Advanced nonlinear fuzzy observer and robust control design for systems subject to cyber-physical attacks

Abstract

In the following contribution, the control design of CPSs (Cyber Physical Systems) usually consists of an observer to estimate the state of the physical system and a controller to compute the control commands based on the state estimation studied. Our objective is to design control methods that are robust against attacks in the model, attenuating their effect and ensuring at the same time a reliable state and attack estimation allowing their detection and isolation while maintaining the system stability, integrity, and performance. The considered approach is based on the Lyapunov theory and LMI resolution approach in order to deduce the observers-controller gains. A robust output H∞ control and quadratic stabilization for nonlinear systems subject to actuator and sensor data deception attacks (cyber-physical-attacks) is proposed. The detection & identification issues are also reconsidered since the system states and the malicious signals will be reconstructed via a Polytopic-based T-S (Takagi-Sugeno) observer. An innovative design method where the attacked system is presented as an uncertain one subject to external disturbances is developed. A robust polytopic state feedback stabilizing controller based on a polytopic observer with disturbances attenuation for the resulting uncertain system is considered. To illustrate our proposed approach, we present a numerical example. An algorithm based on a robust polytopic controller ensuring asymptotic stability despite data deception attacks and external perturbations attenuation guaranteed by the H∞ norm will be given. Indeed, a PDC (Parallel Distributed Compensation) controller coupled with a polytopic observer to estimate the unmeasurable state variables and actuator/sensor attack signals will be designed for nonlinear systems subjected to data deception attacks.