Frequency domain analysis of resilient consensus in multi-agent systems subject to an integrity attack

Unmanned systems like autonomous surface vessels are being enhanced with the communication infrastructure to improve their reliability, efficiency and sustainability. Regardless of the significance advantages, their open communication network and connectivity renders these systems to a variety of cyber-attacks. This paper considers the resilient consensus problem of multi-agent systems (MASs) under an integrity attack. Unlike the existing works in the time domain, a resilient consensus controller is designed and analyzed for MASs in the frequency domain. To this end, analysis and modeling of MASs under the integrity attacks (MU-IA) are addressed in the frequency domain in which each agent is a linear continuous system with an input time delay. A resilient H_∞ controller is proposed to tackle the tampering of information due to an integrity attack. The proposed H_∞ controller is designed based on an internal stability method for performance tracking and robustness of the MU-IA. A significant strength of this scheme is that the current approach does not enforce any limit on the number of agents or neighboring agents under the integrity attacks. A quantitative tuning method is used to trade off the nominal performance and robustness of the MU-IA. Simulation results show the effectiveness of the proposed control strategy.