Driven by practical applications, the achievement of distributed observers for nonlinear systems has emerged as a crucial advancement in recent years. However, existing theoretical advancements face certain limitation...Driven by practical applications, the achievement of distributed observers for nonlinear systems has emerged as a crucial advancement in recent years. However, existing theoretical advancements face certain limitations: They either fail to address more complex nonlinear phenomena, rely on hard-to-verify assumptions, or encounter difficulties in solving system parameters.Consequently, this paper aims to address these challenges by investigating distributed observers for nonlinear systems through the full-measured canonical form(FMCF), which is inspired by full-measured system(FMS) theory. To begin with, this study addresses the fact that the FMCF can only be obtained through the observable canonical form(OCF) in existing FMS theories.The paper demonstrates that a class of nonlinear systems can directly obtain FMCF through state space equations, independent of OCF. Also, a general method for solving FMCF in such systems is provided. Furthermore, based on the FMCF, A distributed observer is developed for nonlinear systems under two scenarios: Lipschitz conditions and open-loop bounded conditions.The paper establishes their asymptotic omniscience and demonstrates that the designed distributed observer in this study has fewer design parameters and is more convenient to construct than existing approaches. Finally, the effectiveness of the proposed methods is validated through simulation results on Van der Pol oscillators and microgrid systems.展开更多
To investigate the leader-following formation control, in this paper we present the design problem of control protocols and distributed observers under which the agents can achieve and maintain the desired formation f...To investigate the leader-following formation control, in this paper we present the design problem of control protocols and distributed observers under which the agents can achieve and maintain the desired formation from any initial states, while the velocity converges to that of the virtual leader whose velocity cannot be measured by agents in real time. The two cases of switching topologies without communication delay and fixed topology with time-varying communication delay are both considered for multi-agent networks. By using the Lyapunov stability theory, the issue of stability is analysed for multi-agent systems with switching topologies. Then, by considering the time-varying communication delay, the sufficient condition is proposed for the multi-agent systems with fixed topology. Finally, two numerical examples are given to illustrate the effectiveness of the proposed leader-following formation control protocols.展开更多
This paper develops both adaptive distributed dynamic state feedback control law and adaptive distributed measurement output feedback control law for heterogeneous discrete-time swarm systems with multiple leaders.The...This paper develops both adaptive distributed dynamic state feedback control law and adaptive distributed measurement output feedback control law for heterogeneous discrete-time swarm systems with multiple leaders.The convex hull formed by the leaders and the system matrix of leaders is estimated via an adaptive distributed containment observer.Such estimations will feed the followers so that every follower can update the system matrix of the corresponding adaptive distributed containment observer and the system state of their neighbors.The followers cooperate with each other to achieve leader-follower consensus and thus solve the containment control problem over the network.Numerical results demonstrate the effectiveness and computational feasibility of the proposed control laws.展开更多
In this paper, distributed event-triggered performance constraint control is proposed for Heterogeneous Multiagent Systems (HMASs) including quadrotor unmanned aerial vehicles and unmanned ground vehicles in the prese...In this paper, distributed event-triggered performance constraint control is proposed for Heterogeneous Multiagent Systems (HMASs) including quadrotor unmanned aerial vehicles and unmanned ground vehicles in the presence of unknown external disturbances. To tackle the problem of different dynamic characteristics and facilitate the controller design, the virtual variable is introduced in the z axis of the nonlinear model of unmanned ground vehicles. By using this approach, a universal model is established for the HMAS. Moreover, a distributed disturbance observer is established to cope with the adverse influence of the external disturbances. Then, an Appointed-Time Prescribed Performance Function (ATPPF) is designed to restrict the tracking error in the predefined regions. On this basis, the distributed performance constraint controller is proposed for the HMAS based on the ATPPF and the distributed disturbance observer. Furthermore, the improved event-triggered mechanism is proposed with a dynamic threshold, which depends on the distance between the tracking error and the boundary of the ATPPF. Finally, the effectiveness of the proposed control method is verified by the comparative experiments on an HMAS.展开更多
To address the problem of instability and inaccuracy when the Unmanned Aerial Vehicles(UAVs) formation equipped with bearing-only sensor network tracks a maneuvering target,this paper proposes a distributed cooperativ...To address the problem of instability and inaccuracy when the Unmanned Aerial Vehicles(UAVs) formation equipped with bearing-only sensor network tracks a maneuvering target,this paper proposes a distributed cooperative tracking control method considering the effectiveness of passive detection. First, the system model of passive detection in UAV formation is constructed.Then, the Geometric Dilution of Precision(GDOP) of bearing-only sensor nodes pair on the observation plane is analyzed. Building on this foundation, the pairwise form is expanded to obtain the optimal geometric configuration for the entire network. Subsequently, the Distributed Cubature Information Filtering(DCIF) is integrated with the weighted average consensus protocol to design the distributed cooperative observer suitable for the system model, enabling state estimation of the target. Finally, within the distributed architecture, the Nonlinear Model Predictive Controller(NMPC) is designed. This controller autonomously assembles the UAV formation during the assembly phase and forms an optimal detection array. The UAV formation then tracks the target using the virtual geometric center based on the established rigid geometric configuration. The simulation experiments validate that the proposed model and method can enhance the passive detection effectiveness of the UAV formation, thereby achieving stable and efficient distributed cooperative tracking for the maneuvering target.展开更多
With the rapid development of information technologies and cloud computing, sensor networks play an increasingly important role in our society. Over the past few decades, distributed observer theory has attracted unpr...With the rapid development of information technologies and cloud computing, sensor networks play an increasingly important role in our society. Over the past few decades, distributed observer theory has attracted unprecedented attention due to its wide potential applications in different areas. Meanwhile, various approaches and algorithms have been proposed and investigated. The design of distributed observers is one of the frontier topics of system and control research, which has the significant theoretical values and broad application prospects. This paper attempts to review the representative models and the corresponding approaches for distributed observer design in linear time-invariant(LTI) systems. Firstly, the research backgrounds and main advances of distributed observer designs are briefly reviewed. Then, recent results of distributed observer designs for discrete-time and continuous-time LTI multi-agent systems(MASs) are introduced in detail, respectively. Finally, the prospects and the future work directions of the design of distributed observers are put forward. The main purpose of this paper is to promote the emerging topic on the designs of distributed observers, with focuses on the interdisciplinary interest from technological sciences.展开更多
This paper addresses a multicircular circumnavigation control for UAVs with desired angular spacing around a nonstationary target.By defining a coordinated error relative to neighboring angular spacing,under the premi...This paper addresses a multicircular circumnavigation control for UAVs with desired angular spacing around a nonstationary target.By defining a coordinated error relative to neighboring angular spacing,under the premise that target information is perfectly accessible by all nodes,a centralized circular enclosing control strategy is derived for multiple UAVs connected by an undirected graph to allow for formation behaviors concerning the moving target.Besides,to avoid the requirement of target’s states being accessible for each UAV,fixed-time distributed observers are introduced to acquire the state estimates in a fixed-time sense,and the upper boundary of settling time can be determined offline irrespective of initial properties,greatly releasing the burdensome communication traffic.Then,with the aid of fixed-time distributed observers,a distributed circular circumnavigation controller is derived to force all UAVs to collaboratively evolve along the preset circles while keeping a desired angular spacing.It is inferred from Lyapunov stability that all errors are demonstrated to be convergent.Simulations are offered to verify the utility of proposed protocol.展开更多
In this paper,we present a sufficient condition for the exponential stability of a class of linear switched systems.As an application of this stability result,we establish an output-based adaptive distributed observer...In this paper,we present a sufficient condition for the exponential stability of a class of linear switched systems.As an application of this stability result,we establish an output-based adaptive distributed observer for a general linear leader system over a periodic jointly connected switching communication network,which extends the applicability of the output-based adaptive distributed observer from a marginally stable linear leader system to any linear leader system and from an undirected switching graph to a directed switching graph.This output-based adaptive distributed observer will be applied to solve the leader-following consensus problem for multiple double-integrator systems.展开更多
The distributed observer approach has been an effective way to synthesise a distributed control law for a multi-agent system.However,this approach assumes that all the followers know the system matrix of the leader sy...The distributed observer approach has been an effective way to synthesise a distributed control law for a multi-agent system.However,this approach assumes that all the followers know the system matrix of the leader system,and this assumption may not be desirable in some applications.In this note,we will further introduce an adaptive distributed observer,which is able to estimate both the state and the system matrix of the leader and thus does not require that all the followers know the system matrix of the leader system.We will also point out some applications of the adaptive distributed observer to several cooperative control problems of multiagent systems such as the leader-following consensus problem,the cooperative output regulation problem and rendezvous and/or flocking.展开更多
In the process of signal transmission,an inevitable phenomenon is that the signal may change abruptly at certain discrete moments,negatively contributing to the performance of the system.In this paper,we focus on the ...In the process of signal transmission,an inevitable phenomenon is that the signal may change abruptly at certain discrete moments,negatively contributing to the performance of the system.In this paper,we focus on the distributed state estimation problem for continuous-time linear time-invariant(LTI)systems with intermittent abrupt jumps in communication information.First,the phenomenon of intermittent sudden jumps during information transmission is characterized as impulsive communication disturbances.Under impulsive communication disturbances,a distributed reduced order observer(DROO)is designed with each local observer grouped with two modules:a reduced-order observer and a consensus-based observer.Then,sufficient conditions for the existence of the DROO are presented,by using the graph theory and impulsive analysis.The relationship between the feedback gain and the unstable system matrix,the network topology,the impulse intensity,and the average impulsive interval is obtained.Finally,the validity of the proposed DROO under impulsive communication disturbances is substantiated by numerical simulations.展开更多
Multiple earth observing satellites need to communicate with each other to observe plenty of targets on the Earth together. The factors, such as external interference, result in satellite information interaction delay...Multiple earth observing satellites need to communicate with each other to observe plenty of targets on the Earth together. The factors, such as external interference, result in satellite information interaction delays, which is unable to ensure the integrity and timeliness of the information on decision making for satellites. And the optimization of the planning result is affected. Therefore, the effect of communication delay is considered during the multi-satel ite coordinating process. For this problem, firstly, a distributed cooperative optimization problem for multiple satellites in the delayed communication environment is formulized. Secondly, based on both the analysis of the temporal sequence of tasks in a single satellite and the dynamically decoupled characteristics of the multi-satellite system, the environment information of multi-satellite distributed cooperative optimization is constructed on the basis of the directed acyclic graph（DAG）. Then, both a cooperative optimization decision making framework and a model are built according to the decentralized partial observable Markov decision process（DEC-POMDP）. After that, a satellite coordinating strategy aimed at different conditions of communication delay is mainly analyzed, and a unified processing strategy on communication delay is designed. An approximate cooperative optimization algorithm based on simulated annealing is proposed. Finally, the effectiveness and robustness of the method presented in this paper are verified via the simulation.展开更多
This paper investigates the power sharing and voltage regulation issues of islanded single-/three-phase microgrids(S/T-MGs)where both sources and loads are unbalanced and the presence of adversarial cyber-attacks agai...This paper investigates the power sharing and voltage regulation issues of islanded single-/three-phase microgrids(S/T-MGs)where both sources and loads are unbalanced and the presence of adversarial cyber-attacks against sensors of distributed generator(DG)units is considered.Firstly,each DG unit is modeled as a heterogeneous linear dynamic agent with disturbances caused by sources and loads,then the problem is formulated as a distributed containment control problem.After that,to guarantee satisfactory power sharing and voltage control performance asymptotically achieved for the S/T-MGs,an attack-resilient distributed secondary control approach is developed by designing a distributed adaptive observer.With this approach,the effect of the cyber-attacks can be neutralized to ensure system stability and preserve bounded voltage synchronization.Simulation results are presented to demonstrate the effectiveness of the proposed control approach.展开更多
This paper is concerned with the cooperative target tracking of multiple autonomous surface vehicles(ASVs)under switching interaction topologies.For the target to be tracked,only its position can be measured/received ...This paper is concerned with the cooperative target tracking of multiple autonomous surface vehicles(ASVs)under switching interaction topologies.For the target to be tracked,only its position can be measured/received by some of the ASVs,and its velocity is unavailable to all the ASVs.A distributed extended state observer taking into consideration switching topologies is designed to integrally estimate unknown target dynamics and neighboring ASVs'dynamics.Accordingly,a novel kinematic controller is designed,which takes full advantage of known information and avoids the approximation of some virtual control vectors.Moreover,a disturbance observer is presented to estimate unknown time-varying environmental disturbance.Furthermore,a distributed dynamic controller is designed to regulate the involved ASVs to cooperatively track the target.It enables each ASV to adjust its forces and moments according to the received information from its neighbors.The effectiveness of the derived results is demonstrated through cooperative target tracking performance analysis for a tracking system composed of five interacting ASVs.展开更多
A set of vertical profiles of aerosol number concentrations, size distributions and cloud condensation nuclei（CCN）spectra was observed using a passive cloud and aerosol spectrometer（PCASP） and cloud condensation n...A set of vertical profiles of aerosol number concentrations, size distributions and cloud condensation nuclei（CCN）spectra was observed using a passive cloud and aerosol spectrometer（PCASP） and cloud condensation nuclei counter, over the Tongliao area, East Inner Mongolia, China. The results showed that the average aerosol number concentration in this region was much lower than that in heavily polluted areas. Monthly average aerosol number concentrations within the boundary layer reached a maximum in May and a minimum in September, and the variations in CCN number concentrations at different supersaturations showed the same trend. The parameters c and k of the empirical function N = c S^kwere 539 and1.477 under clean conditions, and their counterparts under polluted conditions were 1615 and 1.42. Measurements from the airborne probe mounted on a Yun-12（Y12） aircraft, together with Hybrid Single-Particle Lagrangian Integrated Trajectory model backward trajectories indicated that the air mass from the south of Tongliao contained a high concentration of aerosol particles（1000–2500 cm^（-3）） in the middle and lower parts of the troposphere. Moreover, detailed intercomparison of data obtained on two days in 2010 indicated that the activation efficiency in terms of the ratio of NCCNto N_a（aerosols measured from PCASP） was 0.74（0.4 supersaturations） when the air mass mainly came from south of Tongliao, and this value increased to 0.83 on the relatively cleaner day. Thus, long-range transport of anthropogenic pollutants from heavily polluted mega cities,such as Beijing and Tianjin, may result in slightly decreasing activation efficiencies.展开更多
A consensus algorithm proposed in the paper is applied to tackle remarkable problems of unmeasurable velocities,the environmental disturbances, and the limited communication environment for the multiple unmanned under...A consensus algorithm proposed in the paper is applied to tackle remarkable problems of unmeasurable velocities,the environmental disturbances, and the limited communication environment for the multiple unmanned underwater vehicles(multi-UUVs). Firstly, for a complex nonlinear and coupled model of the unmanned underwater vehicle(UUV), a technique of feedback linearization is developed to transform the nonlinear UUV model into a secondorder integral UUV model. Secondly, to address the problem of the unavailable velocity information and environmental disturbances for the multi-UUVs system, we design a distributed extended state observer(DESO) to estimate the unmeasurable velocities and environmental disturbances using the relative position information. Finally,we propose a protocol based on the estimation information from the DESO and demonstrate that the multi-UUVs system with the switching directed topologies under the protocol can reach consensus asymptotically. The theoretical result proposed in the literature is verified by one numerical example.展开更多
This paper studies the formation control problem for a group of nonholonomic mobile robots with unknown orientations,where all follower robots are treated as identical and anonymous without requiring direct access to ...This paper studies the formation control problem for a group of nonholonomic mobile robots with unknown orientations,where all follower robots are treated as identical and anonymous without requiring direct access to the leader's state information.Different from existing formation control methods,a novel observer-based formation control strategy is proposed to remove the requirement of the global position and orientation measurement,which is fully distributed.An orientation observer and a distributed observer are designed for the follower to estimate their orientations and the leader's state,based on which a dynamic feedback linearisation controller is developed to achieve the formation objective for mobile robots with unknown orientations.Notably,each follower robot relies solely on local relative position measurement and communication from its neighbours to maintain a desired formation pattern within a directed graph network.Finally,simulation results and comparisons verify the effectiveness and advantages of the proposed control scheme.展开更多
This paper presents a solution to the leaderless consensus of multiple spacecraft on SO(3)under a connected undirected graph.An algorithm is proposed to generate an undirected tree graph from a connected undirected co...This paper presents a solution to the leaderless consensus of multiple spacecraft on SO(3)under a connected undirected graph.An algorithm is proposed to generate an undirected tree graph from a connected undirected communication topology.A distributed observer is designed to estimate the desired attitude and angular velocity for each spacecraft under the generated tree graph.An adaptive controller with a general connected undirected graph is developed to complete the synchronization task.Cases with zero and nonzero final angular velocities are considered.Theoretical proofs and numerical simulations are presented to demonstrate the effectiveness of the proposed controllers.展开更多
Background Future distribution of dengue risk is usually predicted based on predicted climate changes using general circulation models(GCMs).However,it is difficult to validate the GCM results and assess the uncertain...Background Future distribution of dengue risk is usually predicted based on predicted climate changes using general circulation models(GCMs).However,it is difficult to validate the GCM results and assess the uncertainty of the predictions.The observed changes in climate may be very different from the GCM results.We aim to utilize trends in observed climate dynamics to predict future risks of Aedes albopictus in China.Methods We collected Ae.albopictus surveillance data and observed climate records from 80 meteorological stations from 1970 to 2021.We analyzed the trends in climate change in China and made predictions on future climate for the years 2050 and 2080 based on trend analyses.We analyzed the relationship between climatic variables and the prevalence of Ae.albopictus in different months/seasons.We built a classification tree model(based on the average of 999 runs of classification and regression tree analyses)to predict the monthly/seasonal Ae.albopictus distribution based on the average climate from 1970 to 2000 and assessed the contributions of different climatic variables to the Ae.albopictus distribution.Using these models,we projected the future distributions of Ae.albopictus for 2050 and 2080.Results The study included Ae.albopictus surveillance from 259 sites in China found that winter to early spring(November–February)temperatures were strongly correlated with Ae.albopictus prevalence(prediction accuracy ranges 93.0–98.8%)—the higher the temperature the higher the prevalence,while precipitation in summer(June–September)was important predictor for Ae.albopictus prevalence.The machine learning tree models predicted the current prevalence of Ae.albopictus with high levels of agreement(accuracy>90%and Kappa agreement>80%for all 12 months).Overall,winter temperature contributed the most to Ae.albopictus distribution,followed by summer precipitation.An increase in temperature was observed from 1970 to 2021 in most places in China,and annual change rates varied substantially from-0.22℃/year to 0.58℃/year among sites,with the largest increase in temperature occurring from February to April(an annual increase of 1.4–4.7℃ in monthly mean,0.6–4.0℃ in monthly minimum,and 1.3–4.3℃ in monthly maximum temperature)and the smallest in November and December.Temperature increases were lower in the tropics/subtropics(1.5–2.3℃ from February–April)compared to the high-latitude areas(2.6–4.6℃ from February–April).The projected temperatures in 2050 and 2080 by this study were approximately 1–1.5℃ higher than those projected by GCMs.The estimated current Ae.albopictus risk distribution had a northern boundary of north-central China and the southern edge of northeastern China,with a risk period of June–September.The projected future Ae.albopictus risks in 2050 and 2080 cover nearly all of China,with an expanded risk period of April–October.The current at-risk population was estimated to be 960 million and the future at-risk population was projected to be 1.2 billion.Conclusions The magnitude of climate change in China is likely to surpass GCM predictions.Future dengue risks will expand to cover nearly all of China if current climate trends continue.展开更多
基金supported by the National Natural Science Foundation of China(62133008,62303273,62188101,62373226,62473173)Young Taishan Scholars Program of Shandong Province of China(tsqn202408206)+2 种基金a Project of Shandong Province Higher Educational Youth and Innovation Talent Introduction and Education Programthe Natural Science Foundation of Shandong Province,China(ZR2023QF072)China Postdoctoral Science Foundation(2022M721932)
文摘Driven by practical applications, the achievement of distributed observers for nonlinear systems has emerged as a crucial advancement in recent years. However, existing theoretical advancements face certain limitations: They either fail to address more complex nonlinear phenomena, rely on hard-to-verify assumptions, or encounter difficulties in solving system parameters.Consequently, this paper aims to address these challenges by investigating distributed observers for nonlinear systems through the full-measured canonical form(FMCF), which is inspired by full-measured system(FMS) theory. To begin with, this study addresses the fact that the FMCF can only be obtained through the observable canonical form(OCF) in existing FMS theories.The paper demonstrates that a class of nonlinear systems can directly obtain FMCF through state space equations, independent of OCF. Also, a general method for solving FMCF in such systems is provided. Furthermore, based on the FMCF, A distributed observer is developed for nonlinear systems under two scenarios: Lipschitz conditions and open-loop bounded conditions.The paper establishes their asymptotic omniscience and demonstrates that the designed distributed observer in this study has fewer design parameters and is more convenient to construct than existing approaches. Finally, the effectiveness of the proposed methods is validated through simulation results on Van der Pol oscillators and microgrid systems.
基金Project supported by the National Natural Science Foundation for Distinguished Young Scholars of China (Grant No. 60525303)the National Natural Science Foundation of China (Grant No. 60704009)+1 种基金the Key Project for Natural Science Research of the Hebei Educational Department (Grant No. ZD200908)the Doctorial Fund of Yanshan University (Grant No. B203)
文摘To investigate the leader-following formation control, in this paper we present the design problem of control protocols and distributed observers under which the agents can achieve and maintain the desired formation from any initial states, while the velocity converges to that of the virtual leader whose velocity cannot be measured by agents in real time. The two cases of switching topologies without communication delay and fixed topology with time-varying communication delay are both considered for multi-agent networks. By using the Lyapunov stability theory, the issue of stability is analysed for multi-agent systems with switching topologies. Then, by considering the time-varying communication delay, the sufficient condition is proposed for the multi-agent systems with fixed topology. Finally, two numerical examples are given to illustrate the effectiveness of the proposed leader-following formation control protocols.
基金co-supported by the National Key R&D Program of China(No.2018YFB1600500)。
文摘This paper develops both adaptive distributed dynamic state feedback control law and adaptive distributed measurement output feedback control law for heterogeneous discrete-time swarm systems with multiple leaders.The convex hull formed by the leaders and the system matrix of leaders is estimated via an adaptive distributed containment observer.Such estimations will feed the followers so that every follower can update the system matrix of the corresponding adaptive distributed containment observer and the system state of their neighbors.The followers cooperate with each other to achieve leader-follower consensus and thus solve the containment control problem over the network.Numerical results demonstrate the effectiveness and computational feasibility of the proposed control laws.
基金supported in part by the National Natural Science Foundation of China(Nos.U23B2036,U2013201).
文摘In this paper, distributed event-triggered performance constraint control is proposed for Heterogeneous Multiagent Systems (HMASs) including quadrotor unmanned aerial vehicles and unmanned ground vehicles in the presence of unknown external disturbances. To tackle the problem of different dynamic characteristics and facilitate the controller design, the virtual variable is introduced in the z axis of the nonlinear model of unmanned ground vehicles. By using this approach, a universal model is established for the HMAS. Moreover, a distributed disturbance observer is established to cope with the adverse influence of the external disturbances. Then, an Appointed-Time Prescribed Performance Function (ATPPF) is designed to restrict the tracking error in the predefined regions. On this basis, the distributed performance constraint controller is proposed for the HMAS based on the ATPPF and the distributed disturbance observer. Furthermore, the improved event-triggered mechanism is proposed with a dynamic threshold, which depends on the distance between the tracking error and the boundary of the ATPPF. Finally, the effectiveness of the proposed control method is verified by the comparative experiments on an HMAS.
基金supported by the National Natural Science Foundation of China (Nos. 62176214 and 61973253)。
文摘To address the problem of instability and inaccuracy when the Unmanned Aerial Vehicles(UAVs) formation equipped with bearing-only sensor network tracks a maneuvering target,this paper proposes a distributed cooperative tracking control method considering the effectiveness of passive detection. First, the system model of passive detection in UAV formation is constructed.Then, the Geometric Dilution of Precision(GDOP) of bearing-only sensor nodes pair on the observation plane is analyzed. Building on this foundation, the pairwise form is expanded to obtain the optimal geometric configuration for the entire network. Subsequently, the Distributed Cubature Information Filtering(DCIF) is integrated with the weighted average consensus protocol to design the distributed cooperative observer suitable for the system model, enabling state estimation of the target. Finally, within the distributed architecture, the Nonlinear Model Predictive Controller(NMPC) is designed. This controller autonomously assembles the UAV formation during the assembly phase and forms an optimal detection array. The UAV formation then tracks the target using the virtual geometric center based on the established rigid geometric configuration. The simulation experiments validate that the proposed model and method can enhance the passive detection effectiveness of the UAV formation, thereby achieving stable and efficient distributed cooperative tracking for the maneuvering target.
基金supported in part by the National Key Research and Development Program of China(Grant No.2018AAA0101100)in part by the National Natural Science Foundation of China(Grant Nos.61621003,92067204 and 61903017)in part by the China Postdoctoral Science Foundation(Grant Nos.2020TQ0027 and 2020M680285)。
文摘With the rapid development of information technologies and cloud computing, sensor networks play an increasingly important role in our society. Over the past few decades, distributed observer theory has attracted unprecedented attention due to its wide potential applications in different areas. Meanwhile, various approaches and algorithms have been proposed and investigated. The design of distributed observers is one of the frontier topics of system and control research, which has the significant theoretical values and broad application prospects. This paper attempts to review the representative models and the corresponding approaches for distributed observer design in linear time-invariant(LTI) systems. Firstly, the research backgrounds and main advances of distributed observer designs are briefly reviewed. Then, recent results of distributed observer designs for discrete-time and continuous-time LTI multi-agent systems(MASs) are introduced in detail, respectively. Finally, the prospects and the future work directions of the design of distributed observers are put forward. The main purpose of this paper is to promote the emerging topic on the designs of distributed observers, with focuses on the interdisciplinary interest from technological sciences.
基金supported in part by the National Natural Science Foundation of China under Grant Nos.62173312,61922037,61873115,and 61803348in part by the National Major Scientific Instruments Development Project under Grant 61927807+6 种基金in part by the State Key Laboratory of Deep Buried Target Damage under Grant No.DXMBJJ2019-02in part by the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi under Grant 2020L0266in part by the Shanxi Province Science Foundation for Youths under Grant No.201701D221123in part by the Youth Academic North University of China under Grant No.QX201803in part by the Program for the Innovative Talents of Higher Education Institutions of Shanxiin part by the Shanxi“1331Project”Key Subjects Construction under Grant 1331KSCin part by the Supported by Shanxi Province Science Foundation for Excellent Youths。
文摘This paper addresses a multicircular circumnavigation control for UAVs with desired angular spacing around a nonstationary target.By defining a coordinated error relative to neighboring angular spacing,under the premise that target information is perfectly accessible by all nodes,a centralized circular enclosing control strategy is derived for multiple UAVs connected by an undirected graph to allow for formation behaviors concerning the moving target.Besides,to avoid the requirement of target’s states being accessible for each UAV,fixed-time distributed observers are introduced to acquire the state estimates in a fixed-time sense,and the upper boundary of settling time can be determined offline irrespective of initial properties,greatly releasing the burdensome communication traffic.Then,with the aid of fixed-time distributed observers,a distributed circular circumnavigation controller is derived to force all UAVs to collaboratively evolve along the preset circles while keeping a desired angular spacing.It is inferred from Lyapunov stability that all errors are demonstrated to be convergent.Simulations are offered to verify the utility of proposed protocol.
基金the Research Grants Council of the Hong Kong Special Administrative Region under Grant Nos.14202619 and PDFS2223-4S02the National Natural Science Foundation(NSFC)of China under Grant No 61973260.
文摘In this paper,we present a sufficient condition for the exponential stability of a class of linear switched systems.As an application of this stability result,we establish an output-based adaptive distributed observer for a general linear leader system over a periodic jointly connected switching communication network,which extends the applicability of the output-based adaptive distributed observer from a marginally stable linear leader system to any linear leader system and from an undirected switching graph to a directed switching graph.This output-based adaptive distributed observer will be applied to solve the leader-following consensus problem for multiple double-integrator systems.
基金supported by the Research Grants Council of the Hong Kong Special Administration Region[grant number 14200515].
文摘The distributed observer approach has been an effective way to synthesise a distributed control law for a multi-agent system.However,this approach assumes that all the followers know the system matrix of the leader system,and this assumption may not be desirable in some applications.In this note,we will further introduce an adaptive distributed observer,which is able to estimate both the state and the system matrix of the leader and thus does not require that all the followers know the system matrix of the leader system.We will also point out some applications of the adaptive distributed observer to several cooperative control problems of multiagent systems such as the leader-following consensus problem,the cooperative output regulation problem and rendezvous and/or flocking.
基金supported in part by the National Natural Science Foundation of China under Grant Nos.62425602 and 62273159
文摘In the process of signal transmission,an inevitable phenomenon is that the signal may change abruptly at certain discrete moments,negatively contributing to the performance of the system.In this paper,we focus on the distributed state estimation problem for continuous-time linear time-invariant(LTI)systems with intermittent abrupt jumps in communication information.First,the phenomenon of intermittent sudden jumps during information transmission is characterized as impulsive communication disturbances.Under impulsive communication disturbances,a distributed reduced order observer(DROO)is designed with each local observer grouped with two modules:a reduced-order observer and a consensus-based observer.Then,sufficient conditions for the existence of the DROO are presented,by using the graph theory and impulsive analysis.The relationship between the feedback gain and the unstable system matrix,the network topology,the impulse intensity,and the average impulsive interval is obtained.Finally,the validity of the proposed DROO under impulsive communication disturbances is substantiated by numerical simulations.
基金supported by the National Science Foundation for Young Scholars of China(6130123471401175)
文摘Multiple earth observing satellites need to communicate with each other to observe plenty of targets on the Earth together. The factors, such as external interference, result in satellite information interaction delays, which is unable to ensure the integrity and timeliness of the information on decision making for satellites. And the optimization of the planning result is affected. Therefore, the effect of communication delay is considered during the multi-satel ite coordinating process. For this problem, firstly, a distributed cooperative optimization problem for multiple satellites in the delayed communication environment is formulized. Secondly, based on both the analysis of the temporal sequence of tasks in a single satellite and the dynamically decoupled characteristics of the multi-satellite system, the environment information of multi-satellite distributed cooperative optimization is constructed on the basis of the directed acyclic graph（DAG）. Then, both a cooperative optimization decision making framework and a model are built according to the decentralized partial observable Markov decision process（DEC-POMDP）. After that, a satellite coordinating strategy aimed at different conditions of communication delay is mainly analyzed, and a unified processing strategy on communication delay is designed. An approximate cooperative optimization algorithm based on simulated annealing is proposed. Finally, the effectiveness and robustness of the method presented in this paper are verified via the simulation.
基金This work was supported in part by the National Natural Science Foundation of China(No.51907098)in part by the China Postdoctoral Science Foundation(No.2020T130337).
文摘This paper investigates the power sharing and voltage regulation issues of islanded single-/three-phase microgrids(S/T-MGs)where both sources and loads are unbalanced and the presence of adversarial cyber-attacks against sensors of distributed generator(DG)units is considered.Firstly,each DG unit is modeled as a heterogeneous linear dynamic agent with disturbances caused by sources and loads,then the problem is formulated as a distributed containment control problem.After that,to guarantee satisfactory power sharing and voltage control performance asymptotically achieved for the S/T-MGs,an attack-resilient distributed secondary control approach is developed by designing a distributed adaptive observer.With this approach,the effect of the cyber-attacks can be neutralized to ensure system stability and preserve bounded voltage synchronization.Simulation results are presented to demonstrate the effectiveness of the proposed control approach.
基金supported in part by the National Science Foundation of China(61873335,61833011)the Project of Scie nce and Technology Commission of Shanghai Municipality,China(20ZR1420200,21SQBS01600,19510750300,21190780300)。
文摘This paper is concerned with the cooperative target tracking of multiple autonomous surface vehicles(ASVs)under switching interaction topologies.For the target to be tracked,only its position can be measured/received by some of the ASVs,and its velocity is unavailable to all the ASVs.A distributed extended state observer taking into consideration switching topologies is designed to integrally estimate unknown target dynamics and neighboring ASVs'dynamics.Accordingly,a novel kinematic controller is designed,which takes full advantage of known information and avoids the approximation of some virtual control vectors.Moreover,a disturbance observer is presented to estimate unknown time-varying environmental disturbance.Furthermore,a distributed dynamic controller is designed to regulate the involved ASVs to cooperatively track the target.It enables each ASV to adjust its forces and moments according to the received information from its neighbors.The effectiveness of the derived results is demonstrated through cooperative target tracking performance analysis for a tracking system composed of five interacting ASVs.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA05100304)the Chinese Natural Science Foundation(Grant Nos.41475028 and 41405128)
文摘A set of vertical profiles of aerosol number concentrations, size distributions and cloud condensation nuclei（CCN）spectra was observed using a passive cloud and aerosol spectrometer（PCASP） and cloud condensation nuclei counter, over the Tongliao area, East Inner Mongolia, China. The results showed that the average aerosol number concentration in this region was much lower than that in heavily polluted areas. Monthly average aerosol number concentrations within the boundary layer reached a maximum in May and a minimum in September, and the variations in CCN number concentrations at different supersaturations showed the same trend. The parameters c and k of the empirical function N = c S^kwere 539 and1.477 under clean conditions, and their counterparts under polluted conditions were 1615 and 1.42. Measurements from the airborne probe mounted on a Yun-12（Y12） aircraft, together with Hybrid Single-Particle Lagrangian Integrated Trajectory model backward trajectories indicated that the air mass from the south of Tongliao contained a high concentration of aerosol particles（1000–2500 cm^（-3）） in the middle and lower parts of the troposphere. Moreover, detailed intercomparison of data obtained on two days in 2010 indicated that the activation efficiency in terms of the ratio of NCCNto N_a（aerosols measured from PCASP） was 0.74（0.4 supersaturations） when the air mass mainly came from south of Tongliao, and this value increased to 0.83 on the relatively cleaner day. Thus, long-range transport of anthropogenic pollutants from heavily polluted mega cities,such as Beijing and Tianjin, may result in slightly decreasing activation efficiencies.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51679057 and 51709062)Heilongjiang Province Outstanding Youth Fund (Grant No. J2016JQ0052)+2 种基金Equipment Preresearch Key Lab Fund (Grant No. 614221580107)China Postdoctoral Science Foundation (Grant No. 2019M651265)Harbin Science and Technology Talent Research Special Fund (Grant No.2017RAQXJ150)。
文摘A consensus algorithm proposed in the paper is applied to tackle remarkable problems of unmeasurable velocities,the environmental disturbances, and the limited communication environment for the multiple unmanned underwater vehicles(multi-UUVs). Firstly, for a complex nonlinear and coupled model of the unmanned underwater vehicle(UUV), a technique of feedback linearization is developed to transform the nonlinear UUV model into a secondorder integral UUV model. Secondly, to address the problem of the unavailable velocity information and environmental disturbances for the multi-UUVs system, we design a distributed extended state observer(DESO) to estimate the unmeasurable velocities and environmental disturbances using the relative position information. Finally,we propose a protocol based on the estimation information from the DESO and demonstrate that the multi-UUVs system with the switching directed topologies under the protocol can reach consensus asymptotically. The theoretical result proposed in the literature is verified by one numerical example.
基金supported in part by the National Key R&D Program of China(2024YFB4707401)the National Natural Science Foundation of China(62173029,62273033,62273191,U1966202,62233015)the Fundamental Research Funds for the Central Universities China(FRF-BD-19-002A).
文摘This paper studies the formation control problem for a group of nonholonomic mobile robots with unknown orientations,where all follower robots are treated as identical and anonymous without requiring direct access to the leader's state information.Different from existing formation control methods,a novel observer-based formation control strategy is proposed to remove the requirement of the global position and orientation measurement,which is fully distributed.An orientation observer and a distributed observer are designed for the follower to estimate their orientations and the leader's state,based on which a dynamic feedback linearisation controller is developed to achieve the formation objective for mobile robots with unknown orientations.Notably,each follower robot relies solely on local relative position measurement and communication from its neighbours to maintain a desired formation pattern within a directed graph network.Finally,simulation results and comparisons verify the effectiveness and advantages of the proposed control scheme.
基金This work was supported by the National Natural Science Foundation of China under Grant Nos.11832005 and 12102174.
文摘This paper presents a solution to the leaderless consensus of multiple spacecraft on SO(3)under a connected undirected graph.An algorithm is proposed to generate an undirected tree graph from a connected undirected communication topology.A distributed observer is designed to estimate the desired attitude and angular velocity for each spacecraft under the generated tree graph.An adaptive controller with a general connected undirected graph is developed to complete the synchronization task.Cases with zero and nonzero final angular velocities are considered.Theoretical proofs and numerical simulations are presented to demonstrate the effectiveness of the proposed controllers.
文摘Background Future distribution of dengue risk is usually predicted based on predicted climate changes using general circulation models(GCMs).However,it is difficult to validate the GCM results and assess the uncertainty of the predictions.The observed changes in climate may be very different from the GCM results.We aim to utilize trends in observed climate dynamics to predict future risks of Aedes albopictus in China.Methods We collected Ae.albopictus surveillance data and observed climate records from 80 meteorological stations from 1970 to 2021.We analyzed the trends in climate change in China and made predictions on future climate for the years 2050 and 2080 based on trend analyses.We analyzed the relationship between climatic variables and the prevalence of Ae.albopictus in different months/seasons.We built a classification tree model(based on the average of 999 runs of classification and regression tree analyses)to predict the monthly/seasonal Ae.albopictus distribution based on the average climate from 1970 to 2000 and assessed the contributions of different climatic variables to the Ae.albopictus distribution.Using these models,we projected the future distributions of Ae.albopictus for 2050 and 2080.Results The study included Ae.albopictus surveillance from 259 sites in China found that winter to early spring(November–February)temperatures were strongly correlated with Ae.albopictus prevalence(prediction accuracy ranges 93.0–98.8%)—the higher the temperature the higher the prevalence,while precipitation in summer(June–September)was important predictor for Ae.albopictus prevalence.The machine learning tree models predicted the current prevalence of Ae.albopictus with high levels of agreement(accuracy>90%and Kappa agreement>80%for all 12 months).Overall,winter temperature contributed the most to Ae.albopictus distribution,followed by summer precipitation.An increase in temperature was observed from 1970 to 2021 in most places in China,and annual change rates varied substantially from-0.22℃/year to 0.58℃/year among sites,with the largest increase in temperature occurring from February to April(an annual increase of 1.4–4.7℃ in monthly mean,0.6–4.0℃ in monthly minimum,and 1.3–4.3℃ in monthly maximum temperature)and the smallest in November and December.Temperature increases were lower in the tropics/subtropics(1.5–2.3℃ from February–April)compared to the high-latitude areas(2.6–4.6℃ from February–April).The projected temperatures in 2050 and 2080 by this study were approximately 1–1.5℃ higher than those projected by GCMs.The estimated current Ae.albopictus risk distribution had a northern boundary of north-central China and the southern edge of northeastern China,with a risk period of June–September.The projected future Ae.albopictus risks in 2050 and 2080 cover nearly all of China,with an expanded risk period of April–October.The current at-risk population was estimated to be 960 million and the future at-risk population was projected to be 1.2 billion.Conclusions The magnitude of climate change in China is likely to surpass GCM predictions.Future dengue risks will expand to cover nearly all of China if current climate trends continue.
