Robust H_∞ and H_2 Static Output Feedback Control of Discrete-time Piecewise Affine Singular Systems with Norm-bounded Uncertainties

This paper is concerned with the problem of designing robust H∞and H2static output feedback controllers for a class of discrete-time piecewise-affine singular systems with norm-bounded time-varying parameters uncertainties. Based on a piecewise singular Lyapunov function combined with S-procedure,Projection lemma and some matrix inequality convexifying techniques,sufficient conditions in terms of linear matrix inequalities are given for the existence of an output-feedback controller for the discrete-time piecewiseaffine singular systems with a prescribed H∞disturbance attenuation level,and the H2norm is smaller than a given positive number. It is shown that the controller gains can be obtained by solving a family of LMIs parameterized by one or two scalar variables. The numerical examples are given to illustrate the effectiveness of the proposed design methods.

Global Robust and Adaptive Output Feedback Dynamic Positioning of Surface Ships

A constructive method was presented to design a global robust and adaptive output feedback controller for dynamic positioning of surface ships under environmental disturbances induced by waves, wind, and ocean currents. The ship's parameters were not required to be known. An adaptive observer was first designed to estimate the ship's velocities and parameters. The ship position measurements were also passed through the adaptive observer to reduce high frequency measurement noise from entering the control system. Using these estimate signals, the control was then designed based on Lyapunov's direct method to force the ship's position and orientation to globally asymptotically converge to desired values. Simulation results illustrate the effectiveness of the proposed control system. In conclusion, the paper presented a new method to design an effective control system for dynamic positioning of surface ships.

Observer-based H-infinity output feedback control with feedback gain and observer gain variations for Delta operator system

Considering that the controller feedback gain and the observer gain are of additive norm-bounded variations, a design method of observer-based H-infinity output feedback controller for uncertain Delta operator systems is proposed in this paper. A sufficient condition of such controllers is presented in linear matrix inequality （LMI） forms. A numerical example is then given to illustrate the effectiveness of this method, that is, the obtained controller guarantees the closed-loop system asymptotically stable and the expected H-infinity performance even if the controller feedback gain and the observer gain are varied.

Output Feedback Controller Design for Discrete-time Switched Singular Systems

This paper is concerned with the problems of robust admissibility and static output feedback( SOF)stabilization for a class of discrete-time switched singular systems with norm-bounded parametric uncertainties.The objective is to design a suitable robust SOF controller guaranteeing the regularity,causality and asymptotic stability of the resulting closed-loop system under arbitrary switching laws. Based on the basic matrix inequality sufficient condition for checking the admissibility of switched singular systems,together with some matrix inequality convexifying techniques,the SOF controller synthesis is developed for the underlying systems. It is shown that the controller gains can be obtained by solving a set of strict linear matrix inequalities( LMIs). A simulation example is given to show the effectiveness of the proposed method.

Robust output-feedback stabilization of a class of nonlinear systems with the nonlinearities of varied form

The back-stepping designs based on confine functions are suggested for the robust output-feedback global stabilization of a class of nonlinear continuous systems; the proposed stabilizer is efficient for the nonlinear continuous systems confined by a bound function, the nonlinearities of the systems may be of varied forms or uncertain; the designed stabilizer is robust means that a class of nonlinear continuous systems can be stabilized by the same output feedback stabilization schemes; numerical simulation examples are given.

Output Feedback Nonlinear General Integral Control

This paper proposes an output feedback nonlinear general integral controller for a class of uncertain nonlinear system. By solving Lyapunov equation, we demonstrate a new proposition on Equal ratio gain technique. By using Equal ratio gain technique, Singular perturbation technique and Lyapunov method, theorem to ensure regionally as well as semi-globally exponential stability is established in terms of some bounded information. Moreover, a real time method to evaluate the ratio coefficients of controller and observer are proposed such that their values can be chosen moderately. Theoretical analysis and simulation results show that not only output feedback nonlinear general integral control has the striking robustness but also the organic combination of Equal ratio gain technique and Singular perturbation technique constitutes a powerful tool to solve the output feedback control design problem of dynamics with the nonlinear and uncertain actions.

Optimal Guaranteed Cost Control via Static Output Fedback for Uncertain Discrete-Time Systems

目的研究在状态空间模型中的状态及控制矩阵中含有范数有界参数不确定线性离散系统的最优保价静态输出反馈控制问题．方法给出了系统二次代价指标的一个上界，并利用拉格朗日乘子法优化了该界．结果与结论给出了保证闭环系统二次稳定且使得二次代价指标界达到最小的静态输出反馈控制器存在的充分条件．并提供了一个求解输出反馈增益的数值算法．

Robust H_∞ control for aseismic structures with uncertainties in model parameters

This paper presents a robust H∞ output feedback control approach for structural systems with uncertainties in model parameters by using available acceleration measurements and proposes conditions for the existence of such a robust output feedback controller. The uncertainties of structural stiffness, damping and mass parameters are assumed to be norm-bounded. The proposed control approach is formulated within the framework of linear matrix inequalities, for which existing convex optimization techniques, such as the LM1 toolbox in MATLAB, can be used effectively and conveniently. To illustrate the effectiveness of the proposed robust H∞ strategy, a six-story building was subjected both to the 1940 E1 Centro earthquake record and to a suddenly applied Kanai-Tajimi filtered white noise random excitation. The results show that the proposed robust H∞ controller provides satisfactory results with or without variation of the structural stiffness, damping and mass parameters.

General Integral Control Design via Feedback Linearization

Based on the feedback linearization technique, we present a systematic design method for the General Integral Control and a new integral control strategy along with a class of fire-new integrator. By using the linear system theory and Lyapunov method along with LaSalle’s invariance principle, the conditions on the control gains to ensure regionally as well as semi-globally asymptotic stability are provided. Theoretical analysis and simulation results demonstrated that: by using this design method, General Integral Control can deal with nonlinearity and uncertainties of dynamics more effectively;the optimum response can be achieved in the whole control domain, even under uncertain payload and varying-time disturbances. This means that General Integral Control has strong robustness, fast convergence, good flexibility, and then makes the engineers design a high performance controller more easily.

Robust Admissibility and Stabilization of Uncertain Singular Fractional-Order Linear Time-Invariant Systems

This paper addresses the robust admissibility problem in singular fractional-order continuous time systems. It is based on new admissibility conditions of singular fractional-order systems expressed in a set of strict linear matrix inequalities(LMIs). Then, a static output feedback controller is designed for the uncertain closed-loop system to be admissible. Numerical examples are given to illustrate the proposed methods.

基于相空间三维动态稳定域的重型车辆稳定性控制策略研究

重型商用车存在转动惯量大、控制响应慢等特点。针对重型商用车,基于质心侧偏角、横摆角速度、垂向载荷转移系数设计了三维相空间分析方法,从而判断车辆的实时稳定状态。针对不同的车辆行驶状态,采用AFS控制和AFS/DYC分级控制,并基于利用附着系数设计了可拓控制方法,从而补偿前轮转角和横摆力矩的控制输出,以保证控制器在不同工况下的鲁棒性。通过TruckSim/Simulink联合仿真和硬件在环实验验证了该方法的有效性,并在仿真中通过B-ψ^(·)-LTR判断和B-ψ^(·)判断对比证明了相空间动态稳定域的优越性。仿真和实验结果表明:相比单纯以驾驶员意图操纵车辆,所设计的基于可拓H_(∞)的AFS/DYC分级控制策略可以保证车辆在不同工况下的稳定性,尤其在低附着路面上表现出更好的稳定性,可有效降低车辆在极端工况下发生交通事故的概率。

船舶纵向运动多输入多输出不稳定系统的非线性反馈控制

为了提高多输入多输出(MIMO)不稳定系统控制器的鲁棒性与节能效果,以大连海事大学教学实习船“育鲲”轮在波浪上纵摇和升沉运动的数学模型为研究对象,将数学模型的分子分母具有不稳定零极点过程使用根轨迹成形技术以及引用数学工具加权矩阵将其根轨迹拉到左半平面.之后运用闭环增益成形算法设计控制器的思路,以成形后的模型用一阶闭环增益成形算法设计鲁棒控制器,再引入双极性S函数驱动的非线性反馈代替原有的误差线性反馈.从仿真结果可以看出,在模型产生摄动时,非线性反馈控制改进了升沉和纵摇,控制能量大幅减少,对模型干扰具有鲁棒性能.该方案求解过程简单,并且整个系统控制器与被控对象物理意义明确,设计所得的控制器阶次较低,且补充完善了MIMO不稳定系统的控制器设计方法.

改进的扰动LPV系统输出反馈预测控制

针对一类带有有界状态干扰的多胞描述LPV系统,文中提出了一种鲁棒预测控制改进方法,并设计了保证系统渐近稳定的输出反馈控制器。为抵消有界状态干扰,该控制器考虑无扰动LPV系统,基于离线状态观测器,采用线性矩阵不等式求解预测控制无穷时域最小-最大优化问题。随后利用离线状态观测器获得扰动LPV系统与无扰动LPV系统状态的估计值之差,以确定保性能的反馈增益,从而得到使扰动LPV系统渐近稳定的最优偏移量,并将其与无扰动系统控制律组合作为最优控制律施加于实际系统。实验结果表明,运用改进的鲁棒预测控制方法能获得较好地控制性能,同时提高了系统的稳定性和解决优化问题的效率,仿真试验也验证了该算法的有效性。

基于输出反馈的鲁棒模型预测多步控制

针对具有持续有界扰动的线性系统,采用基于输出反馈的鲁棒模型预测多步控制算法实现系统的稳定控制。离线算法通过预设一系列渐近趋于稳定点的观测状态变量,由可行性问题求解和多步控制方法的优化方式得到控制可行域较大的嵌套椭圆集。在线算法根据当前观测状态变量在嵌套椭圆集的位置,优化构建新的椭圆集,得到与观测状态变量相对应的控制律,实现系统的精确控制。给出了算法的详细步骤和在线优化构建椭圆集的可行性证明。仿真结果验证了所提算法的有效性,表明所提算法可实现对具有持续有界扰动的线性系统的快速稳定控制。

基于啤酒发酵过程的时变轨迹输出反馈鲁棒模糊预测控制

考虑到实际生产中状态不易测量和设定值变化的情况以及系统本身的非线性特性,针对啤酒发酵过程温度控制系统提出了一种时变轨迹下输出反馈鲁棒模糊预测控制方法;在啤酒发酵罐温度系统的机理模型的基础上,建立包括不确定性和未知干扰的状态空间模型;通过设计模糊集,建立为具有加权系数的T-S模糊状态空间模型;并在状态变量的中引入输出跟踪误差,建立新型多自由度状态空间模型;并运用鲁棒模型预测控制方法优化参数不确定性问题,结合李雅普诺夫稳定性理论推导出线性矩阵不等式形式的稳定性条件,通过求解线性矩阵不等式中参数来计算对应子模型控制律,并对所设计的输出反馈控制器给定权值;通过仿真结果验证了提出方法的有效性和可行性。

基于动态观测器的不确定机器人鲁棒控制研究

针对仅有精确位置测量的机器人系统 ,在系统参数不确定和有界干扰并存的情况下 ,提出一种基于速度观测的鲁棒控制方案。在滑模观测器设计中引入补偿项 ,动态抵消系统偏差对速度重构的影响 ,确保观测误差指数收敛到有界域。采用Lyapunov直接法设计基于标称模型和观测速度的鲁棒控制律 ,使系统闭环满足局部一致最终有界收敛。

一类不确定非线性系统的鲁棒输出反馈控制

本文考虑一类具有输出反馈标准形的非线性系统的输出反馈控制问题．为了给出其不同于自适应控制的解决办法，设计出了新的鲁棒输出反馈控制方案。该方案不需辨识系统未知参数，也不需知道未知参数向量的上界，就能保证所有控制系统信号的全局有界性．并且通过控制器参数的适当选择，可以使系统跟踪误差达到任意小．仿真结果表明可以获得良好的跟踪效果．

不确定长时延网络控制系统的H_∞鲁棒控制

在状态不完全可测的网络控制系统中,针对不确定网络长时延、网络噪声等问题系统性能造成的影响,研究了一类具有不确定长时延网络控制系统的H∞鲁棒控制问题。在不确定网络时延大于一个采样周期时,将采用动态输出反馈的网络控制系统建模为一类具有参数不确定性的线性离散系统。基于Lyapunov稳定性理论和线性矩阵不等式(LMI)方法,导出了闭环系统渐近稳定且满足给定H∞性能指标的充分条件,并给出了输出反馈控制器的设计方法。通过仿真算例证明了该方法的有效性。