A Continuous Terminal Sliding-Mode Observer-Based Anomaly Detection Approach for Industrial Communication Networks

Dynamic traffic monitoring is a critical part of industrial communication network cybersecurity, which can be used to analyze traffic behavior and identify anomalies. In this paper, industrial networks are modeled by a dynamic fluid-flow model of TCP behavior. The model can be described as a class of systems with unmeasurable states. In the system, anomalies and normal variants are represented by the queuing dynamics of additional traffic flow (ATF) and can be considered as a disturbance. The novel contributions are described as follows: (1) a novel continuous terminal sliding-mode observer (TSMO) is proposed for such systems to estimate the disturbance for traffic monitoring; (2) in TSMO, a novel output injection strategy is proposed using the finite-time stability theory to speed up convergence of the internal dynamics; and (3) a full-order sliding-mode-based mechanism is developed to generate a smooth output injection signal for real-time estimations, which is directly used for anomaly detection. To verify the effectiveness of the proposed approach, the real traffic profiles from the Center for Applied Internet Data Analysis (CAIDA) DDoS attack datasets are used.

Full-Order Sliding Mode Bounded Control for Euler-Lagrange Systems with External Disturbances

This paper researches two finite-time bounded control methods for Euler-Lagrange systems exposed to external disturbances. A novel full-order terminal sliding mode surface that is convenient for solving the input constraints is designed based on the characters of the hyperbolic tangent function. By using the designed full-order terminal sliding mode surface, the finite-time controller with input constraints can deal with external disturbances with the exactly known upper bound. Further, an adaptive finite-time bounded controller is designed to deal with the external disturbances with the upper bound that cannot be accurately known. Finally, the finite-time stability of the system is proved by using Lyapunov theory and numerical simulations.

Finite-time stability results for fractional damped dynamical systems with time delays

This paper is explored with the stability procedure for linear nonautonomous multiterm fractional damped systems involving time delay. Finite-time stability (FTS) criteria have been developed based on the extended form of Gronwall inequality. Also, the result is deduced to a linear autonomous case. Two examples of applications of stability analysis in numerical formulation are described showing the expertise of theoretical prediction.

Robust Finite-Time Control Algorithm Based on Dynamic Sliding Mode for Satellite Attitude Maneuver

Robust finite-time control algorithms for satellite attitude maneuvers are proposed in this paper. The standard sliding mode is modified, hence the inherent robustness could be maintained, and this fixed sliding mode is modified to dynamic, therefore the finite-time stability could be achieved. First, the finite -time sliding mode based on attitude quaternion is proposed and the loose finite-time stability is achieved by enlarging the sliding mode parameter. In order to get the strict finite-time stability, a sliding mode based on the Euler axis is then given. The fixed norm property of the Euler axis is used, and a sliding mode parameter without singularity issue is achieved. System performance near the equilibrium point is largely improved by the proposed sliding modes. The singularity issue of finite-time control is solved by the property of rotation around a fixed axis. System finite-time stability and robustness are analyzed by the Lyapunov method. The superiority of proposed controllers and system robustness to some typical perturbations such as disturbance torque, model uncertainty and actuator error are demonstrated by simulation results.

Finite-Time Passivity Analysis of Neutral-Type Neural Networks with Mixed Time-Varying Delays

This research study investigates the issue of finite-time passivity analysis of neutral-type neural networks with mixed time-varying delays. The time-varying delays are distributed, discrete and neutral in that the upper bounds for the delays are available. We are investigating the creation of sufficient conditions for finite boundness, finite-time stability and finite-time passivity, which has never been performed before. First, we create a new Lyapunov–Krasovskii functional, Peng–Park’s integral inequality, descriptor model transformation and zero equation use, and then we use Wirtinger’s integral inequality technique. New finite-time stability necessary conditions are constructed in terms of linear matrix inequalities in order to guarantee finite-time stability for the system. Finally, numerical examples are presented to demonstrate the result’s effectiveness. Moreover, our proposed criteria are less conservative than prior studies in terms of larger time-delay bounds.

Synchronization of a Memristor Chaotic System and Image Encryption

In this paper, a sliding-mode-based controller is designed for finite-time synchronization of Memristor Chaotic Systems (MCSs). It demonstrates that the synchronization errors of the MCSs reach the designed sliding-mode surface within a finite time and the finite-time stability is achieved on the surface, which implies that the finite-time synchronization for MCSs is achieved by employing the proposed sliding-mode-based controller. Furthermore, a new image encryption algorithm is proposed and implemented based on the results of finite-time synchronization. Finally, the numerical simulation and the corresponding statistical performance analysis are presented to verify the practicability, effectiveness and superiority of the presented sliding-mode-based controller and encryption algorithm, especially their potential applications in secure communication.

Finite-time disturbance observer based-control of flexible spacecraft

This paper aims to design an attitude controller for a flexible spacecraft under external disturbance and uncertainty. The spacecraft’s attitude is controlled by a super twisting controller based on a disturbance observer. This paper’s spacecraft system is non-minimum phase since mode-shapes are included in the output; thus, the following four methods are designed to compensate for the constraint: (1) The output redefinition method, where outputs are redefined as a combination of mode-shapes and quaternions. (2) The flexible spacecraft is controlled without measuring the mode-shapes, and only the quaternion parameters are selected as the output. (3) An advanced sliding surface is proposed, in which the mode-shapes are considered in the sliding surface. (4) The difference between flexible and rigid spacecraft dynamics is considered as disturbance, and its effect on the system is compensated. The finite-time stability of the closed-loop system is proved by leveraging the Lyapunov theory. The numerical simulation illustrates the closed-loop system’s effectiveness in terms of robustness compared to the existing controller and the four mentioned methods.