Summary This paper proposes a separation method of a transmission delay and data packet dropouts from a lumped input delay in the stability problem of a networked control system, where both the transmission delay and the data packet dropouts are involved. By modeling data packet dropouts as sampling processes and the transmission delay as a state delay, the networked control system is represented as a sampled‐data system with aperiodic sampling and a state delay. In order to separate the state delay and the sampling, the sampled‐data system is transformed into a new system with an integral operator, where the sampling is embedded into the integral operator. By investigating the integral operator's gain and passivity, a novel Lyapunov functional is constructed to address the stability problem. The obtained stability results are dependent on both the data packet dropouts and the time delay. A numerical example is provided to demonstrate that the stability results are less conservative than some existing ones. Copyright © 2016 John Wiley & Sons, Ltd.
This paper is concerned with the design problem of non-fragile H/sub /spl infin// controller for uncertain descriptor systems with time-varying discrete and distributed delays and controller gain variations. The designed controller is shown to be robust not only to parameter uncertainties, but also to errors in the controller coefficients. The obtained criterion to derive an efficient non-fragile H/sub /spl infin// control design is expressed as a set of nonconvex matrix inequalities, which can be solved by combining both linear matrix inequalities technique and cone complementarity method. A numerical example is given to demonstrate effectiveness of the proposed methods.
The security issue in the state estimation problem is investigated for a networked control system (NCS). The communication channels between the sensors and the remote estimator in the NCS are vulnerable to attacks from malicious adversaries. The false data injection attacks are considered. The aim of this paper to find the so-called insecurity conditions under which the estimation system is insecure in the sense that there exist malicious attacks that can bypass the anomaly detector but still lead to unbounded estimation errors. In particular, a new necessary and sufficient condition for the insecurity is derived in the case that all communication channels are compromised by the adversary. Moreover, a specific algorithm is proposed for generating attacks with which the estimation system is insecure. Furthermore, for the insecure system, a system protection scheme through which only a few (rather than all) communication channels require protection against false data injection attacks is proposed. A simulation example is utilized to demonstrate the effectiveness of the proposed conditions/algorithms in the secure estimation problem for a flight vehicle.
This paper is concerned with the security control problem with quadratic cost criterion for a class of discrete-time stochastic nonlinear systems subject to deception attacks. A definition of security in probability is adopted to account for the transient dynamics of controlled systems. The purpose of the problem under consideration is to design a dynamic output feedback controller such that the prescribed security in probability is guaranteed while obtaining an upper bound of the quadratic cost criterion. First of all, some sufficient conditions with the form of matrix inequalities are established in the framework of the input-to-state stability in probability. Then, an easy-solution version on above inequalities is proposed by carrying out the well-known matrix inverse lemma to obtain both the controller gain and the upper bound. Furthermore, the main results are shown to be extendable to the case of discrete-time stochastic linear systems. Finally, two simulation examples are utilized to illustrate the usefulness of the proposed controller design scheme.
This article is concerned with the distributed secondary frequency and voltage control for islanded microgrids. First, the distributed secondary control problem is formulated by taking both communication delays and switching topologies into account. Second, by using an Artstein model reduction method, a novel delay-compensated distributed control scheme is proposed to restore frequencies of each distributed generator (DG) to a reference level in finite time, while achieving active power sharing in prescribed finite-time regardless of initial deviations generated from primary control. Third, a distributed finite-time controller is developed to regulate voltages of all DGs to a reference level. Fourth, the proposed idea is also applied to deal with the finite-time consensus for first-order multiagent systems. Finally, case studies are carried out, demonstrating the effectiveness, the robustness against load changes, and the plug-and-play capability of the proposed controllers.
The robust stability of uncertain linear neutral systems with time-varying discrete and neutral delays is investigated. The uncertainties under consideration are nonlinear time-varying parameter perturbations and norm-bounded uncertainties, respectively. Both delay-dependent and delay-derivative-dependent stability criteria are proposed and are formulated in the form of linear matrix inequalities (LMIs). The results in this paper contain some existing results as their special cases. A numerical example is also given to indicate significant improvements over some existing results.
In this paper, performance guaranteed consensus tracking is investigated for networked agents with uncertainty. A distributed observer-based controller is propo
This paper is concerned with modelling and controller design for a discrete-time networked control system with limited channels and data drift. For the networked control system, available communication channels are usually limited. Moreover, the data received by the actuator may be different from the data sent by the controller and this phenomenon is referred to as data drift. By taking limited channels and data drift into account, a new model for the networked control system is established. Then a new Lyapunov functional is constructed to drive some stability criteria. Based on these stability criteria, a channel utilization-based switched controller is designed to asymptotically stabilize the networked system in the sense of mean-square. The proposed design method can enhance robustness of the networked control system to data drift and external disturbances. A numerical example is given to illustrate the effectiveness of the proposed controller design.
This paper considers the robust stability problem for a class of time-delay systems with norm-bounded, and possibly time-varying uncertainty. Based on the discretized Lyapunov functional approach, a stability criterion is derived. The time-delay is assumed constant and known. Numerical examples show that the results obtained by this new criterion significantly improve the estimate of the stability limit over some existing results in the literature.
In this paper, we present a novel iterative LMI approach to deal with the control problem for networked control systems (NCSs) with multiple packet dropouts. Two channel packet dropouts are simultaneously considered due to limited communication capacity. One is measurement channel packet dropout which is from the sensor to the controller. The other is control channel packet dropout which is from the controller to the actuator. The NCSs with both multiple measurement and control packet dropouts are first modeled as a stochastic parameter system which contains two independent Bernoulli distributed white sequences. A dynamic output controller is then designed to exponentially stabilize the networked system in the sense of mean square, and also achieve the prescribed H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> disturbance attenuation level. An iterative algorithm is developed to compute the optimal H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> disturbance attenuation and the controller parameters by solving the semi-definite programming problem via interior-point approach. Finally, two illustrative examples are provided to show the applicability of the proposed method.
The motion control of marine vehicles has attracted much attention from control community. This paper reviews the recent results on the motion control of marine vehicles. The approaches dealing with rudder roll stabilization, heading control, dynamic positioning, unmanned marine vehicles, underactuated marine vehicles, marine thruster control, and controller design for marine vehicles are reviewed.
This paper presents stability analysis of the time-delayed equivalent control based single input sliding mode control systems using an LMI approach. Conditions to guarantee the boundedness of the control system trajectories under the time-delayed equivalent control based sliding mode control are obtained. Maximum upper bound of the delay time to guarantee stability is estimated. Digital simulations are conducted to verify the theoretical results.
The sampled-data H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filtering for a Takagi-Sugeno (T-S) model-based fuzzy system with an interval time-varying state delay and a variable sampling period is considered. A new Lyapunov-Krasovskii functional is constructed by utilizing more information about the system's current state and the delayed state. Based on the new Lyapunov-Krasovskii functional and a novel inequality bounding technique, a suitable sampled-data fuzzy H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filter is designed to ensure the asymptotic stability and prescribed H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> attenuation level of the filter error system. A numerical example and a modified continuous stirred tank reactor (CSTR) system are given to illustrate the effectiveness of the proposed method.
