scholarly journals A Distributed Observer-Based Cyber-Attack Identification Scheme in Cooperative Networked Systems under Switching Communication Topologies

Electronics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1912
Author(s):  
Anass Taoufik ◽  
Michael Defoort ◽  
Krishna Busawon ◽  
Laurent Dala ◽  
Mohamed Djemai
Keyword(s):  
Sliding Mode ◽  
Initial Conditions ◽  
A Priori ◽  
Cyber Attacks ◽  
Consensus Algorithm ◽  
Cyber Attack ◽  
Global State ◽  
The Stability ◽  
Switching Communication Topologies ◽  
Entire Network

This paper studies an approach for detecting cyber attacks against networked cooperative systems (NCS) that are assumed to be working in a cyber-physical environment. NCS are prone to anomalies both due to cyber and physical attacks and faults. Cyber-attacks being more hazardous given the cooperative nature of the NCS may lead to disastrous consequences and thus need to be detected as soon as they occur by all systems in the network. Our approach deals with two types of malicious attacks aimed at compromising the stability of the NCS: intrusion attacks/local malfunctions on individual systems and deception/cyber-attacks on the communication between the systems. In order to detect and identify such attacks under switching communication topologies, this paper proposes a new distributed methodology that solves global state estimation of the NCS where the aim is identifying anomalies in the networked system using residuals generated by monitoring agents such that coverage of the entire network is assured. A cascade of predefined-time sliding mode switched observers is introduced for each agent to achieve a fast estimate of the global state whereby the settling time is an a priori defined parameter independently of the initial conditions. Then, using the conventional consensus algorithm, a set of residuals are generated by the agents that is capable of detecting and isolating local intrusion attacks and communication cyber-attacks in the network using only locally exchanged information. In order to prove the effectiveness of the proposed method, the framework is tested for a velocity synchronization seeking network of mobile robots.

scholarly journals GENERAL DIFFERENTIAL-GAME MODEL OF POTENTIALLY DANGEROUS PATTERN OF CYBER-ATTACK

2020 ◽  
Vol 4 (8) ◽  
pp. 113-123
Author(s):  
Volodymyr Okhrimchuk
Keyword(s):  
Differential Game ◽  
A Priori ◽  
Cyber Attacks ◽  
Game Model ◽  
Cyber Attack ◽  
Information Protection ◽  
Telecommunication System ◽  
Telecommunication Systems ◽  
Generalized Differential ◽  
A Priori Uncertainty

Today, there is a significant increase in the number of cyber-attacks in the world. At the same time their technological complexity increases proportionally. In the near future, new potentially dangerous cyber-attacks will appear, which in turn may lead to a deterioration of their detection and neutralization and, as a consequence, adversely affect the level of security of information and information and telecommunication systems of critical information infrastructure. Based on the mentioned in the article is solved the urgent task of identifying and neutralizing potentially dangerous cyber-attacks, which boils down to the development of differential-game model of their pattern. The basis of the created pattern of potentially dangerous cyberattacks is proposed to put the Denning`s model of information protection and the method of differential-game simulation of cyber-attack on information processes. The article shows that the pattern of a potentially dangerous cyberattack is modeled under the a priori uncertainty of the input data, since the potential cyberattacks that will take place may be quite diverse. In view of this, it is proposed that the hybrid model be used as a generic template for a potentially dangerous cyberattack due to the inability to make the correct input requirements for the model. This approach provides the evolving model that is being developed, that is, convergence with real physical phenomena and processes in information and information and telecommunication systems. As a result of the application of the differential-game modeling method in analytical form, a generalized differential-game model of a pattern of potentially dangerous cyber-attacks is generalized. Thus, the article further developed a generalized differential-game model of a potentially dangerous cyber-attack pattern, which is based on a Denning's model of information protection and methods of differential-game modeling of the attack on information, which, unlike the existing ones, takes into account the intensity of the offender and the protected party. It allows to estimate the level of insecurity of the information and telecommunication system in the conditions of a priori uncertainty of the input data. The application of the model in practice allows the creation of effective information security systems that will be able to detect potentially dangerous cyber-attacks in the critical infrastructure information and telecommunication system with minimal errors of the first kind.

scholarly journals Optimized Hierarchical Control for an AC Microgrid Under Attack

Ingeniería ◽  
2019 ◽  
Vol 24 (1) ◽  
pp. 64-82
Author(s):  
Vladimir Toro ◽  
Eder David Baron ◽  
Eduardo Mojica-Nava
Keyword(s):  
Power Flow ◽  
Hierarchical Control ◽  
Active Power ◽  
Cyber Attacks ◽  
Cyber Attack ◽  
Secondary Control ◽  
Confidence Factor ◽  
Communication Links ◽  
Local Controller ◽  
The Stability

Context: An inverter-based microgrid working in islanded mode can suffer cyber- attacks, these can be done against either the local controller or the communication links among the inverters. Secondary control is able to reject those attacks, however, a tertiary control action is necessary in order to stabilize the power flow among the microgrid. Method: Confidence factor technique allows to reject attacks in a microgrid acting directly over the secondary control, however, this technique omits other factor related to the power available. In this case, secondary control was complemented with a tertiary control that includes optimization criteria. Results: An inverter-based microgrid is simulated in Matlab for different scenarios and under cyberattack, this allows checking the correct response of the controller under attacks and the effective powersharing among inverters. Conclusions: The tertiary control allows stabilizing the active power of the system after the rejection of a cyber-attack by the secondary control. Each inverter supplies active power according to its máximum power rating without affecting the stability of the whole system.

scholarly journals Hybrid PD sliding mode control for robotic manipulators

2021 ◽  
Author(s):  
John M Acob
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
A Priori ◽  
Robotic Manipulators ◽  
Pid Controllers ◽  
Control Law ◽  
Mode Control ◽  
Control Schemes ◽  
Added Benefit ◽  
The Stability

This thesis proposes a new control law for the purpose of providing improved tracking and contouring performance of robotic manipulators. The rationale behind the development of this controller involves the hybridization of existing proportional-derivative (PD) and sliding mode control (SMC) laws. The new control law retains similar ease of implementation as traditional PD/PID controllers with the added benefit of a nonlinear switching component inherent from sliding mode control systems. In addition, it eliminates the need for a priori knowledge of the system dynamics that are required in standard SMC laws. The stability analysis of the proposed control law is conducted through the Lyapunov method. Simulations using linear and nonlinear contours, and under varying dynamic conditions are performed in order to compare its performances to existing control schemes. The proposed hybrid PD-SMC control law is proven to provide good, robust tracking and contouring performance

Unexpected Behaviors in a Single Mesh Josephson Junction Based Self-Reproducing Autonomous System

2020 ◽  
Vol 30 (07) ◽  
pp. 2050097
Author(s):  
F. Calvin Talla ◽  
Robert Tchitnga ◽  
P. H. Louodop Fotso ◽  
Romanic Kengne ◽  
Bonaventure Nana ◽  
...  
Keyword(s):  
Josephson Junction ◽  
Initial Conditions ◽  
A Priori ◽  
Period Doubling ◽  
State Variables ◽  
Field Programmable ◽  
Programmable Gate Arrays ◽  
Circuit Component ◽  
Similar Class ◽  
The Stability

In the literature, existing Josephson junction based oscillators are mostly driven by external sources. Knowing the different limits of the external driven systems, we propose in this work a new autonomous one that exhibits the unusual and striking multiple phenomena among which coexist the multiple hidden attractors in self-reproducing process under the effect of initial conditions. The eight-term autonomous chaotic system has a single nonlinearity of sinusoidal type acting on only one of the state variables. A priori, the simplicity of the system does not predict the richness of its dynamics. We also find that a limit cycle attractor widens to a parameter controlling coexisting multiple-scroll attractors through the splitting and the inverse splitting of periods. Multiple types of bifurcations are found including period-doubling and period-splitting (antimonotonicity) sequences to chaos, crisis and Hopf type bifurcation. To the best of our knowledge, some of these interesting phenomena have not yet been reported in similar class of autonomous Josephson junction based circuits. Moreover, analytical investigations based on the Hopf theory analysis lead to the expressions that determine the direction of appearance of the Hopf bifurcation, confirming the existence and determining the stability of bifurcating periodic solutions. To observe this latter bifurcation and to illustrate the theoretical analysis, numerical simulations are performed. Chaos can be easily controlled by the frequency of the linear oscillator, the superconducting junction current, as well as the gain of the amplifier or circuit component values. The circuit and Field Programmable Gate Arrays (FPGA)-based implementation of the system are presented as well.

scholarly journals High-Order Observer-Based Sliding Mode Control for the Isolated Microgrid with Cyber Attacks and Physical Uncertainties

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Hao Wang ◽  
He Jiang ◽  
Yan Zhao ◽  
Huanxin Guan ◽  
Bo Hu ◽  
...  
Keyword(s):  
Sliding Mode Control ◽  
Control Strategy ◽  
Sliding Mode ◽  
System Security ◽  
Lyapunov Stability Theory ◽  
Cyber Attacks ◽  
High Order ◽  
Mode Control ◽  
Excellent Control ◽  
The Stability

System security is essential for the operation of the island microgrid. However, the system security is generally threatened due to the presence of physical uncertainties and cyber attacks. In this article, a novel sliding mode load control strategy is proposed for the microgrid to mitigate cyber attacks and physical uncertainties. Firstly, a high-order disturbance observer (HODO) is designed to estimate the unmeasurable factors in the microgrid. Secondly, a HODO-based sliding mode control (SMC) strategy is proposed where the estimated value observed by the HODO is applied to the sliding mode surface and control law. It can better guarantee the security of the isolated microgrid. Then, the stability of the HODO-based SMC is demonstrated by Lyapunov stability theory. Finally, simulation results show that the proposed control strategy has excellent control performance.

scholarly journals Hybrid PD sliding mode control for robotic manipulators

2021 ◽  
Author(s):  
John M Acob
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
A Priori ◽  
Robotic Manipulators ◽  
Pid Controllers ◽  
Control Law ◽  
Mode Control ◽  
Control Schemes ◽  
Added Benefit ◽  
The Stability

This thesis proposes a new control law for the purpose of providing improved tracking and contouring performance of robotic manipulators. The rationale behind the development of this controller involves the hybridization of existing proportional-derivative (PD) and sliding mode control (SMC) laws. The new control law retains similar ease of implementation as traditional PD/PID controllers with the added benefit of a nonlinear switching component inherent from sliding mode control systems. In addition, it eliminates the need for a priori knowledge of the system dynamics that are required in standard SMC laws. The stability analysis of the proposed control law is conducted through the Lyapunov method. Simulations using linear and nonlinear contours, and under varying dynamic conditions are performed in order to compare its performances to existing control schemes. The proposed hybrid PD-SMC control law is proven to provide good, robust tracking and contouring performance

Target Tracking Using the Smooth Variable Structure Filter

2009 ◽  
Author(s):  
Andrew Gadsden ◽  
Saeid Habibi
Keyword(s):  
Target Tracking ◽  
Sliding Mode ◽  
Initial Conditions ◽  
A Priori ◽  
Variable Structure ◽  
Tracking Problem ◽  
Tracking Accuracy ◽  
State Estimate ◽  
Predictor Corrector ◽  
Smooth Variable Structure Filter

This article discusses the application of the smooth variable structure filter (SVSF) on a target tracking problem. The SVSF is a relatively new predictor-corrector method used for state and parameter estimation. It is a sliding mode estimator, where gain switching is used to ensure that the estimates converge to true state values. An internal model of the system, either linear or nonlinear, is used to predict an a priori state estimate. A corrective term is then applied to calculate the a posteriori state estimate, and the estimation process is repeated iteratively. The results of applying this filter on a target tracking problem demonstrate its stability and robustness. Both of these attributes make using the SVSF advantageous over the well-known Kalman and extended Kalman filters. The performances of these algorithms are quantified in terms of robustness, resilience to poor initial conditions and measurement outliers, tracking accuracy and computational complexity.

scholarly journals Dynamical Analysis and Stabilization of Wind Turbine Drivetrain via Adaptive Fixed-Time Terminal Sliding Mode Controller

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Jianxiang Yang ◽  
Anle Mu ◽  
Nailu Li
Keyword(s):  
Wind Turbine ◽  
Sliding Mode ◽  
Initial Conditions ◽  
Chaotic Oscillation ◽  
Fixed Time ◽  
Dynamical Analysis ◽  
Sliding Mode Controller ◽  
Damping Force ◽  
Terminal Sliding Mode ◽  
The Stability

In order to study the stability of the wind turbine drivetrain in further depth, we present a nonlinear relative rotation mathematical model considering the nonlinear time-varying stiffness and the nonlinear damping force. Meanwhile, the nonlinear dynamics of the model under combined harmonic excitation are studied in detail. And some interesting dynamic phenomena are observed visually. Furthermore, to suppress chaotic oscillation within bounded time independent of initial conditions, a novel adaptive fixed-time terminal sliding mode controller is proposed. The stability of the final closed loop system is guaranteed according to Lyapunov stability theory. Rigorous mathematical analyses are used to prove the validity of the presented approach. Finally, compared with the existing finite-time stability method, simulation results are given to highlight the effectiveness and superiority of the proposed method and verify the theoretical analyses.

The invisible hole of information on SMB's cybersecurity

2019 ◽  
Vol 7 (1) ◽  
pp. 14-26
Author(s):  
Ruti Gafni ◽  
Tal Pavel
Keyword(s):  
Mass Communication ◽  
Cyber Attacks ◽  
Communication Media ◽  
Specific Information ◽  
Exploratory Research ◽  
Cyber Attack ◽  
Public Attention ◽  
Cyber Threats ◽  
Accessible Information ◽  
Types Of Information

Small and Medium Businesses (SMB) use Internet and computer-based tools in their daily processes, sometimes without being aware to the cyber threats, or without knowing how to be prepared in case of a cyber-attack, although they are a major target for cyber-attacks. Specific information about cybersecurity needed by SMBs, in order to cope with cyber threats, is not always available or easily accessible. In this study, a vast search of different types of information about SMBs’ cybersecurity was performed, in order to find whether a hole of accessible information exists in this area. This exploratory research covered general mass communication media channels, technological and professional cybersecurity websites, and academic journals, and found that indeed very few studies, articles and news items were published in this matter. Leveraging knowledge and awareness, diminishing the shame for reporting cyber-attacks, and increasing mass communication media interest and public attention, may be activities to cover this “invisible hole”.

scholarly journals Delay compensation based controller for rotary electrohydraulic servo system

2021 ◽  
Author(s):  
Zakarya Omar ◽  
Xingsong Wang ◽  
Khalid Hussain ◽  
Mingxing Yang
Keyword(s):  
High Frequency ◽  
Dead Time ◽  
Sliding Mode ◽  
Servo System ◽  
Smith Predictor ◽  
Delay Compensation ◽  
Mechanical Parts ◽  
System Output ◽  
Electrohydraulic Servo System ◽  
The Stability

AbstractThe typical power-assisted hip exoskeleton utilizes rotary electrohydraulic actuator to carry out strength augmentation required by many tasks such as running, lifting loads and climbing up. Nevertheless, it is difficult to precisely control it due to the inherent nonlinearity and the large dead time occurring in the output. The presence of large dead time fires undesired fluctuation in the system output. Furthermore, the risk of damaging the mechanical parts of the actuator increases as these high-frequency underdamped oscillations surpass the natural frequency of the system. In addition, system closed-loop performance is degraded and the stability of the system is unenviably affected. In this work, a Sliding Mode Controller enhanced by a Smith predictor (SMC-SP) scheme that counts for the output delay and the inherent parameter nonlinearities is presented. SMC is utilized for its robustness against the uncertainty and nonlinearity of the servo system parameters whereas the Smith predictor alleviates the dead time of the system’s states. Experimental results show smoother response of the proposed scheme regardless of the amount of the existing dead time. The response trajectories of the proposed SMC-SP versus other control methods were compared for a different predefined dead time.

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