Tracking Problems In Multi-agent Systems With Communication Delays

In recent years, with the rapid development of communication technology, computer science theory and automatic control theory, the research on multi-agent system has attracted more and more attention.As one of the most important issues of multi-agent systems, the consensus problem has received increasing attention from both academical and industrial area. The consensus problem of multi-agent systems is defined that states of all the agents in the system trend to agree upon the same status. The consensus of all agents is a fundamental pre-reqirement for the coordination control of the system. Tracking problem is a classical application of consensus. Since all the information have to be exchanged through the networks between agents, time delays will be unavoidable due to the unreliable communication channel, the error of the physical equipment and the limitation of the transmission range in the practical application. It is still a challenge to consider the problem of multi-agent tracking problem with communication time delays. In this work, by employing the theory of algebraic graph theory, matrix theory, modern control theory and stability theory, the tracking problem of multi-agent has been addressed. The main content of this work can generally be categorized into the following aspects:(1) The tracking problems of a first order discrete multi-agent system and a second order discrete multi-agent system are presented. In the case of considering the communication delay, a network predictive control algorithm was proposed and the stability of that method has been analyzed by using the Lyapunov stability theorem. Through the simulations, the effectiveness and robustness of the algorithms are tested.(2) This thesis investigates the time delay tracking problem based on Voronoi graph. By employing the Voronoi graph, the two dimensional space could be divided into many Voronoi cells. In the whole procedure of tracking, the tracking agents of the networks has been changed which is significantly different from the traditional switching topology structure. The relay tracking controller is proposed to solve the problem of variable topology and time delay, and the tracking algorithm is verified by simulation experiments.(3) Finally, the tracking problem of high order multi-agent system with dynamically changing topology and time varying communication delays. In this work, the dynamically changing topology means the topology changes continually along with time rather than switching among several fixed topologies. By designing the corresponding high order tracking controller, the tracking problem is solved in the case of time varying topology and communication time delay. At last, the performance of the provided controller is illustrated by the numerical simulations.