On the robustness to multiple agent losses in 2D and 3D formations

Multi‐agent formations have been recently the subject of many studies. An important operational challenge, largely unaddressed in the literature, is to ensure that functionality of the formation is retained should agents be lost through misadventure, mission reassignment, and so on. In the context of sensor networks, it is also important to allow for the loss of multiple sensors as the low quality of sensor hardware, common unattended implementations, and so on makes it a common issue. In this paper, we address these issues by proposing information structures that are tolerant to the loss of multiple agents. Using graph theory (and more specifically rigidity theory), we characterize several properties of such formations/networks in a unified framework: We characterize the k‐vertex rigidity property of the underling graph of such formations. This is performed by deriving a set of useful conditions that can form a guideline for designing agent‐loss‐tolerant formations. We elaborate the study by characterizing robust formations with the optimal number of control links. We also propose a set of operations preserving the tolerance to multiple agent losses in such formations. These operations provide flexibility in designing the formations in terms of several designing parameters (e.g., geometry, diameter, and max degree). Especially in the case of formations, the ability to handle controller adjustments in a distributed way is important, and the paper addresses this issue for a number of the robustness problems considered. Copyright © 2014 John Wiley & Sons, Ltd.     

基于图刚性的无线传感器网络定位新算法

针对分布式 MDS-MAP 算法的不足,提出了一种基于图刚性理论的无线传感器定位新算法 MDS-MAP (GR)。算法利用图的刚性理论,确定网络中的所有刚性子区域,然后利用合并定理将刚性子区域进行扩展,最后对合并得到的刚性区域利用 MDS-MAP 算法和锚节点实现网络中节点的大规模定位。算法尽可能对刚性区域进行合并,节省了执行 MDS-MAP 算法的次数,提高了执行效率。通过在不同拓扑结构的无线传感器网络中进行了仿真实验,说明了提出的算法能有效定位不同半径下网络中90%以上的节点,另外,新方法比现有方法在定位成功率上提高了4%～5%,并且定位精度提高了2%～3．5%左右。算法适用于大规模无线传感器网络中的快速定位。     

Stabilisation of infinitesimally rigid formations of multi-robot networks

This article considers the design of a formation control for multivehicle systems that uses only local information. The control is derived from a potential function based on an undirected infinitesimally rigid graph that specifies the target formation. A potential function is obtained from the graph, from which a gradient control is derived. Under this controller the target formation becomes a manifold of equilibria for the multivehicle system. It is shown that infinitesimal rigidity is a sufficient condition for local asymptotical stability of the equilibrium manifold. A complete study of the stability of the regular polygon formation is presented and results for directed graphs are presented as well. Finally, the controller is validated experimentally.     

传感器网络的可定位性条件

针对两个节点集合,提出了一组可定位性条件.可定位性条件包含两部分:两个集合之间需要的连接边的数目,以及如何布置这些连接边.本文将每组节点和它们的内部连接边刻画成一个距离图.两个节点集合之间的可定位性判定等同于两个融合图的全局刚性测试.针对两个融合图的可定位性,给出了一系列的充要条件.     

Development of redundant rigidity theory for formation control

Multiagent formation control may proceed by ensuring that designated pairs of agents maintain a specified distance between each other, in order that the overall shape of the formation can be preserved while it translates or rotates. A minimally rigid formation is one in which loss of any one such constraint or link means that individual agent motions can occur, which do not preserve the shape of the formation. Recognizing that real‐world formations may suffer link loss and even agent loss, this paper presents a systematic approach to defining a measure for redundant or nonminimal rigidity, which is the property that formation shape will still be preserved in the face of loss of a certain designated number of distance constraints or formation agents. Most of the results are concerned with advancing a deterministic measure, but this paper also indicates circumstances under which a statistical measure may be relevant. For illustration, the paper analyses a number of standard formations to establish their levels of redundancy. Copyright © 2008 John Wiley & Sons, Ltd.     

基于距离的分布式无线传感器网络定位算法*

针对水下无线传感器节点的定位问题进行研究,提出了一种可实现网络规模升级的分布式无信标节点的自定位算法。该定位算法无须额外的硬件支持,仅采用节点间的距离信息建立相对坐标系,确定各节点的相对位置。详细介绍了该算法的实现过程,通过仿真讨论了求精过程、通信半径等对定位误差的影响,并验证了该算法的合理性。为目标跟踪、地理路由、网络管理等系统功能提供了有力的技术支持。     

基于移动节点的无线传感器网络定位算法

节点定位技术是无线传感器网络应用的重要支撑技术之一,为了提高定位算法的准确性,提出了一种基于移动目标节点的两步定位算法。该算法利用一个移动目标节点遍历整个网络,并周期性地广播包含自身当前位置的信息。而传感器节点的自身定位过程则可用基于无迹卡尔曼滤波(UKF)的目标跟踪方法实现。由于所用的目标状态模型和量测模型有一定的不确定性,所以先选取不共线的3个拥有RSSI测距能力的目标节点信息,利用Euclidean定位法提高滤波的初始位置精度,从而改善定位效果。通过仿真、分析和比较该目标节点在多种移动轨迹情况下的定位误差,这种两步定位法可以改善对目标节点移动轨迹的特殊要求的限制,能取得较好的定位精度,而且更适合于实际情况。     

基于RSSI的无线传感器网络节点定位算法

节点定位技术是无线传感器网络关键技术之一,介绍了节点定位技术的基本原理,提出了一种新的基于接收信号强度(RSSI)的无线传感器网络定位算法.该算法在第一阶段对节点初始位置进行初步估计,第二阶段对节点初始位置进行求精.仿真结果表明,在锚节点比例较低的情况下,该算法仍然可以实现较高的定位精度,并且与dv-distance定位算法比较,表明该算法在相同条件下精度更高.     

Optimized data rate allocation for dynamic sensor fusion over resource constrained communication networks

This article presents a new method to solve a dynamic sensor fusion problem. We consider a large number of remote sensors which measure a common Gauss–Markov process. Each sensor encodes and transmits its measurement to a data fusion center through a resource restricted communication network. The communication cost incurred by a given sensor is quantified as the expected bitrate from the sensor to the fusion center. We propose an approach that attempts to minimize a weighted sum of these communication costs subject to a constraint on the state estimation error at the fusion center. We formulate the problem as a difference-of-convex program and apply the convex-concave procedure (CCP) to obtain a heuristic solution. We consider a 1D heat transfer model and a model for 2D target tracking by a drone swarm for numerical studies. Through these simulations, we observe that our proposed approach has a tendency to assign zero data rate to unnecessary sensors indicating that our approach is sparsity-promoting, and an effective sensor selection heuristic.     

一种基于锚节点分簇的传感器网络节点定位方法*

提出一种基于锚节点分簇的节点定位方法,该方法以锚节点为中心自适应构建成簇,并将处于多个簇重复覆盖的节点作为伪锚节点。在测距方法构建节点间距离矩阵基础上,结合多维尺度分析和锚节点位置信息实现了对节点进行相对位置定位,并通过伪锚节点与锚节点位置信息进行坐标变换实现了绝对位置智能定位,提高了定位的准确性。仿真结果表明,该方法定位精度高,对测量误差、节点连接度以及锚节点比例的变化有很强的鲁棒性。     

An efficient algorithm for mobile localization in sensor networks

Node localization is a fundamental problem in wireless sensor network.There are many existing algorithms to estimate the locations of the nodes.However,most of the methods did not consider the presence of obstacles.In practice,obstacles will lead to blockage and reflection of communication signals between sensor nodes.Therefore,the presence of obstacles will greatly affect the localization result.In this paper,we implement an obstacle-handling algorithm based on the localization tool developed by MIT,The experimental result shows that the enhanced algorithm can reduce the average distance error by up to 46%,compared to the original algorithm.     

无线传感器网络中一种改进的DV-Hop定位算法

针对无线传感器网络中DV Hop定位算法在未知节点到信标节点距离计算中的不足，提出了一种改进算法。该算法考虑了未知节点到信标节点路径中相邻三个节点A, B, C组成的夹角∠ABC对距离的影响，根据与B相邻的A, C节点的邻节点集重叠度估算夹角的大小，从而更精确计算出距离，提高定位精度。     

一种基于约束策略的无线传感器网络定位算法*

节点定位技术是无线传感器网络的关键支撑技术之一,对于无线传感器网络的基本理论方法和应用研究都具有重要意义。在深入研究分析距离无关定位算法的基础上,提出了基于约束策略的无线传感器网络定位算法。该算法无须测距,采用跳数估计节点间距离,并针对未知节点到锚节点距离计算中的不足,对锚节点的平均每跳距离作了修正;在估计未知节点坐标时,根据该未知节点通信范围内的锚节点对其所在位置进行约束。仿真结果表明,该算法具有较好的性能,比已有算法的定位精度有所提高。     

Distance‐based undirected formations of single‐integrator and double‐integrator modeled agents in n‐dimensional space

We study the local asymptotic stability of undirected formations of single‐integrator and double‐integrator modeled agents based on interagent distance control. First, we show that n‐dimensional undirected formations of single‐integrator modeled agents are locally asymptotically stable under a gradient control law. The stability analysis in this paper reveals that the local asymptotic stability does not require the infinitesimal rigidity of the formations. Second, on the basis of the topological equivalence of a dissipative Hamiltonian system and a gradient system, we show that the local asymptotic stability of undirected formations of double‐integrator modeled agents in n‐dimensional space is achieved under a gradient‐like control law. Simulation results support the validity of the stability analysis. Copyright © 2013 John Wiley & Sons, Ltd.     

传感器网络对偶密钥连通图中的关键节点研究

由于传感器节点部署的随机性、以及网络规模迥异的特点,已有的对偶密钥建立机制可能使得网络中出现若干个孤立的连通集团。在提出基于多点认证的信任模型上,分析了可能使得集团互联的一类关键节点的性质。仿真结果表明,通过关键节点间的对偶密钥建立协议,与传统的建立过程相比,在取得相近抗妥协性能的前提下,能够有效地实现孤立集团间的互联。     

一种无线传感器网络定位算法的分析和改进

无线传感器网络(W SNs)能够实时监测和采集网络分布区域内的各种检测对象信息,有着广泛的应用前景。在W SNs中,节点定位技术是许多应用的支撑技术,定位的准确性直接关系到传感器节点采集数据的有效性。目前,已提出多种定位算法,Euc lidean算法由于通信开销小,具有一定的优越性,但在某些应用中存在定位精度较低的问题。针对这一问题,提出了一种新的改进Euc lidean的算法。用距离矢量路由技术替代直接测量节点间的距离,并运用迭代循环思想抑制定位误差的累计。计算机仿真结果证明:该改进算法能够明显地提高定位精度。     

移动sinks无线移动传感器网络时延性能分析*

结合mWSNs体系结构,分析了移动sinks无线传感器网络的时延组成和时延特性,并通过仿真实验分析了移动性对时延的影响。该分析结果既能用于mWSNs时延系统性能评价,又可为mWSNs系统参数（如移动sinks数量、速度、传输半径及数据包长度等）优化提供理论依据。同时,时延性能要与能量消耗综合考虑。     

基于蜂窝网络拓扑的无线传感网定位算法

针对无线传感网中DV-Hop定位算法过于依赖信标节点数量以及定位精度低的问题,提出基于蜂窝网络拓扑的定位算法(LABCNT).通过对网络中节点的有向筛选,选取满足特定条件的节点,构造一个蜂窝的网络拓扑结构,得到网络上节点的相对位置;根据拓扑结构中的第二个信标节点确定网络上节点的绝对位置;将已定位的节点升级为协作节点,采...     

无线充电传感器网络能量效率优化研究

本文将SWIPT技术应用到无线充电传感器网络中,提出了一种基于SWIPT的协作传输协议（简称CTS）,利用无线信息和能量的协作传输来提高无线能量传输的效率。在此基础上,设计了一个以最大化网络效用为目的的资源分配策略优化问题,并提出RAPOA算法来求解问题。仿真实验表明CTS最大化了网络效用,提高了无线充电传感器网络的能量传输效率。     

无线传感器网络的拓扑控制研究*

讨论了拓扑控制的目标,利用随机图理论研究了无线传感器网络拓扑控制的模型及代表性算法;基于网络结构的不同,分析和比较了无线传感器网络中各种拓扑控制机制的特征;深层剖析了无线传感器网络拓扑控制与连通、调度之间的关系;最后对拓扑控制亟待解决的问题进行了总结和展望。