Researches On Distributed Control Of Multi-agent Systems Under Networked Environments

Nowadays,the world is developing towards networking,automation and intelligence,so the automatic control of multi-agent systems has become a hot issue in the research fields.The networked environment is complicated,which is often accompanied by the communication security problems.This paper mainly studies the security control problem of multi-agent systems in the network environments.Since it is difficult for the nodes in the network to obtain the global information of the whole network,we adopt the distributed control strategy to deal with various control problems for the multi-agent systems.Consensus of the multi-agent systems is an issue of great concern in the field of engineering control,and is also a hot topic in the research of automatic control.This paper focuses on the consensus problem of multi-agent systems in the insecure networked environments.The main contents of this dissertation can be summarized as follows.(1)This paper investigates the consensus problem of nonlinear multi-agent systems for directed networks under denial-of-service(Do S)attacks.The Do S attacks maliciously interrupt communication among agents by destroying communication channels,and further break the consensus goal.In the actual situations,the frequency and duration of attacks are constrained because attackers are obstructed from all sides.One question,therefore,is worth considering:is there a criterion to determine whether the consensus can be realized for the directed multiagent networks suffering from Do S attacks with constrained frequencies and durations? In this paper,a sufficient condition is provided for guaranteeing the global exponentially consensus of nonlinear multi-agent systems over insecure networks under Do S attacks with restricted frequencies and durations.Furthermore,an impulsive control protocol is designed to attenuate the destructive effects of the Do S attacks.It is shown that consensus of the multi-agent systems under this proposed impulsive control scheme can be realized by choosing an appropriate impulse gain.(2)The event-triggered bipartite consensus is addressed for multi-agent systems with communication delays.Communication lines are often subject to malicious electromagnetic interference,which will cause delay in the communication between agents.For the directed signed networks,an event-based interaction protocol is firstly proposed.Then it is shown that with the proposed protocol,bipartite consensus can be realized for the structurally balanced signed networks with distributed communication delay.As for the structurally unbalanced signed networks with communication delay,it is proved that consensus can also be reached under the proposed event-triggered scheme,and the final consensus value is 0.It should be emphasized that the proposed event-triggered controllers depend only on the local information.Furthermore,Zero phenomenon can be excluded,and the positive lower bound of the interevent times is simultaneously provided.(3)The asymmetric bipartite consensus is investigated for multi-agent systems under communication delays.First,we propose the concept of asymmetric bipartite consensus for multi-agent systems.For structurally balanced signed digraphs,by constructing a new class of general Laplacian matrices,it is obtained that all agents will converge to two values with different modulus if the signed digraph is strongly connected.Interestingly,these two values completely depend on the left eigenvector of the general Laplacian matrix corresponding to the zero eigenvalue and the initial states of all agents.Furthermore,it is shown that all agents can reach interval asymmetric bipartite consensus if the associated signed digraph contains a spanning tree.In particular,some useful results are also presented for specific signed digraphs with spanning trees.Malicious electromagnetic interference can cause communication delay,then the pinning asymmetric bipartite consensus for multi-agent networks with antagonistic interactions and communication delays is investigated.A pinning asymmetric bipartite consensus protocol is designed firstly for the considered delayed multi-agent systems.It is shown that,under the proposed consensus protocol,the pinning asymmetric bipartite consensus can be realized if the addressed signed digraph is strongly connected and structurally balanced.Furthermore,for the signed digraph with spanning trees,we subtly design a pinning interval asymmetric bipartite consensus protocol to make all the agents converge within a predetermined interval.(4)The scaled consensus of multi-agent systems under random network attacks is studied.In practical engineering applications,the communication between agents is often vulnerable to random network attacks.This paper mainly investigates the attacks with semi-Markov property and studies the stochastic scaled consensus of multi-agent systems under such attacks.Sufficient conditions are established to guarantee the addressed system to realize the scaled consensus with probability one,which means that all agents' states almost surely reach a dictated proportion.Here,the semi-Markov process concerned is much more general than those utilized in the recent literature,which can be characterized by two important factors: 1)the transition probability matrix,and 2)the polytropical distribution functions of the sojourn times.In addition,pinning scaled consensus protocol is designed by employing the pinning control technique,where only the root nodes of the union set of all the topologies are chosen to be pinned,and the final desired state value of the considered system can be realized with probability one.