结构振动的滑模变结构半主动控制

研究应用磁流变阻尼器(MRD)对结构振动半主动控制的算法和原理。研制并对磁流变阻尼器进行了阻尼特性实验，采用非线性滞回双粘性模型描述磁流变阻尼器的阻尼特性，模型结果与实验结果非常一致。采用滑模控制算法和趋近律方法设计了半主动控制器。利用滑模控制方法所建立的控制器，本文给出了地震激励下结构振动半主动控制算例。计算分析表明，半主动滑模控制具有控制效果明显、鲁棒性好等优点，是一种非常有发展前途的控制方法。     

时滞对结构振动半主动控制效果的影响

应用磁流变阻尼器对结构振动进行控制，采用最优控制原理设计了控制器，给出在地震激励下结构半主动控制的仿真计算。研究了时滞对结构振动半主动控制效果的影响。数值结果表明：本文设计的半主动控制策略可有效地减小结构的振动响应，时滞对磁流变半主动控制效果随着时滞的增大而变差，但时滞不会导致该反馈控制系统的失稳。     

随机激励下汽车悬架磁流变阻尼半主动控制研究

本文研究了在被动控制、半主动线性控制、半主动磁流变非线性控制三种控制策略情况下，采用磁流变阻尼的1／4车体模型的运行效果，所采用的路面激励为对正弦的摄动激励和随机激励。研究结果表明磁流变阻尼应用于车辆半主动控制后具有很好的效果，证实了磁流变阻尼在汽车控制中的可行性及优越性。     

可调磁流变阻尼在汽车悬架的半主动控制中的应用

本文研究了采秀磁流变阻尼的汽车半主动控制悬架在确定性激励和随机激励下的运行效果,分析了可调磁流变阻尼半主动控制的控制规律及响应情况,并与采用传统阻尼的汽车被动悬架和主动悬架进行了对比,证实了磁流变阻尼应用于汽车半主动控制的可行性及优越性。     

磁流变阻尼器半主动控制方法的实验研究

由于磁流变阻尼器是一种高度非线性的装置,因此建立与之相适应的控制系统是半主动控制问题的关键。本文采用改进的Bingham模型建立了磁流变阻尼器的动力学特性模型,根据天棚阻尼开关控制、天棚阻尼连续控制和模糊控制三种控制方法,确立了从系统速度响应到磁流变阻尼器励磁电流之间的关系,并开发了一套半主动控制系统。在一个两自由度的简化车辆试验平台上进行半主动控制试验,对比研究了三种控制方法的控制效果。实验结果表明,在1.3Hz~2.0Hz的低频段内,开关控制的最佳减振效果为15.1%,连续控制的最佳减振效果为14.9%,模糊控制的最佳减振效果为20.1%。可见,三种控制方法都能有效的减小车体的振动,模糊控制的减振效果最佳。     

基于广义预测控制的结构半主动控制研究

相对于主动控制和被动控制来讲,半主动控制具有一些更好的特色,对结构控制的应用有着较强的吸引力。本文以可调液柱阻尼器(TLCD)作为作动器来实现结构半主动控制,考虑到TLCD具有非线性阻尼特性,为了使结构控制能够顺利实现,本文采用了阶跃控制函数。为了使TLCD能够应用于实际结构,本文研究了基于离散状态方程的广义预测控制方法,并提出了单向控制策略。本文最后给出了计算实例。算例表明这一方法是有效的。     

地震作用下巨子型有控结构的半主动控制研究

在巨子型有控结构(MSCSS)的巨结构、子结构之间设置磁流变(MR)阻尼器,利用模糊神经网络建立了MR阻尼器的控制规则,并且运用遗传算法对控制器的规则库进行优化,研究了MSCSS在地震作用下的半主动控制问题。时程分析结果表明:在El-Centro地震波和Taft地震波作用下,本文建立的MR阻尼器均能很好地发挥调频子结构的减振功能,使巨结构的响应大为减小,两种地震波下结构顶层位移响应最大值的降幅分别为64%和74%,而层间位移响应的减小幅度也分别达到42%和61%。利用概率密度演化算法计算了结构在强度-频率双非平稳地震谱激励下的随机振动,计算结果显示本文对MSCSS进行的半主动控制能够使结构顶层位移均方响应峰值降低79%,提高了结构的抗震性能。     

含分数阶Bingham模型的阻尼减振系统时滞半主动控制

针对基于磁流变液阻尼器的半主动控制系统中存在的时滞问题, 采用了一种将可控的时滞变量引入半主动控制切换条件的控制策略, 研究了考虑时滞的天棚阻尼控制切换条件对半主动阻尼减振系统的影响, 分析了含有分数阶Bingham模型的线性刚度系统在基础激励下的振动特性. 利用平均法得到了系统在含时滞半主动控制策略下主共振响应的近似解析解, 根据Lyapunov理论分析了系统的稳定性. 通过数值解验证了近似解析解的准确性, 二者具有较好的一致性. 利用近似解析解分析了固定激励频率下时滞对系统幅频响应特性的影响, 以及主共振峰值响应和共振频率随时滞变化的特性规律. 结果表明, 含时滞的半主动控制系统存在一个小时滞区间, 使得系统的振幅在主共振峰对应的频率附近低于不考虑时滞时系统的振幅, 且存在最优时滞使得系统的振幅大幅度降低; 而大时滞的引入会加剧系统的振动, 导致系统的颤振. 确定了基于分数阶Bingham模型的线性刚度系统在天棚阻尼半主动控制下的时滞选取原则, 为振动系统半主动阻尼控制中的时滞选取提供了参考.      

斜拉索振动控制中MR阻尼器选型的研究

以全索全时段振动响应的均方根(RMS)评价MR阻尼器对斜拉索的减振效果。计算结果表明MR阻尼器型号是影响斜拉索减振效果的最主要因素。斜拉索的减振效果在选用合适的MR阻尼器时达到最佳。进而研究了MR阻尼器型号与阻尼器安装位置、施加的电压、斜拉索基频(张力、索长、质量)、激励荷载(类型、频率、幅值)等各种因素的关系,为MR阻尼器合理选型提供了优化设计的方法。型号选用主要是与斜拉索基频和MR阻尼器安装位置有关。在引起索基频变化的因素中,索质量对型号的选取影响最大;而索长对型号影响不大。对于索质量较大、张力较大、MR阻尼器安装位置较低、外界激励较大、频谱特征多变、低频为主时需要较强的MR阻尼器。进一步研究表明,半主动控制与开环控制的最优MR阻尼器型号有较好的一致性,因此半主动控制所选用的MR阻尼器型号可参照被动控制时最优MR阻尼器型号。     

MR阻尼器的半主动控制研究

MR阻尼器能提供可以调节的阻尼力,适合用作减少结构地震响应的半主动控制器。本文对MR阻尼器的半主动控制进行研究,提出了状态跳跃算法,根据结构响应的大小实现MR阻尼器的状态切换,使结构响应得到有效的控制。这种控制策略简便,不需要在线计算,便于实施。由于速度响应直接影响MR阻尼器的阻尼力,建议用速度响应作为MR阻尼器进行状态切换的变量。文中给出了两个算例,进行了计算分析和比较,说明了状态跳跃控制算法的特点。     

Some aspects of control systems as dynamical systems

Linear control semigroupsL=Gl(d,R) are associated with semilinear control systems of the form whereA:R ^m gl(d,R) is continuous in some open set containingU. The semigroupL then corresponds to the solutions with piecewise constant controls, i.e., L acts in a natural way onR ^d {0}, on the sphereS ^d–1, and on the projective spaceP ^d–1. Under the assumption that the group generated byL in Gl(d,R) acts transitively onP ^d–1, we analyze the control structure of the action ofL onP ^d–1: We characterize the sets inP ^d–1, where the system is controllable (the control sets) using perturbation theory of eigenvalues and (generalized) eigenspaces of the matrices g L For nonlinear control systems on finitedimensional manifoldsM, we study the linearization on the tangent bundleTM and the projective bundleP M via the theory of Morse decompositions, to obtain a characterization of the chain-recurrent components of the control flow onU×PM. These components correspond uniquely to the chain control sets onP M, and they induce a subbundle decomposition ofU×TM. These results are used to characterize the chain control sets ofL acting onP ^d–1 and to compare the control sets and chain control sets.Research supported in part by NSF Grant DMS 8813976 and DFG Grant Co 124/6-1.     

结构振动的非线性控制及其试验研究

本文分析了结构振动控制系统的特点，提出了一种结构振动的非线性离散控制方案，该方案仅利用受控结构的输出信号，实现容易，对结构参数变化具有一定的鲁棒性，本文还建立了一套具有浮点运算功能的结构振动计算机控制装置，并就某受控结进行了试验，试验表明，该非线性控制方案是可行的，理论结果与试验结果具有良好的一致性。     

Model-Based Feedback Control of Acoustic Radiation from Vibrating Structures by Means of Structural Control

In this work, it is investigated how classical techniques of linear feedback control design can be applied to the problem of the reduction of acoustic radiation from vibrating structures for cases where the disturbance is broadband and where no reference is available. Much of the work carried out to date in the field of active noise and vibration control has concentrated on applications where either the disturbance to be cancelled is periodic (propeller noise in aircraft,...) or a reference signal, highly correlated with the disturbance, is available (air conditioning duct noise,...) such that a feedforward control approach can be used. When the disturbance is broadband and where no reference is available, feedforward control cannot be used and feedback control must instead be used. Feedback control theory is well established and a vast amount of analytical tools are available to the feedback control designer. However, due to the inherent delays associated with the propagation of sound waves, feedback control of acoustic fields is prone to being unstable. In this paper, a controller is presented which feeds back a measure of the structural response (vibration) of the system in order to determine the control force that needs to be applied to the vibrating structure in order to reduce the total acoustic energy radiated by the vibrating structure. This revised version was published online in July 2006 with corrections to the Cover Date.     

石英挠性加速度计二元调宽数字脉冲控制系统的研制

本文介绍了石英挠性加速度计二元调宽数字脉冲控制系统的研制及其应用。提出了通过提高系统采样频率来抑制石英挠性加速度计摆片摆幅，从而最大限度地减小其疲劳强度的方法。并基于这一思想设计了石英挠性加速度计二元调宽数字脉冲控制模型，对模型进行了模拟仿真，证明该方案是合理可行的。其已成功地应用于各新型导航产品中     

Control of chaotic oscillations of a satellite

Analytical conditions and practical methods of their realization are proposed to solve a problem of a command signal tracking for a nonlinear disturbed system.Non- linear disturbed plants consisting of linear dynamic block and nonlinear block in feedback are considered.Nonlinear part of the plant and disturbance are unknown and bounded. The paper illustrates a possibility of applications of proposed algorithms to control libra- tion angle of satellite.     

复杂动态网络控制研究进展

研究复杂网络结构性质与模型的主要目的之一就是为了了解网络结构与网络功能之间的关系,并在此基础上考虑改善网络性能的有效途径.综述了近年关于利用分布式控制的方法使得一个动态网络具有期望行为的一些研究进展.对于具有固定和连通的拓扑结构的复杂动态网络,牵制控制策略的有效性与网络拓扑密切相关.综述了牵制控制的可行性、稳定性分析以及控制策略比较研究. 另一方面,对于具有时变拓扑结构的动态网络的控制,着重综述了移动多自主体网络系统的蜂拥控制,并特别阐述了如何把牵制控制的思想用于蜂拥控制.      

压电智能结构模糊自学习控制(FSLC)

将模糊逻辑与学习控制的基本思想相结合,根据控制系统的动态输出特性,采用模糊控制对学习控制律中的参数进行实时校正,实现系统的动态学习过程,提出了一种适用于压电智能结构振动控制的模糊自学控制方法FSLC（FuzzySelf-LearningContr01）。分别采用三维8节点实体单元（Solid45）和耦合单元模拟主结构和压电致动器／传感器,基于ANSYS参数化语言编写了压电智能结构振动控制分析的有限元程序。通过数值仿真证明了模糊自学习控制方法能有效控制压电结构的振动,并提高了自学习控制的收敛速度和获得了很好的控制效果。     

Numerical study comparing RANS and LES approaches on a circulation control airfoil

A numerical study over a nominally two-dimensional circulation control airfoil is performed using a large-eddy simulation code and two Reynolds-averaged Navier–Stokes codes. Different Coanda jet blowing conditions are investigated. In addition to investigating the influence of grid density, a comparison is made between incompressible and compressible flow solvers. The incompressible equations are found to yield negligible differences from the compressible equations up to at least a jet exit Mach number of 0.64. The effects of different turbulence models are also studied. Models that do not account for streamline curvature effects tend to predict jet separation from the Coanda surface too late, and can produce non-physical solutions at high blowing rates. Three different turbulence models that account for streamline curvature are compared with each other and with large eddy simulation solutions. All three models are found to predict the Coanda jet separation location reasonably well, but one of the models predicts specific flow field details near the Coanda surface prior to separation much better than the other two. All Reynolds-averaged Navier–Stokes computations produce higher circulation than large eddy simulation computations, with different stagnation point location and greater flow acceleration around the nose onto the upper surface. The precise reasons for the higher circulation are not clear, although it is not solely a function of predicting the jet separation location correctly.     

Adaptive robust fuzzy control for a class of uncertain chaotic systems

In this paper, the output feedback control of uncertain chaotic systems is addressed via an adaptive robust fuzzy approach. Fuzzy logic systems are employed to approximate uncertain nonlinear functions in the chaotic systems. Because only partial information of the system’s states is needed to be known, an observer is given to estimate the unmeasured states. Compared with the existing results in the observer design, the prior knowledge on dynamic uncertainties is relaxed and a class of more general chaotic systems is considered as well as robustness to the approximation error is improved. It can be proven that the closed-loop system is stable in the sense that all the variables are bounded. Simulation example for the unified chaotic systems is given to verify the effectiveness of the proposed method. This work was supported in part by the National Natural Science Foundation of China (60874056) and the Foundation of Educational Department of Liaoning Province (2008312).     

Design of bounded feedback controls for linear dynamical systems by using common Lyapunov functions

For a linear dynamical system, we address the problem of devising a bounded feedback control, which brings the system to the origin in finite time. The construction is based on the notion of a common Lyapunov function. It is shown that the constructed control remains effective in the presence of small perturbations.