Networked Control Systems Research Papers (original) (raw)

2025

One of the main challenges in wireless cyber-physical systems is to reduce the load of the communication channel while preserving the control performance. In this way, communication resources are liberated for other applications sharing the channel bandwidth. The main contribution of this work is the design of a remote control solution based on an aperiodic and adaptive triggering mechanism considering the current network delay of multiple robotics units. Working with the actual network delay instead of the maximum one leads to abandoning this conservative assumption, since the triggering condition is fixed depending on the current state of the network. This way, the controller manages the usage of the wireless channel in order to reduce the channel delay and to improve the availability of the communication resources. The communication standard under study is the widespread IEEE 802.11g, whose channel delay is clearly uncertain. First, the adaptive self-triggered control is validated through the TrueTime simulation tool configured for the mentioned WiFi standard. Implementation results applying the aperiodic linear control laws on four P3-DX robots are also included. Both of them demonstrate the advantage of this solution in terms of network accessing and control performance with respect to periodic and non-adaptive self-triggered alternatives.

2025, arXiv (Cornell University)

Analytical computation methods are proposed for evaluating the minimum dwell time and average dwell time guaranteeing the asymptotic stability of a discrete-time switched linear system whose switchings are assumed to respect a given directed graph. The minimum and average dwell time can be found using the graph that governs the switchings, and the associated weights. This approach, which is used in a previous work for continuous-time systems having non-defective subsystems, has been adapted to discrete-time switched systems and generalized to allow defective subsystems. Moreover, we present a method to improve the dwell time estimation in the case of bimodal switched systems. In this method, scaling algorithms to minimize the condition number are used to give better minimum dwell time and average dwell time estimates.

2025

Discrete-time switched linear systems where switchings are governed by a digraph are considered. The minimum (or average) dwell time that guarantees the asymptotic stability can be computed by calculating the maximum cycle ratio (or maximum cycle mean) of a doubly weighted digraph where weights depend on the eigenvalues and eigenvectors of subsystem matrices. The graph-based method is applied to systems with defective subsystem matrices using Jordan decomposition. In the case of bimodal switched systems scaling algorithms that minimizes the condition number can be used to give a better minimum (or average) dwell time estimates.

2025

Industrial Control Networks (ICNs) are vital for critical infrastructure operations, yet they face escalating cybersecurity threats due to increased connectivity. This paper examines cybersecurity challenges within ICNs, evaluates... more

2025, IEEJ Transactions on Electrical and Electronic Engineering

This paper examines the effects of networked induced time delays on the dissolved oxygen (DO) concentration in the activated sludge process (ASP) of a networked wastewater treatment plant (WWTP). This is a situation in which the controller and the wastewater plant are separated by wide geographical distance. This is a new type of WWTP control that allows two or more WWTPs to be controlled by a single controller placed in a remote location. The objective is to achieve flexibility of control and to reduce its cost. The communication medium between the controller and the WWTPs introduces communication drawbacks into the control system. The influences of network‐induced time delays [controller to actuator delay (τca) and the sensor to controller delay (τsc)] over the behavior of the DO process controlled by both nonlinear linearizing and proportional‐integral controllers are investigated for constant and random delays. Investigation of the DO process under random delays was also perform...

2025, Systems & Control Letters

In this paper, the problem of estimating signals from a dynamic system at regular periods from scarce, delayed and possibly time disordered measurements acquired through a network is addressed. A model based predictor that takes into account the delayed and irregularly gathered measurements from different devices is used. Robustness of the predictor to the time-delays and scarce data availability as well as disturbance and noise attenuation is dealt with via H ∞ performance optimization. The result is a time variant estimator gain that depends on the measurement characteristics, but belonging to an offline precalculated finite set, and hence, the online needed computer resources are low. An alternative to reduce the number of gains to be stored has been proposed, based on defining the gain as a function of the sampling parameters. The idea allows reaching a compromise between online computer cost and performance.

2025

This paper studies a control strategy for reducing congestions in freeway systems by applying ramp metering as control measure. More specifically, the objective is to define a Model Predictive Control scheme to be applied on line, characterized by a finite-horizon optimal control problem with a mixed-integer linear form, in order to be efficiently solved with commercial solvers. In this optimal control problem the prediction model is obtained by linearizing the first-order macroscopic traffic model, hence binary variables must be introduced and the resulting model has a piecewise linear structure. In the paper, the adopted control scheme is first of all analysed in order to evaluate its effectiveness in improving the traffic conditions; secondly, the analysis has been devoted to evaluate the computational time necessary to solve the finitehorizon optimal control problem depending on the problem sizes and the traffic scenarios.

2025, Proceedings of the Annual International Conference on Advances in Distributed and Parallel Computing ADPC 2010 ADPC 2010

Controlling physical systems is a common task of embedded systems. The requirements for a control system are correctness, stability and control performance. This leads to realtime constraints which have to be hold by the implemented controller. We present an approach that supports the control engineer to get guaranteed bounds for the timing behavior of the controller at early design steps. This is done by connecting the Matlab/Simulink environment widely used for controller design to real-time analysis using a mapping between graphs.

2025, Conference on Learning Theory

The logistic loss function is often advocated in machine learning and statistics as a smooth and strictly convex surrogate for the 0-1 loss. In this paper we investigate the question of whether these smoothness and convexity properties make the logistic loss preferable to other widely considered options such as the hinge loss. We show that in contrast to known asymptotic bounds, as long as the number of prediction/optimization iterations is sub exponential, the logistic loss provides no improvement over a generic non-smooth loss function such as the hinge loss. In particular we show that the convergence rate of stochastic logistic optimization is bounded from below by a polynomial in the diameter of the decision set and the number of prediction iterations, and provide a matching tight upper bound. This resolves the COLT open problem of .

2025, Journal of Computing Sciences in Colleges

The patterns movement in software design has provided a framework for codifying and communicating solutions for commonly encountered design challenges. Design patterns are not intended to be only entries in a cookbook, however; they emerge by following good design principles to balance the forces present in a software development context. According to the authors' experience, design patterns are best presented in concert with the design principles that bring them to life. This paper discusses the interrelation between design patterns and principles and reports on a pilot course in teaching the principles and patterns of software design that, after two successful semesters, has recently been adopted as a requirement in a newly inaugurated bachelor's degree in software engineering.

2024, IFAC-PapersOnLine

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

2024, he 2nd National Conference on Green Energy (NCGE’2024)

Microgrids (MGs) have become increasingly important in recent years for integrating Distributed Generation (DG) sources, energy storage systems, and controllable loads into low-and medium-voltage networks. These systems, often powered by Renewable Energy Sources (RESs) like solar and wind, are managed using a hierarchical control structure. At the primary control level, the focus is on balancing power among multiple converters while keeping voltage and frequency stable. However, deviations in these parameters can still occur, requiring secondary control to correct and restore them to their nominal values. This paper introduces a secondary control method based on Double Enhanced Second Order Integrator Frequency Locked Loop (DESOGI-FLL), aimed at enhancing DC offset rejection and improving performance in MG systems. The proposed approach addresses gaps in parameter tuning and control design for greater system stability.

2024, arXiv (Cornell University)

We study the stabilization of networked control systems with asynchronous sensors and controllers. Offsets between the sensor and controller clocks are unknown and modeled as parametric uncertainty. First we consider multi-input linear systems and provide a sufficient condition for the existence of linear time-invariant controllers that are capable of stabilizing the closed-loop system for every clock offset in a given range of admissible values. For first-order systems, we next obtain the maximum length of the offset range for which the system can be stabilized by a single controller. Finally, this bound is compared with the offset bounds that would be allowed if we restricted our attention to static output feedback controllers. I. INTRODUCTION In networked and embedded control systems, the outputs of plants are often sampled in a nonperiodic fashion and sent to controllers with time-varying delays. To address robust control with such imperfections, various techniques have been developed, for example, the input-delay approach [11], [22], the gridding approach [7], [12], [25], and the impulsive systems approach

2024, arXiv (Cornell University)

This article provides a tool for analyzing mechanisms that aim to achieve resilience against stealthy, or undetectable, attacks on cyber-physical systems (CPSs). We consider attackers who are able to corrupt all of the inputs and outputs of the system. To counter such attackers, a response scheme must be implemented that keeps the attacker from corrupting the inputs and outputs of the system for certain periods of time. To aid in the design of such a response scheme, our tool provides sufficient lengths for these periods of time in order to ensure safety with a particular probability. We provide a conservative upper bound on how long the system can remain under stealthy attack before the safety constraints are violated. Furthermore, we show how a detector limits the set of biases an attacker can exert on the system while still remaining stealthy, aiding a system operator in the design of the detector. Our contributions are demonstrated with an illustrative example.

2024, arXiv (Cornell University)

In this report, we introduce a comprehensive design framework for Event-Triggered Networked Control Systems based on the passivity-based concept of Input Feed-Forward Output Feedback Passive (IF-OFP) systems. Our approach is comprehensive in the sense that we show finite-gain L 2-stability and robustness for the networked control system by considering the effects of time-varying or constant network induced delays, signal quantizations, and data losses in communication links from the plant to controller and the controller to plant. Our design is based on the need for a more efficient utilization of band-limited shared communication networks which is a necessity for the design of Large-Scale Cyber-Physical systems. To achieve this, we introduce simple triggering conditions that do not require the exact knowledge of the subsystems and are located on both sides of the communication network: the plant's output and the controller's output. This specifically leads to a great decrease in the communication rate between the controller and plant. Additionally, we show lower-bounds on inter-event time intervals for the triggering conditions and show the design's robustness against external noise and disturbance. We illustrate the relationship amongst stability, robustness and passivity levels for the plant and controller. We analyze our design's robustness against packet dropouts and loss of communication. Our results are design-oriented in the sense that based on our proposed framework, the designer can easily observe the trade-offs amongst different components of the networked control system, time-varying delays, effects of signal quantizations and triggering conditions, stability, robustness and performance of networked control system and make design decisions accordingly.

2024, IEEE Transactions on Power Electronics

This paper presents a novel approach to conceive the secondary control in droop-controlled MicroGrids. The conventional approach is based on restoring the frequency and amplitude deviations produced by the local droop controllers by using a MicroGrid Central Controller (MGCC). A distributed networked control system is used in order to implement a distributed secondary control (DSC) thus avoiding its implementation in MGCC. The proposed approach is not only able to restore frequency and voltage of the MicroGrid but also ensures reactive power sharing. The distributed secondary control does not rely on a central control, so that the failure of a single unit will not produce the fail down of the whole system. Experimental results are presented to show the feasibility of the DSC. The time latency and data drop-out limits of the communication systems are studied as well.

2024

In this paper, we discuss the stability of stochastic type differential equations through obtaining the stability condition for the respective stochastic difference equation. The system formulation is done by considering the stochastic differential equation that describes the dynamics of single isolated neuron involving delay. Here the discretization of the stochastic differential equation is done through the Euler- Maruyama Method. And the desired stability is obtained by applying suitable assumptions and through the help of theorems. The obtained theoretical results are represented through numerical simulation using MATLAB

2024, IFAC Proceedings Volumes

In this paper, with regards to discrete-time networked control systems with incomplete observations, a novel optimal linear estimator design is presented. Through a threshold-length buffer coupled to the estimator and a dropping over-delayed packet strategy, the packet arrival process is artificially limited to time pre-threshold at current moment. According to statistics and probability theory, we model the packet arrival probability subject to the choice of threshold. Based on linear matrix inequality (LMI) theorem and modified Riccati equation with packet arrival probability, with the existence of a critical bound of packet arrival rate, we can completely establish the relation between the filter convergence and the threshold-based packet arrival process as well as characterize the filter performance. Examples demonstrate the feasibility and practicability of the proposed method.

2024, Proceedings of WOON'96

Object references in object-oriented languages suffer from their pointer heritage. In this paper we discourage the use of a single magic value, shared among all reference types, to denote a nonreferencing state. The advantages of void values, which include uniform treatment of void and nonvoid data, provision of default-behavior, termination of recursive definitions, and gracefully dealing with error situations are presented in pattern form. We then investigate the impact of the Void Value pattern for language design, extending the ...

2024

The view presented here is that although the object-oriented paradigm is a powerful basis, it is incomplete in its inherent concepts and therefore restricts the design space to inappropriate solutions. It is assumed that both software development and language design are restrained from achieving their full potential when restricted to a purely object-oriented world view.

2024

The use of the word ‘pattern’ is ubiquitous in written and spoken discourse. Furthermore, most authors assume the intended reader knows what a pattern is, and hence do not define the term. We present an exploration of the variety of definitions of ‘pattern’ used in different domains of mathematics, the sciences, the arts, and the humanities, with the goal of searching for an overarching definition of pattern or at least a metapattern in the sea of definitions. Due to space limitations this paper is necessarily an incomplete survey of how the term pattern is used in different fields, but it provides a sample from which the interested reader may explore the topic further, and it points a direction in which to search for a practical computational approach to measure the amount of pattern contained in an entity.

2024

Matthew Newhook, Bernard NormierMany of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book and ZeroC was aware of the trademark claim, the designations have been printed in initial caps or all caps. The authors and publisher have taken care in the preparation of this book, but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of the use of the information or programs contained herein. Copyright © 2003-2006 by ZeroC, Inc.

2024, Majlesi Journal of Electrical Engineering

This paper is concerned with a controller design method for Networked Control Systems (NCSs) with time-varying random delays. The proposed controller is an event-based controller and is able to effectively save the network bandwidth and energy resources of the system in comparison with common control schemes while guaranteeing the stability of the system. The proposed controller switches between two main triggering schemes: event-triggered control scheme and self-triggered control scheme. The stability issue in this combinatorial method is also considered. The validity of the proposed algorithm is confirmed via simulation results and the results are well compared with results from exerting event-triggered and self-triggered control individually.

2024, Proceedings of the ... American Control Conference

We establish asymptotic and exponential stability theorems for delay impulsive systems by employing Lyapunov functionals with discontinuities. Our conditions have the property that when specialized to linear delay impulsive systems, the stability tests can be formulated as Linear Matrix Inequalities (LMIs). Then we consider Networked Control Systems (NCSs) consisting of an LTI process and a static feedback controller connected through a communication network. Due to the shared and unreliable channels, sampling intervals are uncertain and variable. Moreover, samples may be dropped and experience uncertain and variable delays before arriving at the destination. We show that the resulting NCSs can be modeled by linear delay impulsive systems and we provide conditions for stability of the closed-loop in terms of LMIs. By solving these LMIs, one can find a positive constant that determines an upper bound between a sampling time and the subsequent input update time, for which stability of the closed-loop system is guaranteed.

2024, Stability and Security Analysis with Identification of Attack on Industrial Networked Control System : An Overview

A networked control system (NCS) is sensitive to the different types of attacks and it is essential to secure and stabilize it. In this manuscript, to represent the impact on the stability of the control system, an industrial NCS is considered. The process noise and measurement noise alongside certain attacks are assumed to be affecting the performance of this system. It is also assumed that the agent may inject false data to disrupt the performance of the control system. An overview of recent work done for stabilization of NCS in such scenario is presented here. Kalman filter along with some control system stability conditions are used to mitigate the effect of noise and attacks on NCS. A numerical example is presented here to exemplify the performance of the Kalman filter and Linear Quadratic Gaussian (LQG) controller along with PID controller on system state estimation. It is shown that Kalman filter estimates the states optimally which indicted by the eigenvalues of-4.87,-1.77,-12. The simulation and sampling timea were 20s and 10ms, respectively.

2024

Controlling the process is the main issue that rises in the process industry. It is very important to keep the process working probably and safely in the industry, for environmental issues and for the quality of the product being processed. PID control is a control strategy that has been successfully used over many years. Simplicity, robustness, a wide range of applicability and near optimal performance are some of the reasons that have made PID control so popular in the academic and industry sectors. Recently, it has been noticed that PID controllers are often poorly tuned and some efforts have been made to systematically resolve this matter. In the paper a brief summary of PID theory is given, then, some of the most used PID tuning methods are discussed.

2024, Real-time Systems

Functionality and performance of modern machines are directly affected by the implementation of real-time control systems. Especially in networked teleoperation applications, force feedback control and networked control are two of the most important factors, which determine the performance of the whole system. In force feedback control, generally it is necessary but difficult and expensive to attach sensors (force/torque/pressure sensors) to detect the environment information in order to drive properly the feedback force. In networked control, there always exist inevitable random time-varying delays and packet dropouts, which may degrade the system performance and, even worse, cause the system instability. Therefore in this chapter, a study on a real-time bilateral teleoperation control system (BTCS) over an imperfect network is discussed. First, current technologies for teleoperation as well as BTCSs are briefly reviewed. Second, an advanced concept for designing a bilateral teleoperation networked control (BTNCS) system is proposed, and the working principle is clearly explained. Third, an approach to develop a force-sensorless feedback control (FSFC) is proposed to simplify the sensor requirement in designing the BTNCS, while the correct sense of interaction between the slave and the environment can be ensured. Fourth, a robust-adaptive networked control (RANC)-based master controller is introduced to deal with control of the slave over the network containing both time delays and information loss. Case studies are carried out to evaluate the applicability of the suggested methodology.

2024, 2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

We consider distributed optimization where N nodes in a generic, connected network minimize the sum of their individual, locally known, convex costs. Existing literature proposes distributed gradient-like methods that are attractive due to computationally cheap iterations and provable resilience to random inter-node communication failures, but such methods have slow theoretical and empirical convergence rates. Building from the centralized Nesterov gradient methods, we propose accelerated distributed gradient-like methods and establish that they achieve strictly faster rates than existing distributed methods. At the same time, our methods maintain cheap iterations and resilience to random communication failures. Specifically, for convex, differentiable local costs with Lipschitz continuous and bounded derivative, we establish (with respect to the cost function optimality) convergence in probability and convergence rates in expectation and in second moment.

2024

2024, Circuits Systems and Signal Processing

This paper deals with the problem of synthesizing an anti-windup compensator for time-delay systems subject to actuator saturation, and uncertain sampling period with the known upper bound on the sampling intervals. By incorporating Lyapunov-Krasovskii functional, Jensen's integral inequality and Wirtingers integral inequality, some sufficient conditions are obtained via LMI formulation. The conditions guarantee the stability of the closed-loop system, an H ∞ norm bound performances and enlarge the estimation of domain of attraction. Finally, to demonstrate the effectiveness of the developed results, simulation examples are provided. Keywords Sampled-data control • Anti-windup • Time-delay system • Actuator saturation 1 Introduction Since time delay is often a source of instability, oscillation and poor performance in practical systems, considerable attention has been paid to the problem of stability analysis and controller synthesis for time-delay systems, and a great number of results have been reported in the literature [6, 10, 17, 22, 37-39, 41, 45].

2024

In this paper, we develop a system-of-systems framework to address cyber-physical resilience, the ability to withstand the combined presence of both cyber attacks and physical faults. This framework incorporates a definition of resilience, a resilience metric as well as a resilient control design methodology. The resilient control architecture utilizes a hybrid optimal control methodology combined with a dynamic regulation market mechanism (DRMM), and is evaluated in the context of frequency regulation at a transmission grid. The framework enables the evaluation of both the classical robust control properties and emerging resilient control properties under both cyber attacks and physical faults. The proposed framework is used to assess resilience of a CyberPhysical Energy System (CPES) when subjected to both cyber and physical faults via DETERLab. DETERLab, a testbed capable of emulating high fidelity, cybersecure, networked systems, is used to construct critical scenarios with phys...

2024, International journal of intelligent machines and robotics

This paper addresses the design and presents the experimental results of an aperiodic remote-controlled mechatronic plant using a MiniDK2 electronic development board. We compare the classic periodic control solution with our self-triggered approach. The triggering mechanism consists of evaluating if the measurement error exceeds a predefined value. This measurement error is defined as the difference between the output signal of a model with and without a sample-and-hold that is activated only at the triggering instants. The minimum inter-execution time is the reference period and the maximum time is set by the designer, guaranteeing the stability of the closed loop system. At each new triggering instant, the remote controller receives a new measurement of the system and sends the actuation signal to the mechatronic plant.

2024, Sensors (Basel, Switzerland)

This paper describes the theoretical and practical foundations for remote control of a mobile robot for nonlinear trajectory tracking using an external localisation sensor. It constitutes a classical networked control system, whereby event-based techniques for both control and state estimation contribute to efficient use of communications and reduce sensor activity. Measurement requests are dictated by an event-based state estimator by setting an upper bound to the estimation error covariance matrix. The rest of the time, state prediction is carried out with the Unscented transformation. This prediction method makes it possible to select the appropriate instants at which to perform actuations on the robot so that guidance performance does not degrade below a certain threshold. Ultimately, we obtained a combined event-based control and estimation solution that drastically reduces communication accesses. The magnitude of this reduction is set according to the tracking error margin of ...

2024, International Journal of Control, Automation and Systems

This paper inspects the consensus problem of nonlinear mixed delay multi-agent systems with random packet losses through the sampled-data control using the undirected graph without any specified leader for the other following agents. The probabilistic time varying delay is taken in the control input delay that Bernoulli distributed white sequence is engaged to formulate the random packet losses between the agents. The consensus problem can be changed over into a stabilization problem by using the Laplacian matrix which can be obtained by undirected graph. By framing a Lyapunov-Krasovskii functional with triple integral terms and implementation of the property of Kronecker product together with some well known matrix inequality techniques, a mean square consensus for mixed delay multi-agent system can be achieved. Terminally, two numerical examples are provided to illuminate the advantages of the suggested techniques.

2024, IFAC Proceedings Volumes

This paper investigates a new alternative approach to compensate for the effects of packet dropouts (data do not arrive at destination) on a dynamic networked control system (NCS). The approach uses an observer-based control computation using time-delay predicted values as the sampling times of the NCS. To obtain the predicted values of time delays we propose the use a one-step-ahead and multistep prediction algorithms based on an adaptive time delay neural network (TDNN). The control gains are calculated using optimal control.

2024

In this work, we present a decentralized scheme for the control of a freeway traffic system over a non-ideal transmission channel, involving network delays ultimately resulting in possible packet losses in the digital communication. The feedback scheme exploits the well-known Cell Transmission Model (CTM) and a ramp metering control, with actuation consisting of on-ramp traffic lights. In this context, the Model Predictive Control (MPC) approach is applied locally, in a decentralized way, which is preferable from the computational viewpoint with respect to centralized solutions, the complexity of which would grow rapidly with the dimension of the system at hand, making real-time traffic control potentially ineffective. The simulation setup is based on a traffic model whose parameters are identified using data produced by a commercial microscopic simulator of the traffic system. Preliminary performance results show the effectiveness of the approach taken, also in the case of parameter uncertainties, and look promising in view of future investigations.

2024, Chinese Optics Letters

A signal processing method of realizing a large-range displacement measurement in a sinusoidal phasemodulating laser diode interferometer is proposed. The method of obtaining the dynamic value of the effective sinusoidal phase-modulating depth is detailed, and the residual amplitude modulation is also taken into account. Numerical simulations and experiments are carried out to compare this method with the traditional one. We prove that, with this method, the sinusoidal phase-modulating laser diode interferometer can realize a centimeter-level displacement measurement range with high precision, which is much better than the traditional method.

2024, IFAC-PapersOnLine

In the paper a switched controller for freeway traffic systems is proposed. First of all, the Cell Transmission Model, a first-order model commonly used for freeway traffic systems, is described and a switched version of this model is proposed. According to this version, a freeway can be seen as a piecewise-affine system, i.e. a system which switches among different sets of linear difference equations. Then, based on this model, a switched controller is proposed so that different control laws are applied depending on the operation mode of the system. More specifically, the controller computes the current control law depending on the mode of the system and on the probabilities to reach future states, on the basis of a Discrete-Time Markov Chain modelling the state space and the possible transitions among them.

2024, Journal of Control Engineering and Applied Informatics

In view of the fact that real networked control systems (NCSs) with uncertain events and traffic are subject to violation of the nominal conditions used in the design and analysis of their behavior, it is essential to consider (somehow) the probability of these conditions being (or not) fully satisfied. This paper focuses on practical issues and discusses the effect of the distributions of delays on the determination of the most likely stability regions to be considered in the design of a NCS. An alternative methodology for the analysis of NCSs is proposed here for implementation in real cases. The methodology is based on the Monte Carlo method coupled with a sorting algorithm and a gradient search using the analysis of time responses. The proposed method is compared with a traditional technique based on the polytopic overapproximation method to provide the maximum possible delays. The obtained results yielded less conservative stability limits, aligned with the tendency to use adap...

2024, IEEE Transactions on Systems, Man, and Cybernetics, Part C (Applications and Reviews)

In this paper, the effects of network delay among interconnecting elements of a distributed computer network control system are analyzed. Experimental tests have been accomplished to show the influence of the combined effects of the network delay (between sensor/controller and controller/actuator) on the overall performance of a feedback control system. For this purpose, a proportional-plus-integral (PI) controller has been used. This controller has been designed, using the well-known direct synthesis method and implemented in a didactic networked control system platform. Corresponding (z-transform) difference equations have been used, assuming time-triggered (regular) samplings. The augmented PI controller (with compensation of the control signal and estimation of missing measurements) is developed. Stability analysis is performed to verify the validity of this scheme. The results presented in the paper show that the dynamic behavior of the closed-loop system can be improved using the proposed technique. Index Terms-Digital controllers, effects of time delay, networked control systems (NCSs), time-delay compensation. I. INTRODUCTION W HILE conventional control systems make use of analog or digital technology to send control signals over the loop, in modern computer control systems, the control loop is almost entirely closed over a communication network. In this networked system, the sensor, the actuator, and the controller are elements that share information by exchanging messages over the network. The great availability and ever-decreasing costs of the networked digital technology have been responsible for the replacement of the traditional point-to-point link for broadcast transmission. This change represents an important breakthrough toward effective control decentralization, resulting in significant cost reduction with wiring and maintenance [1], [2]. Such a control architecture is now been denominated networked control systems (NCSs) [3], [4]. NCSs present better characteristics in terms of modularity and scalability, offering more design options. Nevertheless, the presence of a network in the control loop has the drawback of introducing time delays in the communications among field

2024, International journal of simulation: systems, science and technology

A number of internet users is increasing every day, making the traffic load increases. The presence of new internet users exceeds the load-carrying capacity and affects the long-time users. The result can happen of high latency and low throughput. The problem will be high demand from various corners to the server, coupled by the relevant limited server capacity, making this study feasible proposed as reference material to resolve the issue. A great overview of this research using web-caching server, where the server caching placed in one country, in this case Indonesia. The server will store the data that is frequently accessed website. This study took a sample of 10 websites, will be evaluated in terms of RTT and throughput. The system by using a cache server, evidenced RTT latency decreased approximately 24.18% and throughput increased an average of 28 %.

2024, IFAC-PapersOnLine

This short paper first explains the general principle of "borrowed feedback" for linear systems with constant input delay, and in its dual form of observation with delayed measurements. This is of interest in problems where the external interaction with the system incurs a delay. One application is the control of systems over a network. In this case the delay cannot be considered constant, but depends on a congestion state of the network. It is shown that if the causality constraint, which imposes an upper bound on the rate of change of the delay, does not hold the design method fails to give consistent results.

2024, IEEE Transactions on Automatic Control

This technical note deals with the design of stable interval observers and estimators for continuous-time linear dynamic systems under uncertain initial states and uncertain inputs enclosed within time-varying zonotopic bounds. No monotony assumption such as cooperativity is required in the vector field: the interval observer stability directly derives from the stability of the observer state matrix, where any poles (real or complex, single or multiple) are handled in the same way.

2024, IEEE Transactions on Control Systems Technology

This paper addresses a Networked Control System (NCS) application on an unstable triple-magnetic levitation setup. A hierarchical dual-rate control using a Profibus-DP network has been used in order to stabilise a triangular platform composed of three maglevs. The control difficulty is increased due to the existence of time-varying network-induced delays. To solve this issue, a local decentralised H∞ control action is complemented by means of a lower-rate output-feedback controller in the remote side. Experimental results show a good stabilization and reference position accuracy under disturbances.

2024, IEEE Control Systems Magazine

R ecent years have witnessed a significant increase in the number of securityrelated incidents in control systems. These include high-profile attacks in a wide range of application domains, from attacks on critical infrastructure, as in the case of the Maroochy Water breach [1], and industrial systems (such as the StuxNet virus attack on an industrial supervisory control and data acquisition system [2], [3] and the German Steel Mill cyberattack [4], [5]), to attacks on modern vehicles [6]-[8]. Even high-assurance military systems were shown to be vulnerable to attacks, as illustrated in the highly publicized downing of the RQ-170 Sentinel U.S. drone [9]-[11]. These incidents have greatly raised awareness of the need for security in cyberphysical systems (CPSs), which feature tight coupling of computation and

2024, arXiv (Cornell University)

In this paper, we establish a zero-sum, hybrid state stochastic game model for designing defense policies for cyber-physical systems against different types of attacks. With the increasingly integrated properties of cyber-physical systems (CPS) today, security is a challenge for critical infrastructures. Though resilient control and detecting techniques for a specific model of attack have been proposed, to analyze and design detection and defense mechanisms against multiple types of attacks for CPSs requires new system frameworks. Besides security, other requirements such as optimal control cost also need to be considered. The hybrid game model we propose contains physical states that are described by the system dynamics, and a cyber state that represents the detection mode of the system composed by a set of subsystems. A strategy means selecting a subsystem by combining one controller, one estimator and one detector among a finite set of candidate components at each state. Based on the game model, we propose a suboptimal value iteration algorithm for a finite horizon game, and prove that the algorithm results an upper bound for the value of the finite horizon game. A moving-horizon approach is also developed in order to provide a scalable and real-time computation of the switching strategies. Both algorithms aims at obtaining a saddle-point equilibrium policy for balancing the system's security overhead and control cost. The paper illustrates these concepts using numerical examples, and we compare the results with previously system designs that only equipped with one type of controller.

2024, IEEE Transactions on Control of Network Systems

We introduce the problem of learning-based attacks in a simple abstraction of cyber-physical systems-the case of a discrete-time, linear, time-invariant plant that may be subject to an attack that overrides the sensor readings and the controller actions. The attacker attempts to learn the dynamics of the plant and subsequently overrides the controller's actuation signal, to destroy the plant without being detected. The attacker can feed fictitious sensor readings to the controller using its estimate of the plant dynamics and mimic the legitimate plant operation. The controller, on the other hand, is constantly on the lookout for an attack; once the controller detects an attack, it immediately shuts the plant off. In the case of scalar plants, we derive an upper bound on the attacker's deception probability for any measurable control policy when the attacker uses an arbitrary learning algorithm to estimate the system dynamics. We then derive lower bounds for the attacker's deception probability for both scalar and vector plants by assuming an authentication test that inspects the empirical variance of the system disturbance. We also show how the controller can improve the security of the system by superimposing a carefully crafted privacy-enhancing signal on top of the "nominal control policy." Finally, for nonlinear scalar dynamics that belong to the Reproducing Kernel Hilbert Space (RKHS), we investigate the performance of attacks based on nonlinear Gaussian-processes (GP) learning algorithms.

2024, 2021 IEEE Conference on Control Technology and Applications (CCTA)

This paper proposes a distributed cyber-attack detection method in communication channels for a class of discrete, nonlinear, heterogeneous, multi-agent systems that are controlled by our proposed formation-based controller. A residual-based detection system, exploiting a neural network (NN)-based observer, is developed to detect false data injection attacks on agents' communication channels. A Lyapunov function is used to derive the NN weights tuning law and the attack detectability threshold. The uniform ultimate boundedness (UUB) of the detector residual and formation error is proven based on the Lyapunov stability theory. The proposed method's attack detectability properties are analyzed, and simulation results demonstrate the proposed detection methodology's performance.

2024, arXiv (Cornell University)

2024, 2021 IEEE Conference on Control Technology and Applications (CCTA)

This paper proposes a distributed cyber-attack detection method in communication channels for a class of discrete-time, nonlinear, heterogeneous, multi-agent systems controlled by the proposed formation-based controller. To detect false data injection attacks on agents communication channels, each agent exploits a residual-based detection system equipped with a neural network (NN)-based observer. Moreover, the NN weights tuning law and the attack detectability threshold are derived using a Lyapunov function. The uniform ultimate boundedness (UUB) of the formation error and detector residual are proven based on the Lyapunov stability theory. Finally, the attack detectability condition of the proposed method is analyzed, and a simulation example is provided to demonstrate the performance of the proposed detection methodology.