利用压电元件的空间挠性结构振动主动控制研究

挠性结构是一种典型的空间结构形式,这种结构有模态频率低、模态密集和阻尼小的特点,在外界扰动下易引起振动,对航天器的定位精度和精密仪器的正常工作造成影响,但传统的被动振动控制方法难以奏效。基于压电元件的振动主动控制是最有潜力的一种振动抑制方法。本文模拟空间结构制作一挠性梁,通过实验分析和压电传感器／驱动器布置位置和数量的优化设计,采用独立模态方法对梁的振动进行控制,取得了良好的抑振效果。     

挠性结构的输出反馈低阶自适应控制

在模型参考自适应方法的框架上,研究了挠性空间结构的输出反馈鲁棒自适应控制方法,对其稳定性与动态性能进行了理论分析,该方法通过在标准控制律中增加控制补偿项,利用挠性结构的特点,将所能容许的乘性模型不确定性的H∞范数提高到接近1的程度,控制系统的动态性能可由控制器的设计参数调节.对该方法进行了数值实验验证.     

基于路径规划的挠性航天器姿态自适应控制

针对挠性航天器存在动力学参数不确定性以及三轴非线性强耦合的特点,提出了一种基于余弦函数路径规划的姿态自适应控制方法。首先,分析挠性航天器动力学模型,给出了其姿态控制系统的总体结构;然后,为有效抑制挠性附件振动对控制性能的影响,设计了一种余弦角加速度姿态路径规划方法对指令信号进行柔化,以减少指令信号中的高频成分;最后,将柔化指令信号作为控制系统的期望输入信号,并采用基于多输入多输出特征建模理论,设计了姿态自适应跟踪控制器。通过MATLAB/Simulink仿真,验证了所提姿态控制策略的有效性。     

挠性悬臂板的变结构控制研究

针对航天器太阳帆板这种悬臂外伸薄板结构的挠性附件,在存在建模参数不确定及外部扰动条件下所引起的振动,本文采用压电致动片作为执行器,将变结构控制应用于板的主动振动控制。通过仿真研究结果与应变律反馈控制比较,可知变结构控制具有较强的鲁棒性,同时控制器结构简单,易于实现。     

挠性智能梁的振动控制

研究采用共位配置的压电敏感器和致动器的挠性是臂梁的振动控制问题,建立了智能梁的模型,设计了一种线性反馈控制律,并应用无空维空间的ＬａＳａｌｌｅ不变原理和线性半群理论证明了当敏感器和控制器的分布使得系统能镇条件成立时,所设计的控制抑制了梁的振动。     

压电机敏结构振动响应的多通道自适应控制

论述了实现结构振动控制的多通道自适应滤波前馈控制方法,对自适应控制系统进行了研究与开发;在此基础上,对一压电机敏平板结构振动响应进行了多通道自适应控制实验,取得了良好的抵消振动效果。     

挠性结构中智能材料配置和振动控制的一体化最优设计

针对挠性结构振动控制中智能材料的特性，综合考虑压电敏感器／致动器的位置、尺寸、质量及其对挠性结构刚度特性的影响和控制律，建立系统状态空间模型，提出一种新的优化配置的性能指标和最优设计方法。运用李雅普诺夫稳定性定理证明了闭环系统的全局渐近稳定性，性能指标的最小值可取为相应矩阵的迹而不依赖于系统的初始状态。采用遗传算法寻优，仿真表明该设计方法能够快速的抑制系统的振动。     

压电智能挠性悬臂板主动振动控制试验研究

航天器上太阳帆板这种悬臂外伸薄板结构的挠性附件，存在有扰动条件下引起的振动，可采用压电智能结构对悬臂板进行主动振动控制。文章对设计的挠性悬臂板系统进行系统辨识，得到板系统的前三阶模态频率及阻尼比，并采用PD控制和PPF控制算法对板的前三阶模态(包括弯曲模态和扭转模态)进行主动振动控制。试验结果表明，采用压电智能结构可以抑制挠性悬臂板的振动．效果明显。     

带有挠性附件卫星的自适应内模控制

挠性部件诱导的振动干扰有时严重影响大型卫星姿态指向和稳定度。为了保证姿态控制的高精度和高稳定度,本文导出了带有“拍打”运动的挠性卫星数学模型,并指出模型的不确定性;给出了卫星姿态控制器的基本形式,分析了控制器参数的选取准则以保证姿态控制系统的稳定性;进而利用在轨辨识在线修正控制器参数形成了卫星姿态的自适应内模控制器。分析和实验表明,本文提出的自适应内模控制器能够有效提高大型卫星的姿态指向精度和稳定度。     

基于特征模型的柔性结构直接自适应模糊预测控制

为了避免用模态截断方法设计控制器时所引起的控制和观测溢出问题,把柔性结构模型转化为用含有未知系数的二阶差分方程描述的特征模型,对此模型提出了当柔性结构实现位置保持时的直接自适应模糊预测控制方法.此方法直接利用模糊逻辑系统设计预测控制器,并基于广义误差估计值对控制器参数和广义误差估计值中的未知向量进行自适应调整.文中证明了所设计的控制器可使广义误差估计值收敛到原点的一个小邻域内.仿真结果验证了此方法的有效性.     

Adaptive guidance law design based on characteristic model for reentry vehicles

In this paper an adaptive guidance law based on the characteristic model is designed to track a reference drag acceleration for reentry vehicles like the Shuttle. The characteristic modeling method of linear constant systems is extended for single-input and single-output （SlSO） linear time-varying systems so that the characteristic model can be established for reentry vehicles. A new nonlinear differential golden-section adaptive control law is presented. When the coefficients belong to a bounded closed convex set and their rate of change meets some constraints, the uniformly asymptotic stability of the nonlinear differential golden-section adaptive control system is proved. The tracking control law, the nonlinear differential golden-section control law, and the revised logical integral control law are integrated to design an adaptive guidance law based on the characteristic model. This guidance law overcomes the disadvantage of the feedback linearization method which needs the precise model. Simulation results show that the proposed method has better performance of tracking the reference drag acceleration than the feedback linearizaUon one.     

Intelligent fault-tolerant system of vibration control for flexible structures

This paper describes an intelligent fault-tolerant control method for vibration control of flexible structures. We consider a case where the fault phenomena of the control system for flexible structures can be treated as a change of system parameters. Therefore, the adaptive control method can be applied to a vibration control system for flexible structures with a fault. In this paper, a neural network (NN) adaptive control system is used to compensate for the change in the parameters of a plant with a fault. When the characteristics of the plant and of a nominal model have been agreed by a NN adaptive control system, the control method designed for the nominal model, such as decoupling feedback control or linearizing feedback control, can be used even if the change in the system parameters has been caused by a fault. To confirm the effectiveness of the proposed fault-tolerant control method, the simulational results from a 5-link robotic arm are shown at the end of the paper. This work was presented, in part, at the Fourth International Symposium on Artificial Life and Robotics, Oita, Japan, January 19–22, 1999     

Active vibration control of flexible structures using delayed position feedback

The paper discusses the use of a simple position control system approach to improve the performance of lightly damped dynamic systems. This approach uses a delayed position feedback signal to actively control the vibrations of flexible structures. A complete analysis of the stability of a single-link flexible manipulator under time delay control is presented and critical values of time delay for a given controller gain have been determined. The paper also presents a short comparison between the delayed feedback signal control and the linear quadratic regulator.     

A practical approach for robust control of flexible structures

This paper deals with the robust control of linear single-input, single-output (SISO) systems. First, general concepts of the frequency-domain approach are presented. We then focus on the particular problem of flexible structure and control. A new method is proposed which combines the advantages of hyperstability and small gain approaches. Finally, an application of an industrial sight system prototype is detailed.     

基于模糊控制器的自适应广义通用模型控制

广义通用模型控制(GCMC)方法是一般模型控制(GMC)的改进,适用于相对阶大于1的复杂多输入多输出系统,该控制器参数具有明显的物理意义,但鲁棒性不够强。将模糊控制与广义通用模型控制相结合,构成模型参考自适应控制系统,从而加强了系统的鲁棒性,仿真实验证明了该策略的有效性。     

基于递推最小二乘的自适应滤波振动主动控制算法分析

针对自适应滤波X最小均方差(FXLMS)和滤波U最小均方差(FULMS)振动主动控制算法收敛性较为缓慢的问题,给出一种基于递归最小二乘(RLS)方法的自适应滤波控制算法。该算法大致有无限长脉冲响应(IIR)滤波器结构和RLS算法两部分组成,IIR滤波器作为整个算法的主体框架,采用RLS算法针对滤波器的权值进行实时调整,实现了自适应滤波控制算法的功能。仿真对比分析表明,所提算法收敛速度较快。经过实验平台验证,被控对象的整体振动响应下降了65%左右,证明了算法的有效性和可行性。     

Characteristic modeling and the control of flexible structure

Appropriate modeling for a controlled plant has been a remarkable problem in the control field. A new modeling theory, i.e. characteristic modeling, is roundly demonstrated. It is deduced in detail that a general linear constant high-order system can be equivalently described with a two-order time-varying difference equation. The application of the characteristic modeling method to the control of flexible structure is also introduced. Especially, as an example, the Hubble Space Telescope is used to illustrate the application of the characteristic modeling and adaptive control method proposed in this paper.     

Boundary control of flexible aircraft wings for vibration suppression

In this paper, we propose a boundary control strategy for vibration suppression of two flexible wings. As a basic approach, Hamilton's principle is used to ascertain the system dynamic model, which includes governing equations – four partial differential equations and boundary conditions – several ordinary differential equations. Considering the coupled bending and torsional deformations of flexible wings, boundary control force and torque act on the fuselage to regulate unexpected deformations of flexible wings. Then, we present the stability analysis of the closed-loop system through Lyapunov's direct method. Simulations are carried out by using finite difference method. The simulation experimental results illustrate the significant effect of the developed control strategies.     

Vibration control for a nonlinear three-dimensional flexible manipulator trajectory tracking

This paper proposes an innovative approach to the trajectory tracking in three-dimensional space and vibration control problems in the presence of a nonlinear three-dimensional flexible manipulator based on the partial differential equation model. Unlike two-dimensional plane, we select spherical coordinates to describe the position of the end point in three-dimensional space. This novel approach makes it possible to realise the trajectory tracking by controlling the two angles in spherical coordinates, meanwhile, a vibration control scheme is proposed to restrain vibrations. In addition, the existence and uniqueness of solutions are demonstrated. Finally, the performance of the desired trajectory tracking, the proposed vibration control scheme and their convergence properties are demonstrated by numerical simulations.