Distributed Cooperative Path Planning for Tracking Ground Moving Target by Multiple Fixed-wing UAVs via DMPC-GVD in Urban Environment

In this paper, a real-time distributed path planning method is developed for cooperatively tracking ground moving target in urban by multiple fixed-wing unmanned aerial vehicles (UAVs). For reasons of changeable movement of target, the commanded speed and turning rate of each UAV are both taken as control input variables. In urban environment, buildings may occlude the line of sight of on-board sensor. Hence the target coverage degree is proposed as objective function instead of distance. To save energy of UAV system as much as possible, the control input cost and sensor energy consumption are also taken as objectives. For preemptive priority requirement, the objective functions are fuzzified and the satisfactory degree order is designed to model priority. To guarantee the feasibility of solution, the varying domain is introduced to replace the strict order constraint. On this basis, generalized varying domain (GVD) method is developed to balance optimization and priority. In terms of the maneuverability of UAVs, the diverse constraints are considered, including real speed and turning rate, control input saturation, collision avoidance between UAVs, and obstacle avoidance between UAV and buildings. Consequently, distributed model predictive control (DMPC) strategy is designed to calculate the optimal path of each UAV, where the state information in finite period of UAV is transferred to the adjacent ones. The simulations show the effectiveness of proposed method by comparing with hierarchical optimization (HO).

     

Cooperative Control of Multiple UAVs for Moving Source Seeking

Advances in multi-agent technologies and UAV technologies make it possible to take advantage of cooperation of multiple UAVs for source seeking. This paper focuses on moving source seeking using multiple UAVs with input constraints. Firstly, a least-squares method is introduced to estimate the gradient of the scalar field at the leader UAV location based on the measurements of all UAVs. Since the moving source velocity is unknown, an adaptive estimator is designed to obtain the velocity. Based on the estimated gradient and source velocity, a guidance law and a sliding mode based heading rate controller are proposed for the leader UAV to achieve level tracking. Heading rate controller for each follower UAV is also developed to achieve circular formation around the leader UAV. Furthermore, the gradient estimation error is analyzed and its influence on moving source velocity estimation and level tracking accuracy is explored as well. Finally, simulation results are provided to verify the proposed approach.     

Adversarial Ground Target Tracking Using UAVs with Input Constraints

This paper deals with the problem of adversarial ground target tracking using Unmanned Aerial Vehicles (UAVs) subject to input constraints. For adversarial ground target tracking, tracking performance and UAV safety are two important considerations during tracking controller design. In this paper, a bang-bang heading rate controller is proposed to achieve circular tracking around the target. Exposure avoidance of the UAV to the target and minimizing the exposure time are studied respectively in terms of the initial state of the UAV. The performance of the proposed controller in both cases is also analyzed. Simulation results demonstrate the effectiveness of the proposed approach.     

Tracking a Ground Moving Target with a Quadrotor Using Switching Control

An unmanned aerial vehicle (UAV) stabilization strategy based on computer vision and switching controllers is proposed. The main goal of this system is to perform tracking of a moving target on ground. The architecture implemented consists of a quadrotor equipped with an embedded camera which provides real-time video to a computer vision algorithm where images are processed. A vision-based estimator is proposed, which makes use of 2-dimensional images to compute the relative 3-dimensional position and translational velocity of the UAV with respect to the target. The proposed estimator provides the required states measurements to a micro-controller for stabilizing the vehicle during flight. The control strategy consists of switching controllers, which allows making decisions when the target is lost temporarily or when it is out of the camera’s field of view. Real time experiments are presented to demonstrate the performance of the target-tracking system proposed.     

基于主动漂移矫正的运动目标跟踪算法

针对传统的图像仿射配准(Affine image alignment, AIA)算法无法有效兼顾算法效率和鲁棒性的问题, 提出了一种快速鲁棒的新仿射配准算法---主动漂移矫正(Active drift correction, ADC)算法用于跟踪视频运动目标. 该算法的基本思想是: 通过引入一个漂移矫正项, 来改进传统算法的目标能量函数, 使算法具备抗漂移的能力, 从而提高算法的鲁棒性. 改进后的算法不需要传统算法中为增强鲁棒性而采用的许多复杂措施(如: 被动漂移矫正). 实验结果表明: 本文提出的算法简单、有效, 在不必牺牲算法效率和复杂度的条件下, 可以获得比传统算法更好的鲁棒性.     

一种运动目标多特征点的鲁棒跟踪方法研究

提出了一种基于特征光流分割和卡尔曼滤波估计的鲁棒性的运动目标跟踪方法。该方法具有很多特点：首先在特征光流的计算中采用由粗到细的层级匹配算法，因而能够计算大的运动速度和具有更好的匹配精度；其次采用了有效的遮挡判决算法，该算法综合利用了先验的信息，对噪声的干扰不敏感；最后建立了线性卡尔曼滤波模型，当特征点被遮挡或丢失时，能够预测它们的位置，这使得跟踪更具有主动性。实验表明，该方法具有高精度、快速跟踪和很好的鲁棒性。     

Decentralised Standoff Tracking of Moving Targets Using Adaptive Sliding Mode Control for UAVs

This paper proposes a decentralised vector field guidance algorithm for coordinated standoff tracking of a ground moving target by multiple UAVs. In particular, this study introduces additional adaptive terms in an existing sliding mode control concept for standoff tracking guidance, in order to reduce the effect of unmodelled dynamics and disturbances. Decentralised angular separation control between UAVs, in conjunction with decentralised estimation, is also introduced using either velocity or orbit radius change by different information/communication structures. Numerical simulations are performed to verify the feasibility and benefits of the proposed approach under a realistic ground vehicle tracking scenario, using multiple UAVs having unknown parameters in the heading-hold autopilot.     

Standoff Tracking of a Moving Target for Quadrotor Using Lyapunov Potential Function

International Journal of Control, Automation and Systems - This paper presents a control scheme for standoff tracking of a ground moving target by a quadrotor unmanned aerial vehicle (UAV). The...     

利用Jetson TK1平台的行人运动目标跟踪系统

针对图像检测识别和目标跟踪技术中存在的抗遮挡性弱、无法应对目标丢失、对目标多尺度变化适应不了等问题,设计开发了基于Jetson TK1平台及计算机视觉OpenCV(Open Source Computer Vision Library)的行人运动目标跟踪系统,利用GPU高效图像处理能力,结合改进的KCF(Kerneli...     

基于IR-UWB雷达的多视角融合动态目标追踪

近年来,对运动目标的定位和追踪被广泛地应用于室内导航、智能家居、安防监控和智慧医疗等场景.基于无线射频信号的非接触式定位追踪受到了研究人员的广泛关注,其中基于商用IR-UWB的技术能够以较低的成本和功耗实现目标定位和追踪的功能,具有较强的发展潜力.然而,现有工作大多存在以下问题:1)追踪场景受限,只针对理想情况下室外或者相对空旷的室内场景进行建模和处理; 2)目标的运动状态受限且建模过于理想; 3)虚假动态目标引起的追踪精度不足.为了解决这些问题,在理解多径场景下接收信号谱组成的基础上,提出一个基于IR-UWB的动态目标追踪方法.首先提取原始信号谱中动态成分,并利用基于高斯模糊的多径消除和距离提取算法,消除了多径干扰,仅保留与运动目标直接相关的一次反射信息,从而准确地获取了目标的距离变化曲线.随后,提出多视角融合算法,将不同视角上的设备距离信息进行融合,实现对自由活动目标的准确定位和追踪.此外,还搭建一个基于低成本商用IR-UWB雷达的实时动态目标追踪系统.真实室内家居场景中的实验结果表明,系统估计的人体中心的位置与真实运动轨迹的误差始终小于20 cm.在改变实验环境、实验者、活动速度...     

Cooperative Target Tracking of Multiple Autonomous Surface Vehicles Under Switching Interaction Topologies

This paper is concerned with the cooperative target tracking of multiple autonomous surface vehicles(ASVs) under switching interaction topologies.For the target to be tracked,only its position can be measured/received by some of the ASVs,and its velocity is unavailable to all the ASVs.A distributed extended state observer taking into consideration switching topologies is designed to integrally estimate unknown target dynamics and neighboring ASVs’ dynamics.Accordingly,a novel kinematic controlle...     

Cooperative Control of Multiple UAVs for Source Seeking

This paper considers the problem of unknown scalar field source seeking using multiple UAVs subject to input constraints. In this problem, each UAV can only measure the scalar field value at its current location. In order to seek the scalar field source, cooperation of multiple UAVs is carried out by adopting a leader-follower formation strategy. A least squares method is introduced to estimate the gradient of the scalar field at the leader UAV location based on the measurements of all UAVs. By using the estimated gradient, this paper proposes a guidance law for the heading of the leader UAV, and a sliding mode based heading rate controller is designed for the leader UAV to follow the desired heading angle. Furthermore, a heading rate controller is developed for each follower UAV to achieve circular formation around the leader UAV. Finally, simulation results are provided to demonstrate the effectiveness of the proposed approach.     

一种利用信息融合的运动目标跟踪算法

论文针对灰度相关模板匹配跟踪算法的局限性,提出了一种基于信息融合的运动目标跟踪算法。该方法同时利用图象中的灰度信息和边缘信息,从而克服了只依靠单一信息源的不足。实验结果表明,该方法明显提高了跟踪性能。     

Target Tracking Using Multiple Patches and Weighted Vector Median Filters

This paper presents an approach for object tracking based on multiple disjoint patches. Initially, the target is subdivided into a set of rectangular patches, and each patch is represented parametrically by the mean vector and covariance matrix computed from a set of feature vectors that represent each pixel of the target. Each patch is tracked independently based on the Bhattacharyya distance, and the displacement of the whole template is obtained using a Weighted Vector Median Filter (WVMF), which reduces the influence of incoherently tracked patches. To smooth the obtained trajectory and also cope with short-term total occlusions, a predicted displacement vector based on the motion of the target in the previous frames is also used, and an updating scheme is applied to deal with appearance changes of the template. Experimental results indicate that the proposed scheme is robust to partial and short-time total occlusions, presenting a good compromise between accuracy and execution time when compared to other approaches.     

随机网格回归Monte Carlo双UAVs最优目标协调跟踪

针对多个无人机(unmanned aerial vehicle,UAV)执行基于视觉的目标跟踪的最佳协调问题,提高不可预知的地面目标的最佳结合点的视觉测量效果,提出了一种基于随机网格回归Monte Carlo的UAV最优目标跟踪策略。首先,通过无人机动力学和目标动力学分析,获得双UAV情况下的随机最优协调控制目标;其次,针对提出的控制目标,引入Monte Carlo求解方案,同时为解决标准Monte Carlo方案中存在的状态空间维度较高,计算复杂且精度不高的问题,利用随机网格方式构建回归Monte Carlo方案,实现UAV的最优协调控制;最后,通过仿真实验验证了所提方法的有效性。     

Binaural Tracking of Multiple Moving Sources

This paper addresses the problem of tracking multiple moving sources using binaural input. We observe that binaural cues are strongly correlated with source locations in time-frequency regions dominated by only one source. Based on this observation, we propose a novel tracking algorithm that integrates probabilities across reliable frequency channels in order to produce a likelihood function in the target space, which describes the azimuths of all active sources at a particular time frame. Finally, a hidden Markov model (HMM) is employed to form continuous tracks and automatically detect the number of active sources across time. Results are presented for up to three moving talkers in anechoic conditions. A comparison shows that our HMM model outperforms a Kalman filter-based approach in tracking active sources across time. Our study represents a first step in addressing auditory scene analysis with moving sound sources.     

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...     

视频监控中的运动目标跟踪算法

研究复杂背景下多目标跟踪问题.首先阐述了蒙特卡罗粒子滤波器基本理论;然后给出序列图像多目标跟踪系统的状态方程、观测方程、背景模型、重采样方法以及目标跟踪中的一些特殊情况的处理方法.该算法有效解决了目标跟踪算法中的新目标出现、老目标消失、目标遮挡和蒙特卡罗粒子滤波器实时性差等问题.实验结果证明,该算法对固定摄像机复杂背景下多目标跟踪是快速且有效的.     

基于模板匹配技术的运动物体跟踪方法研究

通过视频输入设备动态采集图像帧,然后在模板匹配基本思想的方法上加入改进后的匹配原则和搜索策略,同时结合模板更新技术,计算前后两帧图像中待跟踪物体的坐标,得到偏差数据,接着通过串口把偏差数据发送给下位机,最后根据偏差数据控制步进电机,带动摄像头运动,达到动态跟踪运动物体的目标.     

Implementation and Testing of a Backstepping Controller Autopilot for Fixed-wing UAVs

The ability of backstepping controllers to deal with nonlinearities make this technique a suitable candidate for the control of small fixed-wing Unmanned Aerial Vehicles (UAVs). The authors have already proposed a comprehensive approach combining backstepping with PID controllers for simultaneous longitudinal and latero-directional control of fixed-wing UAVs, achieving good performance even with considerable levels of signal noise Sartori et al (2013). In further detail, the ability of the mixed approach to control different size and configuration aircraft in the presence of parametric uncertainties or noise, and when implemented on a microcontroller board was demonstrated. The present paper illustrates integration and testing of the backstepping controller on a real unmanned aircraft. After a summarizing the adopted control design and strategy, initial software and hardware simulations validate the control action for the selected aircraft. The implementation of the microcontroller on the aircraft and the integration with other aircraft systems is also illustrated. Experimental results obtained for ground and flight tests are presented, validating the applicability of the backstepping controller.