The Research Of Underground Personnel Positioning System Based On Wireless Sensor Networks

As the important primary energy, coal accounts for more than 70 percent of the primary energy consumption in China. In recent years, coal mine safety accidents often occur, which caused heavy losses of life and property. Therefore, accelerating and strengthening the construction of coal mine automation and information system become an inevitable trend. Because the coal mine environment is harsh and complicated, and most of the existing monitoring systems are difficult to provide real-time and accurate information of dynamic distribution and operating conditions of the underground personnel, deeply study and analyze the characteristics of wireless sensor networks and its current situation of domestic and international application research. Combing with the underground operation demand, the paper designed a personnel positioning system based on wireless sensor networks which makes it possible for the monitoring center to master the information of the underground personnel position and working status and so on, and provide a guarantee for the improving of the scientific management and safety of underground workers. The study not only has academic value, but also has an important economic value and far-reaching social significance.Analyze and compare the characteristics and applications of wireless sensor networks technology, including the WIFI, Bluetooth, and Zigbee, etc. Study the basic structure of the wireless sensor networks and communication. Design an underground personnel positioning system based on the Zig Bee technology. Thereby, add a method for the real-time online monitoring of the underground operating information, and the management level and producing safety have been improved.Study the ranging algorithm based on received signal strength indication(RSSI). Then establish the mathematical ranging model based on RSSI. Collect the data in the experiment simulated filed and obtained the ranging empirical formulas through a polynomial fitting, then use the multilateral measurement maximum likelihood estimation method to solve the unknown node coordinates. Deeply study the interference of environment illegal factors which comes from the computing process of ranging algorithm and the error caused by the least squares method. Both of these are likely to cause the ill-posed problem which may make the positioning results appear a relatively large fluctuation. To solve these problems, propose the Tikhonov regularization algorithm to optimize ill-posed problem in which we choose the reasonable parameters by using L curve criterion. The simulation results show that the ill-posed problem equation is effectively suppressed and the positioning results is improved.Study the centroid localization algorithm. For the shortcomings of existing algorithms, propose a new weighted centroid localization algorithm to solve the unknown node. Experimental results show that the improved algorithm can improve the accuracy of the results.On the basis of the design of the overall structure of the underground personnel positioning system, design the hardware and software of the system. Select a teaching building corridor of our school to simulate the coal mine environment, collect data, and simulate the system algorithm.