Delay‐range‐dependent control of nonlinear time‐delay systems under input saturation

This paper describes a delay‐range‐dependent local state feedback controller synthesis approach providing estimation of the region of stability for nonlinear time‐delay systems under input saturation. By employing a Lyapunov–Krasovskii functional, properties of nonlinear functions, local sector condition and Jensen's inequality, a sufficient condition is derived for stabilization of nonlinear systems with interval delays varying within a range. Novel solutions to the delay‐range‐dependent and delay‐dependent stabilization problems for linear and nonlinear time‐delay systems, respectively, subject to input saturation are derived as specific scenarios of the proposed control strategy. Also, a delay‐rate‐independent condition for control of nonlinear systems in the presence of input saturation with unknown delay‐derivative bound information is established. And further, a robust state feedback controller synthesis scheme ensuring L₂ gain reduction from disturbance to output is devised to address the problem of the stabilization of input‐constrained nonlinear time‐delay systems with varying interval lags. The proposed design conditions can be solved using linear matrix inequality tools in connection with conventional cone complementary linearization algorithms. Simulation results for an unstable nonlinear time‐delay network and a large‐scale chemical reactor under input saturation and varying interval time‐delays are analyzed to demonstrate the effectiveness of the proposed methodology. Copyright © 2015 John Wiley & Sons, Ltd.     

Robust H ∞ filter design for time-delay systems with saturation

This paper investigates the H∞ filtering problem for a class of linear continuous-time systems with both time delay and saturation. Such systems have time delay in their state equations and saturation in their output equations, and their process and measurement noises have unknown statistical characteristics and bounded energies. Based on the Lyapunov-Krasovskii stability theorem and the linear matrix inequalities (LMIs) technique, a generalized dynamic filter architecture is proposed, and a filter design method is developed. The linear H∞ filter designed by the method can guarantee the H∞ performance. The parameters of the designed filter can be obtained by solving a kind of LMI. An illustrative example shows that the design method proposed in this paper is very effective.     

Maximum allowable delay bound of networked control systems with multi-step delay

This paper is concerned with a new method to obtain a maximum allowable delay bound guaranteeing the stability of networked control systems with multi-step delay. The proposed method is formulated in terms of linear matrix inequalities. Simulation results show that the proposed method is effective.     

Delay-discretization-based sliding mode $$H_{\infty }$$ load frequency control scheme considering actuator saturation of wind-integrated power system

This paper investigates the combined effect of actuator saturation and time-delay on load frequency control (LFC) of a wind-integrated power system (WIPS). Actuator saturation is represented in two different approaches such as polytopic and sector bounding. Delay-discretization-based sliding mode \(H_{\infty }\) control approach is proposed to design a novel LFC scheme. The proposed control scheme requires present as well as delayed states information as input to the controller. This requirement of control scheme is fulfilled by adopting a finite known delay. This finite known delay used in controller design is discretized into delay intervals. Lyapunov–Krasovskii functional is defined for each delay interval, and \(H_{\infty }\) stabilization criteria for the closed loop WIPS are derived in linear matrix inequality framework using Wirtinger-based inequality. The proposed control scheme is tested by considering a numerical example of two-area WIPS.

     

Adaptive synchronization control design for flexible telerobotics with actuator fault and input saturation

This paper addresses the synchronization control problem of flexible telerobotics with actuator fault, input saturation, and asymmetrical time‐varying delays. A new adaptive antisaturation nonlinear fractional power proportional+damping fault‐tolerant control scheme is designed. With the new control algorithm, faster convergence rate and higher convergence precision can be guaranteed, as compared with the general proportion+damping control method. By choosing Lyapunov‐Krasovskii functional, it shows that the teleoperation system is stable under specific linear matrix inequality conditions. Thus, the allowable maximal transmission delay can be computed with the given controller‐design parameters. To validate the effectiveness of the proposed method, simulations on synchronization control system composed of 2 manipulators (master is rigid, and slave is flexible) are developed. Experiments on the PHANToM Premium 1.5A manipulators are also conducted and numerous experimental results are presented to show the superior performance of the proposed control scheme.     

Dynamic anti‐windup method for a class of time‐delay control systems with input saturation

An anti‐windup‐based approach is newly attempted to deal with time‐delay control systems with input saturation. Following the anti‐windup paradigm, we assume that controllers have been designed beforehand for time‐delay control systems based on existing design techniques which will show desirable performance. Then, an additional compensator is designed to provide graceful performance degradation under control input saturation. By taking the difference of controller states in the absence and presence of input saturation as a performance index, a dynamic compensator which minimizes it is derived. The resulting anti‐windup compensator is expressed in plant and controller parameters. The proposed method not only provides graceful performance degradation, but also guarantees the stability of the overall systems. Illustrative examples are provided to show the effectiveness of the proposed method. Copyright © 2000 John Wiley & Sons, Ltd.     

基于LMI的小时滞饱和系统稳定域估计方法

基于Pade近似变换,将小时滞饱和系统的稳定域估计转化为估计奇异摄动饱和系统的稳定域问题.证明了此奇异摄动饱和系统的稳定域具有可解耦性,并在此基础上建立LMI优化模型并提出小时滞饱和系统稳定域估计的降阶方法.算例仿真验证了方法的正确性和有效性.     

基于LMI方法的网络闭环控制系统离散鲁棒模糊控制

针对网络闭环控制系统中时延和不同步等不确定因素,将时延的不确定性转换为系统状态方程系数矩阵的不确定性,提出了一种新的网络闭环控制系统建模方法———具有时滞的不确定离散模糊T-S模型;并在此模型的基础上,利用并行分布补偿原理和Lyapunov理论及LMI方法,证明了通过状态的静态反馈模糊控制,使闭环系统稳定的充分条件等价于求解一组LMI。仿真示例验证了该控制方法的有效性.     

Set-membership filtering for systems with sensor saturation

This paper addresses the set-membership filtering problem for a class of discrete time-varying systems with sensor saturation in the presence of unknown-but-bounded process and measurement noises. A sufficient condition for the existence of set-membership filter is derived. A convex optimisation method is proposed to determine a state estimation ellipsoid that is a set of states compatible with sensor saturation and unknown-but-bounded process and measurement noises. A recursive algorithm is developed for computing the ellipsoid that guarantees to contain the true state by solving a time-varying linear matrix inequality. Simulation results are provided to demonstrate the effectiveness of the proposed method.     

执行器受限下离散网络控制系统容错控制

随着自动控制、计算机科学以及通讯技术等飞速发展,近十年来网络控制系统(NCSs)已经在工业控制、航空航天以及物联网等领域得到广泛的应用。针对离散时间网络控制系统存在执行器饱和与故障的情况,充分考虑网络诱导时延和参数不确定等影响,提出了一种容错控制设计方法,将被控系统转化为一类存在扇形有界不确定性和非线性项的闭环控制系统,利用Lyapunov稳定性理论和时延上界信息进行泛函构造并利用Jenson不等式放大技术估计泛函差分更紧上界,得到确保闭环系统渐近稳定的充分性条件,再基于线性矩阵不等式(LMI)技术得到控制器增益设计方案,最后利用对比仿真验证了方法的有效性并且能降低保守性。     

Delay-dependent Stabilization Conditions of Controlled Positive Continuous-time Systems

The stabilization problem for a class of linear continuous-time systems with time-varying non differentiable delay is solved while imposing positivity in closed-loop. In particular, the synthesis of state-feedback controllers is studied by giving sufficient conditions in terms of linear matrix inequalities(LMIs). The obtained results are then extended to systems with non positive delay matrix by applying a memory controller. The effectiveness of the proposed method is shown by using numerical examples.     

Time delay and packet dropout compensation for networked control systems: a linear estimation method

This article studies the problem of H _∞ controller design for networked control systems (NCSs) with time delay and packet dropout. A linear estimation-based time delay and packet dropout compensation method is proposed. The delay switching-based method is presented to deal with the variation of time delay, and H _∞ controller design is presented for NCSs with packet dropout compensation by using linear matrix inequality (LMI)-based method. Then the combined delay switching and parameter uncertainty-based method is presented to model the variation of time delay, and H _∞ controller design is also presented. The simulation results illustrate the effectiveness of the newly proposed linear estimation-based time delay and packet dropout compensation.     

Improved results for linear discrete-time systems with an interval time-varying input delay

This paper addresses the problem of delay-dependent stability analysis and controller synthesis for a discrete-time system with an interval time-varying input delay. By dividing delay interval into multiple parts and constructing a novel piecewise Lyapunov–Krasovskii functional, an improved delay-partitioning-dependent stability criterion and a stabilisation criterion are obtained in terms of matrix inequalities. Compared with some existing results, since a tighter bounding inequality is employed to deal with the integral items, our results depend on less number of linear matrix inequality scalar decision variables while obtaining same or better allowable upper delay bound. Numerical examples show the effectiveness of the proposed method.     

A vehicle cloud control system considering communication quantization and stochastic delay

A novel kind of networked feedback controller is designed for the vehicle cloud control system in the presence of both sensor-controller/controller-actuator delay and communication quantization. Firstly, the vehicle cloud control system with delayed and quantized communication is modeled using the lateral/longitudinal vehicle dynamic and Markovian jump linear system (MJLS) theory. Then, some efficient stabilization conditions in matrix inequalities forms are derived for the considered cloud-controlled vehicles. Furthermore, a cone complementary linearization method is utilized to solve the nonlinear matrix inequalities involved in the stabilization conditions. Simulation tests on connected vehicle lateral and longitudinal control are conducted to verify the effectiveness of the analytical results. Compared with the commonly used constant-parameter controllers, the proposed method is practical to design vehicle cloud controllers under stochastic delay and communication quantization scenarios, with known delay distribution. Lastly, the stability of the vehicle cloud control system is guaranteed under the infection of unreliable communication factors with the proposed control method.     

离散奇异时滞系统时滞依赖稳定性分析与镇定

分别研究了离散奇异时滞系统时滞依赖稳定性分析与镇定问题. 首先给出了一个新的离散奇异时滞系统时滞依赖容许性充分条件. 经过证明, 所提出的方法与现有结论相比, 具有一定的优势. 然后, 运用矩阵理论技巧,设计出状态反馈控制器保证闭环离散奇异时滞系统是容许的. 最后,两个数值例子说明了所用方法的有效性.     

含时变滞后的不确定系统的时滞相关型鲁棒控制设计

研究含时变滞后的不确定系统的控制综合问题. 基于Lyapunov方法提出了一种含滞后补偿的鲁棒控制设计方法. 闭环稳定性条件由一组线性矩阵不等式表示. 在这些条件中给出了稳定性和滞后以及其导数之间的关系. 实例显示, 利用提供的方法所给出的结果比以往文献给出的结果保守性小.     

深亚微米工艺下逻辑功效法延时估算的改进

逻辑功效法延时估算是由Sutherland I E提出的，可以在设计初期快速估算逻辑门和逻辑电路的延时，减小逻辑电路设计的难度。但是，随着深亚微米CMOS工艺的普及，短沟道效应开始影响经典逻辑功效法的正确性。为了提高逻辑功效法估算精度，提出一种考虑速度饱和效应的改进方法,该方法主要分两步：首先，考虑反相器PMOS与NMOS宽之比，精确估算反相器的延时，并归一化；然后，基于反相器的延时和速度饱和的影响，估算逻辑门的延时。仿真模型采用了美国亚利桑那州立大学的PTM 32nm、65nm、90nm和130nm的模型，45nm采用了北卡罗来纳州立大学的FreePDK的模型，结合hspice仿真。经实验数据对比，该方法对与非门延时的估算精度提高约10%。     

$H_{infty} $ Filter Design for Nonlinear Systems With Time-Delay Through T–S Fuzzy Model Approach

This paper is concerned with the H_infin filter design for nonlinear systems with time-varying delay via Takagi-Sugeno fuzzy model approach. Delay-dependent design method is proposed in terms of linear matrix inequalities (LMIs), which forms the main contribution of this paper. The main technique used is the free-weighting matrix method combined with a matrix decoupling approach. The results for rate-independent case, delay-independent case, and delay-free case are also given as easy corollaries. An illustrative example is given to show the effectiveness of the present method.     

时延网络控制系统的模型预测控制

针对有输入约束的不确定时延网络控制系统,提出鲁棒模型预测控制方法;其中,将不确定时延建模为范数有界的输入矩阵的不确定性．给出了鲁棒性能指标的上界和系统渐近稳定的充分条件,通过在线求解LMI凸优化问题得到状态反馈控制律．仿真例子验证了该方法的有效性．