Cyber-Physical Defense for Heterogeneous Multi-Agent Systems Against Exponentially Unbounded Attacks on Signed Digraphs

Cyber-physical systems (CPSs) are subjected to attacks on both cyber and physical spaces. In reality, attackers could launch any time-varying signals. Existing literature generally addresses bounded attack signals and/or bounded-first-order-derivative attack signals. In contrast, this paper proposes a privacy-preserving fully-distributed attack-resilient bilayer defense framework to address the bipartite output containment problem for heterogeneous multi-agent systems (MASs) on signed digraphs, in the presence of exponentially unbounded false data injection (EU-FDI) attacks on both the cyber-physical layer (CPL) and observer layer (OL). First, we design attack-resilient dynamic compensators that utilize data communicated on the OL to estimate the convex combinations of the states and negative states of the leaders. To enhance the security of transmitted data, a privacy-preserving mechanism is incorporated into the observer design. The privacy-preserving attack-resilient observers address the EU-FDI attacks on the OL and guarantee the uniformly ultimately bounded (UUB) estimation of the leaders' states in the presence of the eavesdroppers. Then, by using the observers' states, fully-distributed attack-resilient controllers are designed on the CPL to further address the EU-FDI attacks on the actuators. The theoretical soundness of the proposed bilayer resilient defense framework is proved by Lyapunov stability analysis. Finally, a comparative case study for heterogeneous MASs and the application in DC microgrids as a specific case study validate the enhanced resilience of the proposed defense strategies.