Hybrid robust controller design: Cyber attack attenuation for Cyber-Physical Systems

This paper considers controller design for Cyber-Physical Systems (CPSs) that are robust to various types of cyber attacks. While the previous studies have investigated a secure control by assuming a specific attack strategy, in this paper we propose a hybrid robust control scheme that contains multiple sub-controllers, each matched to a specific type of cyber attacks. Then the system can be adapted to various cyber attacks (including those that are not assumed for sub-controller design) by switching its sub-controllers to achieve the best performance. We propose a method for designing the secure switching logic to counter all possible cyber attacks and mathematically verify the system´s performance and stability as well. The performance of the proposed control scheme is demonstrated by an example with the hybrid H₂ - H_∞ controller applied to an Unmanned Aerial System (UAS).