Stealthy replay attack detection of 3-DOF helicopter benchmark system using dynamic watermarking approach

Cyber security for unmanned systems has drawn tremendous research attention in recent years owing to its priority in ensuring system performance and safety. This paper presents a dynamic watermarking-based active detection approach for unmanned helicopter system under stealthy replay attacks. First, the dynamic model of the 3-DOF helicopter and the replay attack model are constructed, respectively. Statistical analysis is conducted using Kalman filter residuals to interpret the concealment of stealthy replay attacks for a system under intrusion. Then, as traditional chi-square detector is unable to detect stealthy replay attacks, an active detector by incorporating dynamic watermarking with the chi-square detector is explored. Finally, by conducting simulations of the detection procedures under different test scenarios comparatively using traditional chi-square detector and the proposed approach, the effectiveness and merits of the watermarking approach is verified sufficiently. The watermarking-based approach is promising in comprehensive detections against stealthy replay attacks for enhancing system security.