Static output-feedback synchronisation of multi-agent systems: a secure and unified approach

In this study, a unified distributed static output-feedback (OPFB) control protocol is presented for multi-agent systems. The proposed approach is unified in the sense that it is applicable to both homogeneous and heterogeneous multi-agent systems. Despite its importance, distributed OPFB control design is not considered for heterogeneous systems in the literature. Moreover, as will be shown, existing static OPFB controllers for homogeneous systems are vulnerable to attacks on sensors and actuators. More precisely, it is shown that a compromised agent can make an intact agent turn away from the leader if there is a directed path of any length from the compromised agent to the intact agent. To overcome these shortcomings, a distributed OPFB controller is presented which is (i) applicable to both homogeneous and heterogeneous systems, and (ii) is resilient against attacks on sensors and actuators. The proposed framework prevents attacks on sensors and actuators from propagating across the network and, thus, guarantees synchronisation of intact agents to the leader. To further improve the resiliency and guarantee synchronisation of even compromised agents, a disturbance compensator is designed. A significant advantage of this approach is that no assumption on topological connectivity and the number of agents under attack is required.