Global output‐feedback control of systems with dynamic nonlinear input uncertainties through singular perturbation‐based dynamic scaling

A general class of uncertain nonlinear systems with dynamic input nonlinearities is considered. The system structure includes a core nominal subsystem of triangular structure with additive uncertain nonlinear functions, coupled uncertain nonlinear appended dynamics, and uncertain nonlinear input unmodeled dynamics. The control design is based on dual controller/observer dynamic high‐gain scaling with an additional dynamic scaling based on a singular perturbation‐like redesign to address the non‐affine and uncertain nature of the input appearance in the system dynamics. The proposed approach yields a constructive global robust adaptive output‐feedback control design that is robust to the dynamic input uncertainties and to uncertain nonlinear functions allowed throughout the system structure. Copyright © 2015 John Wiley & Sons, Ltd.     

Adaptive robust H∞ state feedback control for linear uncertain systems with time‐varying delay

This paper considers the problem of adaptive robust H_∞ state feedback control for linear uncertain systems with time‐varying delay. The uncertainties are assumed to be time varying, unknown, but bounded. A new adaptive robust H_∞ controller is presented, whose gains are updating automatically according to the online estimates of uncertain parameters. By combining an indirect adaptive control method and a linear matrix inequality method, sufficient conditions with less conservativeness than those of the corresponding controller with fixed gains are given to guarantee robust asymptotic stability and H_∞ performance of the closed‐loop systems. A numerical example and its simulation results are given to demonstrate the effectiveness and the benefits of the proposed method. Copyright © 2008 John Wiley & Sons, Ltd.     

H∞滑模鲁棒励磁控制器设计

电力系统的鲁棒励磁控制模型具有非线性和不确定性等特点。并且，其不确定不性满足匹配条件。该文结合反馈线性化、H∞干扰抑制和滑模变结构控制，利用反馈线性化技术，将鲁棒励磁控制模型转化为线性不确定模型；利用H∞干扰抑制技术，获得了具有抑制满足匹配条件干扰能力的动脉滑动模态；利用滑模变结构控制，获得了具有完全抑制满足匹配条件干扰的控制律。并设计了H∞滑模鲁棒励磁控制器。仿真结果表明：文中所设计的控制器能够有效地稳定电力系统。     

不确定微分代数系统的多指标非线性鲁棒自适应控制方法

针对含不确定因素的多输入多输出微分代数系统,提出一种多指标非线性鲁棒自适应控制方法(multi-index nonlinear robust adaptive control,MINRAC),并将其应用于汽门开度与发电机励磁的协调控制上。数字仿真表明：在系统参数不确定和存在外部扰动的情况下,该方法能够使得系统的多个指标都运行在期望的工作点上而不发生静态偏移。对于不同类型的扰动,如有功功率阶跃,三相短路,该控制方法都能很好地镇定系统,并且能够消除机端电压偏差。与多指标非线性控制(multi-index nonlinear control,MINC)和多指标非线性鲁棒控制(multi-index nonlinear robust control,MINRC)相比,该文提出的方法能更好地兼顾系统的动静态性能。     

不确定性电力系统鲁棒自适应励磁控制

为降低电力系统不确定参数和外部干扰在建模和控制设计中对系统品质的影响,利用Backstepping方法,递归构造闭环系统耗散不等式的能量存储函数,进而得到具有干扰抑制的反馈控制.推证了存储函数又是Lyapunov函数,保证闭环系统渐进稳定.设计过程用估计值代替不确定参数,故系统对不确定参数具有适应能力.仿真结果表明,该...     

基于扩张状态观测器的电力系统非线性鲁棒协调控制

该文提出了一种基于扩张状态观测器的非线性鲁棒协调控制方法(Extended-State-Observer based Nonlinear Robust Coordinated Control，ENRCC）；将电力系统对象归纳为一类内环为非线性系统、外环为伪线性系统的多输入多输出对象。在此基础上，完整地阐述了ENRCC的控制原理；利用一簇低阶扩张状态观测器对内环非线性系统进行动态反馈线性化和解耦设计，利用线性鲁棒控制方法对已线性化的内环系统和外环伪线性系统进行预期动力学设计，最终可实现观测器 线性化 鲁棒协调控制三者的有机结合。实例仿真结果表明：该控制规律严谨简单，方法原理直观清晰，便于工程应用，具有很强的适应性和鲁棒性，能有效地解决一类不确定 非线性 分散性的电力系统多输入多输出(MIMO)对象的控制问题。     

基于模糊逻辑的磁悬浮混合悬浮磁极控制方案

电磁永磁混合悬浮是电磁型(EMS)高速磁悬浮列车悬浮系统的发展方向之一,由于系统具有强非线性和慢时变的特点,传统的状态反馈控制在系统参数变化较大时有可能使系统失稳.本文在简要分析系统数学模型的基础上首先给出了传统的状态反馈控制器的设计方法,并在此基础上,提出了一种非线性模糊PD控制器结合线性加速度阻尼环节和线性积分环节的混合控制器.由于模糊控制器的设计过程综合了专家经验,从而使得整个系统更具有鲁棒性,并且动态特性也得到了改善,系统响应速度更快,超调量也更小.试验结果证明了该方案是正确的.     

Decentralized robust adaptive-output feedback controller for power system load frequency control

In this paper, a new model reference-decentralized robust adaptive-output feedback controller is proposed for the load frequency control (LFC) of large-scale power systems with unknown parameters. This control strategy requires only local input–output data and can follow random changes in the operating conditions. The controller is designed such that the trajectory errors and the control gains of each area remain uniformly bounded. In the proposed method, firstly an adaptive observer is designed to estimate the state variables and system parameters using local data only. Then a locally linear combination of the estimated states and the model reference states are used to design a robust adaptive-output feedback controller for each area. Simulation results for a three-area power system show that the proposed controller achieves good performance even in the presence of plant parameter changes and system non-linearities. Received: 18 October 2001/Accepted: 24 October 2001     

A convex optimization approach to adaptive stabilization of discrete‐time LTI systems with polytopic uncertainties

This paper suggests a simple convex optimization approach to state‐feedback adaptive stabilization problem for a class of discrete‐time LTI systems subject to polytopic uncertainties. The proposed method relies on estimating the uncertain parameters by solving an online optimization at each time step, such as a linear or quadratic programming, and then, on tuning the control law with that information, which can be conceptually viewed as a kind of gain‐scheduling or indirect adaptive control. Specifically, an admissible domain of stabilizing state‐feedback gain matrices is designed offline by means of linear matrix inequality problems, and based on the online estimation of the uncertain parameters, the state‐feedback gain matrix is calculated over the set of stabilizing feedback gains. The proposed stabilization algorithm guarantees the asymptotic stability of the overall closed‐loop control system. An example is given to show the effectiveness of the proposed approach. Copyright © 2014 John Wiley & Sons, Ltd.     

Adaptive robust control of a class of nonlinear systems in semi‐strict feedback form with non‐uniformly detectable unmeasured internal states

This paper proposes a novel control method for a special class of nonlinear systems in semi‐strict feedback form. The main characteristic of this class of systems is that the unmeasured internal states are non‐uniformly detectable, which means that no observer for these states can be designed to make the observation error exponentially converge to zero. In view of this, a projection‐based adaptive robust control law is developed in this paper for this kind of system. This method uses a projection‐type adaptation algorithm for the estimation of both the unknown parameters and the internal states. Robust feedback term is synthesized to make the system robust to uncertain nonlinearities and disturbances. Although the estimation error for both the unknown parameters and the internal states may not converge to zero, the tracking error of the closed‐loop system is proved to converge to zero asymptotically if the system has only parametric uncertainties. Furthermore, it is theoretically proved that all the signals are bounded, and the control algorithm is robust to bounded disturbances and uncertain nonlinearities with guaranteed output tracking transient performance and steady‐state accuracy in general. The class of system considered here has wide engineering applications, and a practical example—control of mechanical systems with dynamic friction—is used as a case study. Simulation results are obtained to demonstrate the applicability of the proposed control methodology. Copyright © 2010 John Wiley & Sons, Ltd.     

不确定组合时滞系统的鲁棒分散可靠控制

研究一类不确定组合时滞系统的状态反馈鲁棒分散可靠控制问题,系统包含状态时滞,非线性扰动和参数不确定性。目的是设计分散线性无记忆状态反馈控制器,使得对于任意容许的不确定性以及在每一个子系统中预先指定的执行器子集合内执行器的失效,相应的闭环系统渐近稳定。最后给出一个数值例子验证了本文所结结果的有效性。     

一类非线性系统的微分与积分滑模自适应控制及其在电液伺服系统中的应用

针对一类参数不确定的非线性系统，提出了一种微分与积分滑模自适应控制策略。在滑模控制中引入积分控制项，消除了传统滑模变结构控制需要被跟踪信号导数已知的假设，同时基于Lyapunov方法引入参数自适应律，使系统具有优良的抗干扰特点。利用一非线性微分控制减弱了参数自动调整阶段引起的系统抖动。给出了积分滑模控制中切换函数的定义方法，以及非线性微分控制中微分系数的非线性函数表达式。采用该控制方法，对电液伺服系统的液压缸位置进行跟踪控制。仿真结果显示，该方法具有较强的鲁棒性及良好的跟踪性能。     

基于鲁棒扰动观测器的交流电力弹簧反馈线性化解耦控制

交流电力弹簧(ACES)可有效抑制由高渗透率可再生能源发电引起的交流微电网有功功率波动,但ACES是典型的强耦合、非线性对象,而依赖于模型局部线性化的传统矢量控制难以实现存在不确性扰动情形下的宽范围功率精确控制.为此,文中提出一种基于鲁棒扰动观测器的ACES反馈线性化解耦控制方法.针对ACES的强耦合特性,构建了ACES两输入/两输出李导数仿射模型,设计了解耦矩阵,解耦矩阵与ACES耦合模型联合观测,可等效为全解耦的dq两相电流积分器,简化控制器设计.针对ACES的非线性特性,采用精确反馈线性化控制方法,设计状态变换矩阵,反馈线性化控制律与ACES非线性模型联合观测,可等效为完全线性化对象,采用简单线性控制,即可实现期望功率轨迹准确跟踪与系统全局渐进稳定运行.针对参数摄动影响精确反馈线性化控制性能的问题,设计了形式简单的鲁棒扰动观测器,消除不确性扰动对精确反馈线性化控制跟踪性能的影响.基于MATLAB/Simulink的仿真结果和基于dSPACE的实验结果表明所提方法具有结构简单、动态性能好、稳定域宽、鲁棒性强的特点.     

线性时滞不确定连续系统的鲁棒容错控制研究

以线性不确定时滞系统为模型,应用李雅普诺夫稳定性理论和LMI工具箱,采用状态反馈控制器设计连续系统的容错控制器,研究了线性不确定时滞连续系统的状态反馈鲁棒稳定问题.给出了系统在执行器失效情况下渐近稳定的充分条件及相应的状态反馈鲁棒容错控制器的设计方法,仿真结果验证了该方法的可靠性和有效性.     

基于状态反馈精确线性化Buck变换器的最优控制

加权矩阵的选取在最优反馈系统的综合设计中具有重要意义。该文基于无源性控制思想,提出一种二次型性能指标。应用状态空间平均建模法,建立电流连续型(current conduction mode,CCM)Buck变换器的仿射非线性模型。采用状态反馈精确线性化方法,推导出非线性状态反馈表达式,实现非线性系统的线性化。进一步,利用二次型最优控制对状态反馈反馈系数进行优化设计。所得控制律简单、容易实现。数值仿真验证了该控制方案的优越性,仿真波形对比分析显示与传统无源性控制方法相比,基于该控制方法的系统静态误差小,启动性能优越,且开关频率固定,对输入电压扰动和负载扰动均具有较强的鲁棒性。     

基于微分几何理论和自抗扰控制技术的励磁控制器设计

针对仿射非线性系统,通过微分几何坐标变换将系统非线性因素转换到含有控制输入的状态方程中.由于微分几何方法坐标变换本身是精确无误的,所以转换后的系统中,线性部分是精确的;系统参数的不确定、模型的不精确最终反映到转换后的非线性部分.利用自抗扰技术中的扩张状态观测器观测该部分的非线性摄动,通过反馈将其线性化并消除扰动.推导了单机无穷大系统的非线性励磁控制规律,在PSASP上进行仿真试验.理论论证和仿真试验证明该方案提高了非线性励磁控制的鲁棒性.     

非线性网络控制系统的双通道时延和丢包鲁棒H∞控制

研究了一类具有双通道时延和丢包的非线性不确定网络控制系统的鲁棒H∞镇定问题.将网络诱导时延和数据丢包对系统的影响,转化为服从Bernoulli二区间分布的等价时延,并考虑系统的不确定性和外部干扰问题,基于T-S模糊系统建立了非线性系统的新模型,通过构造Lyapunov-Krasovkii泛函和线性矩阵不等式方法,给出了...     

不确定非线性系统的鲁棒输出跟踪控制

基于状态反馈线性化,最优控制及Ｌｙａｐｕｎｏｖ方法,对不确定非线性系统进行了实际跟踪鲁棒控制策略研究,在一定的假设前提下,得到了一个光滑、简单、性能优良的控制器。仿真研究表明控制策略是可行的。     

电液伺服系统的积分滑模自适应控制

针对一类参数不确定的非线性系统,提出了一种积分滑模自适应控制策略.在滑模控制中引入积分控制项,消除了传统滑模变结构控制需要被跟踪信号导数已知的假设,同时基于Lyapunov方法引入参数自适应律,使系统具有优良的抗干扰特点.本文采用该控制方法,对电液伺服系统的液压缸位置进行跟踪控制.仿真结果显示,该方法具有较强的鲁棒性及良好的跟踪性能.     

基于微分同坯映射和扩张状态观测器的鲁棒励磁控制器设计

通过微分同坯映射将仿射非线性系统方程的非线性因素转换到含有控制输入的状态方程,转换后的系统中所有不确定项都归结到扩张状态变量中。利用扩张状态观测器观测该部分,并经状态反馈将其线性化。由于实际系统存在观测误差和模型误差,为了进一步考虑反馈线性之后系统的不确定性,将鲁棒控制引入励磁控制器的设计之中,使得设计的控制器具有更好的鲁棒性,最后在Matlab上进行仿真试验。仿真结果证明了该方法的有效性。