Research On The Key Technologies Of Wireless Sensor Node For Coal Mine Emergency Rescue

According to the existing problems of the coal mine serious catastrophe emergency rescue sensor node, which include the poor anti-disaster performance, and hard to get the catastrophe information, and aimed at building the wireless sensor node of coal mine emergency rescue, and close combined the characteristic of coal mine catastrophe, this thesis research on the key technologies of wireless sensor node for coal mine emergency rescue. The main research works can be described as follows:(1) The mode of data communication between nodes after the coal mine disaster was built. First, the electromagnetic wave communication mode covered with coal rock was established based on the geographic feature of coal mine emergency rescue. The transfer characteristic of electromagnetic wave which contain 2.4GHz and 433 MHz frequency band on the inside of coal seam was analyzed. The analysis showed that the absorption constant at this communication mode changed obviously at low frequency band and inconspicuously at high frequency band, which is proportional to the conductivity of coal seam and inverse proportion to the conductivity of coal rock. The theoretical calculation shows that the transmission distance of electromagnetic wave under coal seam is greater than the deployment and communication covering distance of node, which can ensure the communication reliability of nodes under coal seam.(2) The functional hardware design of wireless sensor node for coal mine emergency rescue was designed, and the function of the node was tested. First, the overall architecture of the node was proposed, which contained data acquisition module, data processing & control module, two communication module and power module. Then, the circuit components were selected and the circuit schematics were drawn for each circuit modules. The anti-interference measures of digital-analog hybrid circuits were proposed further, the node was processed based on the node PCB; then, the hardware function of the designed node was tested, and the test software was designed by LABVIEW. In order to solve the synchronism between the bodes, the RF switch algorithm was proposed; Finally, the experiment was conducted. The experiment result show that the RF switch algorithm and the test PC software are feasible, which also show that the designed node can meet the function requirement.(3) The mechanical structure of node protector was designed, and the node protector reliability was analyzed under three catastrophe conditions which contain the analysis of free-falling, tunnel collapse and gas explosion. This study result shows that the node protector can ensure the wireless sensor node safety after disaster. Then, the node protector was manufactured further. The conclusion lay the basis of the experiment research development in the future.(4) Networking strategy of wireless sensor node for coal mine emergency rescue was proposed. According to the geographic feature of coal mine, A determined deployment strategy of three-dimensional linear partition coverage is proposed based on the model of wireless sensor network node in underground tunnel. Then a load balance routing algorithm based on cluster and data fusion mechanism. With the method of the three-dimensional linear partition coverage arrangement, the node deployment position and the network coverage degree were solved in accordance with the underground tunnel length, the node model parameters and the node deployment number. The proposed routing algorithm was better than the traditional routing algorithm in network lifetime which was improved 46.8%, the new routing algorithm has lower energy consumption.