Constrained robust sampled‐data control for nonlinear uncertain systems

In industrial process control, computer control, which makes the closed‐loop system a sampled‐data one containing both continuous‐ and discrete‐time signals, is widely used. In contrast with traditional approximation methods, sampled‐data synthesis, a direct digital controller design procedure without approximation, has received increasing attention during the past few years. However, many of the existing results cannot be applied to sampled‐data control design for the uncertain systems. In this paper, a result of robust asymptotic stability of sampled‐data systems with constraints on the state is presented based on a result on practical stability for these systems. Then the robust sampled‐data control for a class of uncertain nonlinear systems with constraints on the output is developed. The problem is formulated from vehicle steering control with constraint on the side slip angle of body. The result is described by some matrix inequalities which could be solved by an iterative algorithm based on the linear matrix inequality technique. Finally, a numerical example is presented to demonstrate the result. Copyright © 2002 John Wiley & Sons, Ltd.     

Stability condition for sampled data based control of linear continuous switched systems

Most practical systems are continuous in nature but with discrete (sampled) feedback when digital control is utilized. This paper investigates the stabilization problem of switched linear continuous-time systems with sampled data based control. For both known and unknown arbitrary switching processes, on the basis of Lyapunov stability theory, a sufficient global exponential stability condition related to Dwell time and sampling period is established. For the latter case, on-line one-step adaptive estimation algorithm is derived and integrated with sampled feedback for control design. Validation and verification of the established result are conducted through cruise control of train systems.     

Robust control of a family of uncertain nonminimum‐phase systems via continuous‐time and sampled‐data output feedback

The problem of global robust stabilization is studied by both continuous‐time and sampled‐data output feedback for a family of nonminimum‐phase nonlinear systems with uncertainty. The uncertain nonlinear system considered in this paper has an interconnect structure consisting of a driving system and a possibly unstable zero dynamics with uncertainty, ie, the uncertain driven system. Under a linear growth condition on the uncertain zero dynamics and a Lipschitz condition on the driving system, we show that it is possible to globally robustly stabilize the family of uncertain nonminimum‐phase systems by a single continuous‐time or a sampled‐data output feedback controller. The sampled‐data output feedback controller is designed by using the emulated versions of a continuous‐time observer and a state feedback controller, ie, by holding the input/output signals constant over each sampling interval. The design of either continuous‐time or sampled‐data output compensator uses only the information of the nominal system of the uncertain controlled plant. In the case of sampled‐data control, global robust stability of the hybrid closed‐loop system with uncertainty is established by means of a feedback domination method together with the robustness of the nominal closed‐loop system if the sampling time is small enough.     

不确定时滞线性系统的采样控制

采样控制作为一种数字控制的直接设计方法,近年来引起了广泛的重视,目前采样控制不易处理模型的不确定性和时滞,本语文给不确定时滞系统的采样控制算法,结果表示为一些矩阵不等式,并给中用ＬＭＩ求解的迭代算法。     

输出多采样反馈控制器及系统稳定性

针对由连续被控对象和数字控制器构成的数字控制系统,将现有的线性系统输出多采样线性反馈数字控制器设计方法推广到非线性系统．并相应地研究了非线性输出多采样反馈控制器及摄动非线性系统．给出了这类非线性输出多采样数字控制系统及其摄动系统的稳定性和鲁棒性条件．     

Sampled‐data control of nonlinear networked systems with time‐delay and quantization

In this paper, the stabilization problem of a class of nonlinear networked systems with time‐delay and quantization through sampled‐data control is investigated. With sampled‐data control, sufficient conditions to guarantee the trivial solution of the nonlinear networked system to be asymptotically stable without any quantization or with uniform quantization are derived. Finally, an example of a continuous‐time nonlinear system controlled through a digital controller and a communication channel is given to illustrate the effectiveness of the proposed control methods. Copyright © 2015 John Wiley & Sons, Ltd.     

非线性系统的鲁棒采样最优控制

采样系统控制作为一种数字控制的直接设计方法,近年来引起了广泛的重视,另一方面系统的时域约束在工业控制中是不可避免的。利用实用稳定性理论,研究了具有输出约束的一类非线性系统的鲁棒采样最优控制问题,结果表示为一些矩阵不等式,最后给了出了一个迭代算法。     

保代价采样控制在打浆过程中的应用

针对打浆过程计算机控制系统提出了保代价采样控制,当系统存在结构不确定时,该方法能使系统闭环鲁棒稳定,且系统的性能指标达到一定的要求,理论分析和仿真结果表明,保代价采样控制是打浆过程一种有效可行的控制方案。     

非均匀采样数据系统时变故障估计与调节最优集成设计

针对一类发生连续时变故障的非均匀采样数据系统,建立了一套主动容错控制最优设计方案. 首先,为了实现基于非均匀离散采样输出对连续故障的估计,同时鉴于现有自适应故障诊断方法无法直接推广于非均匀采样数据系统,提出一种连续时间增广观测器最优设计方法,既能保证故障估计误差快速收敛同时又对外界干扰鲁棒;并且提出一个迭代算法对故障估计延迟与系统鲁棒性进行权衡;进一步地,基于所获得的故障信息,并考虑估计误差和时变故障内采样特性对容错控制带来的不利因素,设计基于状态反馈的非均匀采样容错控制器来快速恢复故障系统性能;最后,通过对四容水箱基准实例的仿真来验证所提方法的有效性.     

Global finite‐time stabilization for a class of high‐order switched nonlinear systems via sampled‐data control

This paper investigates the global finite‐time stabilization for a class of high‐order switched nonlinear systems via the sampled‐data output feedback control. Firstly, we design a continuous‐time output feedback controller for the nominal part via adding a power integrator technique. Based on the homogeneous theory, together with the Gronwall‐Bellman inequality, a sampled‐data output feedback controller is designed with suitable sampling periods to ensure that the closed‐loop system can be globally stabilized in finite time. In the meantime, the proposed control method can be extended to the switched nonlinear systems with an upper‐triangular growth condition. Finally, two examples are presented to illustrate the validity of the proposed control scheme.     

Sampled‐data H∞ control for networked systems with random packet dropouts

This paper is concerned with the H_∞ control problem for networked control systems (NCSs) with random packet dropouts. The NCS is modeled as a sampled‐data system which involves a continuous plant, a digital controller, an event‐driven holder and network channels. In this model, two types of packet dropouts in the sensor‐to‐controller (S/C) side and controller‐to‐actuator (C/A) side are both considered, and are described by two mutually independent stochastic variables satisfying the Bernoulli binary distribution. By applying an input/output delay approach, the sampled‐data NCS is transformed into a continuous time‐delay system with stochastic parameters. An observer‐based control scheme is designed such that the closed‐loop NCS is stochastically exponentially mean‐square stable and the prescribed H_∞ disturbance attenuation level is also achieved. The controller design problem is transformed into a feasibility problem for a set of linear matrix inequalities (LMIs). A numerical example is given to illustrate the effectiveness of the proposed design method. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

时滞系统采样迭代学习控制

针对一类具有状态时滞的连续系统提出一种采样迭代学习控制算法。给出并证明了算法指数收敛的充分条件,该条件可保证系统输出无论在采样点或非采样点上,都能以指数收敛速率收敛至期望输出的一个与采样周期有关的误差范围内。仿真结果表明了该算法的有效性。     

Event‐triggered adaptive backstepping control for parametric strict‐feedback nonlinear systems

This paper proposes a novel adaptive backstepping control method for parametric strict‐feedback nonlinear systems with event‐sampled state and input vectors via impulsive dynamical systems tools. In the design procedure, both the parameter estimator and the controller are aperiodically updated only at the event‐sampled instants. An adaptive event sampling condition is designed to determine the event sampling instants. A positive lower bound on the minimal intersample time is provided to avoid Zeno behavior. The closed‐loop stability of the adaptive event‐triggered control system is rigorously proved via Lyapunov analysis for both the continuous and jump dynamics. Compared with the periodic updates in the traditional adaptive backstepping design, the proposed method can reduce the computation and the transmission cost. The effectiveness of the proposed method is illustrated using 2 simulation examples.     

采样控制系统时间响应特性及其计算方法

本文针对采样控制系统连续信号与离散信号共存的特点，指出传统离散比分析方法因忽略了系统在采样时刻之间的信息导致无法精确、真实地反映采样控制系统的时间响应特性，在此基础上，应用采样控制系统直接设计方法，基于提升技术，在考虑系统在采样时刻之间全部信息的条件下，推导给出了采样控制系统时间响应的计算方法，最后通过一个具体计算实例说明了本文方法的有效性。     

Adaptive stabilization of sampled systems

A simple discrete adaptive control scheme is proposed for stabilizing minimum phase continuous time systems under fast sampling. Even though the sampled system is not necessarily minimum phase, information about the pole-zero locations of the sampled system can be incorporated to complete the proof of stability.     

Global stabilization of a class of uncertain upper‐triangular systems under sampled‐data control

This paper considers the problem of using a sampled‐data controller to globally stabilize a class of uncertain upper‐triangular systems. First, we design a continuous‐time controller by integrating the nested saturation and Lyapunov design methods together. Then, the explicit formula for the maximum allowable sampling period is computed such that the discretized controller will guarantee global stability and robustness against uncertainties of the closed‐loop system. The bound of a proposed sampled‐data controller can be adjusted to any small level to accommodate the actuation bound in practical implementation. Copyright © 2012 John Wiley & Sons, Ltd.     

非线性系统的鲁棒采样控制

研究在汽车转向控制中遇到的、具有输出约束的一类非线性不确定系统的鲁棒采样 控制和鲁棒采样最优控制问题,结果表示为一些矩阵不等式.最后基于线性矩阵不等式,给出 了一个迭代算法和算例.数值计算实例证明了该算法的有效性.     

Robustness of linear uncertain sampled‐data control systems with generalized sampled‐data hold functions

This paper investigates robust stability of linear time‐invariant (LTI) uncertain sampled‐data control systems with generalized sampled‐data hold functions (GSHFs). A new sufficient condition for robust stability of such systems is developed. Unlike that of most of the previous works, it directly uses the data of the continuous‐time plant and therefore it is less conservative. The condition is expressed in terms of the spectral radius of a certain matrix and is shown to be a unimodal function of a free parameter. This property enabled us to use standard one‐dimensional optimization algorithm to perform the proposed test. Copyright © 2006 John Wiley & Sons, Ltd.     

引用广义保持器的采样系统——结构性质与自适应鲁棒控制

研究一类线性时变不确定系统的采样控制.分析了采用的广义保持器和离散化系统 的结构性质,提出了考虑微处理器主频和字长的自适应鲁棒采样控制方案,证明了闭环系统 的稳定性.针对倒摆系统进行了计算机仿真研究.     

Construction of linear time‐invariant equivalent plants for nonlinear continuous‐time and sampled‐data systems

In this paper, a technique is presented for constructing the so‐called linear time‐invariant equivalent (LTIE) plants used in the nonlinear quantitative feed back theory (QFT) approach. The proposed technique is applicable equally well to both continuous‐time and sampled‐data nonlinear plants described by nonlinear integro‐differential equation and nonlinear autoregressive moving average with exogenous inputs (NARMAX) models, respectively. The technique uses inclusion function and interval integration tools of interval analysis. A nonlinear chemical reactor example is used to illustrate the procedure for both nonlinear continuous‐time and sampled‐data systems, and found to yield satisfactory results in both cases. Copyright © 2003 John Wiley & Sons, Ltd.