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A Scheme for Group Target Tracking in WSN Based on Boundary Detecting
Quanlong Li, Zhijia Zhao, Xiaofei Xu and Tingting Zhou

When a mass of individual targets move closely, it is unpractical or unnecessary to localize and track every specific target in wireless sensor networks (WSN) under some situation, but they can be tracked as a whole by view of group target. A scheme for tracking group target in WSN based on binary sensing model is proposed in this paper. In order to obtain the global estimated position information of group target and decrease the amount of energy spent on active sensing and communications, it only needs to estimate and track the boundary of group target, and let be involved as few as possible sensors into the tracking process. So, the scheme consists of three parts mainly. First, a flexible Boundary Detecting Model is proposed to divide sensors into three categories, named INNER, BOUNDARY and OUTER separately, where, only BOUNDARY sensors take part in tracking group target, and the number can be adjustable too. Second, BOUNDARY sensors are divided into several clusters according to a new clustering algorithm based on Boundary Clustering Model, which just divides BOUNDARY sensors into several clusters, without considering the INNER and OUTER ones. Third, as a first attempt, a divide-merge algorithm using convex hull is designed to localize and track group target. In this algorithm, group target’s boundary is divided into several small pieces, and each one is enclosed by a convex hull which is constructed through a cluster of BOUNDARY sensors. Then, these convex hulls are sent back to a sink respectively, and merged into a big convex hull as the group target’s contour. According to a criteria of precision evaluation introduced in this paper, the simulation experiments confirm efficiency and accuracy of the method.

Keywords: Sensor networks, target tracking, group target, group target tracking, boundary detecting model, convex hull merging.

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