Novel Defense Strategy Against Zero-Dynamics Attack in Multi-Agent Systems

TL;DR

This paper proposes a topology-switching defense strategy for second-order multi-agent systems to detect and mitigate zero-dynamics attacks, even when attack start times are unknown, using a Luenberger observer.

Contribution

It introduces a novel topology-switching detection method that does not require prior knowledge of attack start times or the number of attacked agents.

Findings

Effective detection of ZDA with unknown start times.

Luenberger observer works with minimal output observations.

Simulation confirms the strategy's robustness.

Abstract

This paper considers the defense strategy of strategic topology switching for the second-order multi-agent system under zero-dynamics attack (ZDA) whose attack-starting time is allowed to be not the initial time. We first study the detectability of ZDA, which is a sufficient and necessary condition of switching topologies in detecting the attack. Based on the detectability, a Luenberger observer under switching topology is proposed to detect the stealthy attack. The primary advantages of the attack-detection algorithm are twofold: (i) in detecting ZDA, the algorithm allows the defender (system operator) to have no knowledge of the attack-starting time and the misbehaving agents (i.e., agents under attack); (ii) in tracking system in the absence of attacks, Luenberger observer has no constraint on the magnitudes of observer gains and the number of observed outputs, i.e., only one agent's observed output is sufficient. Simulations are provided to verify the effectiveness of the strategic topology-switching algorithm.