Showing papers by "Hamid Reza Karimi published in 2019"

Asynchronous Finite-Time Filtering of Networked Switched Systems and its Application: an Event-Driven Method

Abstract: To effectively use the network resources, a suitable event-driven communication scheme is proposed for the networked switched systems in this paper. Under the EDCS, a finite-time filter is designed for switched systems, which does not synchronize with the switched systems. Different from the existing finite-time problems, finite-time boundedness (FTBs) and input–output finite-time stability (IO-FTSy) are simultaneously considered in this paper. Some sufficient conditions are established to check the properties of the FTBs and the IO-FTSy of the event-driven asynchronous filtering error system by constructing a reasonable Lyapunov–Krasovskii functional and using the average dwell time approach. All the matrix inequalities can be converted to linear matrix inequalities so as to design the event-driven asynchronous filter. The applicability of the proposed filtering scheme is demonstrated via a mass-spring system model.

Accurate Trajectory Tracking of Disturbed Surface Vehicles: A Finite-Time Control Approach

Abstract: In this paper, accurate trajectory tracking problem of a surface vehicle disturbed by complex marine environments is solved by creating a finite-time control (FTC) scheme whereby the nonsingular fast terminal sliding mode (NFTSM) and finite-time disturbance observer (FDO) techniques are deployed. Salient features are as follows. By devising an FDO, complex disturbances arising from marine environments can be exactly identified within a short time, in conjunction with the defined NFTSM manifold, and thereby contributing to exact trajectory tracking. Finite-time disturbance observation is completely decoupled from the nominal FTC scheme, and achieves stronger disturbance rejection and faster transient response, simultaneously. Both disturbance observation and trajectory tracking errors can exactly reach to zero in a finite time. Simulation results and comparisons are comprehensively conducted on CyberShip II and demonstrate remarkable superiority of the FTC scheme.

Fuzzy-Model-Based Sliding Mode Control of Nonlinear Descriptor Systems

Abstract: This paper addresses the problem of sliding mode control (SMC) for a type of uncertain time-delay nonlinear descriptor systems represented by T–S fuzzy models. One crucial contributing factor is to put forward a novel integral fuzzy switching manifold involved with time delay. Compared with previous results, the key benefit of the new manifold is that the input matrices via different subsystems are permitted to be diverse, and thus much more applicability will be achieved. By resorting to Frobenius’ theorem and double orthogonal complement, the existence condition of the fuzzy manifold is presented. The admissibility conditions of sliding motion with a strictly dissipative performance are further provided. Then, the desired fuzzy SMC controller is synthesized by analyzing the reachability of the manifold. Moreover, an adaptive fuzzy SMC controller is also proposed to adapt the input saturation and the matched uncertainty with unknown upper bounds. The feasibility and virtue of our theoretical findings are demonstrated by a fuzzy SMC controller implementation for a practical system about the pendulum.

An Event-Based Asynchronous Approach to Markov Jump Systems With Hidden Mode Detections and Missing Measurements

Abstract: This paper is concerned with event-based $ {\mathcal {H}}_{ {\infty }}$ control for a class of networked Markov jump systems (MJSs) with missing measurements. The phenomenon of asynchronism occurs in both the controller and the actuator-failure model, which is estimated by the hidden Markov model, is taken into consideration. In addition, to reduce the burden of data transmission, a mode-dependent event-triggered mechanism (ETM) is proposed. Together with ETM, a network-induced delay is introduced. Subsequently, to guarantee that the MJS is stochastically stable, an event-based asynchronous controller is designed. Finally, to reveal the effectiveness of the proposed method, a simulation example of pulse width-modulation-driven boost converter is considered.

Some Improved Razumikhin Stability Criteria for Impulsive Stochastic Delay Differential Systems

Abstract: This paper is devoted to study the Razumikhin stability theorem for a class of impulsive stochastic delay differential systems. By developing a new lemma, stochastic analysis technique, and Razumikhin approach, several novel criteria of the $p$ th moment exponential stability are derived for the related systems. The key feature of the criteria is that time-derivatives of the Razumikhin functions are allowed to be indefinite, which loosens the constraints of the existing results greatly. Finally, two examples are given to illustrate the usefulness and significance of the theoretical results.

$\mathscr {L}_\infty$ Control for Positive Delay Systems With Semi-Markov Process and Application to a Communication Network Model

Abstract: This paper deals with the problem of $\mathscr {L}_\infty$ control for positive delay systems with semi-Markov process. The system is subjected to a semi-Markov process that is time-varying, dependent on the sojourn time, and related to Weibull distribution. The main motivation for this paper is that the practical systems such as the communication network model (CNM) described by positive semi-Markov jump systems (S-MJSs) always need to consider the sudden change in the operating process. To deal with the corresponding problem, some criteria about stochastic stability and $\mathscr {L}_\infty$ boundedness are presented for the open-loop positive S-MJSs. Further, some necessary and sufficient conditions for state-feedback controller satisfying $\mathscr {L}_\infty$ boundedness and positivity of the resulting closed-loop system is established in standard linear programming. Finally, the practical system about the CNM is given to verify the validity of the proposed method.

$H_{\infty}$ Output Tracking Control for Networked Systems With Adaptively Adjusted Event-Triggered Scheme

Abstract: The $\boldsymbol {H_{\infty }}$ output tracking control problem of the networked control systems (NCSs) under an adaptively adjusted event-triggered scheme is investigated in this paper. Firstly, a novel adaptively adjusted event-triggered scheme developed in the NCSs with stochastic sensor faults is proposed to choose the necessary packets of sampled data to be transmitted through the networks. Then, the considered system is described as a time-delay system with a delay-distribution for investigation. Based on the established model, a novel stability criterion and the state-feedback controller design with a desired performance of $\boldsymbol {H_{\infty }}$ output tracking control for the systems are both derived by using Lyapunov functional. An algorithm is also presented to explain the process of adaptively adjusted event-triggered scheme method. Finally, a satellite tracking case is provided to demonstrate the effectiveness of the proposed approach.

Asynchronous Control of Continuous-Time Nonlinear Markov Jump Systems Subject to Strict Dissipativity

Abstract: This paper addresses the strictly dissipative control problem for continuous-time nonlinear Markov jump systems via Takagi–Sugeno fuzzy rules. The modes of a devised fuzzy controller are assumed to run asynchronously with the modes of original system, which is widespread in practice and described through a hidden Markov model. A sufficient condition is acquired to ensure the stochastic stability and strict dissipativity of the closed-loop systems, based on which the design method of an asynchronous fuzzy controller is provided. Finally, one example is presented to illustrate the effectiveness and new features of the proposed design techniques.

Takagi–Sugeno Model-Based Sliding Mode Observer Design for Finite-Time Synthesis of Semi-Markovian Jump Systems

Abstract: This paper is concerned with finite-time sliding mode control (SMC) of continuous-time semi-Markovian jump systems with immeasurable premise variables via fuzzy approach. First, an integral sliding surface is constructed based on fuzzy observer. Second, an observer-based SMC law is synthesized to guarantee finite-time reachability of the predefined sliding surface before the prescribed time. Third, through finite-time boundedness analysis, the required boundedness performance is conducted at the reaching phase first and then the sliding motion phase, respectively. Furthermore, sufficient conditions in terms of linear matrix inequalities (LMIs) are established to guarantee the required boundedness performance of the overall closed-loop controlled system during the two phases with generally uncertain transition rates (TRs) simultaneously. Finally, a practical example is given to show the validity of the established method numerically.

Asymptotic Tracking Control for a More Representative Class of Uncertain Nonlinear Systems With Mismatched Uncertainties

Abstract: This paper is mainly focusing on the problem of high-accuracy tracking control design for a class of nonlinear systems subject to mismatched uncertainties. A novel asymptotic control framework is presented. This is achieved by developing an estimator-based controller with an observer-based estimator, which is applied to precisely estimate all the system uncertainties. It is proved that the overall tracking system can be asymptotically stabilized. The estimation error of the system uncertainties is also ensured to be asymptotically stable. The main contribution of this paper is that the proposed solution can control a more representative class of nonlinear systems. Another key feature of this control framework is that the incorporated observer-based estimator can eliminate the assumption that system uncertainties should vary slowly or even have no variation in the existing estimators for uncertainties. This superior tracking control property of the scheme is validated by a robotic manipulator example.

Observer-Based Adaptive Consensus for a Class of Nonlinear Multiagent Systems

Abstract: This paper investigates an adaptive consensus problem of a class of nonlinear multiagent systems in which the states are unmeasurable and the dynamics of all agents are supposed to be in strict-feedback form with unknown time-varying control coefficients. Due to the presence of uncertain nonlinearities in agents’ dynamics, radial basis function neural networks are used to approximate the unknown nonlinear functions, and a neural-network-based observer is designed to estimate the unmeasured states. The adaptive observer-based protocols are based on the relative output information of neighbors, and are constructed by adopting the dynamic surface control technique. It is proved that practical consensus of the system can be achieved with the proposed protocols. A simulation example is given to show the effectiveness of the proposed method.

Exponential Stability, Passivity, and Dissipativity Analysis of Generalized Neural Networks With Mixed Time-Varying Delays

Abstract: In this paper, we analyze the exponential stability, passivity, and $\boldsymbol {(\mathfrak {Q},\mathfrak {S},\mathfrak {R})}$ - $\boldsymbol {\gamma }$ -dissipativity of generalized neural networks (GNNs) including mixed time-varying delays in state vectors. Novel exponential stability, passivity, and $\boldsymbol {(\mathfrak {Q},\mathfrak {S},\mathfrak {R})}$ - $\boldsymbol {\gamma }$ -dissipativity criteria are developed in the form of linear matrix inequalities for continuous-time GNNs by constructing an appropriate Lyapunov-Krasovskii functional (LKF) and applying a new weighted integral inequality for handling integral terms in the time derivative of the established LKF for both single and double integrals. Some special cases are also discussed. The superiority of employing the method presented in this paper over some existing methods is verified by numerical examples.

Conditions for the Stability of Switched Systems Containing Unstable Subsystems

Abstract: This brief studies the stability of switched systems in which all the subsystems may be unstable. In addition, some of the switching behaviors of the systems are destabilizing. By using the piecewise Lyapunov function method and taking a tradeoff between the increasing scale and the decreasing scale of the Lyapunov function at switching times, the maximum dwell time for admissible switching signals is obtained and the extended stability results for switched systems in a nonlinear setting are first derived. Then, based on the discretized Lyapunov function method, the switching stabilization problem for linear context is solved. By contrasting with the contributions available in the literature, we do not require that all the switching behaviors of the switching system under consideration are stabilizing. More specifically, even if all the subsystems governing the continuous dynamics are not stable and some of the switching behaviors are destabilizing, the stability of the switched system can still be retained. A numerical example is given to illustrate the validity of the proposed results.

An Adaptive Event-Triggered Synchronization Approach for Chaotic Lur’e Systems Subject to Aperiodic Sampled Data

Abstract: This brief deals with the problem of master–slave synchronization for chaotic Lur’e systems with aperiodic sampled data. Specifically, a novel aperiodic adaptive event-triggered communication mechanism is introduced to reduce the transmission load, which covers the previous ones as special cases. By partially resorting to the time-dependent Lyapunov function, a new synchronization criterion is derived, which depends on both the upper and lower bounds of variable sampling interval. Finally, Chua’s circuit system is chosen as an illustrative example to show the virtue and effectiveness of the achieved synchronization strategies.

Observer-Based Fuzzy Adaptive Dynamic Surface Control of Uncertain Nonstrict Feedback Systems With Unknown Control Direction and Unknown Dead-Zone

Abstract: In this paper, an observer-based fuzzy adaptive controller for a class of uncertain nonstrict nonlinear systems with unknown control direction and unknown dead-zone is presented. First, by using equivalence dead-zone inverse and a linear state transformation, the original system is converted to a new one. Then, by using fuzzy logic systems, the unknown nonlinearities are approximated based on an adaptive mechanism, and a nonlinear fuzzy state observer is designed to estimate immeasurable states. The dynamic surface control technique is employed to solve the problem of explosion of complexity in the traditional backstepping approach, and then, this method is combined with Nussbaum gain function to address the problem of unknown control direction. Besides, barrier Lyapunov function is employed to overcome the violation of system output. The proposed controller guarantees that the closed-loop system is stable; all the system states are bounded, and tracking errors converge to a neighborhood of the origin. A numerical simulation is provided to confirm the usefulness of the proposed control design.

A data-driven ground fault detection and isolation method for main circuit in railway electrical traction system.

Abstract: Due to the complex and harsh operation conditions, like corrosion, aging cable and static electricity, of electrical traction drive system, ground fault will generate large short circuit current to harm the key components. Effective fault diagnosis is important, but also challenging. The conventional method used for ground fault detection only takes advantage of voltage measurements of DC-link. Other measurements onboard are also available, which are correlated with the voltage measurements. Taking the correlation into account will improve the detection performance. To this end, this paper presents a data-driven solution, which makes full use of the correlation between the voltage measurements with other measurements onboard. The proposed method consists of two components: (1) a canonical correlation analysis-based fault detection method, which takes into account the correlation within measurements; (2) a fault isolation method by means of the fault direction, which can be obtained with the available faulty data stored in the long-term operation. The developed method is applied to a traction drive system. It is shown that the proposed approach is able to improve the fault detection and isolation performance significantly with respect to three performance indicators, namely fault detection rate, detection delay and correct isolation rate, in comparison with the conventional method, which only uses the voltage measurements of DC-link.

Finite-Time Passivity-Based Stability Criteria for Delayed Discrete-Time Neural Networks via New Weighted Summation Inequalities

Abstract: In this paper, we study the problem of finite-time stability and passivity criteria for discrete-time neural networks (DNNs) with variable delays. The main objective is how to effectively evaluate the finite-time passivity conditions for NNs. To achieve this, some new weighted summation inequalities are proposed for application to a finite-sum term appearing in the forward difference of a novel Lyapunov–Krasovskii functional, which helps to ensure that the considered delayed DNN is passive. The derived passivity criteria are presented in terms of linear matrix inequalities. A numerical example is given to illustrate the effectiveness of the proposed results.

Observer-Based Sliding Mode Control for T–S Fuzzy Descriptor Systems With Time Delay

Abstract: This paper examines the problem of observer-based sliding mode control designs for a class of descriptor Takagi–Sugeno fuzzy systems with time delay and uncertainties. Specifically, based on the detailed discussions on the existence conditions, a reduced-order robust observer is designed first where the influences of the uncertainties are totally removed. Second, by choosing appropriate coordinate transformations and matrix decompositions, an actual and a virtual sliding mode variables are constructed, and an observer-based sliding mode controller is developed to handle the uncertainties such that the virtual sliding mode surface can be reached and maintained in a finite time, whereas the actual sliding mode variable approaches to zeros asymptotically. And then, we prove that the system asymptotic stability can be guaranteed after the virtual sliding mode surface has been reached or the actual sliding mode variable approached to zero. In addition, the existence conditions for both the observer and the sliding mode controller are given in strict linear matrix inequality forms. Finally, a simulation example is given to demonstrate the effectiveness of the proposed method.

Design of inerter-based multi-actuator systems for vibration control of adjacent structures

Abstract: Distributed multi-actuator systems can provide effective solutions for mitigating the vibrational response of large structures. In this paper, we present a computational strategy to design inerter-based multi-actuation systems for the seismic protection of adjacent structures. The proposed approach allows considering both interstory and interbuilding Tuned Mass-Inerter Damper (TMID) actuators, and aims at simultaneously reducing the vibrational response of the individual buildings and avoiding the interbuilding impacts. The tuning procedure is based on an H∞ cost-function and uses a constrained global-optimization solver to compute parameter configurations with high-performance characteristics. To illustrate the main features of this work, two different Tuned Inerter Damper (TID) multi-actuator schemes are considered for the seismic protection of a particular multi-story two-building system. A multi-actuator Tuned Mass Damper (TMD) system is also designed and is taken as a reference in the performance assessment. The obtained results demonstrate the flexibility and effectiveness of the proposed design methodology, and clearly show the superior performance and robustness of the TID actuation systems.

Output Tracking Control for Fractional-Order Positive Switched Systems With Input Time Delay

Abstract: The objective of this brief is to focus on the problem of output tracking control for a class of fractional-order positive switched systems via an observer-based controller method that combines equivalent-input-disturbance approach and Smith predictor. By employing Lyapunov theory together with average dwell-time approach, a new exponential stability criterion is derived in terms of linear matrix inequalities for the resulting closed-loop system. Based on the derived delay-dependent criterion, a design method of the proposed controller is then presented. The designed controller can assure that the output signals of the system trace the specified reference signals within the preferred neighborhood of the equilibrium. Furthermore, the solvability inclusive conditions for the proposed controller design of the considered system are established according to the state being available or not. Numerical simulation results are provided to demonstrate the strong disturbance rejection capability and the superiority of the proposed control design method over some existing ones.

A Uniform Modeling Method Based on Open-Circuit Faults Analysis for NPC-Three-Level Converter

Abstract: A uniform modeling method for the neutral point clamped (NPC)-three-level converter is proposed based on open-circuit faults analysis The main contributions of this brief are twofold One is the proposed model can represent the converter not only in the normal condition but also the abnormal conditions that open-circuit faults occurring in any insulated gate bipolar transistors The other is the model can be used for real-time simulation purposes First, the NPC-three-level converter is simplified to a switch equivalent circuit by introducing the switch functions Second, when the open-circuit faults occur, current paths of the NPC-three-level converter are analyzed and the values of switch functions with the open-circuit faults in the converter are acquired The values of the switch functions in normal condition are obtained as well Then, the uniform model of NPC-three-level converter is established, which integrates rectifier, inverter, and DC-link models The uniform model can represent the converter in normal condition as well as in open-circuit fault conditions The effectiveness and accuracy of the proposed model have been verified by simulation and experiment results