Passivity Based Control of Cyber Physical Systems Under Zero-Dynamics Attack

Abstract

Introduction of computer networks in communication and control of the industrial setups has given rise to the new concept of Cyber Physical System. These control systems are vulnerable to the stealthy cyber-attacks as they are connected to communication networks. Cyber Attacks can cause malfunctioning of plants i.e. abnormal operational behavior, instability, etc. So it is of prime importance to control the unit under cyber-attack in order to protect the whole setup from damage. Passivity is a system property that enables the system designer to devise an energy based control of general dynamic systems. In this paper passive architecture of Cyber Physical Systems is discussed. To prevent the excitation of unstable zeros of system in stealthy attacks like zero-dynamics attack, back-stepping technique is employed to make zero-dynamics of closed loop the system stable. This technique is also used to develop a control law that will prevent the system from reaching unstable region if it is under zero-dynamics attack.