Stability of networked control systems with multi-step delay based on time-division algorithm

1IntroductionFeedback control systems in which the control loops areclosed through a real_time network are called networkedcontrol systems(NCS)[1,2].Conventional controltheories should be reevaluated before they are applied toNCS because of the existence of sensor_to_controller delayτscand controller_to_actuator delayτca.They may degradethe performance of control systemand even destabilize thesystem.There are two kinds of design methods for NCS:deterministic design methods and stochastic…     

Survey on the stability of networked control systems

The insertion of the communication network in the feedback control loop makes the analysis and design of a network control system more complex, and induces some issues that degrade the control system’s performance and even cause system instability. The main aspects are focused on the stability analysis of Network Control Systems (NCSs) with network-induced delays, data packet dropouts, and multiple-packet transmission. These issues must be considered in the design of an NCS. This work summarizes the main research results, and remarks on some related handling approaches and techniques. The main purpose of the survey is to present the new research state of NCSs and to point out some fields of future work.     

Quantized H ∞ fault-tolerant control for networked control systems

Quantized H_∞ fault-tolerant control for networked control systems (NCSs) with partial actuator fault with respect to actuators is concerned in this paper. Considering transmission delay, packet dropout and quantization, a synthesis model with partial actuator fault is established. The piecewise constant controller is adopted to model NCS with the transmission delay and packet dropout. Due to data transmitted in practical NCSs should be quantized before they are sent to the next network node, the logarithmic static and time-invariant quantizers at the sensor and controller sides are proposed in the paper. For the established model, an appropriate type of Lyapunov functions is provided to investigate the delay-dependent H_∞ control problem. According to an optimal problem, the controller that makes the system achieve the best performance is designed. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed approach.     

Kalman filter based fault diagnosis of networked control system with white noise

The networked control system NCS is regarded as a sampled control system with output time-variant delay. White noise is considered in the model construction of NCS. By using the Kalman filter theory to compute the filter parameters, a Kalman filter is constructed for this NCS.By comparing the output of the filter and the practical system,a residual is generated to diagnose the sensor faults and the actuator faults. Finally, an example is given to show the feasibility of the approach.     

Exponential stabilization of networked control systems and design of switching controller

1 Introduction Networked control systems (NCS) are feedback control systems whose feedback paths are implemented by a real- time network. This type of systems has advantages of more ?exibility with respect to traditional control systems. It also allows for reduced wiring, as well as a lower installation cost. Examples of such systems can be seen in remote sur- vey [1], telerobotics [2], unmanned aerial vehicles [3] and remote control laboratory [4,5]. Most of the times, sensors will transmit…     

一类具有状态反馈NCS的H∞优化控制

研究一类网络控制系统(NCS)的H∞优化控制问题.状态反馈是兼顾系统性能和敏感性的最有效的控制方式,因此,针对一类不确定时延和有限能量干扰输入的状态反馈NCS,将其建模为不确定的线性时滞系统,并利用Lyapunov理论和线性矩阵不等式(LMI)研究H∞优化控制问题.首先给出NCS的鲁棒稳定的充分条件;然后给出NCS状态反馈次优和最优H;∞控制律的设计方法.仿真结果表明了该方法的可行性和有效性.

Abstract：

The H∞ optimal control problems of a class of networked control systems(NCS) is studied. The statefeedback is the most effective control mode, which combines system function and sensibility. Therefore, a class of state-feedback NCS with uncertain time-delay and limited energy disturbance input is modeled as the uncertain linear time-delay system. Then by using the Lyapunov theory and LMI, the problems about the H∞ optimal control are researched. The sufficient condition is first given for the robust stability of networked control system, and then the design methods of NCS state-feedback suboptimum and optimum H∞ control laws are obtained consequently. The simulation results show the feasibility and effectiveness of the results.     

具有通信约束的网络化控制系统容错控制研究

Implementing a control system over a communication network induces inevitable time delays that may degrade performance and even cause instability. One of the most effective ways to reduce the negative effect of delays on the performance of networked control system (NCS) is to reduce network traffic. In this paper, adjustable deadbands are explored as a solution to reduce network traffic in NCS. A method of fault-tolerant control of networked control system is presented, which takes into account system response as well as network traffic. The integrity design for a kind of NCS with sensor failures and actuator failures is analyzed based on robust fault-tolerant control theory and information scheduling. After detailed theoretical analysis, the paper also provides the simulation results, which further validate the proposed scheme.     

Secure design for cloud control system against distributed denial of service attack

Nowadays, the development of cloud computing has given power to the resource constrained network control system (NCS) to out source heavy computations to the cloud server. However, the development of Cloud Computing produced many security challenges regarding the cyber physical connection between the cloud and control system. The connection between the control system and cloud server can be subjected to distributed denial of service (DDoS) attack by an attacker to destabilize the NCS. In this paper, we will address this issue by building a secure mechanism for such systems. We will design a detection approach and a mitigation approach for better stable performance of NCS. To ensure the stability of NCS at the time of DDoS attack, we will also design a switching mechanism (SM) for cloud control system (CCS) when there are no more real time solutions available from the cloud. Finally, we will apply the proposed mechanism to an unmanned arial vehicle (UAV). Our simulation results show that the mechanism works well in stability and protection of NCS under DDoS attack.     

Primary exploration of nonlinear information fusion control theory

By introducing information fusion techniques into a control field, a new theory of information fusion control (IFC) is proposed. Based on the theory of information fusion estimation, optimal control of nonlinear discrete control system is investigated. All information on control strategy, including ideal control strategy, expected object trajectory and dynamics of system, are regarded as measuring information of control strategy. Therefore, the problem of optimal control is transferred into the one of information fusion estimation. Firstly, the nonlinear information fusion estimation theorems are described. Secondly, an algorithm of nonlinear IFC theory is detailedly deduced. Finally, the simulation results of manipulator shift control are given, which show the feasibility and effectiveness of the presented algorithm.     

Decentralized Networked Control System Design Using Takagi-Sugeno (TS) Fuzzy Approach

This paper proposes a new method for control of continuous large-scale systems where the measures and control functions are distributed on calculating members which can be shared with other applications and connected to digital network communications.At first, the nonlinear large-scale system is described by a Takagi-Sugeno(TS) fuzzy model. After that, by using a fuzzy LyapunovKrasovskii functional, sufficient conditions of asymptotic stability of the behavior of the decentralized networked control system(DNCS),are developed in terms of linear matrix inequalities(LMIs). Finally, to illustrate the proposed approach, a numerical example and simulation results are presented.     

H-infinity control for networked control systems (NCS) with time-varying delays

This paper discusses H-infin it y state feedback control for a networked control system with time-varying delays.Based on the free-weighing matri x method,a delay-dependent stability criterion satisfying a prescribed H-infini ty norm bound is presented for an NCS with unknown,time-varying and bounded del ays.And then,the criterion is transformed into suffici ent conditions based on linear matrix inequalities f or H-infinity control.The conditions thus obtained a re also used to design an H-infinity state feed back controller.This design method is further extend ed to solve the design problem of robust H-infin ity state feedback control.A numerical example demo nstrates the validity of the method.     

Observer-based robust H-infinity control for uncertain switched systems

The problem of observer-based robust H-infinity control is addressed for a class of linear discrete-time switched systems with time-varying norm-bounded uncertainties by using switched Lyapunov function method. None of the individual subsystems is assumed to be robustly H-infinity solvable. A novel switched Lypunov function matrix with diagonal-block form is devised to overcome the difficulties in designing switching laws. For robust H-infinity stability analysis, two linear-matrix-inequality-based sufficient conditions are derived by only using the smallest region function strategy if some parameters are preselected. Then, the robust H-infinity control synthesis is studied using a switching state feedback and an observer-based switching dynamical output feedback. All the switching laws are simultaneously constructively designed. Finally, a simulation example is given to illustrate the validity of the results.     

数值界不确定性关联大系统分散鲁棒H∞控制

针对一类状态阵,控制输入阵及关联阵中存在数值界不确定性的关联大系统,研究其分散鲁棒H∞状态反馈和输出反馈控制器设计问题.基于有界实引理,推导出了其存在分散鲁棒H∞控制器的充分条件,即一组矩阵不等式有解.利用Schur补引理,通过固定不同变量,提出了一种构建分散控制器的同伦迭代线性矩阵不等式方法.所获得的控制器使闭环大系统鲁棒稳定,并且达到给定的H∞性能指标.最后用数值例子说明了所提的设计方法的有效性.     

具有方差和极点约束的不确定系统鲁棒H∞输出反馈控制

针对一类具有范数有界不确定性的连续系统和二次矩阵不等式区域,考虑系统具有方差和区域极点约束的输出反馈控制器设计问题．为此首先导出闭环系统区域稳定的充分必要条件．然后用线性矩阵不等式方法给出输出反馈控制器存在的一个充分条件．在此充分条件下闭环系统是鲁棒区域稳定的且具有H∞性能以及当干扰为白噪声信号时其稳态状态方差有限．接下来用矩阵分解方法给出输出反馈控制器增益矩阵的求解过程．最后通过一个仿真实例说明本文所提出的控制器设计方法的有效性．     

一类脉冲随机混杂系统的鲁棒H无穷控制

本文研究具有外在扰动的脉冲Markov切换线性随机系统的鲁棒H无穷控制问题,分别从系统的鲁棒稳定性及鲁棒性能两方面进行分析,首先,利用多Lyapunov函数法对系统的稳定性进行分析,给出了系统鲁棒依概率稳定的充分条件,进一步,运用线性矩阵不等式(LMI)法对系统的鲁棒性能进行分析,给出相应的状态反馈增益矩阵和脉冲控制增益矩阵的求解方法,在此基础上得出了一个鲁棒H无穷控制律,并提出了一套基于Matlab软件的鲁棒控制器的设计方法。最后,数值算例说明所设计方法的有效性。     

关于一类脉冲切换系统的鲁棒H∞控制

研究一类具有扰动的脉冲切换线性系统的鲁棒H控制问题.分别从系统的鲁棒稳定性及其鲁棒性能两方面进行分析.首先利用Lyapunov函数法对系统的稳定性进行分析,给出了系统鲁棒渐近稳定的几个重要的充分条件,通过它很容易判断系统是否鲁棒稳定.进一步运用线性矩阵不等式(LMI)法对系统鲁棒性能进行分析,得到了一般系统的状态反馈矩阵和脉冲控制矩阵,并在此基础上得出了一个鲁棒H控制律.最后提出了一套基于MAT-LAB软件的鲁棒控制器的设计方法,并通过一个数值例子很好地验证了文中主要结论的有效性.     

具有方差和极点约束的不确定系统鲁棒H∞输出反馈控制

针对一类具有范数有界不确定性的连续系统和二次矩阵不等式区域, 考虑系统具有方差和区域极点约束 的输出反馈控制器设计问题. 为此首先导出闭环系统区域稳定的充分必要条件. 然后用线性矩阵不等式方法给出输出反馈控制器存在的一个充分条件. 在此充分条件下闭环系统是鲁棒区域稳定的且具有H-infinity性能以及当干扰为白噪声信号时其稳态状态方差有限. 接下来用矩阵分解方法给出输出反馈控制器增益矩阵的求解过程. 最后通过一个仿真实例说明本文所提出的控制器设计方法的有效性.     

Robust H-infinity fuzzy control for uncertainMarkovian jump nonlinear singular systems withwiener process

This paper deals with the problems of robust stochastic stabilization and H-infinity control for Markovian jump nonlinear singular systems with Wiener process via a fuzzy-control approach. The Takagi-Sugeno (T-S) fuzzy model is employed to represent a nonlinear singular system. The purpose of the robust stochastic stabilization problem is to design a state feedback fuzzy controller such that the closed-loop fuzzy system is robustly stochastically stable for all admissible uncertainties. In the robust H-infinity control problem, in addition to the stochastic stability requirement, a prescribed performance is required to be achieved. Linear matrix inequality (LMI) sufficient conditions are developed to solve these problems, respectively. The expressions of desired state feedback fuzzy controllers are given. Finally, a numerical simulation is given to illustrate the effectiveness of the proposed method.     

不确定关联大系统分散鲁棒H∞输出反馈控制

针对一类状态矩阵和控制矩阵存在参数不确定性关联大系统,研究其分散鲁棒H∞输出反馈控制问题.基于有界实引理将其鲁棒分散H∞动态输出反馈控制器的解归结为一个非线性矩阵不等式(NLMI),先通过选取适当的同伦函数来表示该非线性矩阵不等式,再通过Schur补引理将其化为两个双线性矩阵不等式,最后通过迭代算法求解该控制器,使闭环大系统鲁棒渐进稳定,并且满足给定的H∞性能指标.