Sensor-controller Channels Research Articles

H∞ Controller Design for Networked Systems With Two-Channel Packet Dropouts and FDI Attacks.

In this article, the stochastic analysis and H∞ controller design problems of networked systems with packet dropouts and false data injection attacks are investigated. Different from the existing literature, we focus on the linear networked systems with external disturbances and both sensor-controller channel and controller-actuator channel are studied. First, we present a discrete-time modeling framework that leads to a stochastic closed-loop system with randomly varying parameters. To facilitate the analysis and H∞ control of resulting discrete-time stochastic closed-loop system, an equivalent yet analyzable stochastic augmented model is further constructed by matrix exponential computation. Based on this model, a stability condition is derived in the form of linear matrix inequality (LMI) with the aid of a reduced-order confluent Vandermonde matrix, Kronecker product operation, and law of total expectation. Specifically, the dimension of the LMI obtained in this article does not increase as the upper bound of consecutive packet dropouts does, which is also different from the existing literature. Subsequently, a desired H∞ controller is obtained such that the original discrete-time stochastic closed-loop system is exponentially mean-square stable with a prescribed H∞ performance. Finally, a numerical example and a direct current motor system are exploited to substantiate the effectiveness and practicability of the designed strategy.

Observer-Based Adaptive NN Security Control for Switched Nonlinear Systems Against DoS Attacks: An ADT Approach.

In this article, a novel switched observer-based neural network (NN) adaptive control algorithm is established, which addresses the security control problem of switched nonlinear systems (SNSs) under denial-of-service (DoS) attacks. The considered SNSs are described in lower triangular form with external disturbances and unmodeled dynamics. Note that when an attack is launched in the sensor-controller channel, the controller will not receive any message, which makes the standard backstepping controller not workable. To tackle the challenge, a set of NN adaptive observers are designed under two different situations, which can switch adaptively depending on the DoS attack on/off. Further, an NN adaptive controller is constructed and the dynamic surface control method is borrowed to surmount the complexity explosion phenomenon. To eliminate double damage from DoS attacks and switches, a set of switching laws with average dwell time are designed via the multiple Lyapunov function method, which in combination with the proposed controllers, guarantees that all the signals in the closed-loop system are bounded. Finally, an illustrative example is offered to verify the availability of the proposed control algorithm.

Security Interval Type-2 Fuzzy Sliding Mode Control Under Multistrategy Injection Attack: Design, Analysis, and Optimization

In this work, the security sliding mode control problem is considered for interval type-2 (IT2) fuzzy systems, where the sensor-controller channel may be subject to the false data injection attack with multi-strategy attack model. The different attack patterns at each instant is described via a random categorical distribution. It is noted that the injected false data may result in the system state to exceed the modeling domain. In order to cope with the above phenomenon, a reconstruction method of the controller's membership functions is proposed via analyzing the variation range of the attacked state, and then, an IT2 fuzzy sliding mode controller is designed. The explicit relation between the raw state signal and attacked state is established, based on which stability conditions dependent on the regional boundaries of membership functions are obtained for the input-to-state stability in probability of the closed-loop system. Meanwhile, a framework of security performance optimization is established via searching a desirable sliding matrix, which may be solved via the particle swarm optimization algorithm. Furthermore, the proposed security control scheme is extended to the case of imperfectly matched premises, where the controller may have different fuzzy rules from the fuzzy system. Finally, the proposed security control scheme is verified by two simulations examples.

Event-triggered robust distributed output feedback model predictive control for nonlinear MASs against false data injection attacks

In this paper, an event-triggered distributed output feedback model predictive control scheme for the nonlinear disturbed multiagent systems with sensor–controller channel false data injection attacks is proposed. To provide valid system states to the controller in the event of cyber attacks, a robust multivariate observer is designed to realize the estimation and separation of uncompromised system states, false data injection attacks, and measurement disturbances, simultaneously. Based on these reconstructed signals and a newly-designed linear robustness constraint, the distributed predictive controller is established to achieve smooth cooperative stabilization among agents. Meanwhile, an event-triggered mechanism is applied to save computing resources, and it restricts the error of predictive states and estimated states to guarantee the feasibility of the optimization control problem. Theoretical analyses on robustness and security for the nonlinear multiagent systems under event-triggered distributed output feedback model predictive control are presented. Finally, a simulation on two pairs of one-link flexible joint manipulator systems verifies the theoretical results.

A jointly optimal 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 on the sensor-controller channel. We assume both the controller and the attacker are rational in a game-theoretic sense and 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 ϵ-Nash equilibrium. Numerical examples are provided to illustrate the interactions between the controller and the attacker.

Secure Synchronization of Coupled Systems via Double Event-Triggering Mechanisms With Actuator Fault

This paper studies the global exponential synchronization almost surely (GES a.s.) for coupled systems (CSs) with stochastic switching topology by using event-based output feedback control. It is assumed that the sensor-controller channel is subject to stochastic deception attacks and the actuator faults may occur to some modes. Novel double mode-dependent adaptive event-triggering mechanisms (ETMs) are introduced based on sampled data technique. Not only the Zeno phenomenon is naturally excluded, but also the asynchronous phenomenon is skillfully avoided. Based on the Lyapunov-Krasovskii functional method and the linear matrix inequality (LMI) technology, some sufficient conditions are presented to guarantee GES a.s. of the concerned system. Moreover, the event-based output feedback controller and the double ETMs can be designed by solving LMIs. In addition, an event-based pinning control is considered and some sufficient conditions are presented. As a theoretic application, our proposed results can be applied to secure synchronization problem for CSs subject to stochastic mixed attacks consisting of denial-of-service (DoS) attacks and deception attacks. Finally, two numerical examples are presented to demonstrate the effectiveness and the merits of the theoretical analysis.

Dual-channel event-triggered control for positive nonlinear systems

This paper focuses on the problem of dual-channel event-triggered control for positive nonlinear systems. A dual-channel event-triggered transmission scheme is proposed to determine whether the data packets should be released or not. Two 1-norm-based event-trigger conditions are designed for the sensor-controller channel and controller-actuator channel, respectively. The condition of the system remaining positivity with the designed event-trigger conditions and feedback control law is provided. By using the Lyapunov method and matrix decomposition technique, a sufficient criterion ensuring the closed loop system to be asymptotically stable is proposed. For the linearisation purpose, the control gain is delicately decomposed into a nonnegative component and a non-positive component. Zeno behaviour of the designed event-triggered transmission of sampled data packets is further rigorously proved to be excluded. An example of water pollution control system is provided to show the effectiveness of the obtained results.

Robust Sliding Mode Control for Stochastic Uncertain Discrete Systems with Two-Channel Packet Dropouts and Time-Varying Delays.

In this paper, the control problem is investigated for discrete time-varying delayed systems with stochastic uncertainty, external disturbance, and two-channel packet dropouts. Sliding mode functions with packet loss probabilities are proposed for the packet loss problem in the sensor–controller channel and the controller–actuator channel. Furthermore, by employing the Lyapunov–Krasovskii functional, some new stability conditions are established in terms of solvable linear matrix inequalities (LMIs), and H∞ performance is analyzed for the sliding mode motion of the system. Meanwhile, a sliding mode controller is designed to drive the system state to the pre-designed sliding surface. Moreover, the designed controller can be robust for two-channel packet dropouts, time-varying delays, stochastic uncertainty and external disturbance. Finally, two numerical examples are given to demonstrate the feasibility of the proposed theoretical method.

Event-triggered control of vehicular platoon system with time-varying delay and sensor faults

This paper addresses the problem of control of a vehicular platoon system with limited on-board resources in the presence of time-varying delay and sensor faults. A platoon system with predecessor-leader following topology in which each vehicle suffers from probabilistic sensor faults and time-varying delay is considered. To reduce the utilization of communication and energy resources in the system, a novel event-triggering communication strategy at the sensor-controller channel is proposed. Based on the proposed triggering strategy, a criteria for co-designing of the triggering parameter and the control law ensuring internal stability of the platoon system is developed. Furthermore, additional conditions are established for the obtained controller to guarantee string stability of the platoon system. The efficacy of the proposed methodology is demonstrated through numerical simulations.

Robust sliding mode control for uncertain networked control system with two-channel packet dropouts

A robust sliding mode control algorithm is developed for a class of networked control system with packet dropouts in both sensor-controller channel and controller-actuator channel, and at the same time mismatched parametric uncertainty and external disturbance are also taken into consideration. A two-level Bernoulli process has been used to describe the packet dropouts existing in both channels. A novel integral sliding surface is proposed, based on which the H∞ performance of system sliding mode motion is analyzed. Then the sufficient condition for system stability and robustness is derived in the form of linear matrix inequality (LMI). A sliding mode controller is designed which can guarantee a relatively ideal system dynamic performance and has certain robustness against unknown parameter perturbations and external disturbances. The results from numerical simulations are presented to corroborate the validity of the proposed controller.

Dynamic event-triggered and self-triggered output feedback control of networked switched linear systems

Abstract This paper deals with output feedback control design for switched linear systems where the sensor and the controller are not co-located. The main purpose is to design a dynamic event-triggered output feedback controller together with a switching rule assuring global asymptotic stability of the closed-loop systems. The sensor-controller channel and controller-actuator channel are asynchronously event-triggered and the dynamic event-triggered mechanism is utilized, which yields a larger minimum inter-event time than the static one. In addition, we propose the corresponding self-triggered mechanism which can be easily implemented by software. Finally, an example of F-18 aircraft is provided to illustrate the effectiveness of the proposed approach.

Modified Preview Control for a Wireless Tracking Control System With Packet Loss

In this paper, a modified preview control technique is proposed to compensate packet loss in a wireless tracking control system, where future reference signals over a finite horizon can be previewed. In order to utilize future reference information for the controller design, the system model is augmented with a reference generator whose states are the future reference signals. As a response to the packet loss that occurs in the wireless network, the preview control technique is modified by employing Bernoulli variables to represent packet loss in both controller-actuator and sensor-controller channels. The Bernoulli packet loss model, along with tracking errors and control inputs, is included in a quadratic cost function, and the optimal controller gain that minimizes the cost function is obtained by dynamic programming. A modified Kalman filter considering packet loss is utilized for full-state estimation and state feedback control. The choice of preview horizon is discussed and the performance of the proposed controller is verified by simulation and experimental results.

Research on Networked Control Systems Based on Adaptive Predictive Control

According to the random time-delay exist in sensor-controller channel and controller-actuator channel in networked control systems, an adaptive predictive control strategy was proposed. In this control strategy, an improved generalized predictive control algorithm is adopted to compensate the networked random time-delay. In addition, using the recursive least squares with a variable forgetting factor algorithm to indentify the model parameters of controlled object on-line, through the way, it could adjust the systems with unknown parameters adaptively. Simulation results show that the adaptive predictive control proposed could solve random time-delay of networked control systems effectively.