Vulnerability of Connected Autonomous Vehicles Networks to Periodic Time-Varying Communication Delays of Certain Frequency

In this paper, we consider periodic communication delays within the connected autonomous vehicles platoon. Periodic signals are fundamentally simple to create, and in this study we analyze whether certain amplitude or frequencies can cause instability. This is important as we discover in this study, the classical method of replacing time-varying delays with constant delays does not capture the complex stability boundary of periodic time delays which could be exploited by attackers to cause instability in the vehicle platoon. We use the semi-discretization method to obtain plant stability. Then, we take the average value of the time delay functions to characterize the maximal admissible delay region such that the time-delayed system remains stable and provide string stability analysis. Through numerical simulations, we verify the analytical results. We construct stability charts in different parameter spaces to explore the effects of the model parameters on the system stability. A specific range of frequencies was found that could destabilize the connected autonomous vehicle platoon.