  A network of unmanned aerial vehicles (UAVs) provides distributed coverage,
reconfigurability, and maneuverability in performing complex cooperative tasks.
However, it relies on wireless communications that can be susceptible to cyber
adversaries and intrusions, disrupting the entire network's operation. This
paper develops model-based centralized and decentralized observer techniques
for detecting a class of stealthy intrusions, namely zero-dynamics and covert
attacks, on networked UAVs in formation control settings. The centralized
observer that runs in a control center leverages switching in the UAVs'
communication topology for attack detection, and the decentralized observers,
implemented onboard each UAV in the network, use the model of networked UAVs
and locally available measurements. Experimental results are provided to show
the effectiveness of the proposed detection schemes in different case studies.
