| As an important branch in the field of wireless sensor network (WSN) research,wireless sensor network localization technology has important applications inmany fields.At the current time,our country’s coal mine safety accidents happen frequently.The existing RFID recognition technology can’t achieve real-time monitoring of underground works,which result in failing to get trapped personnel’s exact location and missing the best time to rescue. So the research of personnel real-time positioning technology in mine environmen has become a n important issue that can not be ignored.Based on this background, this paper studies the personnel positioning technology based on wireless sensor network under mine,and complete the design of personnel localization system.Firstly, the commonly used wireless sensor network localization algorithm were researched,which include the localization algorithm based on ranging and ranging free algorithm. The complexity and localization performance of the various localization algorithm were analyzed emphatically.The limitations and shortcomings of various kinds of localization algorithm were summarized.After consideration of the computational complexity,positioning performance,the requirements for the hardware device and the localization scenarios of mine,RSSI algorithm was chosen as the main research direction in this paper.Secondly,the radio signal propagation path loss model was studied and test analysis was carried out on the RSSI in the laboratory corridor environment which is similar to the mine roadway.The parameters of the pathe loss model were obtained by the least square fitting curve of RSSI. Considering the mine roadway environment was quite different everywhere, a dynamic path loss coefficient calculation method was designed in the process of actual location.For RSSI values fluctuate seriously, the Gaussian filter method was adopted which can weaken the random error of RSSI values and the filtering effect was test.For serious signal reflection,refraction,multipath propagation in the mine roadway which result in larger ranging error, a ranging algorithm with reference nodes assisted was designed in the paper.The basic idea of the algorithm is using the communication of the reference nodes whose coordinate information is known to help mobile node complete distance measurement. Considering the special application scenario,two wireless sensor network node localization algorithm is studied:Weighted Centroid localization algorithm (WCL) and Min-Max localization algorithm.These two kinds of localization algorithm have low computational complexity and hardware demand, The algorithms are very suitable for node localization in wireless sensor network,which has very limited computing power and energy. Finally,the paper test the positioning performance of these two kinds of algorithm on real scene.Thirdly,based on the requirement of personnel positioning under mine,the orerall design of the wireless sensor network positioning system was carried out.The detailed design and implementation of hardware and software was completed.The hardware part of wireless sensor localization network mainly complete a portable wireless sensor node based on the Ti CC2530 chip.The software design complete the functional programming of coordinator node,reference node and mobile nodes based on the ZigBee2007/Pro Protocol stack.Then the ground monitor center software and database of positioning system were designed and the test of the whole system was carried out in the lavoratory environment which is very similar to the tunnel. Test resuls show that the designed positioning system can achieve more accurate real-time personnel position.Finally, a summarization of the work in the paper is made,the deficiencies and the next reaearch directions were pointed in the last. |
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