复合材料层板构件气弹振动控制实验研究

飞机局部复合材料构件存在着因涡流作用诱发的弹性振动问题。本文首先研究了表面粘贴型压电元件对复合材料构件的传感和驱动原理;针对结构待控模态的要求,采用了D-准则优化确定同位压电传感/驱动器在构件中的布置方案;应用自适应振动前馈控制原理和方法,构造了闭环控制系统;分别利用正弦和方波信号激发气动声场,对玻纤/环氧圆筒构件进行激振和振动控制实验;结果表明：构件主要待控模态的振动得到了有效抑制,但也出现了高阶模态被激发的问题,导致结构辐射噪声上升。     

柔性板的非线性降阶模型

柔性板是一种典型的空间结构，在外扰下易引起振动，它具有大挠度、非线性、低频模态密集等特点，目前在对柔性板的研究中都忽略了非线性的影响，获得的模型往往具有较大的误差，本文利用K—L展开式对柔性板进行模型降阶，然后采用系统辨识方法来获得低阶模型，并计算出柔性板的模态参数，实验结果表明这是一种有效的方法。     

柔性板的时滞H∞控制的理论与实验研究

以柔性板为对象, 开展时滞H∞控制的理论与实验研究. 首先给出柔性板的时滞动力学方程; 然后利用Lyapunov-Krasovskii泛函和自由权矩阵法, 推导了闭环时滞系统渐近稳定的矩阵不等式;进而根据该矩阵不等式采用参数调节法及遗传算法, 研究了如下两类控制设计问题: 已知控制律求解最大稳定时滞量, 已知最大稳定时滞量求解H∞控制律; 最后对理论研究成果进行了数值仿真和实验验证. 结果显示, 获得的H∞控制律能够有效地抑制板的弹性振动, 所确定出的保证系统稳定性的时滞区间更接近实际情况.      

有前馈的改进ADC方法在Hexapod平台振动控制中的应用

以高稳定精密跟瞄Hexapod平台振动控制为背景,对ADC(Adaptive Disturbance Canceller)方法进行了分析,发现将其应用于平台振动控制中可能存在的两个问题,提出了有前馈的改进ADC方法,从而使方法更好地应用于工程实际.分别将方法应用于复合作动杆单杆实验以及Hexapod平台Adams/Simulink联合仿真,结果一方面说明本文对方法的改进是必要的,一方面说明改进后的方法在实验和仿真中都是有效的,振动可以被抑制90%,相对PID方法结果的优越性是明显的,且可以应用于有较大角度指向功能的Hexapod平台振动控制.     

可控约束阻尼层板的控制实验研究

对具有可控约束阻尼层的板进行了振动控制实验研究． 以压电片作为作动器,根据测量的结构振动信号,反馈控制约束层的变形,抑制板的振动． 对试验件进行了试验模态分析,讨论了压电片的附加位置;采用比例反馈对试验件进行了控制试验;试验给出了控制效果和压电片面积的关系． 研究结果证明,这种利用粘弹性阻尼抑制结构的高频振动,利用压电材料的逆压电效应控制结构的低频振动的主被动杂交控制方式对薄壁结构的振动抑制效果显著,控制频率范围宽,可靠性高．     

折叠式柔性结构振动主动控制的研究

建立了具有刚性运动基的折叠式柔性结构振动主动控制实验系统，采用带实时预测误差修正的预测控制算法进行了这类结构振动主动控制的实验研究。实验结果表明，在实验建模的基础上设计预测控制器对折叠式柔性结构进行振动主动控制，能够有效地抑制柔性结构的振动和提高刚性基姿态定向精度。     

失谐弱耦合卫星天线结构振动分析及预测控制

为了研究弱耦合卫星天线结构的振动控制,建立了该结构的简化计算模型,并针对该模型研究了弱耦合卫星天线结构动力学性能的特殊性:结构失谐时的振动模态局部化现象;针对失谐前后的结构,采用预测控制方法进行了振动控制,并与二次线性最优控制(LQR)方法的振动抑制效果进行了对比. 仿真结果表明:弱耦合星载天线结构参数的微小失谐会导致结构振动产生明显的模态局部化;采用预测控制方法进行结构振动控制的效果明显优于LQR控制方法,且在失谐导致的模型失配时,预测控制方法对结构振动亦有较好的抑制;在进行此种结构的振动主动控制时必须考虑到结构失谐的影响.      

压电促动器存在故障时柔性板的μ综合振动主动控制研究

利用柔性板的实验模型研究了一种考虑作动器驱动力故障的鲁棒控制器。首先识别出粘贴压电促动器的柔性板振动控制系统实验模型,基于此利用改变压电片对联接数量来模拟促动器驱动故障,并设计了将驱动力变化提取成正则不确定块对角阵的方法,同时将剩余模态表示成高通滤波器,再通过引入虚拟不确定,构建了考虑外扰抑制和控制增益约束的综合控制器。数值仿真验证了闭环系统理论上的鲁棒稳定性。实测试验结果显示,与一般的μ控制器相比,当闭环过程中出现压电促动器驱动故障时,初始外扰下,控制结束时振幅峰峰值降低了3V,持续随机外扰下,降噪量提高了近3dB。数值仿真验证了闭环系统理论上的鲁棒稳定性。实测试验结果显示,与一般的μ控制器相比,当闭环过程中出现压电促动器驱动故障时,初始外扰下,控制结束时振幅峰峰值降低了3V,持续随机外扰下,降噪量提高近了3dB。     

压电结构的主动控制仿真与实验研究

结合有限元方法研究了直接负速度反馈和基于LQR(二次线性最优控制)的独立模 态空间主动控制方法来控制结构的振动, 采用一种新的仿真方法：PATRAN与MATLAB 联合仿真,对这两种方法进行主动控制数值仿真. 用MATLAB的xPC实时控制,进 行了主动板的振动控制实验,验证了采用上述控 制仿真方法的正确性. 各种结果表明用压电结构进行振动主动控制效果明显.     

支架振动主动控制的实验研究

用实验方法研究了支架振动主动控制。结果表明，用压电陶瓷片作传感器和作动器，采用速度反馈控制，无论是谐和激励还是随机激励，支架振动都能得到有效抑制。振动控制中压电陶瓷片作传感器既简便易行，又减少了附加质量对被控结构动态特性的影响。     

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.     

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.     

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。     

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。     

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.     

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.