轧辊偏心的H∞输出反馈鲁棒重复控制

针对轧辊偏心问题,用线性矩阵不等式(LMI)方法设计了用于轧辊偏心补偿控制的H∞输出反馈鲁棒重复控制器,首先引入动态输出反馈来保证闭环系统的鲁棒稳定性,把重复控制器设计问题转化为H∞动态反馈控制器的设计问题,采用变量替换法将非线性矩阵不等式转化为线性矩阵不等式并对其求解进而得到控制器参数.另外在采用上述控制器保证系统鲁棒稳定性的同时,通过在重复控制器中引入一个前向系数进一步改善和提高系统的动态性能与稳态控制精度.理论证明与仿真研究表明当系统对象参数存在摄动时,这种控制器仍能有效地补偿轧辊偏心对产品质量的影响.     

基于H∞控制理论的2-DOF内模控制器设计及其在电力系统中的应用

给出一种基于H_∞控制理论的二自由度内模控制器设计方法.考虑了标称模型与实际模型之间存在乘性摄动时的失配性,利用适当的状态变换,将跟踪问题的控制器设计转化成一个调节问题的标准H_∞控制器设计问题,再利用H_∞输出动态反馈完成了控制器设计.以电力系统模型为例设计了一个二自由度H_∞励磁控制器,仿真结果表明了此控制器的有效性.     

Observer‐based compensation control of servo systems with backlash

For compensating backlash phenomenon in servo systems, the authors propose an observer method in this paper to estimate both system states and vibration torque before controller design. First, a systematic scheme is given to obtain plant parameters, which is very important in observing system states. This is a parameter estimation principle that gives a crude estimation and computes the differences between the crude and true values. As a result, the precise value of the parameters is obtained by adding together the crude value and the difference. Then, based on the precise estimated parameters, an extended state observer (ESO) is designed to obtain feedback and feedforward signals. Consequently, robust compensation control is achieved by designing an output feedback controller, consisting of a feedback term and a feedforward term. Finally, in order to validate the proposed approach, extensive experiments are performed on a practical servo system with backlash nonlinearity.     

Constraint feedforward control for thermal processing of quartz photomasks in microelectronics manufacturing

A feedforward control scheme is designed to improve performance of conductive heating systems used for lithography in microelectronics processing. It minimizes the loading effects induced by the common processing condition of placement of a quartz photomask at ambient temperature on a bake plate at processing temperature. The feedforward control strategy is a model-based method using linear programming to minimize the worst-case deviation from a nominal temperature set-point during the load disturbance condition. This results in a predictive controller that performs a pre-determined heating sequence prior to the arrival of the substrate as part of the resulting feedforward/feedback strategy to eliminate the load disturbance. This procedure is based on an empirical model generated from data obtained during closed-loop operation. It is easy to design and implement for conventional thermal processing equipment. Experimental results are performed for two commercial bake plates and depict an order-of-magnitude improvement in the settling time and the integral-square temperature error between the optimal predictive controller and a feedback controller for a typical load disturbance.     

驻留概率信息方法的离散切换系统鲁棒H∞控制

本文通过驻留概率信息的方法,研究了一类离散时间切换系统的鲁棒H∞控制问题.通过对切换系统在每个子系统的驻留概率信息加以利用,建立一种新的切换系统模型.通过共同Lyapunov泛函方法,给出切换系统的鲁棒H∞随机稳定的充分条件.然后,利用锥补线性化的方法得到控制器增益.最后,通过仿真算例验证本文所用方法的有效性.     

基于H∞环路成形和自适应神经模糊推理系统的模糊控制器设计

H_∞环路成形方法设计的控制器阶次较高,不便于工程实现和参数调整;用传统方法确定模糊控制器隶属度函数的参数和模糊规则比较费时且难以保证鲁棒性能和时频域性能指标.针对上述情况,提出了一种综合运用H_∞环路成形和自适应神经模糊推理系统来设计模糊控制器的方法.首先采用H_∞环路成形设计方法,得到鲁棒裕量、动态和稳态性能都符合要求的控制器,然后用自适应神经模糊推理系统来逼近此控制器,最后根据自适应神经模糊推理系统参数确定相应的模糊控制器规则和参数.该方法确定模糊控制器隶属度函数的参数精确而省时,且能保证控制器具有较强的鲁棒性和良好的控制效果.通过对小车倒立摆系统进行的仿真,验证了该控制器设计方法的有效性.     

混合H2/H∞鲁棒控制器设计

在状态空间描述下,定义了混合H₂/H_∞控制的完整信息、完整控制、干扰顺馈、输出估计这4种典型情况.在二次稳定意义上,讨论了混合H₂/H_∞的性能指标,及这4种典型情况的混合H₂/H_∞线性反馈控制器设计,给出了充分必要条件.在典型情况分析的基础上,研究一般意义上的混合H₂/H_∞反馈控制器设计.H₂和H_∞的干扰输入阵及性能评价函数各不相同时的混合H₂/H_∞反馈控制器,与H₂和H_∞控制器设计相似,归结为解两个Riccati方程.但这两个Riccati方程含有参数,最优解要通过搜索这两个参数得到.结果包含了单纯的H₂和H_∞设计,可看作是H₂,H_∞和混合H₂/H_∞的统一设计方法.最后通过一个简单的例子,说明了控制器设计方法的可行性.     

Dynamics and control of benzene hydrogenation via reactive distillation

This work develops a dynamic, first principles-based model of a reactive distillation column used for benzene hydrogenation of a reformate stream and investigates different control structures for this process. The model is used initially to develop and evaluate a feedback control strategy which provides good regulatory performance for small disturbances, however, it tends to be sluggish for significant disturbances in the feed composition. In order to address this point, adding a feedforward controller to the feedback structure has also been investigated. However, the feedforward controller can only be implemented if composition measurements of the feed are taken. As online composition measurements are expensive in practice, several different scenarios have been investigated where samples of the feed are taken and subsequently analyzed in a lab, as represented by measurement time delays. Simulation results show that adding feedforward control to the feedback scheme can be very beneficial for this process, however, this is only the case if the composition disturbance measurements do not involve a significant time delay.     

The variable structure controller design for a class of nonlinear uncertain systems based on robust observer

The variable structure controller is designed for a class of nonlinear uncertain time-delay system by using robust observer, and incorporating H-infinity control technique, the controller can guarantee the H-infinity performance of sliding mode dynamics and satisfy the reaching condition, which also does not require uncertainties to satisfy matching condition and linear boundary condition. The simulation example is given to illustrate the method.     

Sliding mode control of singularly perturbed systems and its application in quad-rotors

This paper presents a sliding mode control scheme for tracking control of nonlinear singularly perturbed systems in the presence of model errors and external disturbances. A dual-loop feedback control is developed to provide accurate tracking capability and sufficient robustness to system uncertainties. A sliding mode controller is proposed in the outer-loop feedback design such that the plant states are stabilised for given reference trajectories, while an additional robust controller is designed in the inner loop to increase the adaptability to uncertainties, and reduce the effect of unmodelled high-frequency dynamics on plant dynamics. An appealing feature of the control scheme is the attenuation of chattering. The effectiveness and merits of the new control scheme developed are shown via a verification example of velocity control of a quad-rotor.     

电压畸变条件下三相三线有源电力滤波器的T–S模糊H∞控制

有源电力滤波器(APF)是解决电力系统谐波治理的有效方法, 由于电源电压存在畸变影响了APF的补偿参考电流的检测精度并影响补偿的效果. 本文采用T–S模糊控制的方法对三相三线APF进行建模, 将电源电压的畸变成分作为理想情况的干扰, 在保性能的前提下给定性能指标, 实现T–S模糊H∞控制性能. 在满足稳定性的要求条件下, 设计的T–S模糊H∞状态反馈控制器使APF在电源电压畸变的情况下, 将电源电流补偿为正弦特性, 满足了APF谐波综合补偿的控制要求. 仿真结果验证了所建T–S模糊模型的有效性, 展示出所设计的H∞控制器的有效性能. 补偿电流可以准确的检测, 在电源电压非正弦条件下可以进行有效的控制.     

Model reference adaptive control for plants with unknown relativedegree

A parameterization scheme for model reference control which guarantees stable model-plant transfer function matching is presented. This scheme has a linear dynamic feedforward block whose numerator and denominator should be stable polynomials for closed-loop stability. An adaptive law is designed to update the controller parameters in the feedback loop and the coefficients of the numerator of the feedforward block as well as some additional parameters. Since, for stability, the inverse of the polynomial differential operator defined by some of the estimated parameters has to be stable, the adaptive law is modified using a projection technique. The stability analysis of the model reference adaptive control (MRAC) scheme is given. The robustness of the MRAC scheme with respect to unmodeled dynamics is established     

Model reference adaptive control of discrete‐time piecewise linear systems

This article presents a switched model reference adaptive controller for discrete‐time piecewise linear systems. In the spirit of the work by Landau in the late seventies, proof of asymptotic stability of the closed‐loop error system is obtained, recasting its dynamics as a feedback system and showing the feedforward and the feedback paths are both passive. The challenge is that both paths can be piecewise linear. Numerical results show excellent performance of the proposed controller even in the face of sudden variations of the plant parameters. Copyright © 2012 John Wiley & Sons, Ltd.     

一种新的非线性离散时间系统迭代学习控制的前馈－反馈机制

This paper presents a new feedback-feedforward configuration for the iterative learning control (ILC) design withfeedback, which consists of a feedback and a feedforward component. The feedback integral controller stabilizes the system,and takes the dominant role during the operation, and the feed-forward ILC compensates for the repeatable nonlinear/unknowntime-varying dynamics and disturbances, thereby enhancing the performance achieved by feedback control alone. As the mostfavorable point of this control strategy, the feedforward ILC and the feedback control can work either independently or jointlywithout making efforts to recongurate or retune the feedforward/feedback gains. With rigorous analysis, the proposedlearning control scheme guarantees the asymptotic convergences along the iteration axis.     

柴油发电机组非线性H2/H∞综合控制器

独立电力系统的稳定性主要取决于柴油发电机组的转速和电压响应特性.柴油发电机组控制系统是一个非线性控制系统,转速和电压相互作用,对二者进行综合控制非常必要.为了分析系统的动态特性,首先建立柴油发电机组的非线性数学模型,然后以此为基础设计非线性H2/H∞综合控制器.将直接反馈线性化和混合H2/H∞控制理论相结合应用于柴油发...     

线性离散时滞重复过程的H∞控制

首先给出了线性离散时滞重复过程的2D(两维)Roesser模型, 采用线性矩阵不等式方法导出了过程稳定并具有H_∞扰动抑制度的一个充分条件. 通过求一个线性矩阵不等式的可行解来构造系统的一个状态反馈H_∞控制器. 进一步, 通过求解一个线性矩阵不等式凸优化问题得到该过程的最优状态反馈H_∞控制器.     

正规和奇异H∞控制器的统一表达式

给出了一种新的H∞控制器设计方法,通过引入设计时可选的非奇异实数阵,取消了控制器设计时对D矩阵的秩限制.适用于正规的H∞控制问题和奇异的H∞控制问题.对状态反馈等四种典型问题和输出反馈控制问题,给出了控制器存在的充分必要条件.控制器通过Riccati方程的解,用参数化方法表示.输出反馈控制器,通过解两个Riccati方程得到.讨论了控制器的相关特性.     

Robot learning control based on recurrent neural network inverse model

A non-linear model-based feedforward, feedback, and learning controller is presented. This controller can control a non-linear plant such as a robot whose dynamics are initially unknown. In the feedforward part, a recurrent neural network (RNN) is used to model the inverse dynamics of the plant. In the feedback part, a PD controller is added to handle unmodeled dynamics and disturbances. Furthermore, an add-on learning controller is established to reduce tracking errors for repetitive tasks. The controller is validated with the control of a simulated two-joint manipulator. Simulation results show that the controller can successfully learn the inverse dynamics of a robot, perform accurate tracking for a general trajectory, and improve its own performance over the repetitions of a trajectory, with and without a payload change. © 1997 John Wiley & Sons, Inc.     

Adaptive H-infinity control of synchronous generators with steam valve via Hamiltonian function method

Based on Hamiltonian formulation, this paper proposes a design approach to nonlinear feedback excitation control of synchronous generators with steam valve control, disturbances and unknown parameters. It is shown that the dynamics of the synchronous generators can be expressed as a dissipative Hamiltonian system, based on which an adaptive H-infinity controller is then designed for the systems by using the structure properties of dissipative Hamiltonian systems. Simulations show that the controller obtained in this paper is very effective.     

基于未知系统动态估计器的Buck型变换器快速固定时间控制

针对存在参数不确定、输入电压波动以及负载变化等未知动态的Buck型变换器系统,提出一种基于未知系统动态估计器的快速固定时间控制方法.首先,设计基于一阶低通滤波器的估计器,实现对系统未知动态的前馈补偿.在此基础上,基于输出电压误差和未知动态估计值设计固定时间滑模面和反馈控制器,保证输出电压快速收敛至参考电压附近邻域内,且...