基于自适应动态簇和预测机制的WSN目标跟踪算法

无线传感器网络由大量能量有限的传感器节点组成,如何高效利用网络中节点的能量是无线传感器网络用于目标跟踪时研究的主要内容。合理构建动态簇可以有效降低网络的能量消耗,延长网络的生命周期,本文通过改进动态簇组建过程中簇头的选举和簇成员的征集过程,达到进一步节能的效果。其中,簇头的选择,综合考虑节点的能量和节点离目标的距离两个因素。簇成员的征集,同时考虑目标的移动速度和网络中节点的分布情况。同时,引入有效的预测机制,通过避免盲目的唤醒网络中的节点和降低跟踪延迟,可以进一步增强网络的跟踪性能,使跟踪过程更加有效和稳定。仿真结果表明本文算法在保证跟踪精度的前提条件下,可以有效节省网络中节点的能量。     

Event-Triggered Bipartite Consensus Tracking and Vibration Control of Flexible Timoshenko Manipulators Under Time-Varying Actuator Faults

For bipartite angle consensus tracking and vibration suppression of multiple Timoshenko manipulator systems with time-varying actuator faults, parameter and modeling uncertainties, and unknown disturbances, a novel distributed boundary event-triggered control strategy is proposed in this work. In contrast to the earlier findings, time-varying consensus tracking and actuator defects are taken into account simultaneously. In addition, the constructed event-triggered control mechanism can achieve a more flexible design because it is not required to satisfy the input-to-state condition. To achieve the control objectives, some new integral control variables are given by using back-stepping technique and boundary control. Moreover, adaptive neural networks are applied to estimate system uncertainties. With the proposed event-triggered scheme, control inputs can reduce unnecessary updates. Besides, tracking errors and vibration states of the closed-looped network can be exponentially convergent into some small fields, and Zeno behaviors can be excluded. At last, some simulation examples are given to state the effectiveness of the control algorithms.

     

The Velocity Snake: Deformable Contour for Tracking in Spatio-Velocity Space

We present a new active contour model for boundary tracking and position prediction of nonrigid objects, which results from applying a velocity control to the class of elastodynamical contour models, known as snakes. The proposed control term minimizes an energy dissipation function which measures the difference between the contour velocity and the apparent velocity of the image. Treating the image video-sequence as continuous measurements along time, it is shown that the proposed control results in robust tracking. This is in contrast to the original snake model which is proven to have tracking errors relative to image (object) velocity, thus resulting in high sensitivity to image clutter. The motion estimation further allows for position prediction of nonrigid boundaries. Based on the proposed control approach, we propose a new class of real time tracking contours, varying from models with batch-mode control estimation to models with real time adaptive controllers.     

基于不可靠节点序列和面感知路由的目标跟踪

目标跟踪是无线传感器网络最基本的应用之一,如何在节约能量的同时保证一定的跟踪精度一直是研究热点之一.本文提出基于不可靠节点序列和面感知路由的目标跟踪算法,采用基于不可靠节点序列的定位模式有效减少网络中数据传输量,大大节约了能量.为了解决基于节点序列的定位算法在节点数目过多时算法复杂度过高的问题,算法引入了面感知路由技术...     

适用于事件触发的分布式随机目标跟踪方法

研究了一类基于RSSI（Received signal strength indication）测距的分布式移动目标跟踪问题,提出了一种适用于事件触发无线传感器网络（Wireless sensor networks,WSNs）的分布式随机目标跟踪方法.首先考虑移动机器人模型的不确定性,引入了带有随机参数的过程噪声协方差,应用改进平方根容积卡尔曼滤波（Square root cubature Kalman filter,SRCKF）得到局部估计;然后采用无模型CI（Covariance intersection）融合估计方法以降低随机过程噪声协方差带来的不利影响.该方法充分利用有模型和无模型方法的优势,实现系统模型和量测不理想情况下的分布式目标跟踪.基于E-puck机器人的目标跟踪实验表明,事件触发的工作模式可有效地减少能量消耗,带随机参数的滤波方法更适合于随机目标的跟踪.     

Novel sensor scheduling and energy-efficient quantization for tracking target in wireless sensor networks

This paper focuses on sensor scheduling and information quantization issues for target tracking in wireless sensor networks (WSNs). To reduce the energy consumption of WSNs, it is essential and effective to select the next tasking sensor and quantize the WSNs data. In existing works, sensor scheduling’ goals include maximizing tracking accuracy and minimizing energy cost. In this paper, the integration of sensor scheduling and quantization technology is used to balance the tradeoff between tracking accuracy and energy consumption. The main characteristic of the proposed schemes includes a novel filtering process of scheduling scheme, and a compressed quantized algorithm for extended Kalman filter (EKF). To make the algorithms more efficient, the proposed platform employs a method of decreasing the threshold of sampling intervals to reduce the execution time of all operations. A real tracking system platform for testing the novel sensor scheduling and the quantization scheme is developed. Energy consumption and tracking accuracy of the platform under different schemes are compared finally.     

面向目标跟踪的传感器网络睡眠调度协议

移动目标跟踪是无线传感器网络中的一项重要应用,将睡眠调度机制引入到目标跟踪算法中可以大大降低能耗。针对目标跟踪的实际需求,提出一种面向目标跟踪的传感器网络睡眠调度协议。根据目标跟踪不同阶段,分别设计了目标跟踪前和跟踪过程中传感器节点的睡眠调度机制;另外给出了目标丢失时,如何唤醒节点继续跟踪目标的调度策略。结果表明:该算法能够在保证跟踪质量的同时,降低跟踪能耗。     

Position and force tracking of a two‐manipulator system manipulating a flexible beam

This article discusses the issue of hybrid position and force control of a two‐manipulator system manipulating a flexible beam in trajectory tracking. Unlike our previous approach of set‐point position control in the trajectory tracking, the system coordinates are hard to be regulated to the desired states with nonzero tracking velocities under continuous feedback control. In this study, we design a hybrid position and force tracking controller while using saturation control to compensate for the effect of beam vibration dynamics on the tracking performance. All parameters and states used in the controller are readily available so that the proposed method is feasible to implement. Under the proposed controller, the tracking error asymptotically converges to a predetermined boundary. Simulation results demonstrate the validity of the proposed approach. © 2001 John Wiley & Sons, Inc.     

基于椭圆吸引律的离散重复控制

针对离散时间系统的周期轨迹跟踪问题,提出一种基于椭圆吸引律的离散重复控制方法.该方法能有效减小抖振,并通过扰动扩张状态观测技术对系统的未知扰动进行有效抑制,采用重复控制技术对系统中存在的周期扰动完全消除.为了刻画系统误差动态性能,推导出单调减区域、绝对吸引层、稳态误差带的表达式以及系统跟踪误差进入稳态误差带的最大步长.通过数值仿真与直线伺服电机实验,验证所提出控制方法的有效性.     

基于信念重用的WSNs能量高效跟踪

针对无线传感器网络(WSNs)中目标跟踪性能与传感器能量消耗难以平衡问题,提出一种信念重用的WSNs能量高效跟踪算法。使用部分可观察马尔可夫决策过程(POMDPs)对动态不确定环境下的WSNs进行建模,将跟踪性能与能量消耗平衡优化问题转化为POMDPs最优值函数求解过程;采用最大报酬值启发式查找方法获得跟踪性能的逼近最优值;采用信念重用方法避免重复获取信念,有效降低传感器通信带来的能量消耗。实验结果表明:信念重用算法能够有效优化跟踪性能与能量消耗之间的平衡,达到以较低的能量消耗获得较高跟踪性能的目的。     

A recognition network model-based approach to dynamic image understanding

In this paper, we present definitions for a dynamic knowledge-based image understanding system. From a sequence of grey level images, the system produces a flow of image interpretations. We use a semantic network to represent the knowledge embodied in the system. Dynamic representation is achieved by ahypotheses network. This network is a graph in which nodes represent information and arcs relations. A control strategy performs a continuous update of this network. The originality of our work lies in the control strategy: it includes astructure tracking phase, using the representation structure obtained from previous images to reduce the computational complexity of understanding processes. We demonstrate that in our case the computational complexity, which is exponential if we only use a purely data-driven bottom-up scheme, is polynomial when using the hypotheses tracking mechanism. This is to say that gain improvement in computation time is a major reason for dynamic understanding. The proposed system is implemented; experimental results of road mark detection and tracking are given.     

基于分布式动态簇结构的WSN自适应目标跟踪算法

目标跟踪是无线传感器网络应用研究的一个重要问题,如何在传感器节点随机分布的条件下对目标进行实时、准确的跟踪,并尽可能地降低网络能耗是目标跟踪问题的一个难点。文章基于分布式动态簇结构和并行粒子滤波算法对目标进行跟踪,提出一种跟踪采样周期自适应调整算法来降低网络能耗,同时也提高了跟踪的稳定性。仿真结果表明,文章提出的算法达到了实时、准确和节能的要求,具有一定的实际应用价值。     

Parallel energy-efficient coverage optimization with maximum entropy clustering in wireless sensor networks

Energy constraint is an important issue in wireless sensor networks. This paper proposes a parallel energy-efficient coverage optimization mechanism to optimize the positions of mobile sensor nodes based on maximum entropy clustering in large-scale wireless sensor networks. According to the models of coverage and energy, stationary nodes are partitioned into clusters by maximum entropy clustering. After identifying the boundary node of each cluster, the sensing area is divided for parallel optimization. A numerical algorithm is adopted to calculate the coverage metric of each cluster, while the lowest cost paths of the inner cluster are used to define the energy metric in which Dijkstra’s algorithm is utilized. Then cluster heads are assigned to perform parallel particle swarm optimization to maximize the coverage metric and minimize the energy metric where a weight coefficient between the two metrics is employed to achieve a tradeoff between coverage area and energy efficiency. Simulations of the optimization mechanism and a target tracking application verify that coverage performance can be guaranteed by choosing a proper weight coefficient for each cluster and energy efficiency is enhanced by parallel energy-efficient optimization.     

基于时空显著性的双核KCF目标跟踪算法

传统的核相关滤波器跟踪算法(KCF)在模板更新上容易出现跟踪误差累计,从而导致目标跟踪过程中出现跟踪漂移问题。针对该问题,提出了一种时空显著性的双核KCF目标跟踪的方法。该算法引入了一种时空显著性方法来搜索目标区域的显著特征和姿态稳定的局部区域。利用该局部区域对跟踪过程中产生的累计误差有较低的敏感度特性,能够减少跟踪过程中的累计误差。然后再结合原目标和显著区域建立一个双核跟踪机制,在跟踪过程中不断对原目标跟踪结果进行微调,降低跟踪累计误差。此外,针对快速运动的目标相邻帧偏移量较大的问题,提出了一种锚点预测机制,使得跟踪锚点与目标位置更接近,能够更准确地跟踪到目标。在大型公共数据上测试的实验结果表明,提出的算法在光照、遮挡、变形、快速运动、旋转以及背景杂波等复杂情况下,均具有较强的适应性。     

基于PSO算法的运动目标跟踪研究

提出一种基于PSO的运动目标跟踪方法,并在TMS320DM642上实现.该方法首先针对采集到图像的Y分量通过帧间差分和背景差分相结合的方法建立背景模型,然后检测出前景运动目标,接着通过前景运动目标初始化目标模板,再对目标模板和待跟踪视频图像分别进行两次金字塔降采样,降低目标模板和待跟踪视频图像的分辨率.在顶层金子塔上采用粒子群优化算法对跟踪目标进行粗定位,在中间层和底层金字塔上采用钻石搜索方法对跟踪目标进行精确定位.在目标跟踪的过程中,目标模板随运动目标的变化而不断更新,实现对目标的实时连续性跟踪.该方法可以有效降低计算复杂度,提高搜索效率.     

无线传感器网络目标跟踪机制的研究与改进

文章对无线传感器网络(WSN)目标跟踪机制进行了研究,针对层次型的WSN,提出一种高效的跟踪机制,包括双层的预测机制,以及泛洪(flooding)扩散的恢复机制,并对这两种机制进行了详细的分析。仿真结果表明,该改进后的目标跟踪机制不仅耗费较少的能量,而且能够获得较高的跟踪精度。     

在线修正的人脸姿态跟踪算法及交互应用

针对人脸在跟踪过程中可能存在大幅度的倾斜、旋转、遮挡以及肤色干扰等问题,提出一种基于在线修正的人脸跟踪算法.该算法当人脸检测失效时,人脸跟踪模块将用于提取目标参数;而在人脸跟踪过程中,为减小由连续跟踪造成的累积误差,利用人脸实时检测机制新检测到的人脸目标参数来修正跟踪模块的参数,包括跟踪窗口的位置和尺度,从而利用了人脸检测和人脸跟踪各自的优点.通过实验,其结果表明,该算法能够精确地跟踪复杂姿态下的人脸目标,并且能够解决肤色干扰和遮挡的问题,具有很好的适应性和鲁棒性.另外,将在线修正的跟踪方法应用于娱乐游戏控制,为人机交互提供了新的方式.     

基于深度学习的分层关联多行人跟踪

由于连续帧之间数据关联的不确定性和所提取外观特征的鉴别力不足,多目标跟踪容易受目标外观变化、运动状态变化、相似目标以及目标消失再出现等干扰因素的影响,出现轨迹ID变换的问题,从而限制基于轨迹分析的行为检测、姿态识别等研究的性能。为了提高数据关联的可靠性从而减少轨迹ID变换,提出了一种基于轨迹置信度的分层数据关联方式。同时,为了提高用于数据关联的外观特征的鉴别力,提出融合了过程层的特征提取网络。在公开的MOT16测试数据集上验证表明,该算法在保证跟踪准确度和精确度的同时,有效降低了轨迹ID变换的次数,提高了跟踪性能。     

基于能量优化的无线传感器网络动态分簇目标跟踪

针对无线传感器网络动态分簇目标跟踪中的数据碰撞与簇首选择过程导致能耗过高问题,提出一种基于能量优化的无线传感器网络动态分簇方法。首先,构建时分竞选传输模型,主动避免动态簇内数据碰撞,降低节点能耗;然后,基于能量信息与跟踪质量,提出能量均衡的最远节点调度策略,优化簇头节点调度;最后,根据加权质心定位算法,完成目标跟踪任务。实验结果表明：在节点随机部署的环境下,所提方法对于非线性运动目标的平均跟踪精度为0.65 m,与多目标跟踪动态簇员选择方法（DCMS）相当,比分布式事件定位动态分簇目标跟踪算法（DELTA）提高了45.8%;能量消耗方面,与DCMS和DELTA相比,所提方法的动态跟踪簇能量消耗有效降低了61.1%,延长了网络寿命。     

生态物联网节点的风光混合能量变换系统设计

为使物联网传感器节点长期用于生态环境监测,设计了一种风光混合微能量变换系统提供节点持续电能.设计了光源自动跟踪和最大功率跟踪两种控制电路,最大程度地进行光伏能量转换;设计低输入电压的能力的升压电路以提高在低风速情况的能量采集.分析了风光混合系统电源管理的工作方式,理论推导传感节点和双轴电机工作所需能量管理的理论条件.实验测试结果表明：研究的混合微能量变换系统能够精确检测光照强度,能采集光能和风能并实时充电存储,节点可以持续工作,采集数据并实时远距离无线传输,能够满足林业生态环境的远程监测功能要求.