Design Of Wireless Sensor Network For Emergency Rescue In Underground Coal Mine

The problem of safe coal mining has always been attached great importance by our country.Improving security technology,achieving safe and efficient production are the goals of the coal industry all the time.However,due to the complex topography,harsh environment and uneven quality of miners,coal mine catastrophe accidents occur frequently,resulting in serious economic,life and property losses.Establishing and improving the emergency rescue communication system in coal mine is of great significance for guiding effective rescue work and reducing accident losses after the coal mine catastrophe.Wireless sensor networks are characterized by low power consumption,self-organization,rapid deployment,and strong survivability.From the perspective of its technical characteristics,it has the significant advantage of becoming a emergency rescue information support system after catastrophic,which can make up for the deficiencies of cable emergency communication system in coal mine to a large extent.However,the underground coal mine belongs to a special limited space.The wireless sensor networks technology still faces many challenges when it is used to construct the communication system for emergency rescue in underground coal mine.For example,the design of emergency rescue sensor nodes adapted to catastrophic scenarios,the optimal deployment strategy of nodes,and the reliability of data transmission after catastrophe.In view of the above problems,this thesis mainly carried out the following research work:(1)The wireless communication technology that can guarantee the effective operation of the underground wireless sensor network is demonstrated.The transmission characteristics of electromagnetic wave in different media under normal and catastrophic conditions are studied,and the ideal communication frequency under different conditions in coal mine is determined by analysis.The results show that 2.4 GHz is suitable for routine communication frequency and 433 MHz is suitable for communication frequency after catastrophe.(2)The hardware of emergency rescue sensor node adapted to underground catastrophe is designed,the components of sensor node are determined.On the basis of fully considering and adopting measures to enhance the anti-interference of the circuit,the circuit schematic and PCB diagram were designed and drawn,the hardware of the node is manufactured.The node is equipped with two wireless communication modules and communicates with different radio frequencies,and the communication frequencies are 2.4GHz and 433 MHz respectively.The control programs of data acquisition,networking communication,radio frequency switching and hopping of the node are designed.The upper computer of the monitoring terminal is developed by using LabVIEW.(3)Combined with the topographic characteristics,actual monitoring requirements and node perception model of underground coal mine,the node deployment strategy with different coverage in different dangerous areas of underground coal mine is put forward,and the specific node deployment algorithm is designed.The relationship between node communication radius and perception radius is analyzed when the network achieves two-connection and three-connection.On this basis,a mechanism about data redundancy forwarding based on radio frequency switching is proposed to improve the reliability of data transmission.(4)The function of the sensor node system designed is tested.The test results show that the node meets the design requirements.A small wireless sensor network composed of five nodes is used to carry out catastrophe simulation communication experiments,and the packet loss rate of nodes in the network under different coverage conditions is tested.