Synthesis of resilient third-party monitoring system against cyberattacks via supervisory control

To allow safe operation of an industrial control system under cyberattacks, we have developed a resilient third-party monitoring system that focuses on the attack resistance of its own detection function and the continuous operation of field devices. This system is composed of programmable logic controllers (PLCs) for normal control and for fallback control. The normal PLC controls the field devices, and the fallback PLC takes over control after the normal PLC is attacked. This paper aims to model the system in terms of timed discrete event system and supervisory control theorem and realize the systematical fallback control design.