Security-Enhancing Filters Against Internal Frequency Principle-based Integrity Attacks

This paper presents a novel frequency-domain approach for control input filtering in networked control systems subject to integrity attacks on control inputs. The proposed approach relies on adding linear time-invariant filters to control loops, placed between received control actions and plant actuators, whose aim is to mitigate the impact of attacks on control performance. The filter synthesis problem can be cast in terms of a multi-objective synthesis problem subject to multiple frequency-domain inequality specifications in finite and infinite frequency ranges. The problem is formulated as a convex optimization problem subject to a set of Linear Matrix Inequalities. Simulation results demonstrate the effectiveness of the proposed security-enhancing approach.