Power Optimization Issues in Wireless Sensor Networks – AmritaWNA Research Area

Power Efficient Wireless Sensor Network for Monitoring Underground Mines to Safeguard the Miners

System Architecture

Mining industry is susceptible to various types of disasters which lead to heavy loss of human lives, property and infrastructure. As per survey, it was seen that the mine explosions are the main cause for majority of the underground mine accidents. Early detection of spontaneous explosions in coal mines can be made possible by monitoring the concentration of toxic gases such as Carbon monoxide (CO), Carbon dioxide (CO2) and Methane (CH4). The main cause for mine explosions is the presence of toxic methane gas in an insufficient oxygen environment. Methane gas detection is very important for outburst prediction. In order to protect people and to avoid destructive sequence, it is necessary to design a system that can predict methane outburst in coal mines. The proposed system aims at developing an advanced power-efficient early warning system to safeguard the miners from high exposure to the toxic methane gas. The wireless sensor network is suitable for toxic gas monitoring in the severe environment of underground coal mines.

In the proposed system we make use of several sensor nodes deployed in the mines. Mostly these nodes are placed along the walls or roof of the mines where the gas concentration can be measured more accurately. There is a central monitoring station above the ground which will have a number of officers monitoring the safety of the miners working underground. Whenever an alarm or warning of some explosion is received at the station, they inform the rescue operators using a wireless network and quick rescue or evacuation operations are carried out. At each sensor node there will be different modules like sensor unit consisting of various sensors, a processing unit to perform several computations, memory to store the values temporarily, power unit to supply external power and a communication module to transmit the sensed values wirelessly. In the proposed system Semiconductor type methane sensor having low power consumption and high sensitivity is used to sense the toxic methane gas concentration.

The chain type clustering of low power sensor nodes along with data aggregation is devised to optimize the power consumption by the WSN. Multi-hop chain type clustering of nodes is devised to have long range communication and to obtain energy efficiency. The proposed system is designed to be a chain type and clustered hierarchy in which there will be number of sensor nodes in a particular region and aggregation function is performed only at the cluster heads (CH). Sensor nodes will be grouped into clusters and elects the CH by considering the remaining energy. The node with maximum remaining energy will be chosen as the CH. The cluster heads are connected to the neighboring cluster heads in order to transmit to central monitoring station which is at a long distance. Additional feature of minimum data transmission and state transitions between listening, sleeping and transmitting modes in sensor nodes also guarantee energy optimization.