Research On Consensus Of Multiagent Systems Based On Switched-Delay System Theory

Recently, distributed coordination of multiagent systems has gained much attention, due to its wide applications in many fields, such as attitude control of satellites, formation control of unmanned aerial vehicles, distributed control of sensor networks etc. The research of multia-gent system is a hot topic. As an important and fundamental issue in the research of multiagent systems, the consensus problem has especially received researchers' attention from various sci-entific communities. Consensus problem means to design a distributed control protocol for each agent based on limited information about itself and its neighbors to make all agents to reach an agreement on certain quantities of interest. It is of importance to study the consensus problem from both practical and theoretical perspectives.The communication noises and networked-induced delays usually cannot be avoided in the research of multiagent systems because agents are connected by a communication network. Based on the existing results in literature, this paper is concerned with the consensus problem for multiagent systems under the communication noises and delays by using the switched delay system theory and stability theory. The main contents of this dissertation are given as follows:Due to the effects of limited bandwidth of the communication network or communication noises, communication link failure phenomenon may happen frequently in the research of multi-agent systems. Therefore, this dissertation first studies the leader-following consensus problems under communication failure. In order to solve such an issue, a novel switched delay system is developed. The theoretical analysis and simulation show that if the communication network contains a spanning tree and the frequency and length of the communication failure satisfy cer-tain conditions, the multiagent systems with communication failure can achieve leader-following consensus. Subsequently, this dissertation studies the consensus problem of nonlinear multiagent systems under the large delay periods with Lipschitz constraints. A pinning control protocol is developed for the nonlinear multiagent systems. We prove that if the length and the frequency of the large delay periods satisfy certain conditions, the multiagent systems can achieve consensus.It is usually hard to ensure that all the agents have the same dynamical behaviors because of various environmental complexities or uncertainties. Thus, in this dissertation, the consen-sus problem of a heterogeneous multiagent system including first-order and second-order agents is investigated. The communication failure and external disturbances are both taken into ac-count for this multiagent system. A sampled-data-based control protocol is developed for such a heterogeneous mutliagent system. The results show that if the communication failure satisfies certain conditions, the heterogeneous multiagent system can achieve consensus and meanwhile possess a desired L2 gain performance.In practice, the states of the neighboring agents of an agent may be unavailable for designing the consensus protocol. Thus, the consensus problem of multiagent systems based on the output information under the stochastic sampling mechanism is studied. Two different observers, i.e., the full-order and reduced-order observers are designed for the multiagent system. Based on the observers' information, two observer-based control protocols are designed. Sufficient conditions guaranteeing consensus of the considered multiagent system are developed in terms of linear matrix inequalities. In addition, the effects of the communication delays are also considered. The effectiveness and the correctness of the proposed method for the full-and reduced-order observers are demonstrated by two numerical simulations.Finally, all the research works of this dissertation are summarized. Then future works for the multiagent system are discussed.