Research And Design Of Localization System For Wireless Sensor Network With Sparse Anchor Nodes For Underground Environment

Personnel and equipment positioning in underground roadway is an important function of smart mines.With the rapid development of Wireless Sensor Network(WSN),many positioning technologies have been applied to the personnel positioning in underground roadway.Most of the current underground positioning systems need to deploy a large number of anchor nodes in the positioning area in advance.However,the coordinates of anchor nodes cannot be obtained by using satellite positioning technology when the underground is tens or even hundreds of meters from the ground,so the coordinates can only be obtained by manual measurement,which will cause high labor cost and difficulty in node deployment.Therefore,a sparse anchor node positioning algorithm for roadway environment is proposed in this paper to reduce the deployment cost of the positioning system and the number of anchor nodes.In order to solve the problem of low utilization rate of anchor node,this paper presents the method of anchor node ranging and positioning with double ranging units.The main idea is to install two ranging units on an anchor node to obtain two different ranging information,the two ranging information is two distance information or a bearing information and a distance information,where the distance refers to the distance between the measuring tag node and the two ranging units on the anchor node,the bearing is the direction of the indicator node.Aiming at the problem of the small number of anchor nodes,this paper proposes the method of setting virtual anchor nodes.The main idea is to upgrade some of the located tag nodes to virtual anchor nodes according to the node promotion strategy,indirectly increase the number and density of anchor nodes,and improve the positioning rate and accuracy of the system.Node promotion strategy is to promote label nodes with large option values to virtual anchor nodes,so as to ensure node positioning accuracy and reduce the accumulation of errors in the subsequent positioning process.Through testing and analysis of underground roadway positioning,it is found that the ranging accuracy and positioning accuracy of this system can reach 0.5m,which can basically meet the requirements of current underground positioning.In the process of simulating the underground environment,the requirement of reducing the number of anchor nodes can be achieved.Using MATLAB to simulate the positioning algorithm can increase the node positioning rate and improve the positioning accuracy in the sparse anchor node environment.