Research On Large Scale Underwater Sensor Network Node Accurate Localization

With the rapid development of the demand on underwater sensor network node application,deep ocean space station and ocean surveilliance attract more and more attentions.The positions of underwater sensor nodes are the significant information for fusion with sensor data and underwater vehicle navigation assistant.The underwater sensor network localization techniques currently are the developing steps.This paper focuses on improving the normalized network localization precision,mainly researches on the large scale centralized network localization techneques,ordinary node high precision localization techniques and large scale distributed network node localization techniques.For large scale centralized network,underwate nodes are in a large number,the communication distance is limited and the collision between node information exchange and localization efficiency is limited.Usually the normal techniques use fixed survey trajectories with GPS data to solve the underwater nodes using trilateration.This method can achieve high precision positions but can be hardly used for multi-node localization because of low efficiency,collisions between information exchange and low efficiency in positioning.This paper is target on high efficiency,high localization precision and large scale.We propose a method of position accumulation based on distance trilateration.This method focuses on the the low precision of area localization scheme to combine the advantages of high distance measurement precision.This paper focuses on the localization efficiency and localization precision.The simulation and experiment prove that this method can achieve high efficient large scale centralized network localization to figure out the problem of low efficiency and low precision.The normalized network localization error in shallow water is better than 1%slant range.Underwater node localization regards reference node positions as references to localize other nodes,while the normal method negelect the position error of reference node with considering distance measerment error only.The ordinary node position is only related to distance measurement errors.To solve this problem,this paper proposes a method to combine reference node position error to solve ordinary node positions.This method combines references node position error and distance measurement error to add into math models.The estimated ordinary node position is the optimized position to improve localization precision.The simulation and experiment prove that this method can compensate reference position error and improve the ordinary node localization precision a lot.The method is especially useful in deep ocean.We use GPS data as reference to evaluate the performance between this method and normal method.The preicison can be improved nearly 2 meters.Large scale distributed network usually use hierarchical method to localizae underwater node.This method has a problem that the localization error will accumulate with the localized node increasing,which is limited the network average localization precision.To solve this method,this paper proposes three efficient methods including increased reference node number,combined reference node position error and reselected ordinary node confidence value.Also,the paper proposes the method to fuse sensor data and position data that improves network average localization precision.This paper uses simulation and experiment,which realizes the high precision distributed network nodes localization.The localization precision in shallow water is centimeters to prove the effectiveness.