Energy Efficient Distributed Target Tracking Using Mobile Sensor Networks

This dissertation studies the problem of target tracking using mobile sensor networks.It focuses on using the capabilities of sensing,communication and locomotion of sensor nodes to keep tracking unknown mobile targets within the sensing area.A mobile sensor network is a wireless network comprising a large number of mobile sensor nodes.These nodes are always low-power and destructible.So energy saving and distributed computation are the most important factors in the tracking design.This dissertation proposes a fully distributed algorithm for target tracking under complicated environment such as noisy sensing,obstacle,diffused target,etc.It tries to maintain the targets being visible to the network all the time while consuming as little motion energy as possible.Meanwhile the network connectivity is maintained,node collision is avoided,etc.This dissertation work is composed of three parts.First,while minimizing the tracking energy consumption during the tracking process is proved to be NP-complete,an approximately optimal solution named breadth-first leader-follower algorithm is presented.It only can be realized in a locally centralized manner.We prove that its consumption is within a scalar factor of the optimal consumption.Second,we deal with the distributed tracking problem which is more practical in reality.The system modeling is set up and the data transmission is scheduled carefully so that only a few nodes are activated while other nodes keep idle.Then a motion strategy for active nodes is proposed which is made up of three modules:â…°) the tracking quality function which reflects the tracking accuracy,â…±) the potential function which reflects the network connectivity status,â…²) the distributed energy saving motion strategy.Third,this algorithm is extended to complicated environment.Various environmental factors are added to the uniform tracking framework.For example,we improve the tracking quality function for the noisy sensing model,diffused target and multi-target.Also the obstacle is considered as virtual neighboring nodes in the potential function.The major contribution of this dissertation lies in four aspects.First,it is the first work that focuses on the energy saving problem in target tracking,while most existing works using mobile network only limit their problems on improving the tracking accuracy.Second,certain objective functions are defined to quantify the main requirements and constraints such as the tracking quality,the network connectivity status and the collision avoidance.They transform the tracking into a classical multi-objective optimization problem.Third,the optimization algorithm is fully distributed.No centralized processor or dynamic central node is needed.Each node acts as the same role,which makes the system more robust and flexible.Fourth,a general tracking framework is set up.It can be applied to many complicated situations such as the heterogeneous network,noisy sensing,diffused target,obstacle,etc.We need not to design a special algorithm for certain application,which means our algorithm has good expansibility.