鲁棒对角优势及在多变量系统鲁棒设计中应用

本文基于多变量系统奈氏阵列设计方法和鲁棒对角优势保证系统鲁棒稳定的结论,提出一种多变量系统鲁棒设计方法,该方法设计的鲁棒预补偿器使广义对象在一定摄动范围内严格符合鲁棒对角优势定义,因而系统一定是鲁棒稳定的,该方法具有保守性小,设计的控制器简单,易于工程实现等优点,用该方法对一参数不确定性工业对象进行了鲁棒系统设计,结果令人满意。     

具有结构不确定性的输出反馈性系统的鲁棒稳定性分析

基于向量的幂变换方法，对具有结构不确定性的输出反馈线性系统的鲁棒稳定性问题作了分析。单参数摄动时给出了闭环系统鲁棒稳定的充要条件，多参数摄动时得到了保证系统鲁棒稳定的充分条件，导出了闭环系统鲁棒稳定区域的一种代数表达形式。最后给出了实例。     

一种多变量系统鲁棒设计方法

本文介绍一种多变量系统鲁棒设计方法.该方法是基于"鲁棒对角优势保证鲁棒稳定"这 个一般性结论,其核心是多模型加权准优势化算法,该算法设计的鲁棒预补偿器,使系统为鲁 棒对角优势.用该设计方法对一大型工业加热炉进行鲁棒系统设计,结果令人满意.     

多变量系统鲁棒稳定性

本文用复变函数理论，证明了摄动系统为鲁棒对角优势，则系统一定是鲁棒稳定这个一般性结论该结合保守性小，与奈氏阵列法联系密切，可用于工业对象鲁棒控制系统设计。     

具有结构不确定性的输出反馈线性系统的鲁棒稳定性分析

基于向量的幂变换方法，对具有结构不确定性的输出反馈线性系统的鲁棒稳定性问题作了分析。单参数摄动时给出了闭环系统鲁棒稳定的充要条件，多参数摄动时得到了保证系统鲁棒稳定的充分条件，导出了闭环系统鲁棒稳定区域的一种代数表达形式。最后给出了实例。     

带有分母因式摄动不确定系统的鲁棒镇定

讨论了带有分母因式不确定性摄动系统的鲁棒镇定问题,给出了控制器K鲁棒镇 定摄动系统G△的充分必要条件,当标称系统G=M-lN∈RL∞时,借助于求解次优Nehari问 题,以状态空间形式给出了摄动系统的鲁棒控制器的参数化公式.     

线性不确定奇异摄动系统的稳定控制鲁棒界

对于具有不确定量的奇异摄动系统，利用Lyapunov稳定性理论研究其稳定鲁棒控制问题。在一定条件下得到了任一理想奇异摄动系统的稳定鲁棒控制，也是不确定奇异摄动系统具有一定鲁棒界的稳定控制。给出了闭环奇异摄动系统渐近稳定的条件，讨论了鲁棒界及其变化范围。     

具有脉冲模的奇异摄动系统鲁棒稳定分析与仿真研究

本文研究了当摄动参数为零时存在脉冲模的奇异摄动系统的鲁棒稳定性问题，得到了使系统鲁棒稳定的摄动参数上界，给出了一个数值仿真例子。     

离散广义系统的鲁棒稳定性

针对具有结构不确定性的离散广义系统,提出了一种新的鲁棒稳定性分析方法;得 到了使所考虑系统鲁棒稳定的条件,该条件保证对所有容许的结构摄动,离散广义系统正则、 因果且稳定;并进一步得到了所考虑系统具有鲁棒极点集的条件.     

基于互质因子摄动的反馈系统的鲁棒稳定性

考虑对象和控制器同时具有互质因子摄动时闭环系统的鲁棒稳定性问题,得到了闭环 系统鲁棒稳定的充要条件并给出了鲁棒控制器的优化设计方法.     

Robust stability analysis of filtered Smith predictor for time-varying delay processes

This paper focuses on the robust stability analysis of the filtered Smith predictor (FSP) dead-time compensator for uncertain processes with time-varying delays. For this purpose, a delay-dependent LMI-based condition is used to compute a maximum delay interval and tolerance to model uncertainties such that the closed-loop system remains stable. Some simulation results illustrate that the proposed controller gives larger delays intervals or better performance than similar approaches proposed in literature applied both to stable and unstable processes.     

Robust stability of uncertain time-delay systems

This paper presents several sufficient conditions, delay-independent or delay-dependent, that guarantee the robust stability of uncertain time-delay systems subjected to parametric perturbations. Both single and composite uncertain systems with one delayed state are considered and each of these results, expressed by a succinct scalar inequality, permits the assessment of the transient behaviour of uncertain systems. The robustness of the time-delay system with respect to delay uncertainty is also discussed. Furthermore, these results are extended to the perturbed systems with multiple non-commensurate time delays. It is shown that the parameter perturbations may destabilize the system; hence the nominal system should be sufficiently stable to ensure robust stability.     

多组多滞后区间系数时变非线性关联控制系统的结构与关联鲁棒镇定（Ⅰ）

建立了多组多滞后区间系数时变非线性控制系统的结构概念，采用刘永清建立的鲁棒镇定的等价法，给出了具有扰动结构参数的多组多滞后区间系数时变非线性关联控制系统的结构与关联鲁棒镇定，同时给出了扰动参数与滞后非线性项界限的估计公式     

Stability of stochastic interval systems with time delays

Consider a given exponentially stable system undergoing a random perturbation which is dependent on a past state of the solution of the system. Suppose this stochastically perturbed system is described by a stochastic differential-functional equation. In this paper, we establish a sufficient condition that the perturbed system remains exponentially stable. Using a specific example, we show how this condition may be used, and we extend it to deal with multiple time delays.     

Robust Stability Analysis of Smith Predictor Based Interval Fractional-Order Control Systems: A Case Study in Level Control Process

The robust stability study of the classic Smith predictor-based control system for uncertain fractional-order plants with interval time delays and interval coefficients is the emphasis of this work. Interval uncertainties are a type of parametric uncertainties that cannot be avoided when modeling real-world plants. Also, in the considered Smith predictor control structure it is supposed that the controller is a fractional-order proportional integral derivative (FOPID) controller. To the best of the authors’ knowledge, no method has been developed until now to analyze the robust stability of a Smith predictor based fractional-order control system in the presence of the simultaneous uncertainties in gain, time-constants, and time delay. The three primary contributions of this study are as follows: i) a set of necessary and sufficient conditions is constructed using a graphical method to examine the robust stability of a Smith predictor-based fractional-order control system—the proposed method explicitly determines whether or not the FOPID controller can robustly stabilize the Smith predictor-based fractional-order control system; ii) an auxiliary function as a robust stability testing function is presented to reduce the computational complexity of the robust stability analysis; and iii) two auxiliary functions are proposed to achieve the control requirements on the disturbance rejection and the noise reduction. Finally, four numerical examples and an experimental verification are presented in this study to demonstrate the efficacy and significance of the suggested technique.      

Optimal linear filtering over observations with multiple delays

In this paper, the optimal filtering problem for a linear system over observations with multiple delays is treated proceeding from the general expression for the stochastic Ito differential of the optimal estimate and its variance. As a result, the optimal filtering equations similar to the traditional Kalman–Bucy ones are obtained in the form dual to the Smith predictor, commonly used for robust control design in time‐delay systems. In the example, the obtained optimal filter over observations with multiple delays is verified for a sample system and compared with the best Kalman–Bucy filter available for delayed measurements. Copyright © 2004 John Wiley & Sons, Ltd.     

A Novel Predictive Control Scheme with an Enhanced Smith Predictor for Networked Control System

This paper presents a novel predictive control scheme with an enhanced Smith predictor for a networked control system with random time delays and system uncertainties. In the scheme, time axis is partitioned into equidistant small intervals to limit the continuous time varying delays into several discrete values. The stability of the networked control system is achieved by establishing an offline database and an online update strategy for Smith predictor, which reduces the reliance on the determined model of delay and system uncertainties in comparison with conventional Smith predictor. In this way, a sequence of finite forward predictive control signals of all possible time delays can be generated in advance and the actual delays will be compensated in real time when achieving the real delay information. Illustrative examples are given to demonstrate the effectiveness and robustness of the proposed predictive methods towards the random transmission delays and system uncertainties integrated in the networked control system.     

Robust stability bounds for multi-delay networked control systems

In this paper, the robust stability of a perturbed linear continuous-time system is examined when controlled using a sampled-data networked control system (NCS) framework. Three new robust stability bounds on the time-invariant perturbations to the original continuous-time plant matrix are presented guaranteeing stability for the corresponding discrete closed-loop augmented delay-free system (ADFS) with multiple time-varying sensor and actuator delays. The bounds are differentiated from previous work by accounting for the sampled-data nature of the NCS and for separate communication delays for each sensor and actuator, not a single delay. Therefore, this paper expands the knowledge base in multiple inputs multiple outputs (MIMO) sampled-data time delay systems. Bounds are presented for unstructured, semi-structured, and structured perturbations.     

Robust convergence of discrete‐time delayed switched nonlinear systems and its applications to cascade systems

Systems in real world are always subject to perturbations. This paper addresses the convergence properties of a class of nominal systems with perturbations. It is assumed that the nominal system is a switched nonlinear exponentially stable one with time‐varying delays and that the perturbation exponentially or asymptotically converges to zero. It is revealed that the trajectories of the perturbed system behave as the perturbation, ie, trajectories exponentially or asymptotically converge to zero, depending on the property of perturbation. Applying these results to cascade switched nonlinear systems, it is shown that such systems are exponentially stable if and only if all the subsystems, obtained by removing the coupling terms, are exponentially stable. A similar conclusion is presented for systems being asymptotically stable. Finally, a numerical example illustrates the proposed theoretical results.     

Deadtime compensation for nonlinear processes with disturbances

The control problem of time delay non-linear systems that are perturbed by disturbances is discussed. By coordinate transformations and feedback and prediction of the transformed states, we first linearize the perturbed non-linear systems into controllable quasi-linear systems with disturbances. Then, we can apply the well-developed linear control theory to stabilize the transformed systems. Thus, stable quasi-linear systems with time delay can be obtained. Furthermore, we may implement powerful deadtime compensation methods to study the performance of the proposed dynamic compensators, a Smith predictor and a new modified Smith predictor, for disturbance rejection. Finally, a typical non-linear chemical process, a continuous stirred tank reactor, is used as an example system to demonstrate the effectiveness of these deadtime compensators