobbyists, DIY circuit
makers, and students. Many low-end products take advantage of low cost, greater accuracy
and used LM35 in their products. Its approximately 15+ years to its first release but the
sensor is still surviving and is used in any products.

Gas Sensor

MQ2 is one of the commonly used gas sensors in MQ sensor series. It is a Metal
Oxide Semiconductor (MOS) type Gas Sensor also known as Chemi-resistors as the detection is based upon change of resistance of the sensing material when the Gas comes in contact with the material. Using a simple voltage divider network, concentrations of gas can be detected.

MQ2 Gas sensor works on 5V DC and draws around 800mW. It can detect LPG,
Smoke, Alcohol, Propane, Hydrogen, Methane and Carbon Monoxide concentrations
anywhere from 200 to 10000ppm.

Humidity Sensor

A humidity sensor is an electronic device that measures the humidity in its environment and converts its findings into a corresponding electrical signal. A humidity sensor is used to measure and report moisture. Humidity sensors vary widely in size and functionality.


A Relay is an electromechanical device that can be used to make or break an electrical
connection. It consists of a flexible moving mechanical part which can be controlled
electronically through an electromagnet, basically, a relay is just like a mechanical switch but you can control it with an electronic signal instead of manually turning it on or off.

Again, this working principle of relay fits only for the electromechanical relay.


A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizer’s. Liquid crystals do not emit light directly, instead using a backlight or reflector to produce images in colour or monochrome.


A direct current (DC) motor is a type of electric machine that converts electrical
energy into mechanical energy. DC motors take electrical power through direct current, and
convert this energy into mechanical rotation.

The MOSFET is three-terminal N-channel silicon MOSFET (P55NF06) with current
conduction capability of about 50A, fast switching speed. Low on-state resistance,
breakdown voltage rating of 60V, and max threshold voltages of 4 volt. Thin semi 50N06 is
three-terminal silicon device with current conduction capability of about 50A, fast switching
speed. Low on-state resistance, breakdown voltage rating of 60V, and max threshold voltages 7 of 4 volt. It is mainly suitable electronic ballast, and low power switching mode power appliances.


A Motor pump is a mechanical device, used to move the liquids/gases from one place
to another by using mechanical action. The working principle of the water pump is, it
converts the motor’s energy from mechanical to fluid flow. Different mechanical pumps
available in the market to serve in an extensive range of applications like water pumping
from wells, filtering of the aquarium, pond, in industries like automobile, energy, medical,

Power Supply
The Arduino Uno power supply can be done with the help of a USB cable or an
external power supply. The external power supplies mainly include AC to DC adapter
otherwise a battery. The adapter can be connected to the Arduino Uno by plugging it into the power jack of the Arduino board. Similarly, the battery leads can be connected to the Vin pin and the GND pin of the POWER connector. The suggested voltage range will be 7 volts to 12 volts.

Steps wise instruction on how to assemble and make a robot /project


To initialize variables, pin modes when a sketch starts, each will power up by using importing the libraries


An overflow will occur for a millisecond so that the Arduino board began running the current program


  • The sensor’s output is connected to an Arduino analog input. 
  • So the Arduino will read the input data from the sensors like humidity and temperature of the respective room.


Convert information data read from the Sensor into normalized data set to turn your data into a percentage scale


  • By using the SD library, we can store our data like temperature, and humidity on the SD cards
  • The maximum capacity is 2GB for SD cards and 16GB for micro SD cards.


  • We can also send data from the Serial Monitor to Arduino by entering text in our system.
  • When we command forward, it will move in the forward direction.

Backward command – backward direction

Right command – right direction

Left command – left direction

Fig 1. Photocopy of the hardware project model
Fig 2.Photocopy of the software result
Fig 3. Photocopy of the LCD Display

If this robot enters into hazardous environments and provides various gases data. This prototype system provides Temperature sensor, it detects the flame under the coal mine and also extinguish it. By using MQ135, LM 35 sensor robot detect environment hazards in the coal mines by monitoring physical parameter and these parameters are observed using monitor status log and display, and increase life safety of coal mine workers.

Temperature and Humidity level can be measured by using LM35 and
humidity sensor ,hazardous gases are detected using a gas sensor, and when flame detected, by temperature sensor in coal mine, the Robot
extinguishes the fire.The values of Temperature, Humidity and Gas are displayed in the computer system using Zigbee wireless technology

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