Research On Mine Target Location Algorithm Based On Wireless Sensor Network

Wireless sensor network is a popular filed,which have attracted much attention and are highly cross-disciplinary and highly integrated.This technology has been widely implemented from national security and military to home and healthcare.These applications have been profoundly embedded into our daily life.Network node positioning is the core technology of our research.If the position of the target in the sensing area cannot be accurately captured,the monitoring data obtained is invalid.Especially to the applications for mine environment involved in this thesis,the requirements of the accuracy of positioning accuracy are much stricter.Therefore,this thesis studies the positioning technology based on ranging algorithm.The research content of this thesis is summarized as follows:Firstly,the characteristics of mine environment are analyzed: meanwhile the ranging technology of Receive Signal Strength Indicator(RSSI)is introduced.There are many situations under the mine environment,significantly influence the stability of network connectivity.As a consequence,this thesis adopts the RSSI ranging technology with better precision.At the same time,it also introduces several wireless signal propagation models related to transmission path loss,including free space transmission model,double line ground reflection model and Shadowing model.Several calculation methods of node location are also described.Secondly,on the basis of RSSI ranging technology,Particle Swarm Optimization(PSO)algorithm is introduced to optimize the positioning algorithm.The characteristics and principles of the algorithm are introduced in detail,and the advantages and disadvantages of PSO algorithm are analyzed.Combined with the previous experience,a certain improvement is proposed to solve the problem of local optimal solution and slow convergence speed,which will fall into the local optimal particle initialization process and return the possible local optimal value.Next the mine positioning process based on improved PSO algorithm is elaborated.Finally,the distance between unknown node and beacon node is modeled and estimated according to the mine RSSI distance measurement model.The estimated distance between the unknown node and beacon node and the mean square error of the measured distance are used as the fitness function of the PSO algorithm,the position of particle is updated according to the velocity and position formula.Then a better particle is found through the iterative operation of the algorithm,and the problem of the mine node location is transformed into an optimal solution.Subsequently,we introduce the implementation process of mine positioning method which is based on improved PSO algorithm.Comparing the original algorithm and the optimized version,the simulation results show that the latter has higher accuracy and convergence speed.Lastly,the positioning performance of the improved PSO location algorithm and least squares method is compared.In conclusion,the mine positioning algorithm based on the improved PSO algorithm has good convergence characteristics and stability,resulting of a better positioning accuracy.