An algebraic detection approach for control systems under multiple stochastic cyber-attacks

in IEEE/CAA Journal of Automatica Sinica (2015), 2(3), 258-266

In order to compromise a target control system successfully, hackers possibly attempt to launch multiple cyberattacks aiming at multiple communication channels of the control system. However, the problem ... [more ▼]

In order to compromise a target control system successfully, hackers possibly attempt to launch multiple cyberattacks aiming at multiple communication channels of the control system. However, the problem of detecting multiple cyber-attacks has been hardly investigated so far. Therefore, this paper deals with the detection of multiple stochastic cyber-attacks aiming at multiple communication channels of a control system. Our goal is to design a detector for the control system under multiple cyberattacks. Based on frequency-domain transformation technique and auxiliary detection tools, an algebraic detection approach is proposed. By applying the presented approach, residual information caused by different attacks is obtained respectively and anomalies in the control system are detected. Sufficient and necessary conditions guaranteeing the detectability of the multiple stochastic cyber-attacks are obtained. The presented detection approach is simple and straightforward. Finally, two simulation examples are provided, and the simulation results show that the detection approach is effective and feasible. [less ▲]

An application of linear algebra theory in networked control systems: stochastic cyber-attacks detection approach

in IMA Journal of Mathematical Control and Information (2015)

Based on the traditional linear algebra theory, this paper propose the attack detection schemes for networked control systems (NCSs) under single stochastic cyber-attack and multiple stochastic cyber ... [more ▼]

Based on the traditional linear algebra theory, this paper propose the attack detection schemes for networked control systems (NCSs) under single stochastic cyber-attack and multiple stochastic cyber-attacks aiming at multiple communication channels of NCSs, respectively. The focus is on designing an anomaly detector for NCSs under cyber-attacks. First, we construct a model of stochastic NCSs with stochastic cyber-attacks which satisfy the Markovian stochastic process. And we also introduced the stochastic attack models that NCSs are possibly exposed to. Next, based on the frequency-domain transformation technique and linear algebra theory, we propose the algebraic detection schemes for possible stochastic cyber-attacks. We transform the detector error dynamics into algebraic equations. By applying the presented approaches, residual information that is caused by different attacks is, respectively, obtained and anomalies on the control system are detected. In addition, sufficient and necessary conditions guaranteeing the detectability of the stochastic cyber-attacks are obtained. The presented detection approaches in this paper are simple, straightforward and easy to implement. The aim of this work is to use traditional mathematics tools to solve new problems that arise from the complex NCSs. Finally, two simulation examples are provided. The simulation results underline that the detection approaches are effective and feasible in practical application. [less ▲]

Nonlinear protocols for distributed consensus in directed networks of dynamic agents

in Journal of the Franklin Institute (2015), 352(9), 3645-3669

This paper deals with the distributed consensus problem of multi-agent systems. While existing work mainly considers the design of linear protocols, we derive nonlinear protocols for directed networks of ... [more ▼]

This paper deals with the distributed consensus problem of multi-agent systems. While existing work mainly considers the design of linear protocols, we derive nonlinear protocols for directed networks of dynamic agents with fi xed and switched topologies, respectively. The obtained nonlinear protocols have the same effectiveness as the existing linear protocols, however they can satisfy the input constraints of real world physical systems, as well as the state value restrictions of agents, which ensure the smooth communication of the whole network and the correct data transmission among agents under the limited bandwidth. In contrast to most existing approaches that commonly use the Lyapunov function theory in order to prove the consensus problem, simple and effective mathematical methods are developed here for this purpose. Based on the equivalent in fi nitesimal functions and differentials as well as linear approximations as comparatively simple mathematical tools, we prove that the distributed consensus is asymptotically reachable and derive the group decision values. For balanced topology structures, these nonlinear protocols in particular guarantee that the agents asymptotically reach an average-consensus. Furthermore, the obtained protocols relax the constraints on the communication links among the agents. Finally, simulations comprising the vertical alignment maneuver of a team of unmanned aerial vehicles (UAVs) and the phase synchronization of three oscillators are studied, respectively. The simulation results underline that the developed nonlinear protocols are effective and feasible for distributed consensus in directed networks of dynamic multi-agent systems. [less ▲]

Robust H ∞ cyber-attacks estimation for control systems

in Proceedings of the 33rd CCC, Nanjing 28-30 July 2014 (2014, July 28)

This paper deals with the robust H ∞ cyber-attacks estimation problem for control systems under stochastic cyber-attacks and disturbances. The focus is on designing a H ∞ lter which maximize the attack ... [more ▼]

This paper deals with the robust H ∞ cyber-attacks estimation problem for control systems under stochastic cyber-attacks and disturbances. The focus is on designing a H ∞ lter which maximize the attack sensitivity and minimize the effect of disturbances. The design requires not only the disturbance attenuation, but also the residual to remain the attack sensitivity as much as possible while the effect of disturbance is minimized. A stochastic model of control system with stochastic cyber-attacks which satisfy the Markovian stochastic process is constructed. And we also present the stochastic attack models that a control system is possibly exposed to. Furthermore, applying H ∞ ltering technique-based on linear matrix inequalities (LMIs), the paper obtains suf cient conditions that ensure the ltering error dynamic is asymptotically stable and satis es a prescribed ratio between cyber-attack sensitivity and disturbance sensitivity. Finally, the results are applied to the control of a Quadruple-tank process (QTP) under a stochastic cyber-attack and a stochastic disturbance. The simulation results underline that the designed lters is effective and feasible in practical application. [less ▲]

Nonlinear Protocols for Output Performance Value Consensus of Multi-Agent Systems

in The 30th Chinese Control Conference (2011)

This paper investigates output performance value consensus issue, which is a new necessarily considered issue for cooperative and coordinate control of multi-agent systems with fixed topology. Based on ... [more ▼]

This paper investigates output performance value consensus issue, which is a new necessarily considered issue for cooperative and coordinate control of multi-agent systems with fixed topology. Based on Lyapunov theory, this paper presents nonlinear protocols for output performance value consensus of systems and proves the asymptotic consensus is reachable. Simulation example shows the nonlinear protocols are effective for output performance value consensus of multi-agent systems [less ▲]

Unbiased H∞ Infinite Filtering for Stochastic Systems with Data Packet Losses

in Advanced Materials Research (2011), 204-210

This paper presents the unbiased H∞ filter design for stochastic systems with data packet losses. By constructing unbiased filter, the complexity and computational burden of the real-time filtering ... [more ▼]

This paper presents the unbiased H∞ filter design for stochastic systems with data packet losses. By constructing unbiased filter, the complexity and computational burden of the real-time filtering process are reduced greatly. Delay-dependent sufficient conditions for stochastic system with data packet losses are proposed in terms of linear matrix inequalities (LMIs). Numerical example demonstrates the proposed approaches are effective. [less ▲]

Unbiased H∞ filtering for a class of stochastic systems with time-varying delay

in The 21st annual international conference on Chinese control and decision conference (2009)

This paper presents the unbiased H∞ filter design for a class of stochastic systems with time-varying delay. The aim is to design an unbiased filter assuring exponential stability in mean square and a ... [more ▼]

This paper presents the unbiased H∞ filter design for a class of stochastic systems with time-varying delay. The aim is to design an unbiased filter assuring exponential stability in mean square and a prescribed H∞ performance level for the filtering error system. Based on the application of the descriptor model transformation and free weighting matrices, delay-dependent sufficient conditions for stochastic systems with time-varying delay are proposed respectively in terms of linear matrix inequalities(LMIs). Numerical examples demonstrate the proposed approaches are effective and are an improvement over existing methods. [less ▲]

Nonlinear consensus protocols for multi-agent systems based on centre manifold reduction

in Chinese Physics B (2009), 18(8), 3355-3366

This paper investigates nonlinear consensus protocols for dynamic directed networks of multiagent systems with fixed and switching topology, respectively. Based on center manifold reduction technic ... [more ▼]

This paper investigates nonlinear consensus protocols for dynamic directed networks of multiagent systems with fixed and switching topology, respectively. Based on center manifold reduction technic, nonlinear consensus protocols are presented. We prove a group of agents can reach a ¯¡consensus , which the group decision value varies from the minimum and the maximum values of the agents’ initial states. Moreover, we derive conditions to guarantee all agents reach a consensus on a desired group decision values. Finally, A simulation study concerning the vertical alignment maneuver of a team of unmanned air vehicles is performed. Simulation results show the nonlinear consensus protocols proposed are more effective than the linear protocols for the formation control of the agents and it is an improvement over existing protocols. [less ▲]

Exponential Stability Criteria for Uncertain Stochastic Systems

in The 27th Chinese Control Conference (2008)

This paper considers the problem of delay-dependent exponential stability in mean square for a class of stochastic systems with polytopic-type uncertainties and time-varying delay. Based on the ... [more ▼]

This paper considers the problem of delay-dependent exponential stability in mean square for a class of stochastic systems with polytopic-type uncertainties and time-varying delay. Based on the application of the descriptor model transformation and free weighting matrices to express this relationship among the system variables and among the terms in the Newton-Leibniz formula, some new delay-dependent exponential stability criteria are obtained in terms of linear matrix inequalities(LMIs). The new criteria are less conservative than existing ones. Numerical examples demonstrate the new criteria are effective and are an improvement over existing ones. [less ▲]

H∞ filtering for stochastic time- delay systems

in The 7th World Congress on Intelligent Control and Automation (2008)

This paper presents the robust H∞ filter design for stochastic systems with time-varying delay. The aim is to design a stable linear filter assuring exponential stability in mean-square and a prescribed ... [more ▼]

This paper presents the robust H∞ filter design for stochastic systems with time-varying delay. The aim is to design a stable linear filter assuring exponential stability in mean-square and a prescribed H∞ performance level for the filtering error system. Based on the application of the descriptor model transformation and free weighting matrices, delaydependent sufficient conditions are respectively proposed in terms of linear matrix inequalities(LMIs). Numerical example demonstrates the proposed approaches are effective and are an improvement over existing ones. [less ▲]