Energy-efficient real-time object tracking in multi-level sensor networks by mining and predicting movement patterns

A number of studies have been written on sensor networks in the past few years due to their wide range of potential applications. Object tracking is an important topic in sensor networks; and the limited power of sensor nodes presents numerous challenges to researchers. Previous studies of energy conservation in sensor networks have considered object movement behavior to be random. However, in some applications, the movement behavior of an object is often based on certain underlying events instead of randomness completely. Moreover, few studies have considered the real-time issue in addition to the energy saving problem for object tracking in sensor networks. In this paper, we propose a novel strategy named multi-level object tracking strategy (MLOT) for energy-efficient and real-time tracking of the moving objects in sensor networks by mining the movement log. In MLOT, we first conduct hierarchical clustering to form a hierarchical model of the sensor nodes. Second, the movement logs of the moving objects are analyzed by a data mining algorithm to obtain the movement patterns, which are then used to predict the next position of a moving object. We use the multi-level structure to represent the hierarchical relations among sensor nodes so as to achieve the goal of keeping track of moving objects in a real-time manner. Through experimental evaluation of various simulated conditions, the proposed method is shown to deliver excellent performance in terms of both energy efficiency and timeliness.     

TGM-COT: energy-efficient continuous object tracking scheme with two-layer grid model in wireless sensor networks

In a resource-constrained wireless sensor network, energy efficiency is a principle issue for monitoring the movement of continuous objects, such as wild fire and hazardous chemical material. In this paper, a continuous object tracking scheme with two-layer grid model (TGM-COT) is proposed. To address the problem of boundary distortion caused by uneven node distribution, we put forward a novel mechanism for boundary nodes identification. Furthermore, a streamlining mechanism is designed to reduce the amount of uploaded data. Simulation results demonstrate that, without sacrificing additional energy consumption, TGM-COT is able to achieve high tracking accuracy and significantly reduce the communication overhead.     

无线传感器网络中的位置隐私保护

随着无线传感器网络的广泛应用,隐私成为无线传感器网络成功使用的主要障碍。当无线传感器网络用于监控敏感对象,被监控对象的位置隐私成为一个重要问题。在传感节点发送一系列分组,通过多跳,向基站报告监控对象时,敌手能够反向追踪分组到信息源位置。基于洪泛的幻影具有消息发送时间长且能量消耗过大的缺陷。为了保护能量受限的无线传感器网络中的位置隐私,提出了定向随机步。定向随机步使敌手难于跳到跳地反向追踪信息源。在定向随机步中,信源节点发出一个分组,此分组被单播给信源节点的父节点。当中介节点收到一个分组,它以等概率的方式转发给它的一个父节点。与基于洪泛的幻影相比,定向随机步具有较小的信息发送时间和较低的能量消耗。特别在中介节点具有多个父节点的情形下,定向随机步具有较大的安全期。     

一种二元探测传感器网络目标跟踪算法

针对二元探测传感器网络目标定位与跟踪问题,提出一种递推的质心定位方法,推导出了质心定位算法的递推公式。采用序贯最小二乘估计方法,提出了基于递推计算的质心定位结果进行目标跟踪的算法。算法以简单的观测噪声模型体现系统的测量和计算误差,利用序贯最小二乘算法的可变增益,提高了跟踪精度;算法不需要先验统计信息以及序贯式的处理方式等因素,降低了算法的计算复杂度。仿真结果验证了递推公式的正确性和跟踪算法的有效性。     

一种基于预测策略的目标跟踪算法研究

移动目标跟踪是无线传感器网络中的一项重要应用,引起了越来越多的关注.采用静态网格网络结构,针对现有无线传感器网络目标跟踪算法不能兼顾精度和能耗的问题,提出了一种基于预测策略的目标跟踪算法.当目标进入监控区域后,节点携带的震动传感器感知到目标,簇头节点根据节点检测目标信号强度值来计算目标位置,目标位置计算采用一种基于检测...     

Two and three-dimensional intrusion object detection under randomized scheduling algorithms in sensor networks

We are interested in wireless sensor networks which are used to detect intrusion objects such as enemy tanks, cars, submarines, etc. Since sensor nodes have a limited energy supply, sensor networks are configured to put some sensor nodes in sleep mode to save energy. This is a special case of a randomized scheduling algorithm. Ignored by many studies, an intrusion object’s size and shape are important factors that greatly affect the performance of sensor networks. For example, an extremely large object in a small sensor field can easily be detected by even one sensor node, no matter where the sensor node is deployed. The larger an intrusion object is, the fewer sensor nodes that are required for detection. Furthermore, using fewer sensor nodes can save resources and reduce the waste of dead sensor nodes in the environment. Therefore, studying coverage based on intrusion object’s size is important. In this paper, we study the performance of the randomized scheduling algorithm via both analysis and simulation in terms of intrusion coverage intensity. In particular, we study cases where intrusion objects occupy areas in a two-dimensional plane and where intrusion objects occupy areas in a three-dimensional space, respectively. We also study the deployment of sensor nodes when intrusion objects are of different sizes and shapes. First, sensor nodes are deployed in a two-dimensional plane and a three-dimensional space with uniform distributions. Then, they are deployed in a two-dimensional plane and a three-dimensional space in two-dimensional and three-dimensional Gaussian distributions, respectively. Therefore, our study not only demonstrates the impact of the size and shape of intrusion objects on the performance of sensor networks, but also provides a guideline on how to configure sensor networks to meet a certain detecting capability in more realistic situations.     

WSN中基于多径距离和神经网络的节点定位

为了实现802.15.4a无线传感器网络中的目标定位,提出了一种新的基于多径距离和神经网络的目标定位检测算法。首先通过目标出现时对多径效应的影响估计出到达时间差,从而计算出通信传感器节点之间的多径距离;然后把多径距离作为神经网络的输入,并将目标位置用于神经网络的训练;最后通过选择多径距离估计值和测量值的差的最小成本组函数来定位目标位置。对单目标和多目标的定位检测仿真结果表明,即使当网络中传感器数量和目标增加时,所提出的定位算法的误差累积分布函数也不会增大,而且其定位误差比其他定位算法的误差小,从而增强了网络的鲁棒性,提高了网络中传感器承受故障的能力。     

Adaptive sensor placement and boundary estimation for monitoring mass objects

Sensor networks are widely used in monitoring and tracking a large number of objects. Without prior knowledge on the dynamics of object distribution, their density estimation could be learned in an adaptive manner to support effective sensor placement. After sensors observe the "current" locations of objects, the estimates of object distribution are updated with these new observations through a recursive distributed expectation-maximization algorithm. Based on the real-time estimates of object distribution, an adaptive sensor placement algorithm could be designed to achieve stable and high accuracy in tracking mass objects. This paper constructs a Gaussian mixture model to characterize the mixture distribution of object locations and proposes a novel methodology to adaptively update sensor placement. Our simulation results demonstrate the effectiveness of the proposed algorithm for adaptive sensor placement and boundary estimation of mass objects.     

WSN源位置隐私技术研究

随着无线传感器网络的应用深入到日常生活领域,隐私已成为无线传感器网络成功应用的一大障碍。当无线传感器网络用于监控敏感对象,被监控对象的位置隐私成为一个重要问题。首先分析无线传感器网络的安全特点、信源位置隐私性能评价标准、面临的隐私威胁,最后,基于对无线传感器网络信源位置隐私问题的分析和评述,指出了今后该领域的研究方向。     

自适应紧致特征的超像素目标跟踪

目的 针对现有的超像素目标跟踪算法（RST）对同一类中分别属于目标和相似干扰物体的超像素块赋予相同特征置信度,导致难以区分目标和相似干扰物的问题,为此提出自适应紧致特征的超像素目标跟踪算法（ACFST）。方法 该方法在每帧的目标搜索区域内构建适合目标大小的自适应紧致搜索区域,并将该区域内外的特征置信度分别保持不变和降低。处于背景中的相似干扰物体会被该方法划分到紧致搜索区域外,其特征置信度被降低。当依据贝叶斯推理框架求出对应最大后验概率的目标时,紧致搜索区域外的特征置信度低,干扰物体归属目标的程度也低,不会被误判为目标。结果 在具有与目标相似干扰物体的两个视频集进行测试,本文ACFST跟踪算法与RST跟踪算法相比,平均中心误差分别缩减到5.4像素和7.5像素,成功率均提高了11%,精确率分别提高了10.6%和21.6%,使得跟踪结果更精确。结论 本文提出构建自适应紧致搜索区域,并通过设置自适应的参数控制紧致搜索区域变化,减少因干扰物体与目标之间相似而带来的误判。在具有相似物体干扰物的视频集上验证了本文算法的有效性,实验结果表明,本文算法在相似干扰物体靠近或与目标部分重叠时,能够保证算法精确地跟踪到目标,提高算法的跟踪精度,具有较强的鲁棒性,使得算法更能适应背景杂乱、目标遮挡、形变等复杂环境。     

WSNs中的位置隐私评述

随着无线传感器网络（WSNs）的广泛应用,隐私已成为WSNs成功应用的一大障碍。当WSNs用于监控敏感对象,被监控对象的位置隐私成为一个重要问题。特别是WSNs在军事上的应用,基站一旦被控制或破坏,后果不堪设想。分析了WSNs的安全特点、位置隐私性能评价、面临的隐私威胁,并基于对WSNs位置隐私问题的分析和评述,指出了今后该领域的研究方向。     

基于像素可信度和空间位置的运动目标跟踪

运动目标跟踪是视频信息处理的重要研究课题之一．首先将时间域上的中值背景建模与空间域上最小交叉熵法相结合,用于检测运动目标所在跟踪区域．在此基础上,提出了跟踪区域内基于像素的可信度与空间位置的权重函数,利用HSV色彩分布模型计算出目标模型与预测模型间的相似性,选出最优相似模型作为当前目标模型,从而实现了多目标的跟踪．实验显示,该算法计算简单,对相似目标能实现准确的跟踪,对非刚性目标的尺度变化、多目标的交叉及部分遮挡具有鲁棒性．     

Object tracking method based on data computing

The data computing process is utilized in various areas such as autonomous driving. Autonomous vehicles are intended to detect and track nearby moving objects avoiding collisions and to navigate in complex situations, such as heavy traffic and dense pedestrian areas. Therefore, object tracking is the core technology in the environment perception systems of autonomous vehicles and requires the monitoring of surrounding objects and the prediction of the moving states of objects in real time. In this paper, a multiple object tracking method based on light detection and ranging (LiDAR) data is proposed by using a Kalman filter and data computing process. We suppose that the movements of the tracking objects are captured consecutively as frames; thus, model-based detection and tracking of dynamic objects are possible. A Kalman filter is applied for predicting posterior state of tracking object based on anterior state of the tracking object. State denotes the positions, shapes, and sizes of objects. By computing the likelihood probability between predicted tracking objects and clusters which registered from tracking objects, the data association process of the tracking objects can be generated. Experimental results showed enhanced object tracking performance in a dynamic environment. The average matching probability of the tracking object was greater than 92.9%.

     

Object motion tracking using a moving direction estimate and color updates

This paper presents a direction detection and tracking object color update algorithm used to track moving objects that change colors. Different from traditional color-based tracking methods, which use an initial color distribution in order to track objects as long as the object carries the full or partial initial color, this method introduces a color update method used to quickly find the new object color in a new location if the object changes its color partially or completely; the updated color is then used to locate the object. In our algorithm, an initial color pattern is used to track an object using the color. During the tracking, an object’s new location is at first estimated and then used to detect any color change. If the color has changed, a new color pattern is updated based on the changes in the previous color distribution, and then the new color pattern is used to calculate the current location of the object. This algorithm utilizes the property that the movement of an object can be estimated either by using the object’s shadow or by background subtraction. The implementation of our algorithm results in an effective real-time object tracking. The validity of the approach is illustrated by the presentation of experiment results obtained using the methods described in this paper.     

运动人体的检测和跟踪

介绍了一个使用三维激光摄像机对道路上的自行车辆和行人进行检测和跟踪的实时系统，系统主要分为物体识别模块和目标匹配跟踪模块两部分，前者采用了迭代自组织的数据分析算法(ISODATA算法)和多阈值分割方法，后者使用了一种新颖的将轨迹连贯性函数和卡尔曼滤波器相结合的多目标匹配跟踪算法，户外实验表明系统具有较高的识别率。     

基于SAD与UKF-MeanShift的主动目标跟踪

针对复杂场景下动态目标难以准确分割以及目标难以准确定位的问题,提出将绝对差值和(SAD)方法、无迹卡尔曼滤波(UKF)和Mean shift算法相结合的混合自主跟踪动态目标的方法。首先,采用SAD方法获相邻两帧的视差信息,利用视差实现动态目标的检测,并依此建立目标的核直方图描述模型和状态空间模型,然后UKF算法对状态空间进行滤波估计,最后采用Mean shift 算法精确定位目标。实验结果表明该方法不仅能有效检测场景的动态目标,同时还能获得目标的运动信息。文中所提出的基于UKF-Mean shift的跟踪策略与相关算法相比,体现出较好的跟踪效果与时间性能。     

Meta-heuristic approaches for minimizing error in localization of wireless sensor networks

Sensor node localization is considered as one of the most significant issues in wireless sensor networks (WSNs) and is classified as an unconstrained optimization problem that falls under NP-hard class of problems. Localization is stated as determination of physical co-ordinates of the sensor nodes that constitutes a WSN. In applications of sensor networks such as routing and target tracking, the data gathered by sensor nodes becomes meaningless without localization information. This work aims at determining the location of the sensor nodes with high precision. Initially this work is performed by localizing the sensor nodes using a range-free localization method namely, Mobile Anchor Positioning (MAP) which gives an approximate solution. To further minimize the location error, certain meta-heuristic approaches have been applied over the result given by MAP. Accordingly, Bat Optimization Algorithm with MAP (BOA-MAP), Modified Cuckoo Search with MAP (MCS-MAP) algorithm and Firefly Optimization Algorithm with MAP (FOA-MAP) have been proposed. Root mean square error (RMSE) is used as the evaluation metrics to compare the performance of the proposed approaches. The experimental results show that the proposed FOA-MAP approach minimizes the localization error and outperforms both MCS-MAP and BOA-MAP approaches.     

Crisis management using MAS-based wireless sensor networks

Wireless communication is increasingly used to manage large-scale crises (e.g., natural disasters or a large-scale city fire). Communication has traditionally been based on cellular networks. However, real-life experience has proven that the base stations of these networks may collapse or become unreachable during a crisis. An incident commander must also know as much information as possible about the occurring events to control them quickly and efficiently. This paper thus proposes a crisis management approach that overcomes the problems encountered by the base stations and insures relevant, rich and real-time information about events. This approach is based on wireless sensor networks, which are distributed in nature with no need for infrastructure and could be deployed in dangerous and inaccessible zones to gather information. Our proposal uses a multi-agent system as a software layer. The multi-agent system aims to improve the wireless sensor network performance by allowing cooperation between sensor nodes, offering better lifetime management and virtualizing the application layer. This virtualization supports several required applications simultaneously, including event monitoring and object tracking. Through successive simulations, we prove the importance of our approach in crisis management using several criteria to estimate the position’s error in object tracking, end-to-end delay and wireless sensor network lifetime management.     

Improved clustering algorithms for target tracking in wireless sensor networks

In recent years, there has been a growing interest in wireless sensor networks because of their potential usage in a wide variety of applications such as remote environmental monitoring and target tracking. Target tracking is a typical and substantial application of wireless sensor networks. Generally, target tracking aims basically at estimating the location of the target while it is moving within an area of interest and consequently report it to the base station in a timely manner. However, achieving a high accuracy of tracking together with energy efficiency in target tracking algorithms is extremely challenging. In this article, we propose two algorithms to enhance the adaptive-head clustering algorithm, formerly lunched, namely, the improved adaptive-head and improved prediction-based adaptive head. Particularly, the first algorithm uses dynamic clustering to achieve impressive tracking quality and energy efficiency through optimally choosing the cluster head that participates in the tracking process. On the other hand, the second algorithm incorporates a prediction mechanism to the first proposed algorithm. Our proposed algorithms are simulated using Matlab considering various network conditions. Simulation results show that our proposed algorithms can accurately track a target, even when random moving speeds are considered and consume much less energy, when compared with the previous algorithm for target tracking, which in turn prolong the network lifetime much more.     

Intelligent visual surveillance — A survey

Detection, tracking, and understanding of moving objects of interest in dynamic scenes have been active research areas in computer vision over the past decades. Intelligent visual surveillance (IVS) refers to an automated visual monitoring process that involves analysis and interpretation of object behaviors, as well as object detection and tracking, to understand the visual events of the scene. Main tasks of IVS include scene interpretation and wide area surveillance control. Scene interpretation aims at detecting and tracking moving objects in an image sequence and understanding their behaviors. In wide area surveillance control task, multiple cameras or agents are controlled in a cooperative manner to monitor tagged objects in motion. This paper reviews recent advances and future research directions of these tasks. This article consists of two parts: The first part surveys image enhancement, moving object detection and tracking, and motion behavior understanding. The second part reviews wide-area surveillance techniques based on the fusion of multiple visual sensors, camera calibration and cooperative camera systems.