Fixed-time cooperative control of multi-agent systems under denial-of-service attacks and its application

Cooperative control of multi-agent systems has been attracting tremendous research interest in control and robotics communities due to their broad application in many areas including formation control of unmanned aerial vehicles, rendezvous of multiple mobile robots, deployment of sensor networks, and so on. Compared with traditional single-agent systems, multi-agent systems have the potential to accomplish more complex tasks with higher efficiency, better robustness, and better scalability. Many theories, techniques, and tools have been developed for cooperative control of multi-agent systems under the assumption that communication networks of multi-agent systems work normally without any cyber-attacks. However in practice, communication networks of multiagent systems are often exposed to cyber-attacks, in addition to other commonly-known communication constraints such as time-delays. The existence of cyber-attacks as well as communication constraints would have great adverse impacts on the performance of the concerned multi-agent systems, or even worse, disrupt their intended functions or services. One of typical cyber-attacks is the so-called denial-of-service attacks, which tend to influence the timeliness of information transfer by blocking or destroying the connectivity of networks. This motivates researchers to investigate and develop resilient cooperative control approaches to multi-agent systems under denial-of-service attacks in the past few years. The recent literature review reveals that most existing works on cooperative control of multi-agent systems under denial-of-service attacks achieve the desired coordination tasks asymptotically or exponentially, that is, they achieve the desired coordination tasks only when time goes to infinity. However, many engineering applications in cooperative control of multi-agent systems call for finite-time or fixed-time convergence instead of exponential or asymptotical convergence, even in the case of denial-ofservice attacks. In other words, coordination tasks are expected to be accomplished in finite-time or fixed-time. As the upper bound of finite-time convergence is dependent on the initial conditions of the concerned systems while that of fixed-time convergence is not, which is more desirable, we will thus focus on fixed-time cooperative control of multi-agent systems under denial-of-service attacks in this project. In particular, we will investigate the following three problems: (i) the fixedtime cooperative control problem of multi-agent systems under denial-of-service attacks over undirected communication graphs; (ii) the fixed-time cooperative control problem of multi-agent systems under denial-of-service attacks over directed communication graphs; and (iii) the fixedtime cooperative control problem of multi-agent systems under both denial-of-service attacks and communication delays. This project, by addressing those problems, will explore and develop novel theories and methodologies for fixed-time cooperative control of multi-agent systems under denialof- service attacks over undirected/directed communication graphs. The outcomes of this project are expected to be novel theories and methodologies for cooperative control of multi-agent systems under denial-of-service attacks, which would provide more solid design tools for engineers in realworld applications.