Dense visual prediction tasks, including object detection and segmentation, inherently require precise and discriminative positional information to delineate object boundaries and pixel regions. Recent DETR-based frameworks advance dense prediction tasks through iterative attention applied to content queries, with sampled proposals as position references. However, this paradigm suffers from the misaligned sampling distribution and insufficient interaction between the content and position features, thereby limiting the encoding effectiveness. To overcome these limitations, we investigate the encoding paradigm for content-position harmonization and propose an effective predictor for dense visual tasks, termed DAPE (DETR with hArmonized content-Position Encoding). DAPE introduces explicit position encoding to facilitate content enhancement while maintaining low memory overhead. To achieves this process, DAPE comprises a Shifted Query Sampler (SQS) that enforces strict alignment between the distributions of content and position queries, and a 2D Low-Rank Position Encoder (LRPE) that progressively modulates attention maps based on the aligned representations. DAPE provides a unified solution for various dense prediction tasks. Extensive experiments on object detection, instance segmentation, and few-shot detection benchmarks demonstrate that DAPE achieves state-of-the-art performance while reducing memory consumption.

In multi-robot coverage control, ground robots aim to cover and monitor a domain optimally. However, when covering an extensive domain like a densely forested potential fire site, the sensing capabilities of ground robots are limited, resulting in poor coverage. Leveraging the aerial robots’ ability to expand sensing ranges through high-altitude flight, this paper proposes a fully distributed, air-ground coverage control scheme to address this challenge. First, aerial robots provide a low-resolution coverage of the domain. Then, they use coarse but broad sensing information to guide ground robots, with short-range but high-resolution sensing, to achieve a high-resolution coverage. Simultaneously, each aerial robot dynamically adjusts its cell size to match its load, enhancing the coverage performance. The convergence of the control scheme is proved and its performance is evaluated through simulations and experiments.

Traffic signal control (TSC) is still one of the most challenging and promising research issues in the field of transportation. Since traditional methods have difficulty in handling dynamically changing traffic flows, reinforcement learning (RL) methods have been introduced into TSC. However, the cost of practical application is critically high due to multiple sampling trials and long learning process. The Transformer architecture has recently attained remarkable results in natural language processing (NLP), but when applied to the field of RL, the standard Transformer architecture is difficult to optimize and faces the problem of hyperparameter sensitivity. In the paper, we transform TSC into a sequence modeling issue and propose a new evolution Transformer architecture to adjust the autoregressive model through reward, past states and actions in the traffic environment to directly generate the best predicted action. In addition, we use the feature evolution module (FEM) instead of residual connections to make the learning process more stable and efficient. Through experiments on public datasets, we demonstrate that our ETLight model achieves a state-of-the-art (SOTA): 1) It achieves the overall best performance on average travel time (ATT) metric, with improvements of up to 6.85%, 3.73% and 3.10% over the best conventional, RL and Transformer methods, respectively; 2) It has a more stable learning process, faster learning speed and better convergence compared to published TSC methods so far; and; 3) it has good robustness and is less sensitive to hyperparameter selection.

As industrial manufacturing quality standards rise, demand for advanced defect detection models has surged. Compared to generic objects, industrial defects exhibit more diverse and complex shapes and sizes. Traditional detection models typically process each instance in isolation, leading to incomplete detections (e.g. fragmented or redundant bounding boxes) when facing such complex defect patterns. To address these challenges, we propose Relational Enhancement Network for defect detection, which enhances defect features by exploring implicit spatial and semantic relations. Our model introduces a position embedding module to map geometric features into a high-dimensional space. A relational enhancement module is proposed to integrate geometric and semantic features, capturing complex interactions among defects to enhance the original features. This process is dynamically adjusted through a relational refining mechanism. The proposed position-sensitive loss further aligns classification task with localization task using spatial metrics. Experiments on three industrial defect benchmark datasets (metals, bearings, engines, and LEDs) show our method outperforms state-of-the-art approaches in detection precision and addresses incomplete defect detection. Additionally, our method exhibits strong transferability, theoretically offering clear improvements to any similar-structured methods. The code is available at https://github.com/lhht/Relational-Enhancement-Network

Probability prediction of photovoltaic power plays an important role in improving photovoltaic absorption capacity. Conditional diffusion model takes numerical weather prediction (NWP) data as input, improving the performance of photovoltaic power day-ahead probability prediction. However, with the improvement of NWP system, there is some redundancy in NWP data. In addition, the previous research on diffusion model did not consider the temporal and spatial correlation between photovoltaic power stations, so there is room for further improvement in performance. Therefore, a day-to-day forecasting method of photovoltaic power interval based on spatio-temporal fusion diffusion model is proposed. Firstly, Pearson and mutual information are used to analyze NWP data to reduce the input dimension of the model. Secondly, a spatio-temporal fusion diffusion model based on graph attention networks and Transformer is constructed to make full use of the spatio-temporal correlation between photovoltaic power stations. Then, the inverse diffusion method of denoising diffusion implicit model is constructed, and multiple groups of photovoltaic power data are generated based on the same NWP input, and the kernel density is estimated and analyzed to obtain the prediction interval. Finally, experiments are carried out on public data sets and compared with other algorithms. The results show that the proposed method can achieve higher comprehensive probability prediction performance.

Despite the significant advancements made in industrial defect detection, accurately and timely identifying complex and small-sized defects remains a challenge. Most current lightweight defect detectors are unable to fully extract both global and local contextual information due to their simplified network architectures. To address the above issues, this paper introduces a novel real-time detector DSK-YOLO, which efficiently enhances global and local contextual information with a lower number of parameters. Specifically, DSK-YOLO comprises two key components: DSKblock and DSKSR. The DSKblock employs dilated separable kernels to expand the effective receptive fields (ERFs) without deep layer stacking, thereby identifying complex defects. For small-sized defects detection, we develop a feature-level super resolution (SR) auxiliary branch to enhance local contextual information in the training phase. Moreover, the train-only SR branch brings no extra computational overhead for inference, making it an impressive choice for real-time tasks. Experimental results demonstrate that, on the industrial datasets NEU-DET and ESD, DSK-YOLO achieves mAP of 45.7% and 64.8%, which are 1.4% and 1.0% higher than those of the baseline model YOLOv8n. Our proposed DSK-YOLO offers a favorable tradeoff between precision and parameters compared to state-of-the-art models.

This letter is concerned with a three-dimensional target motion analysis issue using azimuth and elevation measurements. The nonlinear relationship between these measurements and target dynamics often poses challenges for conventional methods, especially in high-noise environments. To address this challenge, a novel multi-agent deep reinforcement learning (MADRL)-based estimator is proposed for target motion parameter estimation. Specifically, by modeling each component of the target motion parameter as an individual agent, the target motion parameter estimation process is framed as a cooperative Markov game. An MADRL framework is then introduced to solve this problem. Simulation results demonstrate that the proposed algorithm achieves higher estimation accuracy than existing estimators.

Information-based autonomous robot exploration methods, aiming to maximize the exploration rewards, e.g., mutual information (MI), get more prevalent in field robotics applications. However, most MI-based exploration methods assume known poses or use inaccurate pose uncertainty approximation, which may lead to deviation or even failure when exploring prior unknown environments. In this paper, we explicitly consider full-state (pose & map) uncertainty for balancing exploration and localizability, i.e., avoiding the robot guiding itself to complex scenes with high exploration rewards but hard to localize. We first propose a Rao-Blackwellized particle filter-based localization and mapping framework (RBPF-CLAM) for a dense environmental map with continuous occupancy distribution. Then we develop a new closed-form particle weighting method to improve the localization accuracy and robustness. We further use these weighted particles to approximate the unknown pose uncertainty and combine it with our previous confidence-rich mutual information (CRMI) metric to evaluate the expected information utility of the robot’s new control actions. This new information metric is calleduncertainCRMI (UCRMI). Dataset experiments show our RBPF-CLAM improves about 44.7% average root mean square error than the state-of-the-art RBPF localization method, and real-world experimental results show that our UCRMI reduces the pose uncertainty about 32.85% more than CRMI and 25.36% time cost than UGPVR in the exploration of unknown and unstructured scenes given sparse measurements, which shows better performance than other state-of-the-art information metrics.Note to Practitioners—This work was motivated by the problem of ‘planning for state estimation’ for a range-sensing robot, i.e., the robot can choose a better future place to facilitate its localization more accurately and explore new areas rationally to gather more information. Existing methods mainly assume the robot’s poses during the exploration can be estimated by an independent localization approach or simply propagated via a predefined probabilistic distribution. However, localization failure would lead to higher planning deviation for the planner that does not consider the pose uncertainty, and manually set parametric distribution is more prone to overestimate the pose uncertainty. This paper proposes an RBPF-based localization and mapping scheme and an improved particle weight update method in a confidence-rich map, then uses the weighted particles to approximate trajectory entropy and combines it with CRMI to evaluate the expected information gain of a candidate action/node. Our newly defined information function ‘UCRMI’ can prevent the robot from exploring too aggressively without considering its localizability in prior unknown and unstructured environments. These scenes may lack robust features to conduct feature-based SLAM or lack accurate external localization information such as GPS. This method can be applied in underwater, planetary, and subterranean robot exploration tasks, even using low-resolution sensors. Future work mainly involves adapting UCRMI to applications in large-scale scenes using small autonomous platforms.

DETR-like methods have significantly increased detection performance in an end-to-end manner. The main-stream two-stage frameworks of them perform dense self-attention and select a fraction of queries for sparse cross-attention, which is proven effective for improving performance but also introduces a heavy computational burden and high dependence on stable query selection. This paper demonstrates that suboptimal two-stage selection strategies result in scale bias and redundancy due to the mismatch between selected queries and objects in two-stage initial-ization. To address these issues, we propose hierarchical salience filtering refinement, which performs transformer encoding only on filtered discriminative queries, for a bet-ter trade-off between computational efficiency and precision. The filtering process overcomes scale bias through a novel scale-independent salience supervision. To com-pensate for the semantic misalignment among queries, we introduce elaborate query refinement modules for stable two-stage initialization. Based on above improvements, the proposed Salience DETR achieves significant improvements of +4.0% AP, +0.2% AP, +4.4% AP on three challenging task-specific detection datasets, as well as 49.2% AP on COCO 2017 with less FLOPs. The code is available at https://github.com/xiuqhou/Salience-DETR.

To handle the non-stationarity of the environment and the curse of dimensionality issues in multi-agent reinforcement learning, gathering information through communication is a critical part. Existing frameworks have proposed centralized or distributed structures to deal with the problem. However, they either have problems of robustness or problems of high communication costs. This paper adopts a hierarchical zeroth-order policy optimization (HZOPO) algorithm for cooperative multi-agent reinforcement learning (MARL) problems. The agents are divided into different groups with high-and low-level entities. A hierarchical communication structure is implemented to reach global consensus. It is shown that the HZOPO algorithm can balance both convergence and communication efficiency in cooperative MARL environments. The convergence of the algorithm is also proved.

This paper investigates the problem of distributed target tracking via underwater acoustic sensor networks (UASNs) with fading channels. The degradation of signal quality due to wireless channel fading can significantly impact network reliability and subsequently reduce the tracking accuracy. To address this issue, we propose a modified distributed unscented Kalman filter (DUKF) named DUKF-Fc, which takes into account the effects of measurement fluctuation and transmission failure induced by channel fading. The channel estimation error is also considered when designing the estimator and a sufficient condition is established to ensure the stochastic boundedness of the estimation error. The proposed filtering scheme is versatile and possesses wide applicability to numerous scenarios, e.g., tracking a maneuvering underwater target with underwater sensor nodes (USNs) equipped with acoustic sensors. Considering the constraints of network energy resources, the issue of investigating the energy cost of DUKF-Fc is discussed in the simulation and accordingly, the results demonstrate the robustness and energy-efficiency of the proposed filtering procedure.

The localization of underwater acoustic sensor networks (UASNs) has emerged as a critical research area in the marine information fusion field. Generally, the convex optimization method is adopted to solve the localization problem. However, this method has limitations in complex underwater environments, since it is difficult to transform the nonconvex optimization problem into a convex optimization problem under such conditions. Recently, deep reinforcement learning (DRL) has shown great potential and promise in solving intricate optimization tasks. Motivated by this, we propose to adopt DRL for UASNs localization to improve accuracy and robustness. The key challenge is that existing DRL-based methods require discretization of the environment, which leads to a compromise between search time and localization precision. To address this challenge, we first model the localization problem as a Markov decision process (MDP) with continuous state and action spaces and subsequently introduce a continuous control DRL framework to solve the localization problem. Within this framework, we develop three continuous control DRL-based localization estimators to address the localization problem in unsupervised, supervised, and semisupervised scenarios. Comprehensive simulations demonstrate the effectiveness of our approach, as the proposed solutions exhibit several advantageous features compared to traditional methods, such as: 1) compared with the convex optimization-based method, the convex relaxation is not required; 2) compared with the least squares method, the proposed estimators are capable of converging to a global optimal state; and 3) compared with the discrete control DRL method, the proposed estimators reduce localization time and enhance localization accuracy significantly.

Currently, decarbonization has become an emerging trend in the power system arena. However, the increasing number of photovoltaic units distributed into a distribution network may result in voltage issues, providing challenges for voltage regulation across a large-scale power grid network. Reinforcement learning based intelligent control of smart inverters and other smart building energy management (EM) systems can be leveraged to alleviate these issues. To achieve the best EM strategy for building microgrids in a power system, this paper presents two large-scale multi-agent strategy evaluation methods to preserve building occupants’ comfort while pursuing system-level objectives. The EM problem is formulated as a general-sum game to optimize the benefits at both the system and building levels. The α -rank algorithm can solve the general-sum game and guarantee the ranking theoretically, but it is limited by the interaction complexity and hardly applies to the practical power system. A new evaluation algorithm (TcEval) is proposed by practically scaling the α -rank algorithm through a tensor complement to reduce the interaction complexity. Then, considering the noise prevalent in practice, a noise processing model with domain knowledge is built to calculate the strategy payoffs, and thus the TcEval-AS algorithm is proposed when noise exists. Both evaluation algorithms developed in this paper greatly reduce the interaction complexity compared with existing approaches, including ResponseGraphUCB (RG-UCB) and α InformationGain ( α -IG). Finally, the effectiveness of the proposed algorithms is verified in the EM case with realistic data.

Under the purpose of achieving the optimal voltage control strategy in power grid system, multi-agent evaluation algorithms like a-rank are widely used. However, in large-scale systems with massive agents and strategies, these methods are not time feasible. Therefore, a two-stage population-based multi-agent evaluation algorithm is proposed to solve voltage control problem in large-scale power grid systems. For stage one, a population is first established for each agent. And then, individuals in the populations randomly combined to form joint strategies. Base on the max and mean reward from the interaction between joint strategies and the environment, populations evolve to a near-optimal joint strategy. Stage two takes the above near-optimal joint strategy as the starting point, and uses a strategy search algorithm with maximum transfer possibility to find the Markov-Conley chain in the system. Finally, the above two-stage method is simulated in 10 and 32-agent power grid systems to verify the effectiveness.

Passive detection can work for a long time with low energy consumption in underwater surveillance. However, tracking unknown noncooperative targets with only direction angles is challenging, and the tracking performance of multiple targets is poor. Based on several passive sensors in the underwater sensor network (UWSN), a feature-aided state estimation method is used to start tracking unknown targets. The feature-aided joint probabilistic data association combined with the particle filter method is also proposed to improve the passive tracking performance of multiple targets. The track management and the fusion strategy are given to remove fake tracks and obtain correct trajectories of unknown targets. The simulation results show that the feature-aided method can quickly start and effectively track multiple noncooperative targets with passive sensors. Compared with other methods, the proposed method can track targets more accurately with the advantages of low energy consumption and less exposure in various environments.

Defect inspection, also known as defect detection, is significant in mobile screen quality control. There are some challenging issues brought by the characteristics of screen defects, including the following: (1) the problem of interclass similarity and intraclass variation, (2) the difficulty in distinguishing low contrast, tiny-sized, or incomplete defects, and (3) the modeling of category dependencies for multi-label images. To solve these problems, a graph reasoning module, stacked on a classification module, is proposed to expand the feature dimension and improve low-quality image features by exploiting category-wise dependency, image-wise relations, and interactions between them. To further improve the classification performance, the classifier of the classification module is redesigned as a cosine similarity function. With the help of contrastive learning, the classification module can better initialize the category-wise graph of the reasoning module. Experiments on the mobile screen defect dataset show that our two-stage network achieves the following best performances: 97.7% accuracy and 97.3% F -measure. This proves that the proposed approach is effective in industrial applications.

This paper mainly studies the localization and mapping of range sensing robots in the confidence-rich map (CRM) and then extends it to provide a full state estimate for information-theoretic exploration. Most previous works about active simultaneous localization and mapping and exploration always assumed the known robot poses or utilized inaccurate information metrics to approximate pose uncertainty, resulting in imbalanced exploration performance and efficiency in the unknown environment. This inspires us to extend the confidence-rich mutual information (CRMI) with measurable pose uncertainty. Specifically, we propose a Rao- Blackwellized particle filter-based localization and mapping scheme (RBPF -CLAM) for CRM, then we develop a new closed-form weighting method to improve the localization accuracy without scan matching. We further derive the uncertain CRMI (UCRMI) with the weighted particles by a more accurate approximation. Simulations and experimental evaluations show the localization accuracy and exploration performance of the proposed methods.

This article investigates the underwater node dynamic localization and prediction problems in a dynamic sensor network. Node localization in the Internet of underwater things is the basis of target tracking and ocean monitoring. At present, most of the node location algorithms assume calm sea and fixed node location. However, the current velocity is uncertain in space and time. The nodes are drifted with the current motion. Therefore, most of the localization algorithms lose efficacy in the actual marine environment. In order to solve the above problems, a node dynamic prediction algorithm is proposed. First, the node mobility model is improved, which is more suitable for the actual marine environment. Second, a frequency-based anchor node prediction algorithm is designed to improve anchor node location accuracy. Third, when the ordinary node receives the signals sent by anchor nodes of different depths, a deep information-based weighted fusion method is designed for the ordinary node localization in order to mine more information in each direction. Finally, location and prediction simulation in sensor networks is carried out. The results show that the proposed node localization and prediction algorithm is more accurate than SMLP and high-precision localization with mobility prediction algorithms and prove the enhanced effect of our method in dynamic marine.

Robots need more intelligence to complete cognitive tasks in home environments. In this paper, we present a new cloud-assisted cognition adaptation mechanism for home service robots, which learns new knowledge from other robots. In this mechanism, a change detection approach is implemented in the robot to detect changes in the user’s home environment and trigger the adaptation procedure that adapts the robot’s local customized model to the environmental changes, while the adaptation is achieved by transferring knowledge from the global cloud model to the local model through model fusion. First, three different model fusion methods are proposed to carry out the adaptation procedure, and two key factors of the fusion methods are emphasized. Second, the most suitable model fusion method and its settings for the cloud-robot knowledge transfer are determined. Third, we carry out a case study of learning in a changing home environment, and the experimental results verify the efficiency and effectiveness of our solutions. The experimental results lead us to propose an empirical guideline of model fusion for the cloud-robot knowledge transfer.

This paper describes a route planner that enables an autonomous underwater vehicle to selectively complete part of the predetermined tasks in the operating ocean area when the local path cost is stochastic. The problem is formulated as a variant of the orienteering problem. Based on the genetic algorithm (GA), we propose the greedy strategy based GA (GGA) which includes a novel rebirth operator that maps infeasible individuals into the feasible solution space during evolution to improve the efficiency of the optimization, and use a differential evolution planner for providing the deterministic local path cost. The uncertainty of the local path cost comes from unpredictable obstacles, measurement error, and trajectory tracking error. To improve the robustness of the planner in an uncertain environment, a sampling strategy for path evaluation is designed, and the cost of a certain route is obtained by multiple sampling from the probability density functions of local paths. Monte Carlo simulations are used to verify the superiority and effectiveness of the planner. The promising simulation results show that the proposed GGA outperforms its counterparts by 4.7%–24.6% in terms of total profit, and the sampling-based GGA route planner (S-GGARP) improves the average profit by 5.5% compared to the GGA route planner (GGARP).

Older adults who age in place face many health problems and need to be taken care of. Fall is a serious problem among elderly people. In this paper, we present the design and implementation of collaborative fall detection using a wearable device and a companion robot. First, we developed a wearable device by integrating a camera, an accelerometer and a microphone. Second, a companion robot communicates with the wearable device to conduct collaborative fall detection. The robot is also able to contact caregivers in case of emergency. The collaborative fall detection method consists of motion data based preliminary detection on the wearable device and video-based final detection on the companion robot. Both convolutional neural network (CNN) and long short-term memory (LSTM) are used for video-based fall detection. The experimental results show that the overall accuracy of video-based algorithm is 84%. We also investigated the relation between the accuracy and the number of image frames. Our method improves the accuracy of fall detection while maximizing the battery life of the wearable device. In addition, our method significantly increases the sensing range of the companion robot.

This paper investigates the task coordination of multi-robot where each robot has a private individual temporal logic task specification; and also has to jointly satisfy a globally given collaborative temporal logic task specification. To efficiently generate feasible and optimized task execution plans for the robots, we propose a hierarchical multi-robot temporal task planning framework, in which a central server allocates the collaborative tasks to the robots, and then individual robots can independently synthesize their task execution plans in a decentralized manner. Furthermore, we propose an execution plan adjusting mechanism that allows the robots to iteratively modify their execution plans via privacy-preserved inter-agent communication, to improve the expected actual execution performance by reducing waiting time in collaborations for the robots. The correctness and efficiency of the proposed method are analyzed and also verified by extensive simulation experiments.

Smart homes can provide complementary information to assist home service robots. We present a robotic misplaced item finding (MIF) system, which uses human historical trajectory data obtained in a smart home environment. First, a multi-sensor fusion method is developed to localize and track a resident. Second, a path-planning method is developed to generate the robot movement plan, which considers the knowledge of the human historical trajectory. Third, a real-time object detector based on a convolutional neural network is applied to detect the misplaced item. We present MIF experiments in a smart home testbed and the experimental results verify the accuracy and efficiency of our solution.

Underwater mobile sensor networks (UMSNs) with free-floating sensors are more suitable for understanding the immense underwater environment. Target tracking, whose performance depends on sensor localization accuracy, is one of the broad applications of UMSNs. However, in UMSNs, sensors move with environmental forces, so their positions change continuously, which poses a challenge on the accuracy of sensor localization and target tracking. We propose a high-accuracy localization with mobility prediction (HLMP) algorithm to acquire relatively accurate sensor location estimates. The HLMP algorithm exploits sensor mobility characteristics and the multi-step Levinson-Durbin algorithm to predict future positions. Furthermore, we present a simultaneous localization and target tracking (SLAT) algorithm to update sensor locations based on measurements during the process of target tracking. Simulation results demonstrate that the HLMP algorithm can improve localization accuracy significantly with low energy consumption and that the SLAT algorithm can further decrease the sensor localization error. In addition, results prove that a better localization accuracy will synchronously improve the target tracking performance.

Underwater wireless sensor networks (UWSNs) can provide a promising solution to underwater target tracking. Due to limited energy and bandwidth resources, only a small number of nodes are selected to track a target at each interval. Because all measurements are fused together to provide information in a fusion center, fusion weights of all selected nodes may affect the performance of target tracking. As far as we know, almost all existing tracking schemes neglect this problem. We study a weighted fusion scheme for target tracking in UWSNs. First, because the mutual information (MI) between a node’s measurement and the target state can quantify target information provided by the node, it is calculated to determine proper fusion weights. Second, we design a novel multi-sensor weighted particle filter (MSWPF) using fusion weights determined by MI. Third, we present a local node selection scheme based on posterior Cramer-Rao lower bound (PCRLB) to improve tracking efficiency. Finally, simulation results are presented to verify the performance improvement of our scheme with proper fusion weights.

Noise statistics are essential for estimation performance. In practical situations, however, a priori information of noise statistics is often imperfect. Previous work on noise statistics identification in linear systems still requires initial prior knowledge of the noise. A novel approach is presented in this paper to solve this paradox. First, we apply the H ∞ filter to obtain the system state estimates without the common assumptions about the noise in conventional adaptive filters. Then by applying state estimates obtained from the H ∞ filter, better estimates of the noise mean and covariance can be achieved, which can improve the performance of estimation. The proposed approach makes the best use of the system knowledge without a priori information with modest computation cost, which makes it possible to be applied online. Finally, numerical examples are presented to show the efficiency of this approach.

This paper investigates the H ∞ trajectory tracking control for a class of nonlinear systems with time-varying delays by virtue of Lyapunov-Krasovskii stability theory and the linear matrix inequality (LMI) technique. A unified model consisting of a linear delayed dynamic system and a bounded static nonlinear operator is introduced, which covers most of the nonlinear systems with bounded nonlinear terms, such as the one-link robotic manipulator, chaotic systems, complex networks, the continuous stirred tank reactor (CSTR), and the standard genetic regulatory network (SGRN). First, the definition of the tracking control is given. Second, the H ∞ performance analysis of the closed-loop system including this unified model, reference model, and state feedback controller is presented. Then criteria on the tracking controller design are derived in terms of LMIs such that the output of the closed-loop system tracks the given reference signal in the H ∞ sense. The reference model adopted here is modified to be more flexible. A scaling factor is introduced to deal with the disturbance such that the control precision is improved. Finally, a CSTR system is provided to demonstrate the effectiveness of the established control laws.

Long propagation delay, limited bandwidth, and high bit error rate pose great challenges in media access control (MAC) protocol design for underwater acoustic networks. A MAC protocol called slotted floor acquisition multiple access (slotted-FAMA) suitable for underwater acoustic networks is proposed and analyzed. This FAMA based protocol adds a time slot mechanism to avoid DATA packet collisions. However, slotted-FAMA is not suitable for dense networks since the multiple request-to-send (RTS) attempts problem in dense networks is serious and greatly limits the network throughput. To overcome this drawback, this paper proposes a slotted-FAMA based MAC protocol for underwater acoustic networks, called RC-SFAMA. RC-SFAMA introduces an RTS competition mechanism to keep the network from high frequency of backoff caused by the multiple RTS attempts problem. Via the RTS competition mechanism, useful data transmission can be completed successfully when the situation of multiple RTS attempts occurs. Simulation results show that RC-SFAMA increases the network throughput efficiency as compared with slotted-FAMA, and minimizes the energy consumption.

On one hand, due to the energy and bandwidth constraint of underwater wireless sensor networks (UWSNs), local data quantization/compression is not only a necessity, but also an integral part of the design of UWSNs; on the other hand, since underwater nodes provide measurements for target tracking based on UWSNs, node topology, which is made up of the underwater nodes, may affect the performance of target tracking. This paper studies the effect of node topology on the target tracking in UWSNs using quantized measurements. Firstly, by using the knowledge of geometry, the effects of four typical topologies on target tracking using quantized measurements are analyzed qualitatively. The four typical topologies include two nodes are close to each other, three nodes are close to each other, three nodes are co-linear, and three nodes form a regular triangle. Secondly, under the condition of quantized measurements, the relationship between the posterior Cramer-Rao lower bound (PCRLB) and node's position is derived to evaluate the arbitrary topology. Thirdly, our target tracking scheme consisting of the optimal topology selection scheme by minimizing PCRLB, the optimal fusion center selection scheme by minimizing energy consumption, and the multisensor particle filter with quantized measurements is designed. Last, simulation results show the effectiveness of the proposed scheme.

We propose an efficient measurement-driven sequential Monte Carlo multi-Bernoulli (SMC-MB) filter for multi-target filtering in the presence of clutter and missing detection. The survival and birth measurements are distinguished from the original measurements using the gating technique. Then the survival measurements are used to update both survival and birth targets, and the birth measurements are used to update only the birth targets. Since most clutter measurements do not participate in the update step, the computing time is reduced significantly. Simulation results demonstrate that the proposed approach improves the real-time performance without degradation of filtering performance.

This brief proposes an output tracking control for a class of discrete-time nonlinear systems with disturbances. A standard neural network model is used to represent discrete-time nonlinear systems whose nonlinearity satisfies the sector conditions. H∞ control performance for the closed-loop system including the standard neural network model, the reference model, and state feedback controller is analyzed using Lyapunov-Krasovskii stability theorem and linear matrix inequality (LMI) approach. The H∞ controller, of which the parameters are obtained by solving LMIs, guarantees that the output of the closed-loop system closely tracks the output of a given reference model well, and reduces the influence of disturbances on the tracking error. Three numerical examples are provided to show the effectiveness of the proposed H∞ output tracking design approach.

In this paper, H∞ synchronization and state estimation problems are considered for different types of chaotic systems. A unified model consisting of a linear dynamic system and a bounded static nonlinear operator is employed to describe these chaotic systems, such as Hopfield neural networks, cellular neural networks, Chua's circuits, unified chaotic systems, Qi systems, chaotic recurrent multilayer perceptrons, etc. Based on the H∞ performance analysis of this unified model using the linear matrix inequality approach, novel state feedback controllers are established not only to guarantee exponentially stable synchronization between two unified models with different initial conditions but also to reduce the effect of external disturbance on the synchronization error to a minimal H∞ norm constraint. The state estimation problem is then studied for the same unified model, where the purpose is to design a state estimator to estimate its states through available output measurements so that the exponential stability of the estimation error dynamic systems is guaranteed and the influence of noise on the estimation error is limited to the lowest level. The parameters of these controllers and filters are obtained by solving the eigenvalue problem. Most chaotic systems can be transformed into this unified model, and H∞ synchronization controllers and state estimators for these systems are designed in a unified way. Three numerical examples are provided to show the usefulness of the proposed H∞ synchronization and state estimation conditions.

This paper is concerned with the problem of state estimation for a class of discrete-time chaotic systems with or without time delays. A unified model consisting of a linear dynamic system and a bounded static nonlinear operator is employed to describe these systems, such as chaotic neural networks, Chua's circuits, Hénon map, etc. Based on the H∞ performance analysis of this unified model using the linear matrix inequality approach, H∞ state estimator are designed for this model with sensors to guarantee the asymptotic stability of the estimation error dynamic systems and to reduce the influence of noise on the estimation error. The parameters of these filters are obtained by solving the eigenvalue problem. As most discrete-time chaotic systems with or without time delays can be described with this unified model, H∞ state estimator design for these systems can be done in a unified way. Three numerical examples are exploited to illustrate the effectiveness of the proposed estimator design schemes.

This brief studies exponential H(infinity) synchronization of a class of general discrete-time chaotic neural networks with external disturbance. On the basis of the drive-response concept and H(infinity) control theory, and using Lyapunov-Krasovskii (or Lyapunov) functional, state feedback controllers are established to not only guarantee exponential stable synchronization between two general chaotic neural networks with or without time delays, but also reduce the effect of external disturbance on the synchronization error to a minimal H(infinity) norm constraint. The proposed controllers can be obtained by solving the convex optimization problems represented by linear matrix inequalities. Most discrete-time chaotic systems with or without time delays, such as Hopfield neural networks, cellular neural networks, bidirectional associative memory networks, recurrent multilayer perceptrons, Cohen-Grossberg neural networks, Chua's circuits, etc., can be transformed into this general chaotic neural network to be H(infinity) synchronization controller designed in a unified way. Finally, some illustrated examples with their simulations have been utilized to demonstrate the effectiveness of the proposed methods.

A unified neural network model termed standard neural network model (SNNM) is advanced. Based on the robust L(2) gain (i.e. robust H(infinity) performance) analysis of the SNNM with external disturbances, a state-feedback control law is designed for the SNNM to stabilize the closed-loop system and eliminate the effect of external disturbances. The control design constraints are shown to be a set of linear matrix inequalities (LMIs) which can be easily solved by various convex optimization algorithms (e.g. interior-point algorithms) to determine the control law. Most discrete-time recurrent neural network (RNNs) and discrete-time nonlinear systems modelled by neural networks or Takagi and Sugeno (T-S) fuzzy models can be transformed into the SNNMs to be robust H(infinity) performance analyzed or robust H(infinity) controller synthesized in a unified SNNM's framework. Finally, some examples are presented to illustrate the wide application of the SNNMs to the nonlinear systems, and the proposed approach is compared with related methods reported in the literature.