Changing Communication Topology Research Articles

Robust Control for Multiplayer Nonzero‐Sum Differential Games With Switching Topology and Input Delay

ABSTRACTThis article investigates a multiplayer nonzero‐sum differential game (MNDG) with switching topology and input delay. The Hamilton–Jacobi–Isaacs (HJI) equation is used to derive the optimal control strategies. To solve the issue of switching topology, the control strategies are decoupled with the communication topology. Then, the stability of the system can be achieved regardless of changes in communication topology with the designed control strategies. This does not require a restriction on the dwell time, making the system stability conditions more relaxed. The Lyapunov–Krasovskii functional (LKF) is constructed to prove the stability of the system in the presence of time‐varying input delay. To cope with the real‐world situation, the input delay is considered to be disturbed by a time‐varying perturbation in this article. With these treatments, the system is more in line with real‐world applications. Simulation examples are given to validate the efficiency of the presented methods.

Asynchronous Platoon Control for Connected Vehicles With Intermittent and Delayed Information Transmission

This technical note investigates the asynchronous platoon control problem for connected vehicles with intermittent and delayed information transmission under dynamically changing communication topologies. An asynchronous consensus based protocol is proposed for each vehicle based on the state information of its neighbors at discrete times with communication delays, in which the asynchrony means that each agent updates its dynamics at discrete time instants determined by its own clock. The update intervals and the communication delays are allowed to be arbitrary bounded. We employ nonnegative matrix theory and graph theory to prove that the vehicle platoon asymptotically reaches a desired inter-vehicle spacing and a common velocity, if the effective communication topology jointly contains a directed spanning tree. Furthermore, we show that the string stability of the platoon control system is attained under the predecessor-following topology. Finally, we present numerical examples to validate the theoretical results.

RVMF: RELIABLE ROUTING METHOD FOR VEHICULAR AD HOC NETWORKS USING MOTH-FLAME AND FIREFLY OPTIMIZATION ALGORITHMS

With the advancement of wireless communication technology, the intelligent transportation system (ITS) has attracted the attention of vehicle companies and academic researchers. Recently, vehicular ad hoc networks (VANETs) as a leading genuine technology have received serious attention as a kind of mobile ad hoc network (MANET) to ensure the safety of vehicles, drivers, and passengers. However, these networks face many challenges due to the mobility of vehicle nodes, wireless communication, and frequent topology changes. One of the crucial issues of these networks is a cluster-based routing scheme with the ability to provide quality of service (QoS) parameters. A clustering scheme is an appropriate method for increasing the scalability of VANETs. In a cluster-based routing scheme, the cluster head (CH) is responsible for receiving data from its member nodes, and aggregating and transferring data to the next CH node. On the other hand, providing a suitable clustering method is NP-hard problems and meta-heuristic algorithms are suitable for solving these problems. A scalable and reliable routing scheme is necessary and essential in VANETs. In this paper, a routing method based on the clustering technique is presented considering the moth-flame optimization (MFO) algorithm for clustering and the Firefly optimization algorithm (FoA) with a suitable fitness function for routing between CHs. The simulation of the proposed method with MATLAB software shows that the proposed RVMF method improves the parameters of packet delivery rate (PDR), latency, and throughput.

Event-Based Distributed Fuzzy Load Frequency Control for Multiarea Nonlinear Power Systems With Switching Topology

This article investigates the event-based distributed fuzzy load frequency control approach for nonlinear interconnected power systems under a switching topology. Specifically, nonlinear factors and uncertain parameters existing in turbine and governor dynamics are modeled and analyzed under the interval type-2 fuzzy method. New memory-based adaptive event-triggered mechanisms, whose directions and threshold parameters are dynamically updated based on the output change trend and relative output error of multiple memories, are proposed to further save network energy. Aiming at communication topology changes in multiarea power systems, a novel switched control system is established by introducing a time-varying communication matrix. Then, the system’s asymptotic stability is ensured by the piecewise Lyapunov–Krasovskii method. Furthermore, to further relax stability conditions, slack matrices are considered with the boundary information of membership functions. Finally, three-area power systems are shown to demonstrate the effectiveness of proposed distributed load frequency control strategies.

Research into a Consistency Cooperative Control Method for Attitude Orbit Coupling of SAR Satellite Formations under Communication Constraints

To solve the problem of communication delays and topology changes and achieve a high-precision formation configuration control index in the flight control of SAR (synthetic aperture radar) satellite formations, this paper studies the consistency cooperative control of attitude orbit coupling for SAR satellite formations under communication constraints. First, this paper establishes the relative motion state error equation for satellite formations. Considering the capacity constraints for communication and actuators, this paper designs a hierarchical saturated consistency cooperative controller for attitude orbit coupling. Second, this paper uses the Lyapunov direct method to prove the stability of the designed consistent cooperative controller under uncertain space disturbances. Finally, this paper simulates and verifies the designed controller. The results show that the hierarchical saturation consistency cooperative controller designed in this paper can meet the requirements of configuration maintenance accuracy for SAR satellite formation for Earth target observation missions.

Construction and Optimization of Distributed Electronic Archives System Merging Control Messages

This paper analyzes the whole of the electronic archives management system, describes the basic features and functions of the system, and gives the flow of each functional module of the system. Techniques for implementing important functions in the system are discussed and compared. Using the object-oriented idea, this paper designs the electronic archives management system and gives the hybrid structure model of the system. According to the needs of the electronic office, an official document transmission module is established to realize the electronic transmission of official documents, and the specific implementation process is given. According to the characteristics of archives information management and utilization, SQL Server is used as the background database and the database design is carried out. This paper introduces the full-text retrieval technology that realizes the query and retrieval function of electronic archives and gives how to configure the full-text retrieval service in SQL Server. This paper proposes a K-means-based merging control message clustering algorithm to solve the problem of communication topology changes caused by large-scale, high-mobility merging control messages. Based on the idea of K-means clustering, the calculation method of distance in K-means is improved by combining the distribution of the initial electronic archives message, and the fitness function of the electronic archives is designed by using the information of the electronic archives in the cluster and the average distance to the neighboring electronic archives. According to the maximum fitness value, the cluster head is selected to establish clustering. The file management system is tested and analyzed in a simulated environment. Based on the functional positioning of the system and the business environment, the functional performance and performance of the analysis system are examined and analyzed, and the research and development results are inspected according to the system development goals to check whether the development results of the system have reached the advanced stage. At the functional level, it can automate the management of the core business of the distributed electronic archives management department and support the distributed storage management of massive archive data, which effectively improves the informatization level and development efficiency of archives management.

Connected and automated vehicle platoon maintenance under communication failures

Connected and automated vehicles (CAVs) use vehicle-to-vehicle (V2V) wireless communication to drive in platoons, which can improve traffic efficiency and reduce energy consumption. However, some vehicles in a platoon may experience communication failures for various reasons, such as packet loss, signal blocking, or damage to vehicle communication module hardware. This will result in two phenomena: the platoon communication topology will be changed, and the behavior of vehicles without communication capabilities will degenerate to that of automated vehicles (AVs). The platoon will be unstable under the influence of these two phenomena. To mitigate the impact of these two phenomena on platoons, we propose a dynamic communication topology-based CAV-following model. This model takes into account changes in communication topology in a platoon due to communication failures or perceptual errors resulting from vehicle degradation. Two core features ensure that this model is able to perform platoon maintenance under communication failure. First, the CAVs in a platoon dynamically adjust the weight values of the acquired driving information based on the communication topology. Second, an adaptive Kalman filter (AKF) method is applied to reduce perceptual error. The effectiveness of the platoon maintenance scheme proposed in this study is verified by a series of simulation experiments. The results show that the proposed model can effectively maintain CAV platoons regardless of communication failures under steady-state or non-steady-state traffic flows. This finding indicates that CAV designers should design control schemes that take into account possible changes in the communication topology. Furthermore, our method has potential advantages for improving the platoon stability of CAVs driving on roads where communication is poor.

A Fully Distributed Economic Dispatch Method in DC Microgrid Based on Consensus Algorithm

Uncertainties of intermittent renewables and complexities of load demands bring challenges to the optimal operation of the microgrid. This paper proposes a fully distributed method based on consensus algorithm for solving the economic dispatch problem (EDP) of DC microgrid. The proposed distributed method is performed using multiagent system. It only needs information from neighboring agents and does not need a central controller. A two-level control structure is adopted to realize the economic dispatch and voltage regulation simultaneously. The upper level obtains the optimal power reference of dispatchable agents and maintains the power balance of the system. The lower level performs an improved droop control to track the power reference and regulate the average bus voltage for the microgrid. The proposed method’s properties and convergence are analyzed using eigenvalue perturbation theory to obtain a faster convergence speed. By designing the adjacency matrix appropriately, the proposed method can ensure the system stable when the communication topology changes. Finally, several simulations are designed to verify the effectiveness of this novel control method.

Multilayer event‐based distributed control system for DC microgrids with non‐uniform delays and directional communication

The secondary control layer of microgrids is often modelled as a multi-agent distributed system, coordinated based on consensus protocols. Convergence time of consensus algorithm significantly affects transient stability of microgrids, due to changes in communication topology, switching of distributed generations (DGs), and uncertainty of intermittent energy sources. To minimise convergence time in consensus protocol, this work proposes a multilayer event-based consensus control framework, which is resilient to communication delays and supports plug-and-play (P&P) addition or removal of DGs in DC microgrids of cellular energy systems. A novel bi-layer optimisation algorithm minimises convergence time by selecting an optimal communication topology graph and then adjusts controllers' parameters. Average consensus is achieved among distributed controllers using an event-based consensus protocol, considering non-uniform delays between agents. A realisation method has also been introduced using the directional beamforming technique for topology assignment algorithm based on modern telecommunication technologies. Provided feasibility case study has been implemented on a real-time hardware-in-the-loop (HIL) experimental testbed, to validate the performance of the proposed framework for key purposes of voltage stabilisation and balanced power-sharing in DC microgrids.

Time-varying formation control for unmanned intelligent vehicle (UIV) with mobile reference center

This paper studies a time-varying formation control algorithm based on the unmanned intelligent vehicle (UIV) system. First, modeling the multi-agent system. Reference [4] gives the time-varying formation control algorithm of multi-agent under changing communication topology and necessary and sufficient conditions for the establishment of the algorithm. The simulation verifies the effectiveness of the algorithm. On this foundation, based on the consensus theory, this paper proposes a formation algorithm in the case of a formation reference center movement and realizes multiple time-varying formations of a multi-agent system through simulation. The simulation results show that the algorithm proposed in this paper can quickly realize formation under different formation requirements and the algorithm has better control effect and robustness.

Distributed heterogeneous energy storage systems synchronization control with dynamic weights and time-varying unbalanced digraphs

This paper provides a distributed control strategy for battery energy storage systems (BESS) based on multi-agent system. The proposed control laws can guarantee that the state of charge (SoC) is synchronized, and BESS active power can be shared proportionally. Moreover, the heterogeneous characteristics of BESS are considered in modeling BESS and designing control laws, while they are not carefully considered in the existed literature. Besides, the proposed control laws are robust to the changing communication topologies and link broken since they can be applied over the time-varying directed unbalanced communication networks. Simulation studies, which are carried out on matlab/simulink, validate the effectiveness of the control strategy and laws.

FANET optimization: a destination path flow model

Closed-loop routing in flying ad hoc networks (FANET) arises as a result of the quick changes of communication links and topology. As such, causing link breakage during information dissemination. This paper proposed a destination path flow model to improve the communication link in FANET. The models utilized Smell Agent Optimization and Particle Swarm Optimization algorithms in managing link establishment between communicating nodes. The modeled scenario depicts the practical application of FANET in media and sports coverage where only one vendor is given the license for live coverage and must relay to other vendors. Three different scenarios using both optimization Algorithms were presented. From the result obtained, the SAO optimizes the bandwidth costs much better than PSO with a percentage improvement of 10.46%, 4.04% and 3.66% with respect to the 1st, 2nd and 3rd scenarios respectively. In the case of communication delay between the FANET nodes, the PSO has a much better communication delay over SAO with percentage improvement of 40.89%, 50.26% and 68.85% in the first, second and third scenarios respectively.

Routing using reinforcement learning in vehicular ad hoc networks

AbstractIn vehicular ad hoc networks (VANETs), the frequent change in vehicle mobility creates dynamic changes in communication link and topology of the network. Hence, the key challenge is to address and resolve longer transmission delays and reduced transmission stability. During the establishment of routing path, the focus of entire research is on traffic detection and road selection with high traffic density for increased packet transmission. This reduces the transmission delays and avoids carry‐and‐forward scenarios; however, these techniques fail in obtaining accurate traffic density in real‐time scenario due to rapid change in traffic density. Thus, it is necessary to create a model that efficiently monitors the traffic density and assist VANETs in route selection in an automated way with increased accuracy. In this article, a novel machine learning architecture using deep reinforcement learning (DRL) model is proposed to monitor and estimate the data essential for the routing protocol. In this model, the roadside unit maintains the traffic information on roads using DRL. The DRL predicts the movement of the vehicle and makes a suitable routing path for transmitting the packets with improved transmission capacity. It further uses predicted transmission delays and the destination location to choose the forwarding directions between two road safety units (RSUs). The application of DRL over VANETs yields increased network performance, which provides on‐demand routing information. The simulation results show that the DRL‐based routing is effective in routing the data packets between the source and destination vehicles than other existing method.

Two-stage cooperative guidance strategy using a prescribed-time optimal consensus method

This paper addresses the optimal decentralized three-dimensional cooperative guidance problem for multiple interceptors against a stationary target considering dynamically changing and directed communication topologies. A two-stage cooperative strategy is proposed to achieve simultaneous attack regardless of the information on time-to-go. More specifically, a prescribed-time optimal consensus method is applied in the process of the first-stage distributed cooperative guidance law design to generate desired initial conditions for the latter guidance phase, where the consensus arriving time can be off-line pre-appointed according to interception mission requirements without conservative estimation and is independent of the initial conditions of interceptor's states. Furthermore, the optimal consensus control under directed and periodical switching topologies is also considered in the first guidance phase, and the analytically optimal cooperative guidance law is formulated based on Pontryagin's principle. As for the second guidance phase, all interceptors are switched to typical pure proportional navigation guidance law, and the salvo attack can be achieved eventually. Extensive numerical simulations are performed to validate the effectiveness and superiority of the proposed cooperative guidance scheme.

Swarm Control for Self-Organized System With Fixed and Switching Topology.

In this article, we propose the swarm control for a self-organized system with fixed and switching topology, which can realize aggregation, dispersion, or switching formation when swarm moves. The self-organized system can automatically construct the communication topology for intelligent units in swarm. Swarm control can realize aggregation and dispersion of intelligent units based on its communication topology when swarm moves. The proposed swarm control, in which distances between the related intelligent units are time varying, is different from traditional swarm consensus or swarm formation maintenance. To design swarm control, we define the normalization adjacency matrix and normalization degree matrix based on communication topology. The communication topology is automatically generated based on relation-invariable persistent formation. Depending on whether the communication topology changes or not, the swarm control can be classified as fixed topology and switching topology. Then, the swarm control with fixed and switching topology is designed and analyzed, respectively. The swarm control can realize stability asymptotically when topology is fixed and realize stability in finite time when topology is switched. The simulation results show that the proposed approaches are effective.

Voltage Distributed Cooperative Control Considering Communication Security in Photovoltaic Power System

A voltage regulation scheme considering communication security is proposed for photovoltaic (PV) power system. The scheme is a two-level regulation to, respectively, reduce overall voltage deviation (VDE) and voltages difference (VDI). First, the evaluation indexes of VDE and VDI are built. Then, primary regulation through a powers compensation scheme is used. Considering communication topology change and delay under upper bound, secondary regulation through consensus protocol is developed. In addition, communication packet-loss and large delay are solved by predictive compensation. Finally, effectiveness of the proposed method is verified by simulation in MATLAB.

Distributed, fixed‐time, and bounded control for secondary voltage and frequency restoration in islanded microgrids

Microgrid (MG) technology evolves as a promising solution to deal with the intermittent renewable generations and frequently changing load demand. This paper proposes a fully distributed and bounded secondary control algorithm with flexible convergence time for voltage and frequency restoration. It also enables accurate active power sharing for an islanded MG, compared with the well-known consensus-based distributed control approach. The proposed control scheme achieves accelerated fixed-time convergence. The upper bound on the convergence is established by using the Lyapunov stability theory. The bounded, distributed control approach restores the voltage and frequency in fixed-time while sharing the active power precisely. Further, the proposed controller is adaptive to the communication topology change and supports the plug and play feature of MG. Extensive simulations have been pursued using MATLAB/SimPowerSyetem toolbox considering frequent load perturbation and communication topology change. The obtained results are analysed to verify the performance of the proposed control algorithm. It is observed that the proposed bounded input controller converges faster than the conventional method.

Virtual cluster control for active distribution system using Pinning-based distributed secondary control

To facilitate a powerful control for an active distribution system (ADS) with high permeability distributed generators (DGs), a novel virtual cluster control (VCC) that includes a virtual cluster pinning and the pinning-based distributed secondary control (PBDSC) is proposed. The basic objectives of the proposed control are respectively: (1) to control an ADS by pinning the virtually partitioned clusters, which entitled virtual microgrid clusters (VMGCs) and virtual power plant clusters (VPPCs), (2) to implement PBDSC in VMGC and VPPC based on adaptive pinning, and (3) to adapt the uncertain communication topology changes in each cluster. Additionally, the proposed control drastically reduces the control dimension of an ADS and achieves global coordination and local autonomy by making fully use of the features and advantages of both VMGCs and VPPCs. The proposed control is embedded in the IEEE 123-bus system on PSCAD/EMTDC and MATLAB platform, its validity and applicability is investigated by multiple simulation cases.

Noise‐resilient voltage and frequency synchronisation of an autonomous microgrid

We present a new noise-resilient secondary control scheme for voltage and frequency synchronisation of an autonomous microgrid (MG). The communication network is an integral part of distributed secondary control structure. The communication links among the distributed generator units are assumed to be ideal in nature. However, the communication links are subjected to uncertain noises, which can significantly affect the synchronisation performance of MG control. We consider the information received over the communication link is corrupted with generalised Gaussian noise. Further, the complete non-linear model of the MG system has been considered for designing a robust distributed control scheme augmented with an auxiliary corrective control input to counterbalance the impact of noises. The performance of the proposed control scheme is evaluated by pursuing simulation of a MG test system in MATLAB/SimPoweSystem environment under load perturbation, changes in communication topology, communication link delays, data dropout, and variations in noise parameter. The results of a comparative assessment of the proposed control scheme with two approaches first a neighbourhood tracking error-based control scheme and second a noise-resilient control scheme are presented to illustrate the effectiveness of the proposed robust noise-resilient control scheme in voltage and frequency synchronisation and accurate active power-sharing.

Distributed model predictive consensus control for robotic swarm system

This paper proposes a distributed model predictive control method for a consensus of robotic swarm systems. The proposed method is free from any precomputed trajectories, contrast to previous studies. This is huge advantages in cases the system do not work as previously predicted, communication topology changes frequently, and the communication is unreliable. I introduce a concept of local subsystem regulator first, and then the distributed control method and its design concept are described. I also analyze stability of the proposed method and introduce how to handle constraints such as a mutual collision avoidance into the proposed method. Computer simulations are demonstrated to show effectivity of our method.