195 research outputs found
Co-design of Control and Scheduling in Networked Systems under Denial-of-Service attacks
We consider the joint design of control and scheduling under stochastic
Denial-of-Service (DoS) attacks in the context of networked control systems. A
sensor takes measurements of the system output and forwards its dynamic state
estimates to a remote controller over a packet-dropping link. The controller
determines the optimal control law for the process using the estimates it
receives. An attacker aims at degrading the control performance by increasing
the packet-dropout rate with a DoS attack towards the sensor-controller
channel. Assume both the controller and the attacker are rational in a
game-theoretic sense. We establish a partially observable stochastic game to
derive the optimal joint design of scheduling and control. Using dynamic
programming we prove that the control and scheduling policies can be designed
separately without sacrificing optimality, making the problem equivalent to a
complete information game. We employ Nash Q-learning to solve the problem and
prove that the solution is guaranteed to constitute an -Nash
equilibrium. Numerical examples are provided to illustrate the tradeoffs
between control performance and communication cost.Comment: 9 pages, 4 figure
Cost-aware Defense for Parallel Server Systems against Reliability and Security Failures
Parallel server systems in transportation, manufacturing, and computing
heavily rely on dynamic routing using connected cyber components for
computation and communication. Yet, these components remain vulnerable to
random malfunctions and malicious attacks, motivating the need for
fault-tolerant dynamic routing that are both traffic-stabilizing and
cost-efficient. In this paper, we consider a parallel server system with
dynamic routing subject to reliability and stability failures. For the
reliability setting, we consider an infinite-horizon Markov decision process
where the system operator strategically activates protection mechanism upon
each job arrival based on traffic state observations. We prove an optimal
deterministic threshold protecting policy exists based on dynamic programming
recursion of the HJB equation. For the security setting, we extend the model to
an infinite-horizon stochastic game where the attacker strategically
manipulates routing assignment. We show that both players follow a threshold
strategy at every Markov perfect equilibrium. For both failure settings, we
also analyze the stability of the traffic queues under control. Finally, we
develop approximate dynamic programming algorithms to compute the
optimal/equilibrium policies, supplemented with numerical examples and
experiments for validation and illustration.Comment: Major Revision in Automatic
Resilient nonlinear control for attacked cyber-physical systems
In this paper, the problem of resilient nonlinear control for cyber-physical systems (CPSs) over attacked networks is studied. The motivation for this paper comes from growing applications that demand the secure control of CPSs in industry 4.0. The nonlinear physical system considered can be attacked by changing the temporal characteristics of the network, causing fixed time or time-varying delays and changing the orders of received packets. The systems under attack can be destabilized if the controller is not designed to be robust with an adversarial attack. In order to cope with nonlinearity of the physical system, a nonlinear generalized minimum variance controller and a modified Kalman estimator are derived. A worst-case controller is presented for fixed-time delay. In the situations of time-varying delays and out-of-order transmissions, an opportunistic estimator and a resilient controller are designed through an on-line algorithm in the sense that it is calculated by using the information in the received packets immediately. The ability to use the received information immediately leads to the improvement of the controller's performance. Simulation results are provided to show the applicability and performance of control law developed
State of the art of cyber-physical systems security: An automatic control perspective
Cyber-physical systems are integrations of computation, networking, and physical processes. Due to the tight cyber-physical coupling and to the potentially disrupting consequences of failures, security here is one of the primary concerns. Our systematic mapping study sheds light on how security is actually addressed when dealing with cyber-physical systems from an automatic control perspective. The provided map of 138 selected studies is defined empirically and is based on, for instance, application fields, various system components, related algorithms and models, attacks characteristics and defense strategies. It presents a powerful comparison framework for existing and future research on this hot topic, important for both industry and academia
A Comprehensive Survey on the Cyber-Security of Smart Grids: Cyber-Attacks, Detection, Countermeasure Techniques, and Future Directions
One of the significant challenges that smart grid networks face is
cyber-security. Several studies have been conducted to highlight those security
challenges. However, the majority of these surveys classify attacks based on
the security requirements, confidentiality, integrity, and availability,
without taking into consideration the accountability requirement. In addition,
some of these surveys focused on the Transmission Control Protocol/Internet
Protocol (TCP/IP) model, which does not differentiate between the application,
session, and presentation and the data link and physical layers of the Open
System Interconnection (OSI) model. In this survey paper, we provide a
classification of attacks based on the OSI model and discuss in more detail the
cyber-attacks that can target the different layers of smart grid networks
communication. We also propose new classifications for the detection and
countermeasure techniques and describe existing techniques under each category.
Finally, we discuss challenges and future research directions
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