H∞回路成形中的μ综合法

H∞控制理论中的回路成形设计和μ综合都已经是定型的设计方法. 最近有文献提出一种将这两种设计方法结合起来处理弱阻尼谐振模态参数摄动的新方法. 但是实际设计表明, 二者的结合并没有达到预期的效果. 本文分析指出, 回路成形本质上是一种鲁棒稳定性设计, 其H∞范数指标的逆就是系统的稳定裕度. 而μ综合只是一种鲁棒性能的设计工具. μ综合与回路成形结合只是反映在稳定裕度上, 而并不影响设计所允许的摄动大小. 所以在回路成形设计中没有必要再加进μ综合法. 文中附有算例.     

μ-synthesis in H-infinity loop-shaping design

H∞控制理论中的回路成形设计和μ综合都已经是定型的设计方法．最近有文献提出一种将这两种设计方法结合起来处理弱阻尼谐振模态参数摄动的新方法．但是实际设计表明,二者的结合并没有达到预期的效果．本文分析指出,回路成形本质上是一种鲁棒稳定性设计,其H∞范数指标的逆就是系统的稳定裕度．而μ综合只是一种鲁棒性能的设计工具．μ综合与回路成形结合只是反映在稳定裕度上,而并不影响设计所允许的摄动大小．所以在回路成形设计中没有必要再加进μ综合法．文中附有算例．     

基于H∞范数优化的干扰观测器的鲁棒设计

研究干扰观测器的鲁棒优化设计方法, 应用H∞范数定义干扰观测器的优化性能评价函数, 把低通滤波器的设计问题转换为H∞闭环回路成形问题. 通过适当处理相对阶次条件等约束, 把带有约束的回路成形问题转换成无约束的H∞标准问题, 然后利用H∞标准问题的求解算法设计滤波器. 此外, 探讨了性能与频率加权函数的关系, 并在此基础上提出了加权函数的选取方法. 实验结果证明该方法设计简单, 且具有最优性和系统性.     

硬盘驱动器系统的DOBC与H_∞复合控制方法

针对影响硬盘驱动器(HDD)性能的2大主要因素-由硬盘驱动系统引起的干扰和磁头组件中挠性扁电缆引起的扭矩非线性干扰,提出HDD的磁头传动机构-音圈马达(VCM)的DOBC与H∞的复合控制方法.来自硬盘驱动系统的干扰可分为重复性干扰和非重复性干扰.其中的重复性干扰可以和挠性扁电缆引起的扭矩非线性干扰共同看成是VCM输入通道中的干扰,可由动态子系统生成,并用DOBC抵消.非重复性干扰可以和未建模动态、参数和结构的不确定性引起的建模误差、外部扰动共同看成是满足2范数有界的外干扰,并用H∞来抑制.通过将DOBC与H∞控制方法相结合,闭环系统在没有干扰信号时渐近稳定,在有干扰信号时满足H∞控制性能指标.通过IBM硬盘驱动器(DMDM-10340型)的仿真验证了该方法的有效性.     

基于 LMI 的广义系统混合H2/ H∞优化控制

研究了广义线性系统的混合H2／H∞状态反馈优化控制问题。设计一个混合H2／H∞状态反馈控制器，在满足闭环系统的容许性及H∞范数界的同时使得H2范数极小。利用线性矩阵不等式(LMI)方法得到该控制器存在的一个充分条件，并且给出闭环系统H2范数的极小上界。     

基于人工蜂群优化的环形二级倒立摆H∞鲁棒控制器设计

采用H∞回路成形控制方法实现环形二级倒立摆系统的平衡控制;对于H∞回路成形控制器来说,权函数的选择直接影响控制器性能,而往往权函数的选择是需要通过设计人员的不断试凑来完成,不仅设计效率低下,而且无法得到最优的控制性能;因此引入人工蜂群算法,依靠其优异的全局寻优能力,完成对H∞回路成形控制器权函数的求解并保证最优的控制器性能;仿真结果表明,蜂群算法能够寻优到最优的权函数参数,对应的H∞控制器能够保证环形二级倒立摆在受到外界干扰的情况下依然保持在平衡位置。     

参数γ对H∞控制系统动态特性的影响

鲁棒控制系统的H∞范数代表了这个系统的抗干扰性能指标,本文通过实例研究了H∞范数γ的取值对控制系统动态特性几个方面的影响,包括对系统初值扰动响应特性、系统干扰抑制效果以及对闭环系统H∞范数的影响.由于H∞范数只是反映控制系统某一方面的性能指标,当它趋向于最小值时,系统的其它各项重要的性能指标(例如H2范数和动态响应特性等)往往不一定令人满意.文中的计算结果表明,H∞范数最优值几乎是系统其它动态性能指标变化的一个转折点,当设计参数γ在其最小值γopt附近变化时,引起其它性能指标的变化非常剧烈.这些结果同时表明综合考虑系统的各项性能指标以选取合适的γ值尚需进一步的讨论.     

一类不确定非线性系统的鲁棒H∞控制

在一种工程应用背景之下,考虑了一类非线性系统的鲁棒H∞控制问题,不确定性范数有界,基于H JI不等式研究了状态反馈控制器设计问题,使得闭环系统满足H∞干扰抑制性能要求.     

一类线性串联时滞不确定系统的鲁棒H∞控制

本文讨论一类具有串联结构的线性不确定系统的鲁棒Ｈ∞控制器,此类系统除状态及控制输入具有滞后特性外,其状态的时滞常数也不相同。文中考虑用分段状态方程描述受控对象,分别设计相应的鲁棒Ｈ∞控制器,并证明了分段设计方法能保证整体系统在Ｈ∞范数界约束下二次型稳定。     

关联大系统的分散H∞/LTR控制

讨论关联大系统分散回路传递再生的设计问题.利用矩阵的奇异值分解技术,提出了对 关联项进行块对角化处理的一种新方法.基于H∞理论,将多变量系统的回路传递再生方法 推广于分散控制关联大系统,并避免了在所有可能的分散观测器增益构成的集合上,直接计算 再生矩阵的H∞范数下确界的困难.     

Closed‐loop input shaping control of vibration in flexible structures using discrete‐time sliding mode

Input shaping technique is widely used in reducing or eliminating residual vibration of flexible structures. It is easy to implement and achieve the exact elimination of the residual vibration if the dynamics of the system are known accurately. However, it is not very robust to parameter uncertainties and external disturbances. In this paper, a closed‐loop input shaping method is developed for reducing or eliminating residual vibration of flexible structure systems with parameter uncertainties and external disturbances. The algorithm is based on input shaping control and discrete‐time sliding mode control. It is shown that the proposed scheme guarantees closed‐loop system stability, and yields good performance and robustness in the presence of parameter uncertainties and external disturbances as well. The selection of switching surface and the existence of sliding mode are two important issues, which have been addressed. The knowledge of upper bound of uncertainties is not required. Furthermore, it is shown that increasing the robustness to parameter uncertainties does not lengthen the duration of the impulse sequence. Simulation results demonstrate the efficacy of the proposed closed‐loop input shaping control scheme. Copyright © 2010 John Wiley & Sons, Ltd.     

Robust input shaping control for multi-mode flexible structures

Input shaping provides an effective method for suppressing residual vibration of flexible structure systems. However, robustness is not possible without a time penalty. In this paper, a robust input shaping method is developed for suppressing residual vibration of multi-mode flexible structure systems with parameter uncertainties and external disturbances. The proposed scheme integrates both input shaping control and sliding mode output feedback control. The input shaper is designed for the reference model and implemented outside of the feedback loop to reduce the residual vibration. In the feedback loop, the SMOFC technique is employed to make the closed-loop system behave like the reference model with input shaper, where the residual vibration is suppressed. The selection of switching surface and the existence of sliding mode have been addressed. The knowledge of upper bound of uncertainties is not required. Furthermore, it is shown that increasing the robustness to parameter uncertainties does not lengthen the duration of the impulse sequence. Simulation results demonstrate the efficacy of the proposed control scheme.     

高相对阶连续时间系统的间接迭代学习控制

本文提出了一类高相对阶线性连续时间系统的间接迭代学习控制算法,该算法相对独立于系统局部控制器,因此可以应用于已有局部反馈控制器的系统.采用具有极点配置的H∞鲁棒控制器作为系统的内环控制,而在外环通过迭代学习控制调整内环系统的指令信号.通过引入拉氏变化,构建了迭代学习系统的2-D Roesser模型,推导了系统渐近收敛条件,并研究了存在有界初始条件偏移和迭代变化外部干扰时算法的鲁棒性能.最后,利用空中加油对接控制的算例进一步验证了算法的有效性.     

Covariance matrix adaptation evolution strategy based design of fixed structure robust H∞ loop shaping controller

This paper proposes the application of Covariance Matrix Adaptation Evolution Strategy (CMA-ES) in fixed structure H_∞ loop shaping controller design. Integral Time Absolute Error (ITAE) performance requirement is incorporated as a constraint with an objective of maximization of stability margin in the fixed structure H_∞ loop shaping controller design problem. Pneumatic servo system, separating tower process and F18 fighter aircraft system are considered as test systems. The CMA-ES designed fixed structure H_∞ loop-shaping controller is compared with the traditional H_∞ loop shaping controller, non-smooth optimization and Heuristic Kalman Algorithm (HKA) based fixed structure H_∞ loop shaping controllers in terms of stability margin. 20% perturbation in the nominal plant is used to validate the robustness of the CMA-ES designed H_∞ loop shaping controller. The effect of Finite Word Length (FWL) is considered to show the implementation difficulties of controller in digital processors. Simulation results demonstrated that CMA-ES based fixed structure H_∞ loop shaping controller is suitable for real time implementation with good robust stability and performance.     

一种基于预稳定区域的∞控制器参数优化方法

基于控制理论, 提出了一种具有预期闭环极点区域的H_∞ 控制器参数优化设计方法, 该方法设计中既考虑了H_∞ 性能指标又兼顾了动态性能指标, 克服了常规H_∞ 设计方法中不稳定控制器的问题等不足. 实验结果表明, 该方法具有计算简便、可实现性好、鲁棒性和动态品质良好、对模型参数变化的敏感性低等优点.     

Adaptive tracking H-infinity control for switched nonlinear systems with unknown control gain sign

This paper addresses the adaptive tracking control scheme for switched nonlinear systems with unknown control gain sign. The approach relaxes the hypothesis that the upper bound of function control gain is known constant and the bounds of external disturbance and approximation errors of neural networks are known. RBF neural networks (NNs) are used to approximate unknown functions and an H-infinity controller is introduced to enhance robustness. The adaptive updating laws and the admissible switching signals have been derived from switched multiple Lyapunov function method. It’s proved that the resulting closed loop system is asymptotically Lyapunov stable such that the output tracking error performance and H-infinity disturbance attenuation level are well obtained. Finally, a simulation example of Forced Duffing systems is given to illustrate the effectiveness of the proposed control scheme and improve significantly the transient performance.     

Local model networks based mixed-sensitivity H-infinity control of CE-150 helicopters

In this paper, a local model network H-infinity control is proposed for CE-150 helicopter stabilization. The proposed strategy capitalizes on recent developments on H-infinity control and its promising results in robust stabilization of plants under unstructured uncertainties. CE-150 helicopters are known for their varying operating conditions along with external disturbances. Therefore, local model networks are introduced for their adaptive feature and since they provide a powerful combination of fuzzy logic and conventional linear control techniques to control nonlinear systems without the added computational burden of soft-computing techniques. Using the fact that the system can be linearized at different operating points, a mixed sensitivity H-infinity controller is designed for the linearized system, and combined within a network to make transitions between them. The proposed control structure ensures robustness, decoupling of the system dynamics while achieving good performance. A comparison is carried-out against the well-known proportional-integral-derivative (PID) control technique. Results are presented to illustrate the controller''s performance in various operating conditions.     

一种基于LMI的鲁棒故障诊断滤波器设计

研究了一类含有扰动的线性系统鲁棒故障诊断滤波器设计问题. 文中引入一种能同时体现残差对扰动信号鲁棒性和对故障信号灵敏性的性能指标, 利用H_∞理论把求解滤波器的问题转化为H_∞优化设计问题. 应用线性矩阵不等式(LMI)技术, 对此性能指标进行优化, 给出并证明了该设计问题解的存在性条件和滤波器增益阵的求解方法, 最后, 通过仿真实例验证了方法的有效性.