910 publications from this institution
This paper is concerned with the design problem of robust H∞ control for linear networked control systems (NCSs) with network-induced delay and data packet dropout.By choosing a new Lyapunov-Krasovskii functional, a sufficient condition on the existence of robust H∞ controller is derived in the form of a matrix inequality.No model transformation is needed and no redundant matrix variable is introduced.Then an iterative algorithm is introduced for obtaining the robust H∞ controller design method based on the matrix inequality.No parameter needs to be selected in advance.Two numerical examples are finally given to illustrate the effectiveness of the proposed algorithm.
This paper is concerned with the problem of event-triggered consensus for a nonlinear multiagent system. First, an integrated sampled-data-based event-triggered communication scheme is presented to decide when the current sampled-data should be broadcast. This scheme takes full advantage of both absolute and relative error-based event-triggered transmission schemes, and thus leading to a high efficiency of data transmissions. Second, a state-error-dependent delay system is delicately developed to model the multiagent system under the proposed sampled-data-based event-triggered consensus protocol. By virtue of the Lyapunov-Krasovskii functional method, a stability criterion and sufficient conditions on the existence of the consensus protocol and transmission scheme are derived to ensure that the solution of the state error dependent delay system is uniformly ultimately bounded. Finally, two illustrative examples are employed to show the validity and advantage of the proposed transmission scheme and consensus protocol.
This paper investigates the problem of fault-tolerant consensus control (FTCC) for heterogeneous nonlinear fractional-order multi-agent systems with general directed topology, where the systems are subject to heterogeneous unknown and time-varying inertias, coupling nonlinearities, external disturbances, and actuator failures. A continuous robust adaptive FTCC protocol is designed by using a boundary layer technique to compensate for the time-varying unknown inertias, uncertain coupling dynamics/disturbances, and unpredictable actuation failures simultaneously. By artfully choosing a Lyapunov function and by generalizing an important fractional-order inequality, it is shown that the consensus configuration error converges to an adjustable small residual set in finite time. The proposed robust adaptive FTCC protocol is completely distributed in the sense that there is no need for any global information, and also is less demanding without requiring any detailed dynamic/parameters information or complicated/costly fault detection and diagnosis. The effectiveness of the proposed FTCC scheme is illustrated by numerical simulation.
This paper investigates the stability of linear uncertain systems with time-varying delay. Criteria for guaranteed asymptotic stability are derived based on a discretized Lyapunov functional approach. Our results are the generalizations of results reported in Gu (1997) to the case with a time-varying delay. Numerical examples are also included to show the effectiveness of the method.
A guaranteed cost fuzzy control for a class of nonlinear time-delay systems has been reported. The time-delay is assumed to be a time-varying continuous function belonging to a given interval, which means that the lower and upper bounds of the time-varying delay are available. And no restriction on the derivative of the time-varying delay is needed, which allows the time-delay to be a fast time-varying function. The nonlinear time-delay systems are approximated by uncertain Takagi–Sugeno (T–S) fuzzy models with interval time-varying delay. Delay-dependent sufficient conditions on the existence of a guaranteed cost fuzzy controller are derived in terms of matrix inequalities. No model transformation is needed and no slack matrix variable is introduced. A non-convex minimisation problem is formulated for finding the least upper bound of guaranteed cost function under matrix inequality constraints. In order to solve this non-convex minimisation problem, a linearisation iterative algorithm is provided to design a controller achieving a suboptimal guaranteed cost for the considered systems. No parameter needs to be selected in advance. A numerical example is also given to show the effectiveness of the proposed design method.
This brief is concerned with stability for a partial element equivalent circuit model of neutral type. First, the relationship between two recently established integral inequalities is presented. Second, a new Lyapunov-Krasovskii functional is introduced based on the fact that the delay interval is nonuniformly divided into multiple subintervals, and different functionals are chosen on different subintervals. Then, some new delay-dependent criteria are derived. Finally, a numerical example is given to show that the results obtained by the new stability criteria can significantly improve some existing results.
In this chapter, delay distribution-dependent modeling and discrete event-triggered communication (ETC) scheme are introduced for NCSs studied in this book. The main idea of delay distribution-dependent modeling is to use the nonuniform distribution character of...
In this chapter, a self-triggered sampling scheme for an NCS is proposed by considering network-induced delays and data dropouts simultaneously.
This paper deals with the finite-horizon quantized H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> state estimation problem for a class of discrete timevarying genetic regulatory networks with quantization effects under stochastic communication protocols (SCPs). To better reflect the data-driven flavor of today's biological research, the network measurements (typically gigabytes in size by highthroughput sequencing technologies) are transmitted to a remote state estimator via two independent communication networks of limited bandwidths. To lighten the communication loads and avoid undesired data collisions, the measurement outputs are quantized and then transmitted under two SCPs introduced to schedule the large-scale data transmissions. The purpose of this paper is to design a time-varying state estimator such that the error dynamics of the state estimation satisfies a prescribed H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> performance requirement over a finite horizon in the presence of nonlinearities, quantization effects, and SCPs. By utilizing the completing-the-square technique, sufficient conditions are derived to ensure the H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> estimation performance and the parameters of the state estimator are designed by solving coupled backward recursive Riccati difference equations. A numerical example is given to illustrate the effectiveness of the design scheme of the proposed state estimator.
This article is concerned with master–slave synchronization for two chaotic Hindmarsh–Rose neurons. The main contribution of this article is that three synchronization criteria are derived by using linear feedback control without the estimation of bounds of state variables of controlled slave neurons. Three simulation examples are used to illustrate the effectiveness of our results. © 2015 Wiley Periodicals, Inc. Complexity 21: 319–327, 2016
Networked control systems are spatially distributed systems in which the communication between sensors, actuators, and controllers occurs through a shared band-limited digital communication network. Several advantages of the network architectures include reduced system wiring, plug and play devices, increased system agility, and ease of system diagnosis and maintenance. Consequently, networked control is the current trend for industrial automation and has ever-increasing applications in a wide range of areas, such as smart grids, manufacturing systems, process control, automobiles, automated highway systems, and unmanned aerial vehicles. The modelling, analysis, and control of networked control systems have received considerable attention in the last two decades. The ' control over networks ' is one of the key research directions for networked control systems. This paper aims at presenting a survey of trends and techniques in networked control systems from the perspective of ' control over networks ' , providing a snapshot of five control issues: sampled-data control, quantization control, networked control, event-triggered control, and security control. Some challenging issues are suggested to direct the future research.
The main purpose of this article is to investigate the consensus of linear multiagent networks with time-varying characteristics under sampled-data communications, where the time-varying characteristics include both time-varying topologies and the node's linear time-varying dynamics. By using the decoupling method, we prove that the sampled-data consensus problem of multiagent networks is equal to the stability problem of sampled-data systems. Then, the globally asymptotical consensus is investigated for multiagent networks with time-varying characteristics by virtue of the Lyapunov function method. It should be noted that when the Lyapunov function method is utilized to investigate the stability problem of control systems, it is always assumed that the derivative of the constructed Lyapunov function is not more than zero. This assumption is removed here and as a replacement, the average value of the derivative of the Lyapunov function in a period to be negative is needed.
Optimal chiller loading is crucial to reduce energy consumption in chiller operation planning. In existing methods for planning with heterogeneous chillers, minimum-up/down-time constraints are not imposed. This paper addresses receding-horizon chiller operation planning via collaborative neurodynamic optimization. A mixed-integer optimization problem with minimum-up/down-time constraints is formulated for receding-horizon chiller loading with heterogeneous chillers. It is then decomposed into a binary optimization subproblem and a global optimization subproblem, to facilitate the planning process. A neurodynamics-driven algorithm is proposed based on paired discrete Hopfield networks and projection neural networks to solve the subproblems alternatingly and iteratively. Experimental results based on the specifications of two chiller systems are elaborated to substantiate the efficacy of the proposed method.
Railways around the world are facing ever-increasing demands from booming passenger and freight transportation. Constructing new railways is not always possible due to the high cost and the lack of space. Virtual coupling (VC), which allows multiple trains to run cooperatively and closely on the same track, thus stands out as a major technological enabler for improving the existing railway network capacity and operation flexibility. This, however, relies on a feasible longitudinal spacing controller for each train such that the entire virtually coupled train convoy can function smoothly, safely, and efficiently. The design of such a spacing controller is intrinsically challenging as the train-to-train (T2T) communications, the primary enabling component for VC, may be interrupted by malicious cyber attacks. This paper addresses a resilient VC control problem for multiple automatic trains subject to intermittent T2T communications. First, an intermittent data transmission paradigm is presented to account for the effects of attack-incurred sporadic T2T communications. Then, a resilient distributed longitudinal spacing control method is developed to preserve the desired stability of the resultant train control system, while simultaneously guaranteeing attack resilience as well as driving safety and comfort requirements for the train convoy. It is shown that the proposed method is also effective in empowering a better trade-off analysis between traffic efficiency and safety than some traditional methods. Finally, based on the data of a realistic urban rail transit line, numerical case studies are provided to substantiate the efficacy of the proposed method.
This paper addresses the problem of two-target tracking over a heterogenous sensor network under deception attacks. To track the corresponding targets, the spatially distributed sensors are classified into two groups, and the sensors in each group are capable of exchanging measurement information only with their neighboring sensors in accordance with some prescribed interaction topologies. In the presence of deception attacks, the measurement received by each sensor suffers deliberate modification and thus the tracking performance of the two targets may be degraded or even disrupted. First, a heterogenous distributed estimation scheme based on the two distinct groups of sensors is developed to deal with the simultaneous effects of the unknown but bounded process noises as well as the physically constrained deception attacks. Second, criteria for designing the desired distributed estimators and the weights of interacting information links among the inter- and intra-group sensors are derived. It is shown that the true states of the two moving targets are guaranteed to be enclosed by two groups of estimate ellipsoidal sets at each time step regardless of process noises and deception attacks. Third, an optimization problem is proposed to minimize the obtained ellipsoids, aiming to provide optimal tracking performance. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed target tracking method.
This paper is concerned with non-fragile H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</inf> control for offshore steel jacket platforms subject to self-excited nonlinear wave force and external disturbances. A delayed non-fragile H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</inf> controller is designed to attenuate the oscillation amplitudes of the offshore platform. The positive effects of the time-delays on non-fragile H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</inf> control for the offshore platform are investigated. It is shown through simulation results that (i) the proposed non-fragile H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</inf> controller is effective to reduce the vibration of the offshore platform; (ii) the control force required by the delayed non-fragile H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</inf> controller is smaller than the one by the delay-free non-fragile H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</inf> controller; and (iii) the allowable maximum time-delay under the delayed non-fragile H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</inf> controller is much larger than the one under the delayed dynamic output feedback controller.
This paper is concerned with consensus of a second-order linear time-invariant multi-agent system in the situation that there exists a communication delay among
This article addresses the problem of dynamic event-triggered platooning control of automated vehicles over a vehicular ad-hoc network (VANET) subject to random vehicle-to-vehicle communication topologies. First, a novel dynamic event-triggered mechanism is developed to determine whether or not the sampled data packets of each vehicle should be released into the VANET for intervehicle cooperation. More specifically, the threshold parameter in the triggering condition is dynamically adjusted over time according to the vehicular data variations, the dynamic threshold updating laws, and the bandwidth occupancy indication. Second, a unified platooning control framework is established to account for various spacing policies, randomly switching communication topologies, unknown leader control input, and external disturbances. Then, a new scheduling and platooning control co-design approach is presented such that the controlled vehicular platoon can successfully track the leader vehicle under random communication topologies and different spacing policies, including constant spacing, constant time headway spacing, and variable time headway spacing, meanwhile maintaining efficient bandwidth-aware resource management. Finally, comparative studies are provided to substantiate the effectiveness and merits of the proposed co-design approach.
This paper is concerned with the secure event-triggered distributed cooperative longitudinal control problem of virtually coupled high-speed trains (VCHSTs) subject to DoS attacks. First, a DoS-aware dynamic event-triggered transmission mechanism (DETM) is proposed to reduce the frequency of train data transmissions over train-to-train (T2T) information flow channels. Via actively prolonging the inter-event times, the resilience of the developed DETM to DoS attacks can be greatly improved. Second, based on the intermittently arrived T2T data, a distributed event-based secure cooperative control protocol is proposed for each train in the convoy. Third, a sufficient condition is derived to guarantee the asymptotic stability of the train tracking error system under the prescribed H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</inf> performance. Furthermore, a co-design method for solving out the desired train controllers and the triggering conditions is developed. Finally, the efficacy of the derived theoretical results is verified through a case study of a realistic railway line.
