Reduced-order robust compensator design with real parameter uncertainty

A method based on observer theory is presented for the construction of design equations for low-order controllers to provide H_∞ norm constraint for systems with real-parameter uncertainties. The multi-goal robust stability and performance problem is solved in terms of Riccati inequalities. A new design methodology is presented along with a numerical algorithm. An example is also included to demonstrate the proposed design method. © 1997 by John Wiley & Sons, Ltd.     

带边界非线性干扰的反稳定波方程的镇定

本文研究了一类具有边界控制匹配非线性干扰的反稳定波动方程的镇定问题. 本文只用了两个量测, 构造了一个无限维干扰估计器来实时估计状态和总干扰, 该估计器既不要求干扰的导数有界, 也不需要高增益. 基于估计的总干扰和估计的状态, 本文设计了输出反馈控制律稳定原系统. 此外, 本文还证明了闭环系统的其他状态是有界的. 为了说明理论结果, 下文给出了一些数值模拟.     

An adaptive disturbance rejection control scheme for multivariable nonlinear systems

An adaptive disturbance rejection control scheme is developed for uncertain multi-input multi-output nonlinear systems in the presence of unmatched input disturbances. The nominal output rejection scheme is first developed, for which the relative degree characterisation of the control and disturbance system models from multivariable nonlinear systems is specified as a key design condition for this disturbance output rejection design. The adaptive disturbance rejection control design is then completed by deriving an error model in terms of parameter errors and tracking error, and constructing adaptive parameter-updated laws and adaptive parameter projection algorithms. All closed-loop signals are guaranteed to be bounded and the plant output tracks a given reference output asymptotically despite the uncertainties of system and disturbance parameters. The developed adaptive disturbance rejection scheme is applied to turbulence compensation for aircraft fight control. Simulation results from a benchmark aircraft model verify the desired system performance.     

Adaptive algorithms for the rejection of sinusoidal disturbances with unknown frequency

Two algorithms are presented for the rejection of sinusoidal disturbances with unknown frequency. The first is an indirect algorithm where the frequency of the disturbance is estimated, and the estimate is used in another adaptive algorithm that adjusts the magnitude and phase of the input needed to cancel the effect of the disturbance. A direct algorithm that uses the concept of a phase-locked loop is also presented in which frequency estimation and disturbance cancellation are performed simultaneously. Approximate analyses are presented for both schemes and the results are found useful for the selection of the design parameters. Simulations are given which demonstrate the validity of the analytical results and the ability of the algorithms to reject sinusoidal disturbances with unknown frequency. The indirect algorithm is found to have a larger capture region for the parameter estimates, whereas the direct algorithm has superior convergence properties locally about the optimum parameter estimates     

State and Output Feedback Certainty Equivalence M‐MRAC for Systems with Unmatched Uncertainties

The paper presents a certainty equivalence indirect adaptive control design method for parametric strict feedback nonlinear systems of any relative degree with unmatched uncertainties in state and output feedback settings. The approach is based on the parameter identification (estimation) model, which is completely separated from the control design and is capable of producing parameter estimates as fast as the computing power allows. It is shown that the system's input and output tracking errors can be systematically decreased by the proper choice of the design parameters.     

不确定Euler-Bernoulli梁方程的边界输出跟踪

本文讨论边界带有控制输入非同位的内部不确定和外部扰动的Euler-Bernoulli梁方程输出跟踪问题. 为处理边界干扰, 文章首先设计了一个新的总扰动估计器, 在线估计未知扰动. 其次基于估计出来的总扰动, 设计一个伺服系统跟踪参考信号. 最后根据自抗扰方法获得控制输出跟踪的反馈控制. 闭环系统被证明是适定和有界的, 且受控系统的输出指数跟踪参考信号.     

二阶自抗扰控制器的参数简化

为了克服PID控制器自身具有的缺陷,在PID的基础上提出了自抗扰控制器（ADRC）。该控制器由跟踪微分器、扩张状态观测器和非线性状态误差反馈三部分组成,其控制效果优于经典PID控制器,但是参数众多、调节复杂。通过线性简化和参数整合建立简化的线性自抗扰控制器。MATLAB仿真表明,简化的线性自抗扰控制器参数调节过程大大简化,而控制性能并未受到明显影响。     

自抗扰控制对具边界扰动和区间内反阻尼的波动方程的镇定

本文讨论边界具有外部扰动和区域内具有反阻尼的一维波动方程的的镇定问题. 主要的方法是后退反演变换和自抗扰控制方法. 即通过扩张状态观测器将扰动在线估计并在反馈控制中实时消除. 本文在扩张状态观测器中使用了两种增益调整策略——常数高增益与时变增益. 为避免常数高增益带来的峰值问题, 在控制环节中使用了饱和方法. 时变的增益可以在很大程度上减少扩张状态观测器中由于常数高增益引起的峰值问题同时可以达到完全消除干扰的镇定效果.     

自抗扰控制对边界带有干扰的非线性sine-Gordon方程的镇定

本文讨论边界具有内部不确定和外部扰动的非线性sine-Gordon方程的镇定问题. 为处理sine-Gordon方程中的非线性项, 文章给出一个新的总扰动观测器在线估计未知扰动, 并通过自抗扰控制方法, 设计一个控制器使得在反馈控制中实时补偿(消除)总扰动. 闭环系统被证明适定的并且受控系统是指数稳定而扰动观测器是有界的. 数值模拟说明提出方法的有效性.     

Experiments with a very fast substring search algorithm

Sunday devised string matching methods that are generally faster than the Boyer-Moore algorithm. His fastest method used statistics of the language being scanned to determine the order in which character pairs are to be compared. In this paper the performances of similar, but language-independent, algorithms are examined. Results comparable with language-based algorithms can be achieved with an adaptive technique. In terms of character comparisons, a faster algorithm than Sunday's is constructed by using the larger of two pattern shifts.     

基于自抗扰控制的机器人定位策略

机器人定位即需根据传感器测量对自身位置进行估计. 由于机器人系统模型的复杂非线性, 工况环境中的不确定干扰, 定位结果不可避免地会受到系统内外扰动的影响. 现有的定位算法往往仅能依赖模型或传感配置以及算法自身的鲁棒性被动抗扰, 这使得定位系统的抗扰能力有限、应用场景受限. 本文基于自抗扰控制思想提出一种 能够主动补偿系统内外扰动的机器人定位策略. 该策略将系统中所有能够影响最终定位结果的不确定因素统一视为总扰动, 并设计扩张状态观测器实现对总扰动的观测, 在此基础上构建控制器补偿总扰动影响, 以使定位结果更加准确. 与传统的定位抗扰策略相比, 本文所提出的抗扰定位策略并不依赖于模型或特定的传感配置, 能够处理任意有界的扰动类型, 理论上能够成为定位抗干扰的终极解决路径. 最后, 基于李雅普诺夫理论证明了系统的稳定性. 仿真和实车实验验证了本文提出的基于自抗扰控制的机器人定位策略能够有效地观测系统总扰动, 并补偿扰动影响, 提高定位结果的准确度.     

On tracking and disturbance rejection by adaptive control

For linear minimum-phase relative-degree-one systems subject to disturbances and nonlinear perturbations, results pertaining to disturbance rejection and adaptive tracking of constant reference signals are presented and discussed in the context of related results in the literature.