Mobility increases the surface coverage of distributed sensor networks

Coverage is a fundamental issue in sensor networks, which usually dictates the overall network performance. Previous studies on coverage issues mainly focused on sensor networks deployed on a 2D plane or in 3D space. However, in many real world applications, the target fields can be complex 3D surfaces where the existing coverage analysis methodology cannot be applied. This paper investigates the coverage of mobile sensor networks deployed over convex 3D surfaces. This setting is highly challenging because this dynamic type of coverage depends on not only sensors’ movement but also the characteristics of the target field. Specifically, we have made three major contributions. First, we generalize the previous analysis of coverage in the 2D plane case. Second, we derive the coverage characterization for the sphere case. Finally, we consider the general convex 3D surface case and derive the coverage ratio as a function of sensor mobility, sensor density and surface features. Our work timely fills the blank of coverage characterization for sensor networks and provides insights into the essence of the coverage hole problem. Numerical simulation and real-world evaluation verify our theoretical results. The results can serve as basic guidelines for mobile sensor network deployment in applications concerning complex sensing fields.     

Decentralized Dynamic Coverage Control for Mobile Sensor Networks in a Non‐convex Environment

In this paper, we consider the problem of decentralized dynamic coverage control for mobile sensor networks in an environment with unknown obstacles. The goal is to cover each point in the mission domain but outside the obstacles to a desired level. Each agent is modeled as a point mass based on Newton's law. A decentralized control strategy is developed to accomplish the dynamic coverage task without collision with obstacles. Discrete update of the cooperative coverage is also considered to enhance the cooperation of the agents in the fleet. The collision avoidance and global convergence of the proposed control scheme are proved and illustrated via a simulation example.     

基于虚拟力的混合感知网节点部署

感知网一般是由静态的或移动的节点组成,为保证感知网的感知功能,节点应该有自部署和自修复能力.然而全部由移动传感器组成的感知网的成本太高,为保证感知网的覆盖功能和低成本,提出了一种在静态传感器节点中加入移动传感器节点的混合感知网形式.为了更好地部署这些节点,最大化覆盖待感知区域,提出了一种基于节点间虚拟力的移动节点部署方法,利用静态节点和移动节点以及移动节点之间的虚拟人工势场产生的作用力来控制移动节点的运动,使移动节点能够在较短的时间内,以较少的能量消耗到达自己合适的位置.在理论上分析了算法的可行性,用仿真实验验证了此算法的有效性,并和其他3种类似算法进行了性能比较.     

基于移动无线传感器网络的定位研究概论

近来,在无线传感器网络的研究已经集中到了移动无线传感器网络,已经出现了可以控制自我移动的微小传感嚣装置了.尽管移动性加强了传感器网络的覆盖和连接之间的联系,但是仍然存在着很多问题.在这些问题中,最主要的可能就是传感器节点的位置估计了.定位不仅需要知道传感器所在空间环境的数据,也需要知道移动传感器导航的关键特征.对移动无...     

一种混合异构传感网的覆盖洞修补算法

传感网感知节点部署的随机性以及节点能耗殆尽、损坏退出等问题使网络中存在覆盖洞, 利用移动节点来修补覆盖空洞是当前较为可行的方法. 假定网络在静态节点和移动节点处混合, 并且在节点感知半径异构的情况下,研究如何通过移动节点重定位来修复感知覆盖洞, 同时兼顾移动距离或能耗最小以及修复后的感知覆盖率最大化来优化感知覆盖性能. 针对移动节点覆盖洞修补规划的NP-hard 问题, 结合遗传算法, 提出一种覆盖洞修补算法来求解最优解. 仿真实验结果表明, 所提出的算法相比于同类算法能够更有效地修补漏洞并兼顾节点能耗以及感知覆盖率.

     

基于静态和移动传感器的WSN的k-覆盖研究

针对无线传感器网络的k-覆盖问题进行了研究。首先定义一个表征网络覆盖效率的过度提供因子,并在此基础上对静态传感器网络和全移动传感器网络的k-覆盖问题进行分析,得到这两种情形下的过度提供因子以及全移动传感器网络中移动传感器的最大移动距离;进而提出一种由静态传感器和少量移动传感器构成的混合网络结构,并得到了这种网络结构下不依赖于网络大小的k-覆盖以及调度移动传感器移动的分布式移动调度算法,从而实现有效覆盖。仿真结果表明,提出的混合网络结构不仅能够实现精确的k-覆盖,而且相比于其他k-覆盖算法,有更高的覆盖率。     

Distributed extremum seeking and formation control for nonholonomic mobile network

In this paper, an integrated control and optimization problem is studied in the context of formation and coverage of a cluster of nonholonomic mobile robots. In particular, each communication channel is modeled by its outage probability, and hence, connectivity is maintained if the outage probability is less than a certain threshold. The objective of the communication network is to not only maintain resilient communication quality but also extend the network coverage. An information theory based performance index is defined to quantify this control objective. Unlike most of the existing results, the proposed cooperative control design does not assume the knowledge of any gradient (of the performance index). Rather, a distributed extremum seeking algorithm is designed to optimize the connectivity and coverage of the mobile network. The proposed approach retains all the advantages of cooperative control, and it can not only perform extremum seeking individually, but also ensures a consensus of estimates between any pair of connected systems. Simulation results demonstrate effectiveness of the proposed methodology.     

一种无线传感器网络的概率覆盖增强算法

覆盖与连通问题是无线传感器网络的基本问题.研究考虑连通性的概率覆盖增强算法,构建覆盖空洞的修补半径,提出了移动距离和修补半径的关系模型.通过这个关系模型,移动节点在修补圆上选择保持连通的修补位置;根据这个移动距离和空洞面积,移动节点进一步创建空洞的优先级,选择优先级最高的空洞进行修补,节能而高效地实现覆盖增强.仿真结果表明,所提出的算法既能得到较高的覆盖率,又能保证整个网络的连通性.     

Supervised coverage control of multi-agent systems

In this paper, we consider a dynamic coverage problem for multi-agent systems, where the main objective of a group of mobile agents is to explore a given compact region. We propose a novel control scheme, where we introduce a supervisor that assists a group of agents with the centralized coverage control law and the global trajectory tracking control law. The coverage control law ensures the coverage task is done until the agents end up in local minima, and when they do, the global trajectory tracking control law ensures that the agents are deployed to uncovered regions. Our control scheme is designed to be decoupled such that only one control law is active at a given time. In addition to the coverage objective, we design control laws for coverage agents to avoid collisions and maintain proximity to a supervisor. Moreover, we utilize feedback linearization to use the proposed control scheme for coverage control of kinematic unicycle agents. We validate our approach via numerical simulations.     

A grid-based coverage approach for target tracking in hybrid sensor networks

Most existing work on the coverage problem of wireless sensor networks focuses on improving the coverage of the whole sensing field. In target tracking, the interested coverage area is the emerging region of a motorized target, not the whole sensing field. As the motorized target moves, the emerging region is also dynamically changed. In this paper, we propose a grid-based and distributed approach for providing large coverage for a motorized target in a hybrid sensor network. The large coverage is achieved by moving mobile sensor nodes in the network. To minimize total movement cost, the proposed approach needs to solve the following problems: the minimum number of mobile sensor nodes used for healing coverage holes and the best matching between mobile sensor nodes and coverage holes. In the proposed approach, the above two problems are first transformed into the modified circle covering and minimum cost flow problems, respectively. Then, two polynomial-time algorithms are presented to efficiently solve these two modified graph problems, respectively. Finally, we perform simulation experiments to show the effectiveness of proposed approach in providing the coverage for a motorized target in a hybrid sensor network.     

三维水下移动传感网多目标有向路径覆盖增强研究

水下传感网中实现多个移动目标的协同追踪任是一个技术难题,针对这个问题论文提出了一种分布式的多目标有向路径覆盖增强算法。在实际的三维水下传感网中,水下传感器节点会随着水流运动而移动,被追踪的目标具有自主行动能力。假设移动规律遵从Meandering Current Mobility模型,多个运动目标沿着基于概率的Random Walk移动模型轨迹运动。在论文提出的算法中,覆盖运动路径的传感器节点通过两跳邻居节点范围内的水下传感器节点协同决策来实现最大化路径覆盖,通过调整水下传感器节点自身的有向覆盖方向达到多目标轨迹路径有向覆盖率平均值最大,并使多目标轨迹路径有向覆盖率标准方差尽量小。最后论文通过MATLAB软件仿真来验证分布式覆盖增强算法的有效性,能够显著提高多个移动目标的路径覆盖率。     

无线传感器网络中覆盖控制技术综述

覆盖控制是无线传感器网络应用的一个基本问题,反映了网络所能提供的"感知"服务质量,可以使无线传感器网络的空间资源得到优化分配,进而更好地完成环境感知、信息获取和有效传输的任务;立足于无线传感器网络的覆盖控制问题,分析了网络覆盖技术在国内外研究的现状与发展,指出了传感器网络覆盖算法中需要解决的问题,并提出了将多目标进化算法与智能计算技术用于动态覆盖控制技术研究设想。     

Biologically inspired probabilistic coverage for mobile sensor networks

Coupling sensors in a sensor network with mobility mechanism can boost the performance of wireless sensor networks (WSNs). In this paper, we address the problem of self-deploying mobile sensors to reach high coverage. The problem is modeled as a multi-objective optimization that simultaneously minimizes two contradictory parameters; the total sensor moving distance and the total uncovered area. In order to resolve the aforementioned deployment problem, this study investigates the use of biologically inspired mechanisms, including evolutionary algorithms and swarm intelligence, with their state-of-the-art algorithms. Unlike most of the existing works, the coverage parameter is expressed as a probabilistic inference model due to uncertainty in sensor readings. To the best of our knowledge, probabilistic coverage of mobile sensor networks has not been addressed in the context of multi-objective bio-inspired algorithms. Performance evaluations on deployment quality and deployment cost are measured and analyzed through extensive simulations, showing the effectiveness of each algorithm under the developed objective functions. Simulations reveal that only one multi-objective evolutionary algorithm; the so-called multi-objective evolutionary algorithm with decomposition survives to effectively tackle the probabilistic coverage deployment problem. It gathers more than 78 % signals from all of the targets (and in some cases reaches 100 % certainty). On the other hand, non-dominated sorting genetic algorithm II, multi-objective particle swarm optimization, and non-dominated sorting particle swarm optimization show inferior performance down to 16–32 %, necessitating further modifications in their internal mechanisms.     

基于遗传算法的WSN覆盖优化方法

在含有移动节点的混合无线传感器网络中,为优化网络覆盖性能,提出了一种基于遗传算法的移动节点控制策略,最后通过仿真实验验证了算法的有效性。     

基于局部信息的移动感知网覆盖方法*

移动感知网是一个由许多带有传感器的自主移动机器人组成的分布式传感器网络。为了更好地部署这些移动机器人节点,形成最大化覆盖感知区域,提出了一种基于机器人局部信息的分布式感知网覆盖方法。每个节点利用与邻居节点之间的虚拟人工势场产生的虚拟作用力来控制移动节点的运动和节点间的避碰,使移动节点能够在允许的时间内,以较少的能量消耗移动到各自理想的位置。采用李亚普诺夫函数进行了感知网节点势场梯度的理论分析,用计算机仿真实验验证了该方法的有效性,并与模拟退火算法进行了性能比较。     

移动卫星天线的自适应鲁棒控制系统

为了改善移动卫星天线的控制性能和稳定性,本文进行移动卫星天线的自适应鲁棒控制系统的研究．首先针对移动卫星天线数学模型,设计自适应鲁棒控制器和控制系统,所提出的自适应鲁棒控制律和控制系统不仅保证了闭环系统的稳定性,而且实现了所期望的性能,最后通过试验结果证明该控制算法的有效性,尽管外界环境道路条件的变化不同,移动卫星天线控制系统表现了满意的控制性能．     

无线传感器网络中覆盖盲区发现算法

传感器节点的随机部署不均匀或者能量耗尽,可能导致无线传感器网络(WSNs)出现覆盖盲区。针对WSNs中覆盖盲区的问题,提出一种基于几何图形的分布式覆盖盲区发现算法,从理论上证明算法的有效性。算法的基本思想是以传感器节点和它的2个邻居节点构成三角形,计算三角形的外接圆半径和外接圆圆心,根据几何图形学的相关理论判断节点附近是否存在覆盖盲区。仿真实验结果表明:算法不仅能有效地检测覆盖盲区和边界节点,而且对于降低节点能量消耗也有显著成效。     

Cooperative distributed target tracking algorithm in mobile wireless sensor networks

The paper proposes a cooperative distributed target tracking algorithm in mobile wireless sensor networks.There are two main components in the algorithm:distributed sensor-target assignment and sensor motion control.In the key idea of the sensor-target assignment,sensors are considered as autonomous agents and the defined objective function of each sensor concentrates on two fundamental factors:the tracking accuracy and the tracking cost.Compared with the centralized algorithm and the noncooperative distrib...     

基于Voronoi的无线传感器网络栅栏覆盖策略

在栅栏覆盖研究中,针对节点部署区域存在无法被监测到的穿越路径的问题,将[Voronoi]图引入栅栏覆盖,划分整个部署区域,提出了基于[Voronoi]图的无线传感器网络栅栏覆盖策略,并监测部署区域是否存在栅栏覆盖空洞,以决定节点是否通过有限移动重新部署空洞区域,实现了对栅栏部署区域的有效覆盖。仿真实验结果表明,该算法提高了对监测区域的覆盖质量,以较低能耗和较少节点构建栅栏,达到预期覆盖要求。     

与节点位置无关的无线传感器网络覆盖控制算法

提出一个分布的、与节点位置无关的无线传感器网络覆盖控制算法(a Location Independent Coverage Control Algo-rithm for Wireless Sensor Networks,LICA).LICA采用基于节点分层成簇的思想,节点与邻居交换信息,并通过节点距离与覆盖模型找出覆盖节点.在保证覆盖性能的前提下,关闭覆盖节点的通信设备.仿真实验结果表明,LICA算法不仅可以提供高质量的覆盖性能,而且具有良好的节能性能.特别适合低成本、资源缺乏、工作在恶劣环境中的分布式无线传感器网络.