Consensus Of Nonlinear Multi-agent Systems Via Event-triggered Control Strategies

In recent years, the consensus of multi-agent system has attracted great interests from researchers, due to a large number of applications of different fields being dependent on the systems, such as the natural science, engineering, and so on. The specialized results have been widely applied in the robot cooperative control, traffic management, electronic commerce, unmanned aerial vehicles coordinated control, formation control, emergence, cluster and network resource allocation control. In a multi-agent system, the consensus meaning that the state of all agents can exchange and merge the information via nodes, and finally achieve the same state. And the consensus protocols are the rules for the interaction and information transmission among agents. And in this process, information exchange protocol among agents plays a decisive role. According to the objective environment of the multi-agent system, people tend to design different information exchange protocols. Since such application background, the consensus has become one of the most valuable issues.Based on the background of the multi-agent system, this thesis focuses on the leader-following consensus of the nonlinear multi-agent via event-triggered control. The main contents and research results are summarized as follows:(1) The research background and significance of multi-agents are introduced. Meanwhile, the main contributions in this thesis are briefly outlined.(2) Leader-following consensus problem of the multi-agent systems with input delay is studied. Firstly, considering a network with fixed topology, the corresponding event-triggered control protocol is proposed. Suppose that the communication topology of the system has a directed spanning tree. Sufficient conditions are derived to reach a leader-following consensus based on matrix theory, algebraic graph theory and the Lyapunov method approach. Then the switching topology case is considered. The corresponding theoretical results are similar to the situation of a network with switching topology. A numerical example is presented to illustrate the effectiveness of the obtained theoretical results.(3) The problem of semi-global leader-following consensus of the nonlinear multi-agent via event-triggered control. Firstly, in order to overcome the shortcomings of the traditional sampling control method, namely, to further decrease the frequency of controller updates and unnecessary costs of computation and communication resources, event-triggered control protocol is introduced into the consensus of multi-agent systems. This thesis proposed an event-based control strategy with a novel event-triggered function, which can avoid the continuous communication. Based on the proposed controller, sufficient conditions are obtained to ensure a leader-following consensus. Secondly, to reduce the control consumption, we adopt the pinning control strategy. Namely, controllers only apply control actions to a very few fraction of nodes. However, most of the existing works are based on continuous-time communications between nodes that have a obvious insurmountable deficiency: the designed control law requires real-time updates, which promotes network nodes to be equipped with high performance processors and high-speed communication channels. Finally, by using the Lyapunov stability theory, this thesis finds the consensus conditions of multi-agent systems with nonlinear and input time-delay.