tems may not be feasible. Environment monitoring in underground tunnels, which are usually long and narrow, ranging in length of tens of kilometers and widths of meters, has been a crucial task to ensure safe working conditions in coal mines. The safety problems of coal mines have gradually become the nation and society con- cerns. Most of the process control applications are exceptionally crucial jobs and have rigorous requirements. Therefore, a continu- ous monitoring of underground environment is needed to reduce these disasters.
The coal is one of the primary energy sources in India that provides over 54.5% of the total energy [1] . Coal mining is, how- ever, one of the world’s most dangerous occupations. As the un- derground mining becomes deeper and deeper and the earth stress increases, the influence of rock movement caused by mining makes mine safety situation further severe. The mine accidents have been a frequent phenomenon in coal belt [2,35,36,41] . There were 74 miners casualties in Gaslitand, Dhanbad, on September 26, 1995 and 55 in the New Kenda Colliery in 1994. There were 375 work- ers who lost their lives in the Chasnala coal mine disaster in De- cember 1975. Since the dynamite is used for coal-mining opera- tions, sometimes the explosion leaves a big crack and the water from a nearby tank or river floods the mine. Both in the Chasnala and Gaslitand disasters, the water from a nearby reservoir and a rain-fed river rushed into the mines that broke the barrier walls and the workers were trapped in the flooded mines. In 1965, there was an explosion at Dhori colliery near Dhanbad that led to a fire in the mines, resulting in the loss of 268 lives. There have been a huge number of deaths in different countries in mine accidents, but to meet ever-higher production targets, the mine safety mea- sures have not received adequate attention. The miners and other persons involved in mining face many dangers on the job. Some of the important reasons for occurring the above mentioned type hazards are due to the following