H_∞ Controller Design for Networked Control Systems via Active-varying Sampling Period Method

This paper studies the problem of designing H_∞controllers for networked control systems (NCSs) with both network-induced time delay and packet dropout by using an active-varying sampling period method,where the sampling pe- riod switches in a finite set.A novel linear estimation-based method is proposed to compensate packet dropout,and H_∞controller design is also presented by using the multi-objective optimization methodology.The simulation results illustrate the effectiveness of the active-varying sampling period method and the linear estimation-based packet dropout compensation.     

Stochastic optimal control of networked control systems with control packet dropouts

This paper considers the stochastic optimal control problem for networked control systems(NCSs)with control packet dropouts.The proportional plus up to the third-order derivative(PD3)compensation strategy is adopted to compensate for control packet dropouts at the actuator by using the past control packets stored in the buffer.Based on the strategy,a new NCS structure model with packet dropouts is provided,where the packet dropout is assumed to obey the Bernoulli random binary distribution.In terms of the given model,the stochastic optimal control law is proposed. Numerical examples illustrate the effectiveness of the results.     

不确定时滞模糊系统的鲁棒H∞网络控制

A robust H_∞networked control method for Takagi-Sugeno (T-S) fuzzy systems with uncertainty and time delay is presented.A state feedback controller is designed via the networked control system (NCS) theory.Sufficient condition for robust stability with H_∞performance is obtained.Network-induced delay in network transmission and packet dropout are analyzed. Simulation result shows the validity of this control scheme.     

Sensor/actuator faults detection for networked control systems via predictive control

Quantized fault detection for sensor/actuator faults of networked control systems (NCSs) with time delays both in the sensor-to-controller channel and controller-to-actuator channel is concerned in this paper. A fault model is set up based on the possible cases of sensor/actuator faults. Then, the model predictive control is used to compensate the time delay. When the sensors and actuators are healthy, an H ∞ stability criterion of the state predictive observer is obtained in terms of linear matrix inequality. A new threshold computational method that conforms to the actual situation is proposed. Then, the thresholds of the false alarm rate (FAR) and miss detection rate (MDR) are presented by using our proposed method, which are also compared with the ones given in the existing literatures. Finally, some numerical simulations are shown to demonstrate the effectiveness of the proposed method.     

H_∞ Control for 2-D Discrete State Delayed Systems in the Second FM Model

This paper is concerned with the problem of H_∞control for two-dimensional (2-D) discrete state delay systems described by the second Fornasini and Marchesini (FM) state- space model.A sufficient condition to have an H_∞noise atten- uation for this 2-D system is given in terms of a certain linear matrix inequality (LMI).The optimal H_∞controller is obtained by solving a convex optimization problem.Finally,a simulation example is given to illustrate the effectiveness of the proposed result.     

Controller design for networked control system with data packet dropout and transmission delays

In this paper, the stabilization problem for a class of networked control systems （NCSs） with data packet dropouts and transmission time delays is considered, where the delays are time-varying and uncertain, the data packet dropout is modeled as a two-state Markov chain. To compensate the lost packet, a data packet dropout compensator is established. Thus a more realistic model for such NCSs is presented. Sufficient conditions for the stabilization of the new resulting system are derived in the form of linear matrix inequalities （LMIs）. Numerical example illustrates the solvability and effectiveness of the results.     

Robust stabilization for a class of nonlinear networked control systems

The problem of robust stabilization for a class of uncertain networked control systems （NCSs） with nonlinearities satisfying a given sector condition is investigated in this paper. By introducing a new model of NCSs with parameter uncertainty, network-induced delay, nonlinearity and data packet dropout in the transmission, a strict linear matrix inequality （LMI） criterion is proposed for robust stabilization of the uncertain nonlinear NCSs based on the Lyapunov stability theory. The maximum allowable transfer interval （MATI） can be derived by solving the feasibility problem of the corresponding LMI. Some numerical examples are provided to demonstrate the applicability of the proposed algorithm.     

Fault-distribution-dependent reliable control for time-varying delay system

This paper considers the problem of reliable control for continuous-time systems with interval time-varying delay. By introducing a random matrix, a new practical actuator fault model is established. Using the Lyapunov-Krasovskii approach, a sufficient condition for the existence of reliable controller is expressed by a linear matrix inequality(LMI). An illustrative example is exploited to show the effectiveness of the proposed design procedures.     

Design of networked control systems with bounded arbitrary time delays

This paper is mainly concerned with the model predictive control (MPC) of networked control systems (NCSs) with uncertain time delay and data packets disorder. The network-induced time delay is described as bounded and arbitrary process. For the usual state feedback controller, by considering all the possibilities of delays, an augmented state space model of the closed-loop system, which characterizes all the delay cases, is obtained. The stability conditions are given according to the Lyapunov method based on this augmented model. The stability property is inherited in MPC which explicitly considers the physical constraints. A numerical example is given to demonstrate the effectiveness of the proposed MPC.     

Fault Accommodation for a Class of Nonlinear Uncertain Systems With Event-Triggered Input

The event-triggered fault accommodation problem for a class of nonlinear uncertain systems is considered in this paper.The control signal transmission from the controller to the system is determined by an event-triggering scheme with relative and constant triggering thresholds.Considering the event-induced control input error and system fault threat,a novel eventtriggered active fault accommodation scheme is designed,which consists of an event-triggered nominal controller for the time period before detecting the occurrence of faults and an adaptive approximation based event-triggered fault accommodation scheme for handling the unknown faults after detecting the occurrence of faults.The closed-loop stability and inter-event time of the proposed fault accommodation scheme are rigorously analyzed.Special cases for the fault accommodation design under constant triggering threshold are also derived.An example is employed to illustrate the effectiveness of the proposed fault accommodation scheme.     

A stabilizing model predictive control for networked control system with data packet dropout

A constrained model predictive control （MPC） algorithm for networked control system with data packet dropout is proposed in this paper. A buffer is designed to store the predicted control sequence between controller and actuator. It is shown that if the control horizon of MPC is not less than the number of data packets lost continuously, feasibility of MPC at initial time implies asymptotical stability of the closed-loop system. A simulation example illustrates the effectiveness of the proposed approach.     

Robust H∞ Networked Control for Uncertain Fuzzy Systems with Time-delay

A robust H∞ networked control method for Takagi-Sugeno （T-S） fuzzy systems with uncertainty and time delay is presented. A state feedback controller is designed via the networked control system （NCS） theory. Sufficient condition for robust stability with H∞ performance is obtained. Network-induced delay in network transmission and packet dropout are analyzed. Simulation result shows the validity of this control scheme.     

具有传输时延的网络控制系统故障估计与调节

In this paper, a method of fault estimation and fault tolerant control for networked control system (NCS) with transfer delay and process noise is presented. First, the networked control system is modeled as a multiple-input-multiple-output (MIMO) discrete-time system with transfer delays, process noise, and model uncertainties. Under this model and under some conditions, a fault estimation method is proposed to estimate the system faults. On the basis of the information on fault estimation and the sliding mode control theory, a fault tolerant controller is designed to recover the system performance. Finally, simulation results are used to verify the efficiency of the method.     

执行器故障的多模型自适应重构控制

In this paper, an active fault tolerant control strategy is developed to compensate for the effect of actuator fault in the presence of non-measurable rate on the actuator second-order dynamics. The proposed control scheme is a combination between multiple model and adaptive reconfiguration control. By means of the designed method, the system output can track that of the reference model asymptotically, and the simulation results have illustrated the effectiveness of the proposed algorithms.     

Modeling and control for wireless networked control system

In this paper, the stabilization problem is considered for the class of wireless networked control systems (WNCS). An indicator is introduced in the WNCS model. The packet drop sequences in the indicator are represented as states of a Markov chain. A new discrete Markov switching system model integrating 802.11 protocol and new scheduling approach for wireless networks with control systems are constructed. The variable controller can be obtained easily by solving the linear matrix inequality (LMI) with the use of the Matlab toolbox. Both the known and unknown dropout probabilities are considered. Finally, a simulation is given to show the feasibility of the proposed method.     

Decentralized load frequency control for two-area interconnected power system

This paper proposes a decentralized output feedback control scheme applied to two-area interconnected power system. The controller synthesis problem is formulated as the scaled H∞control problem and a new LMI-based algorithm is proposed to compute the decentralized controller. The proposed controller provides robustness with regard to parametric uncertainties and also attenuates bounded exogenous disturbances in the sense of L2-gain. Simulation results clearly show the effectiveness of developed decentralized output feedback control scheme.     

Asymptotic stability and disturbance attenuation properties for a class of networked control systems

In this paper, stability and disturbance attenuation issues for a class of Networked Control Systems (NCSs) under uncertain access delay and packet dropout effects are considered. Our aim is to find conditions on the delay and packet dropout rate, under which the system stability and H∞ disturbance attenuation properties are preserved to a desired level. The basic idea in this paper is to formulate such Networked Control System as a discrete-time switched system. Then the NCSs’ stability and performance problems can be reduced to the corresponding problems for switched systems, which have been studied for decades and for which a number of results are available in the literature. The techniques in this paper are based on recent progress in the discrete-time switched systems and piecewise Lyapunov functions.     

Adaptive RBF neural network control of robot with actuator nonlinearities

In this paper, an adaptive neural network control scheme for robot manipulators with actuator nonlinearities is presented. The control scheme consists of an adaptive neural network controller and an actuator nonlinearities compensator. Since the actuator nonlinearities are usually included in the robot driving motor, a compensator using radial basis function (RBF) network is proposed to estimate the actuator nonlinearities and eliminate their effects. Subsequently, an adaptive neural network controller that neither requires the evaluation of inverse dynamical model nor the time-consuming training process is given. In addition, GL matrix and its product operator are introduced to help prove the stability of the closed control system. Considering the adaptive neural network controller and the RBF network compensator as the whole control scheme, the closed-loop system is proved to be uniformly ultimately bounded (UUB). The whole scheme provides a general procedure to control the robot manipulators with actuator nonlinearities. Simulation results verify the effectiveness of the designed scheme and the theoretical discussion.     

Further control synthesis for time-delay systems with actuator saturation

This paper is concerned with the control synthesis problem for systems with time-varying delay and actuator saturation. A new controller design method is proposed in which auxiliary feedback matrix method is adopted to handle the saturation term in the system. The improvement of the proposed method lies in the application of delay partitioning idea to further enlarge the estimated domain of attraction. All the results are given in terms of linear matrix inequalities. Finally, a numerical example is provided to demonstrate the effectiveness and superiority of our obtained results.     

H2 /H∞ control of networked control system with random time delays

This paper investigates the H 2 /H ∞ control problem for a class of discrete-time networked control systems with random communication time delays. Both sensor-to-controller (S-C) and controller-to-actuator (C-A) random network-induced delays are considered. Two independent Markov chains are used to model the S-C and C-A random delays. The resulting closed-loop system is a jump linear time-delay system induced by two Markov chains. Sufficient conditions for existence of H 2 /H ∞ controller are established by free-weighting matrix and stochastic Lyapunov functions. A simulation example illustrates the effectiveness of the proposed method.