Secure State Estimation and Attack Reconstruction in Cyber-Physical Systems: Sliding Mode Observer Approach

TL;DR

This paper presents a sliding mode observer approach for secure state estimation and attack reconstruction in cyber-physical systems, enhancing protection against malicious attacks by identifying and mitigating corrupted states and measurements.

Contribution

It introduces fixed-gain and adaptive-gain sliding mode observers for online attack reconstruction in CPS, addressing various attack scenarios and demonstrating effectiveness through simulations.

Findings

Effective attack reconstruction using sliding mode observers.

Online detection and mitigation of sensor and state attacks.

Successful application to an electric power network simulation.

Abstract

A cyber-physical system (CPS) is a tight coupling of computational resources, network communication, and physical processes. They are composed of a set of networked components, including sensors, actuators, control processing units, and communication agents that instrument the physical world to make smarter. However, cyber components are also the source of new, unprecedented vulnerabilities to malicious attacks. In order to protect a CPS from attacks, three security levels of protection, detection, and identification are considered. In this chapter, we will discuss the identification level, i.e., secure state estimation and attack reconstruction of CPS with corrupted states and measurements. Considering different attack plans that may assault the states, sensors, or both of them, different online attack reconstruction approaches are discussed. Fixed-gain and adaptive-gain finite-time convergent observation algorithms, specifically sliding mode observers, are applied to the online reconstruction of sensor and state attacks. Next, the corrupted measurements and states are to be cleaned up online in order to stop the attack propagation to the CPS via the control signal. The proposed methodologies are applied to an electric power network, whose states and sensors are under attack. Simulation results illustrate the efficacy of the proposed observers.