Cyber Attack Mitigation for CPS

Hybrid System Approach to Controller Design

This study considers robust controller design for cyber–physical systems (CPSs) subject to cyber attacks.

  • Previous studies have investigated secure control by assuming specific attack strategies.
  • This study proposes a robust hybrid control scheme containing multiple sub-controllers, each matched to a different type of cyber attack.
    • A system using this control scheme is able to adapt its behavior to various cyber attacks (including those which have not been specifically addressed in the sub-controller designs) by switching sub-controllers to achieve the best performance.
    • We propose a method for designing the secure switching logic to counter possible cyber attacks and to mathematically verify the system’s performance and stability as well.

Hybrid controller design for various cyber attacks

proposed switching logic for the robust hybrid controller

Structure of robust hybrid control scheme

The performance of the proposed control scheme is demonstrated by the hybrid H2 - H infinity controller applied to a CPS subject to cyber attacks.

  • H2 optimal controller: optimized to counter a random or noise attack
  • H infinity optimal controller: optimized to counter a worst-case attack

Performance under worst-case attack sequence within finite time horizon

Performance under worst-case attack and random attack combined sequence within finite time horizon

Related Publication

  • C. Kwon and I. Hwang, “Cyber Attack Mitigation for Cyber-Physical Systems: Hybrid System Approach to Controller Design”, IET Control Theory and Applications, Vol.10(7), pp. 731-741, April, 2016, DOI: 10.1049/iet-cta.2014.1013