基于事件触发的网络化T-S模糊系统容错控制

研究了基于事件触发的网络化T-S模糊系统容错控制问题．首先针对一类具有随机执行器故障的网络化T-S模糊系统,提出一种有效减少数据传输量的事件触发机制．然后在综合考虑事件触发机制和控制器与T-S系统前件变量的异步的情况下,建立一种能同时描述事件传送策略、执行器失效、网络诱导时延和异步前件变量的新颖模型．利用李亚普诺夫泛函方法,得到保守性较小的闭环T-S系统均方渐近稳定条件和相应的容错控制器设计方法．实例表明了本文所得结果的有效性．     

Event-triggered fuzzy filtering in networked control system for a class of non-linear system with time delays

This paper focuses on the design of H _∞ filter and event-triggered scheme for a class of continuous non-linear networked control systems (NCSs) based on fuzzy system appeared with time delays. First, we consider the discrete event-triggered (ET) scheme to make efficient utilisation of bandwidth. Under this ET-scheme, sensor releases the data only when our sampled-data plant violates the specific event-triggered condition. Second, the T-S fuzzy system is used to model the non-linear NCSs. Another purpose of this paper is to design filters involving delays. Such filters have a more general form than the delay-free filters that have been mostly considered in the traditional studies. By using the time-delay system, co-design of event-triggered scheme and H _∞ filter for the delayed NCSs is presented in a unified frame work. To choose the latest data packet and discard the dis-ordered packet logic, zero-order hold is inserted between the fuzzy filter and event generator. Then, by using the novel fuzzy Lyapunov–Krasovskii function approach with free-weighting matrix technique, H _∞ filter design of event-triggered delay NCSs is proposed. Finally, to show the effective result of our co-design method, a tunnel-diode example is given.     

Robust fuzzy tracking control for nonlinear networked control systems with integral quadratic constraints

This paper investigates the robust tracking control problem for a class of nonlinear networked control systems (NCSs) using the Takagi-Sugeno (T-S) fuzzy model approach. Based on a time-varying delay system transformed from the NCSs, an augmented Lyapunov function containing more useful information is constructed. A less conservative sufficient condition is established such that the closed-loop systems stability and time-domain integral quadratic constraints (IQCs) are satisfied while both time-varying network-induced delays and packet losses are taken into account. The fuzzy tracking controllers design scheme is derived in terms of linear matrix inequalities (LMIs) and parallel distributed compensation (PDC). Furthermore, robust stabilization criterion for nonlinear NCSs is given as an extension of the tracking control result. Finally, numerical simulations are provided to illustrate the effectiveness and merits of the proposed method.     

非线性时延网络控制系统的模糊建模与控制

针对时变网络诱导时延小于一个采样周期的非线性时延网络控制系统,讨论系统的稳定性及控制器的设计方法.利用基于“IF-THEN”规则的模糊模型近似系统中的非线性,将时延的不确定性转化为系统参数的不确定性,从而将此类非线性网络控制系统建模为一类具有参数不确定性的离散Takagi-Sugeno（T-S）模糊模型.基于建立的模型,利用Lyapunov方法和线性矩阵不等式方法,分析了系统的稳定性及模糊状态反馈控制器的设计方法,最后通过仿真实例验证了所提出方法的有效性.     

Imperfect premise matching controller design for T-S fuzzy systems under network environments

This paper focuses on an imperfect premise matching controller design for T-S fuzzy systems under network environments. Different with the traditional parallel distribution compensation (PDC) method, the same premises between the PDC controller and the T-S fuzzy systems are no longer needed again in the proposed method. Under consideration of the unmatched grades of membership in the networked T-S fuzzy systems, a unified T-S fuzzy model is firstly proposed, in which a networked state-feedback fuzzy controller with communication delays is used to reconstruct the system. Then, based on the constructed model and by use of the Wirtinger-based inequality technique to deal with the cross items, two less conservative stability and stabilization criteria are derived to enhance the design flexibility. Finally, two numerical examples are used to show the effectiveness of proposed method.     

Adaptive event-triggered robust H∞ control for Takagi–Sugeno fuzzy networked Markov jump systems with time-varying delay

This paper considers an adaptive event-triggered robust H_∞ control for the Takagi–Sugeno (T-S) fuzzy under the networked Markov jump systems (NMJSs) with time-varying delay. First, a new adaptive event-triggered scheme is developed to guarantee the T-S fuzzy NMJSs, and as a result, communication energy consumption reduced while device efficiency is maintained. Besides, an asynchronous operation method is adopted to deal with the mismatched premise variables between the fuzzy system and the fuzzy controller. One of the main objectives of this article is to construct the fuzzy state-feedback controller (mode-dependent) in a closed-loop form for stochastic stability for all admissible parameter uncertainties with an H_∞ performance index. Different from the conventional triggering mechanism, in this paper, the parameters of the triggering function are based on a new adaptive law that is obtained online rather than a predefined constant. To achieve the less conservative control design, a new type of stochastic Lyapunov–Krasovskii functional is designed by decomposing method, in which the delay interval transforms into various equidistant subintervals in terms of linear matrix inequalities. An example of a truck-trailer application is used to demonstrate the effectively of the proposed algorithms.     

Robust H ∞ networked control for discrete-time fuzzy systems with state quantisation

The problem of robust H _∞ control for uncertain discrete-time Takagi and Sugeno (T-S) fuzzy networked control systems (NCSs) with state quantisation is investigated. A new model of network-based control with simultaneous consideration of network-induced delays and packet dropouts is proposed. By using a fuzzy Lyapunov–Krasovskii functional (LKF), we derive a less conservative delay-dependent stability condition for the closed-loop NCSs. Robust H _∞ fuzzy controller is developed for the asymptotical stabilisation of the NCSs. Since it is not expressed as strict LMI conditions, the cone complementary linearisation procedure is exploited to solve the nonconvex feasibility problem. A numerical example shows the feasibility applications of the proposed technique.     

Model‐based event‐triggered predictive control for networked systems with communication delays compensation

This paper addresses the model‐based event‐triggered predictive control problem for networked control systems (NCSs). Firstly, we propose a discrete event‐triggered transmission scheme on the sensor node by introducing a quadratic event‐triggering function. Then, on the basis of the aforementioned scheme, a novel class of model‐based event‐triggered predictive control algorithms on the controller node is designed for compensating for the communication delays actively and achieving the desired control performance while using less network resources. Two cases, that is, the value of the communication delay of the first event‐triggered state is less or bigger than the sampling period, are considered separately for certain NCSs, regardless of the communication delays of the subsequent event‐triggered states. The codesign problems of the controller and event‐triggering parameter for the two cases are discussed by using the linear matrix inequality approach and the (switching) Lyapunov functional method. Furthermore, we extended our results to the NCSs with systems uncertainties. Finally, a practical ball and beam system is studied numerically to demonstrate the compensation effect for the communication delays with the proposed novel model‐based event‐triggered predictive control scheme. Copyright © 2014 John Wiley & Sons, Ltd.     

基于事件触发传输机制的非线性系统模糊H∞ 控制

针对离散时间非线性系统, 提出事件触发传输机制下网络化T-S 模糊控制器设计方法. 在事件发生器中引入前提变量偏差触发条件, 从而取消模糊控制器与被控对象的前提变量之间的同步要求. 通过引入一组基于模糊前提变量特性的松弛等式/不等式, 对于无传输时滞和定常传输时滞两种情况, 分别提出具有较小保守性的控制器/事件发生器联合设计算法. 最后, 通过数值算例表明所提出方法的可行性和有效性.

     

Finite-time non-fragile filtering for nonlinear networked control systems via a mixed time/event-triggered transmission mechanism

This paper is aimed at investigating the problem of mixed time/event-triggered finite-time non-fragile filtering for nonlinear networked control systems with delay. First, a fuzzy nonlinear networked control system model is established by interval type-2 (IT2) Takagi-Sugeno (T-S) fuzzy model, the designed non-fragile filter resolves the filter parameter uncertainties and uses different membership functions from the IT2 T-S fuzzy model. Second, a novel mixed time/event-triggered transmission mechanism is proposed, which decreases the waste of network resources. Next, Bernoulli random variables are used to describe the cases of random switching mixed time/event-triggered transmission mechanism. Then, the error filtering system is designed by considering a Lyapunov function and a sufficient condition of finite-time boundedness. In addition, the existence conditions for the finite-time non-fragile filter are given by the linear matrix inequalities (LMIs). Finally, two simulation results are presented to prove the effectiveness of the obtained method.     

基于传感器故障的网络化系统鲁棒容错设计

针对一类具有参数不确定的非线性网络化控制系统,基于T-S模糊模型建模,推证出了确保非线性网络化控制系统在传感器发生失效故障时具有鲁棒完整性的时滞依赖充分条件,并以求解矩阵不等式给出了容错控制器的设计方法.最后以一个仿真算例验证了文中所述方法的可行性和有效性.     

Decentralized dynamic event-triggered control for networked control systems under unreliable communication network and actuator saturation

In this paper, the stochastic stability of networked control systems (NCSs) with nonlinear perturbation and parameter uncertainties is studied. A decentralized dynamic event triggering scheme (DDETS) is introduced to reduce energy consumption and network transmission burden. Each channel can decide whether to transmit signals sampled by corresponding sensors through this mechanism. Due to the unreliability of communication network, a new mathematical model of NCSs based on multi-channel fading and hybrid cyber attacks is established, and the actuator is constrained by saturation. A sufficient condition for stochastic stability based on static controller is derived through Lyapunov stability theory, and two numerical examples are given to demonstrate the effectiveness of the method.     

Stabilizing bit-rates in networked control systems with decentralized event-triggered communication

In a decentralized event-triggered networked control system (NCS), an agent samples and transmits its local state information to the controller when some local event occurs. Such event-triggered NCSs were expected to be more efficient than traditional periodically sampled system in terms of communication channel usage. This paper studies the stability of decentralized event-triggered NCS in the presence of quantization and delays. We point out some potential issues in decentralized event-triggered design and propose an alternative decentralized event with a linear-affine threshold, which avoids infinitely fast data transmission. Conditions on quantizer and communication channel are derived, which, when satisfied, can guarantee stability of the resulting NCS. Based on these conditions, finite stabilizing bit-rates are provided.     

NNCS混合容错控制方法

针对执行器任意失效故障,研究离散事件触发通讯机制下不确定NNCS主被动混合鲁棒$H_\infty$容错控制器设计问题,该控制器对外界有限能量扰动具有良好的抑制性能.首先,基于T-S模糊模型,建立离散事件触发通讯机制下不确定NNCS闭环故障模型;然后,基于$H_\infty$控制思想设计故障检测观测器并得到不确定NNCS鲁棒$H_\infty$容错控制设计准则;最后,通过Matlab仿真算例验证所设计的控制律对系统性能的改善以及事件触发条件的引入对网络资源的节约.     

基于T-S模糊模型非线性网络控制系统改进H∞跟踪控制

研究一类非线性网络控制系统改进H∞跟踪控制问题, 该类网络控制系统中非线性被控对象和被跟踪对象分别采用Takagi-Sugeno(T-S)模糊模型和线性稳定参考模型描述. 首先通过综合考虑网络中的数据传输时滞和数据丢包影响, 采用输入时滞法和并行分布补偿技术, 建立基于零阶保持器刷新时刻的系统状态跟踪误差模型. 然后利用改进的自由权矩阵方法, 并结合Lyapunov直接法给出系统满足H∞跟踪性能的充分条件以及模糊控制器的设计方法. 最后仿真实例表明本文方法的有效性和相比已有方法的优越性.     

欺骗攻击下网络化系统事件触发安全控制

针对网络控制系统受欺骗攻击问题,提出了事件触发器与安全控制器协同设计策略。提出了离散事件触发机制,克服了连续事件触发机制需要新增专用硬件且需要复杂计算避免芝诺现象局限。建立了有机融合欺骗攻击、事件触发机制、网络诱导延时及外部扰动多约束参数的闭环系统时滞模型,推导出了欺骗攻击下事件触发控制系统渐近稳定的充分条件,得到了事件触发器与安全控制器的协同设计条件。仿真验证了方法的有效性。     

Stabilization of uncertain networked control systems with actuator saturation and probabilistic cyberattacks

This paper investigates the stabilization of uncertain networked control systems (NCSs) with actuator saturation and cyberattacks. The cyberattacks are governed by a set of independent random variables satisfying Bernoulli distribution. To relieve the network bandwidth load effectively, an event-triggered communication strategy is proposed. By employing Lyapunov stability theory and stochastic analysis techniques, a stability criterion is obtained for the system with actuator saturation and cyberattacks. Moreover, the desired controller gain is derived by solving some matrix inequalities. Finally, the validity and applicability of the criteria are verified through numerical examples.     

基于T-S 模糊模型的网络控制系统非脆弱H∞ 跟踪控制

针对一类T-S 模糊模型描述的网络控制系统(NCSs) 非脆弱H_∞跟踪控制问题进行研究. 首先, 综合考虑网络中数据传输时滞和数据丢包的影响, 采用输入时滞法和并行分布补偿(PDC) 技术, 建立基于T-S 模糊模型的NCSs 状态跟踪误差模型; 然后, 利用Lyapunov 方法和改进的自由权矩阵方法, 基于线性矩阵不等式(LMI), 给出满足系统H_∞ 跟踪性能的条件, 并给出非脆弱模糊控制器设计方法; 最后, 通过仿真实例表明了该方法的有效性.     

Survey on time-delay approach to networked control

This paper provides a survey on time-delay approach to networked control systems (NCSs). The survey begins from a brief summary on fundamental network-induced issues in NCSs and the main approaches to the modelling of NCSs. In particular, a comprehensive introduction to time-delay approach to sampled-data and networked control is provided. Then, recent results on time-delay approach to event-triggered control are recalled. The survey highlights time-delay approach developed to modelling, analysis and synthesis of NCSs, under communication constraints, with a particular focus on Round-Robin, Try-once-discard and stochastic protocols. The time-delay approach allows communication delays to be larger than the sampling intervals in the presence of scheduling protocols. Moreover, some results on networked control of distributed parameter systems are surveyed. Finally, conclusions and some future research directions are briefly addressed.     

Feedback control with scheduled communication sequences and random delays

This paper establishes an approach to co-design of an output feedback controller and a channel-access managing policy for networked control systems (NCSs) where channel limitations and network-induced delays are present at both sides of the system. In particular, communication sequences and controller co-design conditions for linear NCSs with bounded disturbance are derived in the framework of hybrid control and given in terms of difference linear matrix inequality (DLMI) and difference matrix equation (DME). The results are extended to NCSs with Gaussian noises and random delays that are independent identically distributed (i.i.d.) and Markovian, with corresponding results given in the sense of stochastic stability. Numerical examples have shown the usefulness of the proposed methods.