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Search Results (14)

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Keywords = great maneuvering target

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27 pages, 5279 KiB  
Article
Research on Unmanned Aerial Vehicle Intelligent Maneuvering Method Based on Hierarchical Proximal Policy Optimization
by Yao Wang, Yi Jiang, Huiqi Xu, Chuanliang Xiao and Ke Zhao
Processes 2025, 13(2), 357; https://doi.org/10.3390/pr13020357 - 27 Jan 2025
Viewed by 590
Abstract
Improving decision-making in the autonomous maneuvering of unmanned aerial vehicles (UAVs) is of great significance to improving flight safety, the mission execution rate, and environmental adaptability. The method of deep reinforcement learning makes the autonomous maneuvering decision of UAVs possible. However, the current [...] Read more.
Improving decision-making in the autonomous maneuvering of unmanned aerial vehicles (UAVs) is of great significance to improving flight safety, the mission execution rate, and environmental adaptability. The method of deep reinforcement learning makes the autonomous maneuvering decision of UAVs possible. However, the current algorithm is prone to low training efficiency and poor performance when dealing with complex continuous maneuvering problems. In order to further improve the autonomous maneuvering level of UAVs and explore safe and efficient maneuvering methods in complex environments, a maneuvering decision-making method based on hierarchical reinforcement learning and Proximal Policy Optimization (PPO) is proposed in this paper. By introducing the idea of hierarchical reinforcement learning into the PPO algorithm, the complex problem of UAV maneuvering and obstacle avoidance is separated into high-level macro-maneuver guidance and low-level micro-action execution, greatly simplifying the task of addressing complex maneuvering decisions using a single-layer PPO. In addition, by designing static/dynamic threat zones and varying their quantity, size, and location, the complexity of the environment is enhanced, thereby improving the algorithm’s adaptability and robustness to different conditions. The experimental results indicate that when the number of threat targets is five, the success rate of the H-PPO algorithm for maneuvering to the designated target point is 80%, which is significantly higher than the 58% rate achieved by the original PPO algorithm. Additionally, both the average maneuvering distance and time are lower than those of the PPO, and the network computation time is only 1.64 s, which is shorter than the 2.46 s computation time of the PPO. Additionally, as the complexity of the environment increases, the H-PPO algorithm outperforms other compared networks, demonstrating the effectiveness of the algorithm constructed in this paper for guiding intelligent agents to autonomously maneuver and avoid obstacles in complex and time-varying environments. This provides a feasible technical approach and theoretical support for realizing autonomous maneuvering decisions in UAVs. Full article
(This article belongs to the Special Issue Design and Analysis of Adaptive Identification and Control)
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<p>The UAV motion model.</p>
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<p>Training process of PPO.</p>
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<p>Network structure diagram.</p>
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<p>Framework of H-PPO.</p>
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<p>Diagram of UAV detection areas.</p>
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<p>UAV detection model.</p>
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<p>A schematic diagram of the experimental task area.</p>
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<p>Reward function curves for different learning rates.</p>
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<p>Maneuver reward curve in training phase (5 obstacles).</p>
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<p>Maneuver reward curve in training phase (10 obstacles).</p>
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<p>Maneuver reward curve in training phase (15 obstacles).</p>
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<p>Number of movable threat targets and success rate.</p>
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<p>Intelligent agent maneuver test diagram.</p>
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<p>Dynamic scene test diagram.</p>
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<p>Relationship between success rate and maximum maneuvering speed.</p>
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23 pages, 3672 KiB  
Article
UAV Swarm Centroid Tracking for Edge Computing Applications Using GRU-Assisted Multi-Model Filtering
by Yudi Chen, Xiangyu Liu, Changqing Li, Jiao Zhu, Min Wu and Xiang Su
Electronics 2024, 13(6), 1054; https://doi.org/10.3390/electronics13061054 - 12 Mar 2024
Viewed by 1405
Abstract
When an unmanned aerial vehicles (UAV) swarm is used for edge computing, and high-speed data transmission is required, accurate tracking of the UAV swarm’s centroid is of great significance for the acquisition and synchronization of signal demodulation. Accurate centroid tracking can also be [...] Read more.
When an unmanned aerial vehicles (UAV) swarm is used for edge computing, and high-speed data transmission is required, accurate tracking of the UAV swarm’s centroid is of great significance for the acquisition and synchronization of signal demodulation. Accurate centroid tracking can also be applied to accurate communication beamforming and angle tracking, bringing about a reception gain. Group target tracking (GTT) offers a suitable framework for tracking the centroids of UAV swarms. GTT typically involves accurate modeling of target maneuvering behavior and effective state filtering. However, conventional coordinate-uncoupled maneuver models and multi-model filtering methods encounter difficulties in accurately tracking highly maneuverable UAVs. To address this, an innovative approach known as 3DCDM-based GRU-MM is introduced for tracking the maneuvering centroid of a UAV swarm. This method employs a multi-model filtering technique assisted by a gated recurrent unit (GRU) network based on a suitable 3D coordinate-coupled dynamic model. The proposed dynamic model represents the centroid’s tangential load, normal load, and roll angle as random processes, from which a nine-dimensional unscented Kalman filter is derived. A GRU is utilized to update the model weights of the multi-model filtering. Additionally, a smoothing-differencing module is presented to extract the maneuvering features from position observations affected by measurement noise. The resulting GRU-MM method achieved a classification accuracy of 99.73%, surpassing that of the traditional IMM algorithm based on the same model. Furthermore, our proposed 3DCDM-based GRU-MM method outperformed the Singer-KF and 3DCDM-based IMM-EKF in terms of the RMSE for position estimation, which provides a basis for further edge computing. Full article
(This article belongs to the Special Issue Mobile Networking: Latest Advances and Prospects)
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<p>Scenario of UAV swarm-based edge computing.</p>
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<p>3D coordinate-coupled dynamic model of the UAV swarm’s centroid.</p>
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<p>Network structure for maneuver model estimation.</p>
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<p>Simulated UAV swarm trajectories for network training.</p>
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<p>The tracking scenario used for validating the centroid trajectory tracking.</p>
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<p>Training process of the model estimation network.</p>
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<p>True mode and estimated mode probabilities of the maneuvering centroid. The topmost subgraph represents the true mode. The subgraphs below compare IMM estimates and GRU estimates for each model.</p>
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<p>RMSEs of the position estimates for Monte Carlo simulation of the proposed method and conventional method.</p>
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<p>Comparison of different centroid tracking methods. The subgraph at the top left is a view of the entire flight path. The remaining three subgraphs are fragments selected from the track, and the corresponding areas are shown in the box in the figure.</p>
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<p>(<b>a</b>) Picture of the UAV. (<b>b</b>) Picture of the cooperative flight.</p>
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<p>Flight trajectories with different durations of (<b>a</b>) 1194 s, (<b>b</b>) 1243 s, and (<b>c</b>) 1223 s.</p>
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<p>Confusion matrix of three flight experiments with networks trained by simulation and actual observations. (<b>a</b>) The 1194 s flight with a simulated network. (<b>b</b>) The 1243 s flight with a simulated network. (<b>c</b>) The 1223 s flight with a simulated network. (<b>d</b>) The 1194 s flight with a retrained network. (<b>e</b>) The 1243 s flight with a retrained network. (<b>f</b>) The 1223 s flight with a retrained network.</p>
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36 pages, 46357 KiB  
Article
Research on the Influence of the Disturbance Rejection Rate of a Roll–Pitch Seeker on Stable Tracking Characteristics
by Bowen Xiao, Tianyu Lu, Zeyuan Ma and Qunli Xia
Aerospace 2023, 10(11), 940; https://doi.org/10.3390/aerospace10110940 - 3 Nov 2023
Cited by 2 | Viewed by 1436
Abstract
The disturbance rejection rate (DRR) is an inherent problem of the seeker. The additional line-of-sight (LOS) angular velocity information of the seeker caused by the DRR will affect the attitude of the aircraft through the guidance system, thus forming a parasitic loop in [...] Read more.
The disturbance rejection rate (DRR) is an inherent problem of the seeker. The additional line-of-sight (LOS) angular velocity information of the seeker caused by the DRR will affect the attitude of the aircraft through the guidance system, thus forming a parasitic loop in the guidance and control system of the aircraft, which has a great influence on the guidance accuracy. In this study, the influence of the DRR of the roll–pitch seeker on the stable tracking of a maneuvering target is explored. First, the tracking principle of the roll–pitch seeker is analyzed and the conditions for completely isolating the disturbance of the aircraft attitude are deduced. Then, the expression of the frame error angle is derived, a semi-strap-down stable control closed-loop scheme is established, and the DRR transfer function is derived by adding different disturbance torque models. Finally, the simulation of stability tracking characteristics is carried out. The results show that when the aircraft attitude is disturbed at a low frequency or the target is maneuvering at a low frequency, the DRR caused by the spring torque has a great influence on the tracking angle of the two frames, the line of-sight rate accuracy of the optical axis output and the detector error angle. On the contrary, the damping torque DRR plays a leading role in tracking accuracy. Full article
(This article belongs to the Section Aeronautics)
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<p>Scheme of the roll–pitch seeker.</p>
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<p>Diagram of the seeker detector error angle.</p>
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<p>Coordinate transformation relationship.</p>
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<p>Stable loop of the roll frame.</p>
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<p>Stable loop of the pitch frame.</p>
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<p>Projection of the disturbance on the pitch frame coordinate.</p>
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<p>Principle of the existence of the angular velocity of optical axis disturbance.</p>
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<p>Schematic diagram of detector measurement error angle.</p>
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<p>Schematic diagram of image changes on the detector: (<b>a</b>) Roll frame motion; (<b>b</b>) Pitch frame motion.</p>
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<p>Principle of roll–pitch seeker stable control system.</p>
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<p>Schematic diagram of coordinate transformation of roll–pitch seeker.</p>
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<p>Frame control model.</p>
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<p>DRR generated by roll interference torque: (<b>a</b>) damping torque; (<b>b</b>) spring torque.</p>
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<p>Bode diagram of DRR function under different interference forces: (<b>a</b>) damping torque; (<b>b</b>) spring torque.</p>
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<p>Roll frame angle.</p>
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<p>Pitch frame angle.</p>
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<p>Angular rate of roll frame.</p>
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<p>Angular rate of pitch frame.</p>
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<p>Optical axis pitch LOS rate.</p>
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<p>Optical axis yaw LOS rate.</p>
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<p>Error angle: (<b>a</b>) Detector error angle; (<b>b</b>) Pitch and yaw error angle of the Detector.</p>
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<p>Roll frame angle.</p>
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<p>Pitch frame angle.</p>
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<p>Angular rate of roll frame.</p>
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<p>Angular rate of pitch frame.</p>
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<p>Optical axis pitch LOS rate.</p>
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<p>Optical axis yaw LOS rate.</p>
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<p>Detector error angle.</p>
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<p>Pitch frame Monte Carlo simulation.</p>
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<p>Optical axis pitch LOS rate.</p>
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<p>Optical axis yaw LOS rate.</p>
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<p>Error angle: (<b>a</b>) Detector error angle; (<b>b</b>) Pitch and yaw error angle of the Detector.</p>
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<p>Pitch frame angle.</p>
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<p>Angular rate of pitch frame.</p>
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<p>Optical axis pitch LOS rate.</p>
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<p>Detector error angle.</p>
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<p>Pitch frame angle.</p>
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<p>Angular rate of pitch frame.</p>
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<p>Optical axis pitch LOS rate.</p>
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<p>Detector error angle.</p>
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<p>Pitch frame Monte Carlo simulation.</p>
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<p>Roll frame angle.</p>
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<p>Pitch frame angle.</p>
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<p>Angular rate of roll frame.</p>
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<p>Angular rate of pitch frame.</p>
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<p>Optical axis pitch LOS rate.</p>
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<p>Optical axis yaw LOS rate.</p>
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<p>Error angle: (<b>a</b>) Detector error angle; (<b>b</b>) Pitch and yaw error angle of the Detector.</p>
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<p>Monte Carlo simulation: (<b>a</b>) roll frame; (<b>b</b>) pitch frame.</p>
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<p>Roll frame angle.</p>
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<p>Pitch frame angle.</p>
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<p>Angular rate of roll frame.</p>
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<p>Angular rate of pitch frame.</p>
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<p>Optical axis pitch LOS rate.</p>
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<p>Optical axis yaw LOS rate.</p>
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<p>Error angle: (<b>a</b>) Detector error angle; (<b>b</b>) Pitch and yaw error angle of the Detector.</p>
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<p>Detector error angle in case the DRR exists in the pitch frame.</p>
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<p>Detector error angle in case the DRR exists in the roll frame.</p>
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<p>Pitch frame angle.</p>
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<p>Angular rate of pitch frame.</p>
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<p>Optical axis pitch LOS rate.</p>
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<p>Optical axis yaw LOS rate.</p>
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<p>Error angle: (<b>a</b>) Detector error angle; (<b>b</b>) Pitch and yaw error angle of the Detector.</p>
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<p>Monte Carlo simulation: (<b>a</b>) roll frame; (<b>b</b>) pitch frame.</p>
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25 pages, 954 KiB  
Review
Post-Cardiac Arrest: Mechanisms, Management, and Future Perspectives
by Taline Lazzarin, Carolina Rodrigues Tonon, Danilo Martins, Edson Luiz Fávero, Thiago Dias Baumgratz, Filipe Welson Leal Pereira, Victor Rocha Pinheiro, Raquel Simões Ballarin, Diego Aparecido Rios Queiroz, Paula Schmidt Azevedo, Bertha Furlan Polegato, Marina Politi Okoshi, Leonardo Zornoff, Sergio Alberto Rupp de Paiva and Marcos Ferreira Minicucci
J. Clin. Med. 2023, 12(1), 259; https://doi.org/10.3390/jcm12010259 - 29 Dec 2022
Cited by 24 | Viewed by 9372
Abstract
Cardiac arrest is an important public health issue, with a survival rate of approximately 15 to 22%. A great proportion of these deaths occur after resuscitation due to post-cardiac arrest syndrome, which is characterized by the ischemia-reperfusion injury that affects the role body. [...] Read more.
Cardiac arrest is an important public health issue, with a survival rate of approximately 15 to 22%. A great proportion of these deaths occur after resuscitation due to post-cardiac arrest syndrome, which is characterized by the ischemia-reperfusion injury that affects the role body. Understanding physiopathology is mandatory to discover new treatment strategies and obtain better results. Besides improvements in cardiopulmonary resuscitation maneuvers, the great increase in survival rates observed in recent decades is due to new approaches to post-cardiac arrest care. In this review, we will discuss physiopathology, etiologies, and post-resuscitation care, emphasizing targeted temperature management, early coronary angiography, and rehabilitation. Full article
(This article belongs to the Section Cardiology)
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<p>Post-cardiac arrest management.</p>
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<p>Neuroprognostication algorithm. Abbreviations: EEG—electroencephalogram, SSEP—somatosensory evoked potentials, NSE—neuron-specific enolase, CT—computerized tomography, MRI—Magnetic resonance Imaging. Legends: (1) suppressed background with or without periodic discharges and burst-suppression; (2) Bilateral absence of somatosensory evoked cortical N20-potentials.</p>
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20 pages, 9861 KiB  
Article
Research on Area of Uncertainty of Underwater Moving Target Based on Stochastic Maneuvering Motion Model
by Shasha Ma, Haiyan Wang, Xiaohong Shen, Zhenxin Sun and Ning Sun
Sensors 2022, 22(22), 8837; https://doi.org/10.3390/s22228837 - 15 Nov 2022
Cited by 1 | Viewed by 1441
Abstract
Considering the influence of measurement error on target state estimation, there is an uncertain dispersion region for target position estimate, that is, the area of uncertainty (AOU, area of uncertainty). In underwater target tracking, the state estimation is point estimation without AOU estimation [...] Read more.
Considering the influence of measurement error on target state estimation, there is an uncertain dispersion region for target position estimate, that is, the area of uncertainty (AOU, area of uncertainty). In underwater target tracking, the state estimation is point estimation without AOU estimation and its accuracy is poor in the early stage because of large measurement errors. Fast tracking with higher accuracy and AOU estimation are of great significance to time-sensitive target tracking. To improve the state estimation accuracy in the early stage, and estimate the AOU, a method of AOU estimation of underwater moving target is presented based on a stochastic maneuvering motion (SMM, stochastic maneuvering motion) model. The stochastic maneuvering motion model is established based on the Langevin equation to reflect the movement characteristics of an underwater moving target. Then, the target state is estimated with a noise adaptive Kalman filter by constructing the measurement equation and state equation according to measurement error characteristic and stochastic maneuvering model. Based on the physical significance of the error covariance matrix from the Kalman filter, the parameters of AOU are deduced. Simulation results of underwater target tracking and AOU estimation are presented to demonstrate the relative performance of the proposed algorithm compared with the adaptive Kalman filter. It is clearly shown from the results that SMM tracking algorithm achieves higher accuracy of state estimation in the initial stage of tracking, and the predicted AOU is consistent with the actual distribution of underwater moving targets while yielding more concentrated distribution, which reveals that estimated AOU can be precisely represented by the confidence ellipses. The presented approach and obtained results may be useful in time-sensitive target threat analysis and weapon strike applications. Full article
(This article belongs to the Section Electronic Sensors)
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<p>The schematic diagram of AOU for moving target.</p>
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<p>Target and observer position with estimates.</p>
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<p>Comparison of estimated velocity.</p>
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<p>Comparison of estimated course.</p>
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<p>Comparison of RMSE for estimated velocity and course.</p>
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<p>Comparison of RMSE for estimated position along x axis and y axis.</p>
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<p>Comparison of estimated velocity RMSE between SMM algorithm and adaptive Kalman filter versus different detection error (Scenario 1).</p>
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<p>Comparison of estimated course RMSE between SMM algorithm and adaptive Kalman filter versus different detection error (Scenario 1).</p>
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<p>Comparison of estimated velocity RMSE between SMM algorithm and adaptive Kalman filter versus different detection error (Scenario 7).</p>
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<p>Comparison of estimated course RMSE between SMM algorithm and adaptive Kalman filter versus different detection error (Scenario 7).</p>
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<p>Underwater target tracking and its AOU.</p>
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<p>AOU coverage with 20,000 simulated random points.</p>
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<p>Marginal distribution of AOU.</p>
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<p>RMSE of predicted position versus different prediction time (Scenario 1, <math display="inline"><semantics> <mrow> <msub> <mi>P</mi> <mi>e</mi> </msub> </mrow> </semantics></math> = <math display="inline"><semantics> <mrow> <msub> <mi>P</mi> <mrow> <mi>e</mi> <mn>1</mn> </mrow> </msub> </mrow> </semantics></math>).</p>
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<p>RMSE comparison of predicted position versus different detection error. (<b>a</b>) RMSE of predicted position with seven points. (<b>b</b>) RMSE of predicted position with nine points. (<b>c</b>) RMSE of predicted position with eleven points. (<b>d</b>) RMSE of predicted position with thirteen points.</p>
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<p>AOU semi-major comparison between the SMM algorithm and the adaptive Kalman filter (<math display="inline"><semantics> <mrow> <msub> <mi>P</mi> <mi>e</mi> </msub> </mrow> </semantics></math> = <math display="inline"><semantics> <mrow> <msub> <mi>P</mi> <mrow> <mi>e</mi> <mn>4</mn> </mrow> </msub> </mrow> </semantics></math>).</p>
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<p>AOU semi-minor comparison between the SMM algorithm and the adaptive Kalman filter (<math display="inline"><semantics> <mrow> <msub> <mi>P</mi> <mi>e</mi> </msub> </mrow> </semantics></math> = <math display="inline"><semantics> <mrow> <msub> <mi>P</mi> <mrow> <mi>e</mi> <mn>4</mn> </mrow> </msub> </mrow> </semantics></math>).</p>
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<p>Comparison of estimated AOU size with different measurement errors.</p>
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19 pages, 2757 KiB  
Article
A New Sliding Mode Control Algorithm of IGC System for Intercepting Great Maneuvering Target Based on EDO
by Kang Niu, Xi Chen, Di Yang, Jiaxun Li and Jianqiao Yu
Sensors 2022, 22(19), 7618; https://doi.org/10.3390/s22197618 - 8 Oct 2022
Cited by 4 | Viewed by 1641
Abstract
To intercept the great maneuvering target, combining with the sliding mode and the extended disturbance observer, a new control algorithm for integrated guidance and control (IGC) system is proposed in this paper. Firstly, the paper formulates the Missile–Target problem. Then the paper establishes [...] Read more.
To intercept the great maneuvering target, combining with the sliding mode and the extended disturbance observer, a new control algorithm for integrated guidance and control (IGC) system is proposed in this paper. Firstly, the paper formulates the Missile–Target problem. Then the paper establishes an uncertain IGC dynamic model where the nonlinearities, the perturbations and the maneuvering of the target are regarded as disturbance. Secondly, a second-order disturbance observer is designed to estimate the disturbance and their derivatives.. After this, combining with the second-order disturbance observer, a modified sliding surface and the corresponding reaching law are designed to obtain the rudder deflection command directly. Thus, the real sense of IGC system is achieved. Next, the paper uses the Lyapunov stability theory to prove the stability of the system. Finally, the paper provides different simulation cases, which have different maneuver modes of the target, to demonstrate the superiority of the proposed method in reducing the response time, increasing the rudder response, and having a high interception probability. Full article
(This article belongs to the Section Sensor Networks)
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<p>The relative motion of the missile and target.</p>
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<p>Dynamics of the missile in the pitch plane.</p>
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<p>The maneuver characteristics of the target.</p>
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<p>Missile–Target pursuit trajectory by using EDO and SMCBS.</p>
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<p>(<b>a</b>) The curve of LOS angular rate; (<b>b</b>) The curve of rudder deflection; (<b>c</b>) The curve of the sliding mode surface proposed in this paper; (<b>d</b>) The curve of the pitch angular rate; (<b>e</b>) The curve of the pitch angle; (<b>f</b>) The curve of the attack angle.</p>
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<p>(<b>a</b>) The curve of LOS angular rate; (<b>b</b>) The curve of rudder deflection; (<b>c</b>) The curve of the sliding mode surface proposed in this paper; (<b>d</b>) The curve of the pitch angular rate; (<b>e</b>) The curve of the pitch angle; (<b>f</b>) The curve of the attack angle.</p>
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<p>The maneuver characteristics of the target.</p>
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<p>(<b>a</b>) Missile–Target pursuit trajectory; (<b>b</b>) The curve of the LOS angular rate; (<b>c</b>) The curve of the rudder deflection; (<b>d</b>) The curve of the sliding mode surface; (<b>e</b>) The curve of the pitch angular rate; (<b>f</b>) The curve of the attack angle.</p>
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<p>(<b>a</b>) Missile–Target pursuit trajectory; (<b>b</b>) The curve of the LOS angular rate; (<b>c</b>) The curve of the rudder deflection; (<b>d</b>) The curve of the sliding mode surface; (<b>e</b>) The curve of the pitch angular rate; (<b>f</b>) The curve of the attack angle.</p>
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<p>(<b>a</b>) The miss distance in x and y; (<b>b</b>) The characteristic of the relative distance of M—T.</p>
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30 pages, 6795 KiB  
Article
Simulation-Based Analysis of “What-If” Scenarios with Connected and Automated Vehicles Navigating Roundabouts
by Maria Luisa Tumminello, Elżbieta Macioszek, Anna Granà and Tullio Giuffrè
Sensors 2022, 22(17), 6670; https://doi.org/10.3390/s22176670 - 3 Sep 2022
Cited by 12 | Viewed by 2711
Abstract
Despite the potential of connected and automated vehicles (CAVs), there are still many open questions on how road capacity can be influenced and what methods can be used to assess its expected benefits in the progressive transition towards fully cooperative driving. This paper [...] Read more.
Despite the potential of connected and automated vehicles (CAVs), there are still many open questions on how road capacity can be influenced and what methods can be used to assess its expected benefits in the progressive transition towards fully cooperative driving. This paper contributes to a better understanding of the benefits of CAV technologies by investigating mobility-related issues of automated vehicles operating with a cooperative adaptive cruise control system on roundabout efficiency using microscopic traffic simulation. The availability of the adjustment factors for CAVs provided by the 2022 Highway Capacity Manual allowed to adjust the entry capacity equations to reflect the presence of CAVs on roundabouts. Two mechanisms of entry maneuver based on the entry lane type were examined to compare the capacity target values with the simulated capacities. The microscopic traffic simulator Aimsun Next has been of great help in building the “what-if” traffic scenarios that we analysed to endorse hypothesis on the model parameters which affect the CAVs’ capabilities to increase roundabouts’ throughput. The results highlighted that the increasing penetration rates of CAVs have greater impacts on the operational performances of roundabouts, and provided a synthetic insight to assess the potential benefits of CAVs from an efficiency perspective. Full article
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<p>The summary framework of the proposed methodology. Source: Own research started from data presented in [<a href="#B2-sensors-22-06670" class="html-bibr">2</a>].</p>
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<p>The baseline model for 100% HDVs and the CAV-adjusted roundabout capacity curves under different penetration rates of CAVs for: (<b>a</b>) the one-lane entry conflicted by one circulating lane (where dashed regression is extrapolated beyond the data); (<b>b</b>) the left entry lane of a two-lane entry conflicted by two circulating lanes (where the operational range depends on the geometry under study). Source: Own research based on data presented in [<a href="#B2-sensors-22-06670" class="html-bibr">2</a>].</p>
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<p>The single-lane roundabout (roundabout 1): (<b>a</b>) the sketch of the roundabout; (<b>b</b>) the network model built in Aimsun Next with labels for the centroids (N: North; S: South; E: East; W: West).</p>
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<p>The two-lane roundabout (roundabout 2): (<b>a</b>) the sketch of the roundabout; (<b>b</b>) the network model built in Aimsun Next with labels for the centroids (N: North; S: South; E: East; W: West).</p>
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<p>Comparisons between the CAV-adjusted and simulated entry capacity data for different market penetration rates of CAVs and HDVs for the entry mechanism 1 (i.e., one-lane entry conflicted by one circulating lane) listed as: (<b>a</b>) baseline scenario: 0% CAVs and 100% HDVs; (<b>b</b>) scenario 1: 20% CAVs and 80% HDVs; (<b>c</b>) scenario 2: 40% CAVs and 60% HVs; (<b>d</b>) scenario 3: 60% CAVs and 40% HDVs; (<b>e</b>) scenario 4: 80% CAVs and 20% HDVs; (<b>f</b>) scenario 5: 100% CAVs and 0% HDVs. Notes: to explain the entry mechanisms 1 reference has been made to the eastbound entry in <a href="#sensors-22-06670-f003" class="html-fig">Figure 3</a>a; the black line and dotted blue line regressions were extrapolated by the data.</p>
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<p>Comparisons between the CAV-adjusted and simulated entry capacity data for different market penetration rates of CAVs and HDVs for the entry mechanism 1 (i.e., one-lane entry conflicted by one circulating lane) listed as: (<b>a</b>) baseline scenario: 0% CAVs and 100% HDVs; (<b>b</b>) scenario 1: 20% CAVs and 80% HDVs; (<b>c</b>) scenario 2: 40% CAVs and 60% HVs; (<b>d</b>) scenario 3: 60% CAVs and 40% HDVs; (<b>e</b>) scenario 4: 80% CAVs and 20% HDVs; (<b>f</b>) scenario 5: 100% CAVs and 0% HDVs. Notes: to explain the entry mechanisms 1 reference has been made to the eastbound entry in <a href="#sensors-22-06670-f003" class="html-fig">Figure 3</a>a; the black line and dotted blue line regressions were extrapolated by the data.</p>
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<p>Scattergram analysis to compare the CAV-adjusted and simulated entry capacity data for different proportion of CAVs and HDVs for the entry mechanism 1 (i.e., one-lane entry conflicted by one circulating lane) listed as: (<b>a</b>) baseline scenario: 0% CAVs and 100% HDVs; (<b>b</b>) scenario 1: 20% CAVs and 80% HDVs; (<b>c</b>) scenario 2: 40% CAVs and 60% HVs; (<b>d</b>) scenario 3: 60% CAVs and 40% HDVs; (<b>e</b>) scenario 4: 80% CAVs and 20% HDVs; (<b>f</b>) scenario 5: 100% CAVs and 0% HDVs. Note: to explain the entry mechanisms 1 reference has been made to the eastbound entry in <a href="#sensors-22-06670-f003" class="html-fig">Figure 3</a>a.</p>
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<p>Scattergram analysis to compare the CAV-adjusted and simulated entry capacity data for different proportion of CAVs and HDVs for the entry mechanism 1 (i.e., one-lane entry conflicted by one circulating lane) listed as: (<b>a</b>) baseline scenario: 0% CAVs and 100% HDVs; (<b>b</b>) scenario 1: 20% CAVs and 80% HDVs; (<b>c</b>) scenario 2: 40% CAVs and 60% HVs; (<b>d</b>) scenario 3: 60% CAVs and 40% HDVs; (<b>e</b>) scenario 4: 80% CAVs and 20% HDVs; (<b>f</b>) scenario 5: 100% CAVs and 0% HDVs. Note: to explain the entry mechanisms 1 reference has been made to the eastbound entry in <a href="#sensors-22-06670-f003" class="html-fig">Figure 3</a>a.</p>
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<p>Comparisons between the CAV-adjusted and simulated entry capacity data for different market penetration rates of CAVs and HDVs for the entry mechanism 2 (i.e., the left entry lane of two-lane entry approach conflicted by two circulating lanes) listed as: (<b>a</b>) baseline scenario: 0% CAVs and 100% HDVs; (<b>b</b>) scenario 1: 20% CAVs and 80% HDVs; (<b>c</b>) scenario 2: 40% CAVs and 60% HVs; (<b>d</b>) scenario 3: 60% CAVs and 40% HDVs; (<b>e</b>) scenario 4: 80% CAVs and 20% HDVs; (<b>f</b>) scenario 5: 100% CAVs and 0% HDVs. Notes: to explain the entry mechanisms 2 reference has been made to the northbound left entry lane entry in <a href="#sensors-22-06670-f004" class="html-fig">Figure 4</a>a; the black line and dotted red line regressions were extrapolated by the data.</p>
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<p>Comparisons between the CAV-adjusted and simulated entry capacity data for different market penetration rates of CAVs and HDVs for the entry mechanism 2 (i.e., the left entry lane of two-lane entry approach conflicted by two circulating lanes) listed as: (<b>a</b>) baseline scenario: 0% CAVs and 100% HDVs; (<b>b</b>) scenario 1: 20% CAVs and 80% HDVs; (<b>c</b>) scenario 2: 40% CAVs and 60% HVs; (<b>d</b>) scenario 3: 60% CAVs and 40% HDVs; (<b>e</b>) scenario 4: 80% CAVs and 20% HDVs; (<b>f</b>) scenario 5: 100% CAVs and 0% HDVs. Notes: to explain the entry mechanisms 2 reference has been made to the northbound left entry lane entry in <a href="#sensors-22-06670-f004" class="html-fig">Figure 4</a>a; the black line and dotted red line regressions were extrapolated by the data.</p>
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<p>Scattergram analysis to compare the CAV-adjusted versus simulated entry capacity data for different proportion of CAVs and HDVs for the entry mechanism 2 (i.e., the left entry lane of two-lane entry approach conflicted by two circulating lanes) listed as: (<b>a</b>) baseline scenario: 0% CAVs and 100% HDVs; (<b>b</b>) scenario 1: 20% CAVs and 80% HDVs; (<b>c</b>) scenario 2: 40% CAVs and 60% HDVs; (<b>d</b>) scenario 3: 60% CAVs and 40% HDVs; (<b>e</b>) scenario 4: 80% CAVs and 20% HDVs; (<b>f</b>) scenario 5: 100% CAVs and 0% HDVs. Note: to explain the entry mechanisms 2 reference has been made to the northbound left entry lane entry in <a href="#sensors-22-06670-f004" class="html-fig">Figure 4</a>a.</p>
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<p>Scattergram analysis to compare the CAV-adjusted versus simulated entry capacity data for different proportion of CAVs and HDVs for the entry mechanism 2 (i.e., the left entry lane of two-lane entry approach conflicted by two circulating lanes) listed as: (<b>a</b>) baseline scenario: 0% CAVs and 100% HDVs; (<b>b</b>) scenario 1: 20% CAVs and 80% HDVs; (<b>c</b>) scenario 2: 40% CAVs and 60% HDVs; (<b>d</b>) scenario 3: 60% CAVs and 40% HDVs; (<b>e</b>) scenario 4: 80% CAVs and 20% HDVs; (<b>f</b>) scenario 5: 100% CAVs and 0% HDVs. Note: to explain the entry mechanisms 2 reference has been made to the northbound left entry lane entry in <a href="#sensors-22-06670-f004" class="html-fig">Figure 4</a>a.</p>
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<p>Percentage differences in the “what-if” scenarios compared to the baseline scenario with HDVs only: (<b>a</b>) entry capacity, (<b>b</b>) delay and (<b>c</b>) travel time. Note: (1) 20% CAVs vs. baseline scenario; (2) 40% CAVs vs. baseline scenario; (3) 60% CAVs vs. baseline scenario; (4) 80% CAVs vs. baseline scenario; (5) 100% CAVs vs. baseline scenario.</p>
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25 pages, 4272 KiB  
Article
Deep-Learning-Based Multiple Model Tracking Method for Targets with Complex Maneuvering Motion
by Weiming Tian, Linlin Fang, Weidong Li, Na Ni, Rui Wang, Cheng Hu, Hanzhe Liu and Weigang Luo
Remote Sens. 2022, 14(14), 3276; https://doi.org/10.3390/rs14143276 - 7 Jul 2022
Cited by 10 | Viewed by 2389
Abstract
The effective detection of unmanned aerial vehicle (UAV) targets is of great significance to guarantee national military security and social stability. In recent years, with the development of communication and control technology, the movement of UAVs has become increasingly flexible and complex, presenting [...] Read more.
The effective detection of unmanned aerial vehicle (UAV) targets is of great significance to guarantee national military security and social stability. In recent years, with the development of communication and control technology, the movement of UAVs has become increasingly flexible and complex, presenting diverse trajectory forms and different motion models in different phases. The Gaussian mixture probability hypothesis density filter incorporating the linear Gaussian jump Markov system approach (LGJMS-GMPHD) provides an efficient method for tracking multiple maneuvering targets, as applied to the switching of motions between a set of models in a Markovian chain. However, in practice, the motion model parameters of targets are generally unknown and the model switching is uncertain. When the preset filtering model parameters are mismatched, the tracking performance is dramatically degraded. In this paper, within the framework of the LGJMS-GMPHD filter, a deep-learning-based multiple model tracking method is proposed. First, an adaptive turn rate estimation network is designed to solve the filtering model mismatch caused by unknown turn rate parameters in coordinate turn models. Second, a filter state modification network is designed to solve the large tracking errors in the maneuvering phase caused by uncertain motion model switching. Finally, based on simulations of multiple maneuvering targets in cluttered environments and experimental field data verification, it can be concluded that the proposed method has strong adaptability to multiple maneuvering forms and can effectively improve the tracking performance of targets with complex maneuvering motion. Full article
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<p>Flow diagram of the proposed deep-learning-based multiple model tracking method.</p>
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<p>Structure of the adaptive turn rate estimation network.</p>
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<p>Bi-LSTM structure diagram.</p>
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<p>Structure of the filter state modification network.</p>
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<p>Flowchart of dataset construction.</p>
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<p>Single simulation results for different maneuvering modes: (<b>a</b>) tracking results, (<b>b</b>) turn rate estimates, and (<b>c</b>) tracking errors.</p>
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<p>Single simulation results for different maneuvering modes: (<b>a</b>) tracking results, (<b>b</b>) turn rate estimates, and (<b>c</b>) tracking errors.</p>
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<p>Tracking error comparisons of test datasets: (<b>a</b>) group 1, (<b>b</b>) group 2, (<b>c</b>) group 3, (<b>d</b>) group 4, and (<b>e</b>) group 5.</p>
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<p>Tracking error comparisons of test datasets: (<b>a</b>) group 1, (<b>b</b>) group 2, (<b>c</b>) group 3, (<b>d</b>) group 4, and (<b>e</b>) group 5.</p>
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<p>Simulation scenario. (△—start position, ◯—stop position).</p>
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<p>OSPA distance comparison.</p>
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<p>RMSE of turn rate estimates.</p>
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<p>Tracking results of a single simulation.</p>
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<p>Result comparisons of turn rate estimate: (<b>a</b>) target 1, (<b>b</b>) target 2, (<b>c</b>) target 3, (<b>d</b>) target 4, and (<b>e</b>) target 5.</p>
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<p>Result comparisons of turn rate estimate: (<b>a</b>) target 1, (<b>b</b>) target 2, (<b>c</b>) target 3, (<b>d</b>) target 4, and (<b>e</b>) target 5.</p>
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<p>Experimental scenario.</p>
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<p>Comparisons of real UAV tracking results: (<b>a</b>) GMPHD, (<b>b</b>) GMPHD-ATN, and (<b>c</b>) GMPHD-ATN-FMN.</p>
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20 pages, 3608 KiB  
Article
Ground Maneuvering Target Focusing via High-Order Phase Correction in High-Squint Synthetic Aperture Radar
by Lei Ran, Zheng Liu and Rong Xie
Remote Sens. 2022, 14(6), 1514; https://doi.org/10.3390/rs14061514 - 21 Mar 2022
Cited by 5 | Viewed by 2510
Abstract
Moving target imaging in high-squint synthetic aperture radar (SAR) shows great potential for reconnaissance and surveillance tasks. For the desired resolution, high-squint SAR has a long-time coherent processing interval (CPI). In this case, the maneuvering motion of the moving target usually causes high-order [...] Read more.
Moving target imaging in high-squint synthetic aperture radar (SAR) shows great potential for reconnaissance and surveillance tasks. For the desired resolution, high-squint SAR has a long-time coherent processing interval (CPI). In this case, the maneuvering motion of the moving target usually causes high-order phase terms in the echoed data, which cannot be neglected for precise focusing. Many ground moving target imaging (GMTIm) algorithms have been proposed in the literature, but some high-order phase terms remain uncompensated in high-squint SAR. For this problem, a high-order phase correction-based GMTIm (HPC-GMTIm) method is proposed in this paper. We assumed that the target of interest has a constant velocity in the subaperture CPI, but maneuvering motion parameters for the whole CPI. Within the short subaperture CPI, the target signal can be simplified as a three-order phase expression, and the instantaneous Doppler frequency (DF) was estimated by some time–frequency analysis tools, including the Hough transform and the fractional Fourier transform. For the whole CPI, the subaperture, the instantaneous DF was combined to form a total least-squares problem, outputting the undetermined phase coefficients. Using the proposed local-to-global processing chain, all high-order phase terms can be estimated and corrected, which outperforms existing methods. The effectiveness of the HPC-GMTIm method is demonstrated by real measured high-squint SAR data. Full article
(This article belongs to the Special Issue Radar High-Speed Target Detection, Tracking, Imaging and Recognition)
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<p>High-squint SAR geometry with a ground maneuvering moving target.</p>
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<p>Range: Please add bold for abc in figure, same as others. cell migration and azimuth phase comparison. (<b>a</b>) Linear range walk difference. (<b>b</b>) Quadratic phase difference. (<b>c</b>) Third-order phase difference.</p>
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<p>Flowchart of the proposed HPC-GMTIm algorithm.</p>
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<p>Subaperture processing results. The whole aperture is divided into 8 subapertures, and all 8 subaperture images are well focused by the proposed HPC-GMTIm algorithm.</p>
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<p>Whole aperture image. (<b>a</b>) HPC-GMTIm algorithm. (<b>b</b>) GHHAF method. (<b>c</b>) Cross-range profile comparison.</p>
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<p>Moving target detection for T1. (<b>a</b>) Range–Doppler domain. (<b>b</b>) Moving target detection result.</p>
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<p>The stationary scene image after eliminating the energy of T1.</p>
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<p>The envelope of T1. (<b>a</b>) Before correction. (<b>b</b>) After correction.</p>
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<p>The imaging result of T1. (<b>a</b>) HPC-GMTIm (entropy = 2.97). (<b>b</b>) GHHAF method (entropy = 3.36).</p>
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<p>The stationary scene image containing moving target T2.</p>
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<p>Moving target detection for T2. (<b>a</b>) Subaperture images before detection. (<b>b</b>) Subaperture images after detection.</p>
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<p>The envelope of T2. (<b>a</b>) Before correction. (<b>b</b>) After correction.</p>
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<p>The imaging result of T2. (<b>a</b>) HPC-GMTIm (entropy = 3.62). (<b>b</b>) GHHAF method (entropy = 4.17).</p>
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<p>Moving target detection for T3. (<b>a</b>) Range–Doppler domain. (<b>b</b>) Moving target detection result.</p>
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<p>The stationary scene image corresponding to T3.</p>
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<p>The envelope of T3. (<b>a</b>) Before correction. (<b>b</b>) After correction.</p>
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<p>The imaging result of T3. (<b>a</b>) HPC-GMTIm (entropy = 2.48). (<b>b</b>) GHHAF method (entropy = 2.81).</p>
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<p>The stationary scene containing moving target T4.</p>
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<p>Moving target detection for T4. (<b>a</b>) Subaperture images before detection. (<b>b</b>) Subaperture images after detection.</p>
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<p>The envelope of T4. (<b>a</b>) Before RCMC. (<b>b</b>) After RCMC.</p>
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<p>The imaging result of T4. (<b>a</b>) HPC-GMTIm (entropy = 3.46). (<b>b</b>) GHHAF method (entropy = 4.03).</p>
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14 pages, 10399 KiB  
Review
Targeting Autophagy to Counteract Obesity-Associated Oxidative Stress
by Federico Pietrocola and José Manuel Bravo-San Pedro
Antioxidants 2021, 10(1), 102; https://doi.org/10.3390/antiox10010102 - 12 Jan 2021
Cited by 52 | Viewed by 4343
Abstract
Reactive oxygen species (ROS) operate as key regulators of cellular homeostasis within a physiological range of concentrations, yet they turn into cytotoxic entities when their levels exceed a threshold limit. Accordingly, ROS are an important etiological cue for obesity, which in turn represents [...] Read more.
Reactive oxygen species (ROS) operate as key regulators of cellular homeostasis within a physiological range of concentrations, yet they turn into cytotoxic entities when their levels exceed a threshold limit. Accordingly, ROS are an important etiological cue for obesity, which in turn represents a major risk factor for multiple diseases, including diabetes, cardiovascular disorders, non-alcoholic fatty liver disease, and cancer. Therefore, the implementation of novel therapeutic strategies to improve the obese phenotype by targeting oxidative stress is of great interest for the scientific community. To this end, it is of high importance to shed light on the mechanisms through which cells curtail ROS production or limit their toxic effects, in order to harness them in anti-obesity therapy. In this review, we specifically discuss the role of autophagy in redox biology, focusing on its implication in the pathogenesis of obesity. Because autophagy is specifically triggered in response to redox imbalance as a quintessential cytoprotective mechanism, maneuvers based on the activation of autophagy hold promises of efficacy for the prevention and treatment of obesity and obesity-related morbidities. Full article
(This article belongs to the Special Issue Oxidative Stress in Obesity)
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<p>Obesity and oxidative stress. Cell intrinsic and cell extrinsic factors related to obesity, including inflammation, hyperglycemia, hyperleptinemia, hyperlipidemia, reduced adiponectin levels, obstructive sleep apnea (OSA), or mitochondria-associated Endoplasmic Reticulum (ER) membranes (MAMs) defects, can exacerbate the production of reactive oxygen species (ROS). ROS account for the induction of a detrimental lipogenic response (dependent on SREBP1 and fatty acid synthase (FAS)), which contributes to, or worsens, the obese phenotype.</p>
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<p>Molecular mechanisms of autophagy. In response to diverse stimuli, the activation of AMPK and/or the inhibition of mTORC1 stimulate the function of the ULK1 complex, which in turn activates the BECN1/VPS34 complex, starting the formation of the phagophore. Several ATG proteins catalyze the conjugation of the cargo adaptor LC3 to PE residues on the expanding phagophore membrane. Mature double membrane autophagosome loaded with its cargo eventually undergoes fusion with the lysosome, whereby its content is degraded and recycled. AMPK, 5′-adenosine monophosphate (AMP)-activated protein kinase; ATG, autophagy-related proteins; BECN1, beclin-1; CAV1, Caveolin 1, ER, endoplasmic reticulum; LC3, light chain of protein 1 associated to microtubules 3; MTOR, mechanistic target of rapamycin; PE, phosphatidylethanolamine; SQSTM1, sequestosome 1 protein (p62); ULK, UNC-51–like kinase.</p>
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<p>Reactive oxygen species–mediated autophagy induction. Autophagy is induced by ROS at different levels across the machinery, including initiation (through direct or indirect ROS-mediated modulation of AMPK and mTORC1 activity); nucleation, via Caveolin-1 or PKD-dependent activation of the VPS34/BECN1 complex and elongation, through ROS-dependent activation of Atg4. KEAP1. AMPK, 5′-adenosine monophosphate (AMP)-activated protein kinase; ATG, autophagy related proteins; ATM, ataxia-telangiectasia mutated; BECN1, beclin-1; ER, endoplasmic reticulum; KEAP1, Kelch ECH associating protein 1; LC3, light chain of protein 1 associated to microtubules 3; MTOR, mechanistic target of rapamycin; NRF2, nuclear factor erythroid 2-related factor 2; PE, phosphatidylethanolamine; PKD, protein kinase D; PTEN, phosphatase and tensin homolog; SQSTM1, sequestosome 1 protein (p62); ULK, UNC-51–like kinase.</p>
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16 pages, 3839 KiB  
Technical Note
A Novel Radar Detection Method for Sensing Tiny and Maneuvering Insect Migrants
by Rui Wang, Jiong Cai, Cheng Hu, Chao Zhou and Tianran Zhang
Remote Sens. 2020, 12(19), 3238; https://doi.org/10.3390/rs12193238 - 5 Oct 2020
Cited by 10 | Viewed by 2776
Abstract
The use of radar to monitor insect migration is of great significance for pest control and biological migration mechanism research. However, migrating insects usually have small radar-cross-section (RCS) and are accompanied by maneuvering. The current radar detection algorithms mainly have contradictions in detection [...] Read more.
The use of radar to monitor insect migration is of great significance for pest control and biological migration mechanism research. However, migrating insects usually have small radar-cross-section (RCS) and are accompanied by maneuvering. The current radar detection algorithms mainly have contradictions in detection performance and computational complexity. So it is difficult for traditional radar detection algorithms to detect them effectively. Hence, a novel coherent integration detection algorithm based on dynamic programming (DP) and fractional Fourier transforming (FrFT) is proposed. By combining the advantages of DP and FrFT, the proposed DP-FrFT method can quickly search the target track, and simultaneously perform parameters estimation and motion compensation, achieving high integration gain with relatively low time consumption. The high efficiency of the method is verified with a large number of simulations and sufficient field experiments. Full article
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<p>The processing result of a typical piece of data. (<b>a</b>) is the time-range image of the typical data; (<b>b</b>) is the time-velocity image of the target after short-time Fourier transform</p>
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<p>The histogram of acceleration of 4600 insects.</p>
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<p>The flowchart of the integration algorithm based on dynamic programming and fractional Fourier transforming (DP-FrFT).</p>
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<p>The integration gain in different methods. (<b>a</b>) is the integration gain with the number of integrated pulse in moving target detector (MTD); (<b>b</b>) is the result in Keystone-MTD; (<b>c</b>) is the result in fractional Fourier transforming (FrFT); (<b>d</b>) is the result in DP-FrFT (our method).</p>
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<p>Time-consuming of different methods.</p>
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<p>Detection probability of four methods under different signal-to-noise ratios (SNRs).</p>
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<p>The motion parameters estimation errors of two methods. (<b>a</b>) shows the different speed error with SNR in our method and Drake’s; (<b>b</b>) shows the different acceleration error with SNR in our method and Drake’s.</p>
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<p>The radar system and its working environment. (<b>a</b>) shows the Ku-band vertical-beam entomological radar; (<b>b</b>) shows the working environment of the radar.</p>
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<p>The typical detection result by MTD and DP-FrFT. (<b>a</b>) is the time-range image corresponding to the detection result; (<b>b</b>) is the detection results by MTD; (<b>c</b>) is the detection results by DP-FrFT.</p>
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18 pages, 2658 KiB  
Article
M3C: Multimodel-and-Multicue-Based Tracking by Detection of Surrounding Vessels in Maritime Environment for USV
by Dalei Qiao, Guangzhong Liu, Jun Zhang, Qiangyong Zhang, Gongxing Wu and Feng Dong
Electronics 2019, 8(7), 723; https://doi.org/10.3390/electronics8070723 - 26 Jun 2019
Cited by 16 | Viewed by 4750 | Correction
Abstract
It is crucial for unmanned surface vessels (USVs) to detect and track surrounding vessels in real time to avoid collisions at sea. However, the harsh maritime environment poses great challenges to multitarget tracking (MTT). In this paper, a novel tracking by detection framework [...] Read more.
It is crucial for unmanned surface vessels (USVs) to detect and track surrounding vessels in real time to avoid collisions at sea. However, the harsh maritime environment poses great challenges to multitarget tracking (MTT). In this paper, a novel tracking by detection framework that integrates the multimodel and multicue (M3C) pipeline is proposed, which aims at improving the detection and tracking performance. Regarding the multimodel, we predicted the maneuver probability of a target vessel via the gated recurrent unit (GRU) model with an attention mechanism, and fused their respective outputs as the output of a kinematic filter. We developed a hybrid affinity model based on multi cues, such as the motion, appearance, and attitude of the ego vessel in the data association stage. By using the proposed ship re-identification approach, the tracker had the capability of appearance matching via metric learning. Experimental evaluation of two public maritime datasets showed that our method achieved state-of-the-art performance, not only in identity switches (IDS) but also in frame rates. Full article
(This article belongs to the Special Issue Smart, Connected and Efficient Transportation Systems)
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<p>The architecture of our proposed M<sup>3</sup>C tracking by detection pipeline. It comprises eight modules, among which the video stabilization unit uses the algorithm introduced by [<a href="#B33-electronics-08-00723" class="html-bibr">33</a>]. We proposed the four blue units, and their interaction with the other three green units is discussed in detail later.</p>
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<p>Framework of the detector. Among them, Darknetconv2d_BN_Leaky (DBL) is the basic unit, which consists of a convolutional layer (conv), batch normalization, and a leaky rectified linear unit (ReLU).</p>
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<p>Typical structure of a gated recurrent unit (GRU) neural network. <math display="inline"> <semantics> <mrow> <msub> <mi>O</mi> <mi>t</mi> </msub> <mo stretchy="false">(</mo> <msub> <mi>h</mi> <mi>t</mi> </msub> <mo stretchy="false">)</mo> </mrow> </semantics> </math> is the output at time <math display="inline"> <semantics> <mi>t</mi> </semantics> </math>; <math display="inline"> <semantics> <mrow> <msub> <mi>r</mi> <mi>t</mi> </msub> </mrow> </semantics> </math> denotes the reset gate, which determines the combination of current input and historical memory information; and, <math display="inline"> <semantics> <mrow> <msub> <mi>z</mi> <mi>t</mi> </msub> </mrow> </semantics> </math> is the update gate, which determines the proportion of memory left behind.</p>
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<p>The improved framework of the GRU encoder–decoder with attention. The attention model was embedded between encoders and decoders and learned the attention weights <math display="inline"> <semantics> <mrow> <msub> <mi>c</mi> <mrow> <mi>t</mi> <mo>−</mo> <mi>N</mi> <mi>τ</mi> <mo> </mo> </mrow> </msub> <mo>,</mo> <mo>…</mo> <mo>,</mo> <msub> <mi>c</mi> <mrow> <mi>t</mi> <mo>−</mo> <mi>τ</mi> </mrow> </msub> <mo>,</mo> <msub> <mi>c</mi> <mi>t</mi> </msub> <mo>,</mo> <msub> <mi>c</mi> <mrow> <mi>t</mi> <mo>+</mo> <mi>τ</mi> </mrow> </msub> </mrow> </semantics> </math> via the fully-connected network (FC) and softmax with loss function, output vector of encoder <math display="inline"> <semantics> <mrow> <msub> <mi>h</mi> <mrow> <mi>t</mi> <mo>−</mo> <mi>N</mi> <mi>τ</mi> <mo> </mo> </mrow> </msub> <mo>,</mo> <mo>…</mo> <mo>,</mo> <msub> <mi>h</mi> <mrow> <mi>t</mi> <mo>−</mo> <mi>τ</mi> </mrow> </msub> <mo>,</mo> <msub> <mi>h</mi> <mi>t</mi> </msub> <mo>,</mo> <msub> <mi>h</mi> <mrow> <mi>t</mi> <mo>+</mo> <mi>τ</mi> </mrow> </msub> </mrow> </semantics> </math>, and state vector of decoder <math display="inline"> <semantics> <mrow> <msub> <mi>s</mi> <mrow> <mi>t</mi> <mo>−</mo> <mo stretchy="false">(</mo> <mi>N</mi> <mo>+</mo> <mn>1</mn> <mo stretchy="false">)</mo> <mi>τ</mi> </mrow> </msub> <mo>,</mo> <msub> <mi>s</mi> <mrow> <mi>t</mi> <mo>−</mo> <mi>N</mi> <mi>τ</mi> </mrow> </msub> <mo>,</mo> <mo>…</mo> <mo>,</mo> <msub> <mi>s</mi> <mrow> <mi>t</mi> <mo>−</mo> <mi>τ</mi> </mrow> </msub> <mo>,</mo> <msub> <mi>s</mi> <mi>t</mi> </msub> </mrow> </semantics> </math> as the attention model’s input sequence.</p>
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<p>Sketch map of adaptive association gate of appearance.</p>
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<p>Visual tracking results of video sequence (MVI_1448_VIS_Haze) with occlusion. Six vessels have been stably tracked in frame #0126 (<b>a</b>). Starting in frame #0264 (<b>b</b>), Sb001 was occluded by Tug001 until being completely occluded in frame #0355 (<b>c</b>) and then reappeared in frame #0370 until it was completely visible in frame #0438 as shown in (<b>d</b>).</p>
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<p>Visual tracking results of video sequence (MVI_1448_VIS_Haze) with occlusion. Six vessels have been stably tracked in frame #0126 (<b>a</b>). Starting in frame #0264 (<b>b</b>), Sb001 was occluded by Tug001 until being completely occluded in frame #0355 (<b>c</b>) and then reappeared in frame #0370 until it was completely visible in frame #0438 as shown in (<b>d</b>).</p>
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<p>Visual tracking results of video sequence (MVI_0799_VIS_OB) with reappear after lost. In frame #0075 (<b>a</b>), a vessel has been stably tracked. Due to the rolling of the ego vessel, Passenger001 gradually disappeared from the camera scene in frame #0076 until frame #0078 (<b>b</b>), when it completely disappeared. Subsequently, it began to reappear in frame #0091 until frame #0094 (<b>c</b>), when it was completely visible. As shown in frame #0095 (<b>d</b>), the vessel was re-tracked steadily.</p>
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4895 KiB  
Article
Fuzzy Neural Network-Based Interacting Multiple Model for Multi-Node Target Tracking Algorithm
by Baoliang Sun, Chunlan Jiang and Ming Li
Sensors 2016, 16(11), 1823; https://doi.org/10.3390/s16111823 - 1 Nov 2016
Cited by 11 | Viewed by 5776
Abstract
An interacting multiple model for multi-node target tracking algorithm was proposed based on a fuzzy neural network (FNN) to solve the multi-node target tracking problem of wireless sensor networks (WSNs). Measured error variance was adaptively adjusted during the multiple model interacting output stage [...] Read more.
An interacting multiple model for multi-node target tracking algorithm was proposed based on a fuzzy neural network (FNN) to solve the multi-node target tracking problem of wireless sensor networks (WSNs). Measured error variance was adaptively adjusted during the multiple model interacting output stage using the difference between the theoretical and estimated values of the measured error covariance matrix. The FNN fusion system was established during multi-node fusion to integrate with the target state estimated data from different nodes and consequently obtain network target state estimation. The feasibility of the algorithm was verified based on a network of nine detection nodes. Experimental results indicated that the proposed algorithm could trace the maneuvering target effectively under sensor failure and unknown system measurement errors. The proposed algorithm exhibited great practicability in the multi-node target tracking of WSNs. Full article
(This article belongs to the Special Issue Scalable Localization in Wireless Sensor Networks)
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<p>Interacting multiple model (IMM) algorithm principle frame.</p>
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<p>Membership functions of (<b>a</b>) <b>EoR</b> and (<b>b</b>) Δ<b>R</b>.</p>
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<p>Structure of the single-node fuzzy neural network (FNN) inference machine.</p>
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<p>Principle frame graph of FNN fusion system (FNNFS).</p>
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<p>Decision functions of (<b>a</b>) <b>EoR</b> and (<b>b</b>) <b>R</b>.</p>
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<p>Structure of the multi-node FNN.</p>
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<p>Detected target trajectory of the net nodes. (<b>a</b>) Detected trajectory of node 1; (<b>b</b>) Detected trajectory of node 2; (<b>c</b>) Detected trajectory of node 3; (<b>d</b>) Detected trajectory of node 4.</p>
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<p>Computational results of the FNN–IMM. (<b>a</b>) Position error of each node. (<b>b</b>) Estimated trajectory of Nodes 1, 2, and 3 and the network output.</p>
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<p>Computational results of FNN–IMM, IMM-UKF, IMM-EKF, and VB-IMM. (<b>a</b>) Mean trajectory after 100 Monte Carlo trials. (<b>b</b>) Estimation errors of target position by FNN-IMM, IMM-UKF, IMM-EKF, and VB-IMM.</p>
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<p>Target positional errors of the network outputs and Node 3.</p>
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119 KiB  
Article
An Improved Particle Filter for Target Tracking in Sensor Systems
by Xue Wang, Sheng Wang and Jun-Jie Ma
Sensors 2007, 7(1), 144-156; https://doi.org/10.3390/s7010144 - 29 Jan 2007
Cited by 76 | Viewed by 14063
Abstract
Sensor systems are not always equipped with the ability to track targets. Sudden maneuvers of a target can have a great impact on the sensor system, which will increase the miss rate and rate of false target detection. The use of the generic [...] Read more.
Sensor systems are not always equipped with the ability to track targets. Sudden maneuvers of a target can have a great impact on the sensor system, which will increase the miss rate and rate of false target detection. The use of the generic particle filter (PF) algorithm is well known for target tracking, but it can not overcome the degeneracy of particles and cumulation of estimation errors. In this paper, we propose an improved PF algorithm called PF-RBF. This algorithm uses the radial-basis function network (RBFN) in the sampling step for dynamically constructing the process model from observations and updating the value of each particle. With the RBFN sampling step, PF-RBF can give an accurate proposal distribution and maintain the convergence of a sensor system. Simulation results verify that PF-RBF performs better than the Unscented Kalman Filter (UKF), PF and Unscented Particle Filter (UPF) in both robustness and accuracy whether the observation model used for the sensor system is linear or nonlinear. Moreover, the intrinsic property of PF-RBF determines that, when the particle number exceeds a certain amount, the execution time of PF-RBF is less than UPF. This makes PF-RBF a better candidate for the sensor systems which need many particles for target tracking. Full article
(This article belongs to the Special Issue Intelligent Sensors)
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<p>The shape of function <span class="html-italic">φ</span>(<span class="html-italic">z</span>) with <span class="html-italic">σ</span> = 1.</p>
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<p>Plot of estimated results generated from a single run of the different filters with non-stationary observation model.</p>
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<p>Errors of different filters versus the process noises in a single run.</p>
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<p>The average RMSEs of three algorithms calculated over 100 independent runs with the linear and non-linear observation model.</p>
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<p>The average execution time of three particle filters for 60 steps tracking over 100 independent runs.</p>
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