Localization and time synchronization of sensor network for infrastructure monitoring

摘要

This paper presents a hierarchical sensor network system for robust localization and time synchronization.This system consists of parent nodes with a low priced L1 GPS receiver and child nodes equipped with an acoustic ranging device.Relative positions between child nodes are estimated based on acoustic ranging through the inverse Delaunay algorithm.This algorithm localizes all the nodes simultaneously,thus,the accumulation of the error in the localization is suppressed.Relatively localized child sensor nodes are given global coordinates with the help of GPS on parent nodes.The parent node consists of a low priced L1 GPS receiver and wireless LAN.Noise tolerant acoustic ranging algorithm that employs digital signal processing techniques is implemented in the child node.Experiments show that this ranging algorithm gives average range estimation error below 10 cm.In addition to the capability of localization,ability for time synchronization is implemented.This system consists of three types of nodes,i.e.,i)a time node which broadcasts time stamp,ii)sensing nodes which get data from on-board sensors and iii)a sink node.Every data from sensor node is synchronized by using broadcasted time stamps as reference.