On Redundant Observability: From Security Index to Attack Detection and Resilient State Estimation
For control systems security, this work provides a unified framework and a more efficient estimation method, though it is an incremental theoretical contribution.
The paper introduces redundant observability to unify security notions like security index, attack detectability, and observability under attacks, and proposes an estimator design algorithm that improves computational efficiency and reduces memory usage.
The security of control systems under sensor attacks is investigated. Redundant observability is introduced, explaining existing security notions including the security index, attack detectability, and observability under attacks. Equivalent conditions between redundant observability and existing notions are presented. Based on a bank of partial observers utilizing Kalman decomposition and a decoder exploiting redundancy, an estimator design algorithm is proposed enhancing the resilience of control systems. This scheme substantially improves computational efficiency utilizing far less memory.