Generalized Attack Model for Networked Control Systems, Evaluation of Control Methods

Networked Control Systems (NCSs) have been implemented in several different industries. The integration with advanced communication networks and computing techniques allows for the enhancement of efficiency of industrial control systems. Despite all the advantages that NCSs bring to industry, they remain at risk to a spectrum of physical and cyber-attacks. In this paper, we elaborate on security vulnerabilities of NCSs, and examine how these vulnerabilities may be exploited when attacks occur. A general model of NCS designed with three different controllers, i.e., proportional-integral-derivative (PID) controllers, Model Predictive control (MPC) and Emotional Learning Controller (ELC) are studied. Then three different types of attacks are applied to evaluate the system performance. For the case study, a networked pacemaker system using the Zeeman nonlinear heart model (ZHM) as the plant combined with the above-mentioned controllers to test the system performance when under attacks. The results show that with Emotional Learning Controller (ELC), the pacemaker is able to track the ECG signal with high fidelity even under different attack scenarios.

A Novel Technique for Detection of Time Delay Switch Attack on Load Frequency Control

In this paper, we focus on the estimation of time delays caused by adversaries in the sensing loop (SL). Based on the literature review, time delay switch (TDS) attacks could make any control system, in particular a power control system, unstable. Therefore, future smart grids will have to use advanced methods to provide better situational awareness of power grid states keeping smart grids reliable and safe from TDS attacks. Here, we introduce a simple method for preventing time delay switch attack on networked control systems. The method relies on an estimator that will estimate and track time delays introduced by an adversary. Knowing the maximum tolerable time delay of the plant’s optimal controller for which the plant remains stable, a time-delay detector issues an alarm signal when the estimated time delay is larger than the minimum one and directs the system to alarm state. In an alarm state, the plant operates under the control of an emergency controller that is local to the plant and remains in this mode until the networked control system state is restored. This method is an inexpensive and simple way to guarantee that an industrial control system remains stable and secure.