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In this paper, the problem of fault detection for nonlinear networked control systems subject to both communication constraints and packet dropouts is investigated. Despite the huge bulk of studies in the area of linear networked control systems, nonlinear networked control systems have been less involved. In the proposed method, Takagi–Sugeno fuzzy model is employed to represent nonlinear networked control systems. To model the communication network, access constraints and packet dropouts are respectively considered as periodic sequences and Bernoulli processes. Based on the optimal periodic residual generator theory, a fuzzy-model-based observer is proposed to deal with the problem of fault detection for nonlinear networked control systems. Both residual evaluation and correspondence threshold are also investigated to generate confident fault alarms. Finally, the effectiveness of the proposed fault detection scheme for nonlinear networked control systems is illustrated and some simulation results are carried out to validate the proposed approach. • A novel FD scheme for nonlinear model of NCS is proposed. • Both access constraints and packet dropouts in the model of NCS are considered. • T–S fuzzy model is utilized to represent nonlinear NCS. • A fuzzy-based observer is also proposed to deal with the problem of nonlinear FD. • Residual evaluation & correspondence threshold are used to generate fault alarms. [ABSTRACT FROM AUTHOR]

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Modern Industrial Control Systems (ICS) constitute complex and heterogeneous 'system of systems' embracing the numerous advantages of traditional Information and Communication Technology (ICT). The pervasive integration of off-the-shelf ICT into the core of ICS broadened the palette of features and applications, but it also raised new design challenges and exposed ICS to a new breed of cyber-physical attacks. In addition, despite all the security solutions in place, unavoidably, these systems may be compromised. Therefore, survivability, that is, the ability to face malicious actions and faults, becomes a salient feature/requirement in the design of modern cyber-connected ICS. We present a comprehensive solution for ensuring the survival of ICS under malicious activities and faults. We design a Software Defined Networking (SDN) and Network Function Virtualization (NFV) based communication infrastructure particularly tailored to address the communication requirements of ICS. We develop an attack detection and localization algorithm for bidirectional ICS flows, and we design an optimal intervention strategy that embraces the communication and security requirements of industrial applications. Finally, we present intrinsic details on recreating a real-life and emulated test infrastructure. Experimental results demonstrate the solution's applicability to networked robot control systems. [ABSTRACT FROM AUTHOR]

With the wide application of networked control systems, how to deal with data injection attacks and maintain the stability of control systems including wireless multi-hop networks is a problem that the researchers and technological workers must consider and solve. Based on the construction of a control system including wireless multi-hop networks, the data transmission mode between routing nodes and the stability condition of the control system are given. Considering the existence of data injection attacks to routing nodes, a real-time detection method for anomaly behaviours is presented on the basis of chi-square goodness-of-fit test. In the case of data injection actions taking place, a strategy of switching paths in turn is used to execute the control task. The strategy is satisfied with the resilient stability of the control system. The simulation results show that the detection method can detect the data injection actions in real time, and the control strategy can restore control variables to proper values when the data injection actions exist. These methods have certain application prospects and popularisation values. [ABSTRACT FROM AUTHOR]

In this paper, periodic event-triggered sampling and dual-rate control techniques are integrated in a wireless networked control system (WNCS), where time-varying network-induced delays and packet disorder are present. Compared to the conventional time-triggered sampling paradigm, the control solution is able to considerably reduce network utilization (number of transmissions), while retaining a satisfactory control performance. Stability for the proposed WNCS is ensured using linear matrix inequalities. Simulation results show the main benefits of the control approach, which are experimentally validated by means of an unmanned-aerial-vehicle-based test-bed platform. [ABSTRACT FROM AUTHOR]

Different from the single paths between controllers and plants of networked control systems (NCSs), the complex network provides widespread links and brings plenty of paths from the controller side to the plant side. Benefit from this advantage, a novel data transmission dispatching strategy is proposed. When the direct path can not satisfy the condition of system demand, neither stability nor performance, some specified paths compose a concurrent-path to transmit the control signal concurrently. Firstly, the networked control systems (NCSs) are expressed by the switched systems model with the constant network-induced delay, and the network communication is described as a packet-loss process. Secondly, taking system's exponential decay rate as its performance indicator, the relationship between control signal transmission paths and system performance is quantitatively given by considering packet losses as the compound poisson process and the alternating renewal process. Then, due to that different combination of paths induces the different statistical properties of packet losses, the approach to find an appropriate concurrent-path is proposed concerning two mutually constrained factors, the system performance demand and the utilization of network resources. After the theoretical analysis, a distributed communication platform based on peer-to-peer (P2P) network technology is designed and implemented to realize the concurrent-path transmission on internet. Finally, the practical experiment on the platform demonstrates the validity and effectiveness of proposed approach. [ABSTRACT FROM AUTHOR]

Copyright of Automatisierungstechnik is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A suspension system is one of the most important subsystems in the car; it acts as a bridge between the occupants of a vehicle and the road. This paper presents a simulation of two cases of control for a full model car active suspension system. The first case is a control system without network, while the second is a networked control system. In the first approach, there is a comparison between two control methods (PID and LQR) for active suspension systems. Results shown that PID is better than LQR when the goal is to control the suspension travel of the car, while controlling other parameter of the system is more available using LQR and depends on the complexity of the reference index used. The second case is a networked control for active suspension system using a proposed model of CAN network in Matlab to transfer the readings values of sensors and actuators to/from a controller; the control method inside the controller is either PID or LQR. The results show that LQR method has better performance than PID when the speed of network is low. [ABSTRACT FROM AUTHOR]

Highlights • The time-varying delay is transformed into a mismatched disturbance of the system. • A discrete GESO is proposed to eliminate the effect of the mismatched disturbance. • A composite controller is designed by using GESO-based output feedback control. • The input-to-state stability of the closed-loop system is analyzed. Abstract This paper investigates the generalized extended state observer (GESO) based output feedback control problem for the networked control systems (NCSs) with mismatched uncertainty caused by network-induced delay. First, the time-varying delay is modeled as a nominal part and an uncertainty part, where the uncertainty part is transformed into the mismatched disturbance of the system. Then, a discrete GESO is proposed to estimate the system state and the disturbance, and uses the feed-forward compensation strategy to eliminate the effect of the mismatched uncertainties. A composite controller is designed by using GESO-based output feedback control, and the input-to-state stability of the system is analyzed. Finally, both simulation and experiment are carried out to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Recently, the incorporation of telecommunication technology with control systems provides the usability of remote measurement signals for the designing of networked controllers for geographically distributed large-scale systems. However, communication network introduces new difficulties such as time delays and packet dropouts to the design of networked controllers. This paper presents a new Distributed Networked Control Scheme (DNCS) and its stability analysis for stabilizing of large-scale systems with interconnected subsystems featuring both random delays and random packet dropouts in their communication links. Firstly, a general model for large scale distributed networked system consisting of subsystems is used in which the state of each subsystem has its own time varying delay and there are also delays and packet dropouts in their interconnection communication links. To compensate the influence of subsystems on each other and enhance performance and stability margin of the closed-loop system, a suitable distributed control scheme is proposed. The stability criteria are provided based on Lyapunov-Krasovskii and Linear Matrix Inequality (LMI) techniques. For this, a new type of Lyapunov-Krasovskii functional and certain slack matrices are developed to conclude some LMI-based delay-dependent theorems for designing the control law, as well as the stabilizing of the DNCS. To evaluate the proposed method, three illustrative examples are provided. To indicate the efficiency of the suggested approach, a small-gain-based approach and an observer-based consensus method are applied for comparison. Simulation results show the effectiveness of the proposed approach to enhance the performance of large-scale networked systems among a non-ideal communication network. [ABSTRACT FROM AUTHOR]

Abstract Network-induced imperfections such as transmission delays, time-varying sampling intervals and clock asynchronization among nodes make it complicated to analysis and design a networked control system (NCS). Further, constructing such an NCS becomes tedious and difficult when there are a number of nodes needed to be integrated together through the imperfect network. In this paper, to solve these problems, we design and develop a network interface device termed as information pipeline CAN (IPCAN) that can facilitate rapid integration of network nodes and provide well-designed transmission properties. The IPCAN adopts information pipeline technology (IPT) to construct an endpoint-based data interface, which makes nodes modular and reusable. A time-triggered information-exchange mechanism is proposed for the IPCAN to achieve fixed and predictable transmission delays and temporal-spatial consistency of received data. These properties contribute to realizing synchronous time-driven mode among nodes and simplifying the analysis of the system. In addition, several novel technical methods are proposed to implement the IPCAN with controller area network (CAN) and serial peripheral interface (SPI) as the physical connections of network and user interface, respectively. The IPCAN is applied to a distributed temperature control system and its utility and performance are well demonstrated. [ABSTRACT FROM AUTHOR]

This paper is concerned with the stochastic stabilization problem for a class of networked control system (NCS) with destabilizing transmission factors. By introducing the effective sampling instant to model random time delays and successive packet dropouts as two independent Markov chains, NCS is modeled as a discrete-time Markovian jump linear system with mixed integrated Markovian jumping parameters. In this way, a novel framework to analyze the stochastic stabilization problem of NCS is provided. The necessary and sufficient conditions for the stochastic stabilization of the NCS are obtained by the Lyapunov method and the state-feedback controller gain that depends on the delay modes is obtained in terms of the linear matrix inequalities (LMIs) formulation via the Schur complement theory. Finally, numerical examples are provided to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Future gas turbine engine control systems will be based on a distributed architecture in which the sensors and actuators will be connected to the controllers via a communication network. The performance of the distributed engine control (DEC) system is dependent on the network performance. The network-induced time delay may degrade the performance of the closed-loop systems and even destabilize the systems if the controllers are designed without considering the effects of the delay. This paper introduces a new method to estimate the maximum tolerance of the time delay for analysis of the stability of the GE T700 turboshaft engine DEC system. The sufficient conditions for stability are derived and dynamic output feedback controllers for the turboshaft engine are applied. Hardware-in-the-loop simulation illustrates the effectiveness of the presented method.

From cyber physical system perspective,tightly coupling the communications and computing aspects with physical dynamics is profound.This characteristic is investigated for wireless networked control systems (WNCS).Following the tight coupling principle of CPS,a tight coupling adaptive fuzzy controlling methodology for WNCS is proposed.Through simulation experiments,it is showed that proposed method could adaptively adjust the controlled system's sample period and network channel access priority according to its real time control urgency and the network traffic condition,so as to optimize network utilization and improve the performances of the whole NCS.

Abstract This paper is concerned with estimation and stability of control systems over communication links subject to limited capacity, power constraint, fading, noisy feedback, and different transmission rate rather than system sampling rate. A key issue addressed in this paper is that in the presence of noisy feedback associated with channel, which models transmission of finite number of bits over such links as is the case in most practical scenarios, the well-known eigenvalues rate condition is still a tight bound for stability. Based on an information theoretic analysis, necessary conditions are derived for stability of discrete-time linear control systems via the distant controller in the mean square sense. By construction of a specific coding scheme and by the design of a proper controller, the tight sufficient conditions for stability of control systems are also derived for linear discrete-time control systems over both Additive White Gaussian Noise (AWGN) and fading channels. This implies that the proposed coding scheme is efficient. The results are presented with the mismatch assumption between channel symbol and plant sample rates. As one key result of this paper, it is shown that if the channel symbol rate is less than the system sample rate, the control system is still stabilizable via increasing the transmission power. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we study the networked stabilization of a continuous-time multi-input system wherein the multiple control inputs are transmitted through a small number of shared channels with stochastic multiplicative uncertainties. Transmission scheduling over the shared channels needs to be performed so that at any time instant, each channel transmits only one control input. The main novelty of this work lies in the idea of scheduling/control co-design which suggests that the design of the transmission scheduling and the controller should be treated jointly rather than separately. By virtue of such a co-design, a sufficient condition is obtained for the channels' overall quality of service required for stabilization given in terms of twice of the topological entropy of the plant. A numerical example is provided to illustrate our result. [ABSTRACT FROM AUTHOR]

Summary: This paper examines the problem of codesigning a robust L2‐gain networked control system along with the network's properties such as sampling interval, service rate, and packet dropout. On the basis of the generalized integral inequality of Bessel‐Legendre inequality approach, sufficient conditions for the existence of a robust L2‐gain controller that incorporates the network's properties are derived and expressed in terms of linear matrix inequalities. Finally, two examples are used to illustrate the effectiveness of the proposed methodology. [ABSTRACT FROM AUTHOR]

This study addresses the sliding mode controller design for a networked control system with quantisation and random packet loss. A logarithmic quantiser is adopted in order to guarantee the coarsest density and decrease the possibility of unsuccessful transmission. The quantisation process is designed as an event driven to reduce the amount of data to be transmitted over the channel. A sliding mode controller is adopted to suppress the measurement noise and error caused by the features of a wireless communication channel. The existence of quasi‐sliding mode in the sense of mean‐square and closed loop stability in the sense of mean square are claimed. Simulations are carried out to support the algorithms proposed. [ABSTRACT FROM AUTHOR]

This work studies the stochastic stability of Markovian jump linear systems in a communication network-based environment. By modeling quantization density as well as the sensor-to-controller and controller-to-actuator delays as Markov chains, the closed-loop networked control systems are expressed as switched linear systems. The necessary and sufficient conditions of stochastic stability are derived. By solving a set of linear matrix inequalities with matrix inversion constraints, this work presents a three-mode-dependent state-feedback controller. Its control performance is illustrated via a numerical example. [ABSTRACT FROM AUTHOR]

In this paper, a novel switching event-triggered synchronization scheme is established for chaotic networked control systems with different dimensions. First, a reduced-dimension observer is constructed to help the response system estimate all the states of the drive system. Next, a switching event-triggered networked control method which depends both on relative error and absolute error of the sampled-data is designed to reduce the burden of network bandwidth effectively while ensuring the desirable synchronization performance. On the basis of the above, some sufficient synchronization criterions are derived in the form of linear matrix inequalities. Finally, the numerical simulation is carried out to demonstrate the effectiveness and superiority of the synchronization method. [ABSTRACT FROM AUTHOR]