A fallback control study of networked control systems for cybersecurity

Recent control systems of critical infrastructures are networked systems, which are exposed to the infection of the computer malwares. This paper considers a cybersecurity technology of networked control systems in terms of availability. Architecture of fallback control is proposed, which consists of the remote controller and the local controller. The former achieves the high control performance and the latter guarantees the minimum required control performance. If the malicious behavior of the remote controller is detected by the local controller, the local controller breaks the network communication between the plant and the remote controller and takes over the plant control. This framework aims to prevent the spread of the damage caused by the infection of the computer malwares. As a first step of the research, a prototype fallback control system is applied to a simple automation system simulating the defective discriminator.