一类挠性矩形智能板的建模和振动控制

本文考虑分布压电敏感器和致动器共位配置的挠性矩形智能板的建模和振动控制问题，推导了智能板的动力学方程，设计了一种线性反馈控制方案，应用无穷维空间的ＬａＳａｌｌｅ不变原理和线性算子半群理论，证明了闭环系统的渐近稳定性。     

采用共位配置的分布式压电敏感器和致动器的挠性结构的振动控制

本文研究采用共位配置的分布式压电敏感器和致动器的挠性悬臂梁的振动控制问题，其中敏感器由压电聚乙二烯氟化物薄膜（ＰＶＤＦ）制成，致动器由压电陶瓷（ＰＺＴ）或ＰＶＤＦ制成。本文首先建立系统的模型，设计了一种线性反馈控制方案，并应用无穷维空间的ＬａＳａｌｌｅ不变原理，证明了相应闭环系统的渐近稳定性。     

压电复合梁高阶有限元模型与主动振动控制研究

大型柔性空间结构的振动控制问题引起了广泛的关注.压电材料以其低质量、宽频带和适应性强等特点,非常适合于柔性空间结构的振动控制.本文针对上下表面粘贴有分布式压电传感器和作动器的智能层梁结构,提出了一种考虑压电材料对结构质量、刚度影响的高阶有限元模型.考虑到空间结构可能承受较大的热载荷,在模型中计及了压电材料的热电耦合效应.采用常增益负反馈控制方法、常增益速度负反馈控制方法、Lyapunov反馈控制方法和线性二次型调节器方法(LQR)设计主动控制器,实现了智能层梁结构脉冲激励下的振动主动控制.仿真结果表明,LQR方法更能有效的实现结构振动控制,并且具有更低的作动器峰值电压,但不能消除热载荷引起的结构静变形.     

智能太阳翼有限元建模与振动控制研究

采用空间梁单元和矩形层板单元建立了表面粘贴压电片太阳翼的机电耦合有限元模型．其中,太阳翼与星体之间的连接架、太阳翼基板间连接铰链按空间梁单元处理;不含压电片的太阳翼基板按普通层板单元处理,而含有压电片的基板按压电层板单元处理．推导了多点约束关系式处理空间梁单元和板单元公共节点自由度不协调的问题．利用速度负反馈和线性二次最优调节器设计控制系统,编制有限元分析程序,进行了动力学特性计算和振动控制数值仿真．结果表明,压电传感／作动器的引入对太阳翼振动频率具有重要影响;利用压电传感／作动器和最优控制系统能够有效抑制太阳翼的振动．     

压电柔性机械臂的主动振动控制研究

针对柔性机械臂的振动问题,采用压电智能结构作为敏感器和驱动器进行主动控制.首先建立柔性机械臂的实验装置,其次对设计的柔性机械臂系统进行辨识研究,得到系统的前二阶模态频率,再次采用PD控制和PPF控制算法对柔性机械臂进行主动振动控制.实验结果表明,采用压电智能结构可以抑制柔性机械臂的振动,效果明显.     

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。     

带刚性基柔性附件振动鲁棒控制

研究了刚体基上柔性附件的振动鲁棒控制问题.介绍了结构奇异值μ理论,基于此理论设计鲁棒控制器,用压电材料作传感器和作动器(μ),用输出乘性不确定性结构来描述低阶标称模型与实际系统的误差,给出了系统μ控制器综合框架.以柔性梁附件为对象示例了分析过程.数值仿真结果表明μ控制器具有良好的鲁棒性能,用于振动控制是必要且可行的.     

可伸缩挠性结构的镇定控制

本文是关于可伸缩挠性梁结构的稳定性与稳定化研究的第二部分；镇定控制部分。对于挠性梁收缩过程的不稳定性，提出了边界控制方案并设计了相应的控制律。受控结构的振动能量总是被耗散，系统了阻尼被增强，从而挠性梁的伸展过程，收缩过程和平台保持过程都被镇定。     

低频振动对星敏感器成像影响分析

航天器高速飞行产生的不规则振动会对捷联方式安装的星敏感器星图成像过程带来负面影响.为了提高星敏感器星图成像质量,补偿不规则振动对星图成像带来的图象失真问题,通过采用点扩散函数理论描述运动成像过程,从成像机理角度分析了振动对星图成像的影响,利用该理论分析结论仿真得到了不同振动形式影响下的星图.结果表明:星敏感器成像过程受到环境振动影响会产生拖尾、扩散、旋转等现象,为星敏感器的减震设计和星图还原与提取提高了参考.     

不同作动器布局和时滞下柔性悬臂梁振动控制研究

由于压电作动器自身性能的限制,工程中可能需要使用多个压电作动器.本文研究了双压电作动器下柔性悬臂梁的时滞振动控制.研究发现,控制回路没有时滞时,双作动器在不同布局下都能对梁的振动实现等效控制,此时两个作动器输入电压成线性关系,该线性关系斜率与作动器分布位置相关.进一步地,针对有时滞情况,当改变作动器的布局和时滞,通过分段时滞状态反馈,系统仍能达到相同的控制效果.     

Active vibration control of smart piezoelectric beams: Comparison of classical and optimal feedback control strategies

This paper presents a numerical study concerning the active vibration control of smart piezoelectric beams. A comparison between the classical control strategies, constant gain and amplitude velocity feedback, and optimal control strategies, linear quadratic regulator (LQR) and linear quadratic Gaussian (LQG) controller, is performed in order to investigate their effectiveness to suppress vibrations in beams with piezoelectric patches acting as sensors or actuators. A one-dimensional finite element of a three-layered smart beam with two piezoelectric surface layers and metallic core is utilized. A partial layerwise theory, with three discrete layers, and a fully coupled electro-mechanical theory is considered. The finite element model equations of motion and electric charge equilibrium are presented and recast into a state variable representation in terms of the physical modes of the beam. The analyzed case studies concern the vibration reduction of a cantilever aluminum beam with a collocated asymmetric piezoelectric sensor/actuator pair bonded on the surface. The transverse displacement time history, for an initial displacement field and white noise force disturbance, and point receptance at the free end are evaluated with the open- and closed-loop classical and optimal control systems. The case studies allow the comparison of their performances demonstrating some of their advantages and disadvantages.     

FAULT TOLERANT CONTROL OF FLEXIBLE SMART STRUCTURES USING ROBUST DECENTRALIZED FAST OUTPUT SAMPLING FEEDBACK TECHNIQUE

This paper presents the modeling, design and simulation of a Robust Decentralized Fast Output Sampling (RDFOS) feedback controller for the vibration control of a smart structure (flexible cantilever beam) when there is actuator failure. The beam is divided into 8 finite elements and the sensors / actuators are placed at finite element positions 2, 4, 6, and 8 as collocated pairs. The smart structure is modeled using the concepts of piezoelectric theory, Euler‐Bernoulli beam theory, Finite Element Method (FEM) techniques and the state space techniques. Four multi‐variable state‐space models of the smart structure plant are obtained when there is a failure of one of the four actuators to function. The effect of failure of one of the piezo actuators to function during the vibration of the beam is observed. The tip displacements, open and closed loop responses with and without the controller are observed. For all of these models, a common stabilizing state feedback gain F is obtained. A robust decentralized fast output sampling feedback gain L which realizes this state feedback gain is obtained using the LMI approach. In this designed control law, the control inputs to each actuator of the multi‐model representation of the smart structure is a function of the output of that corresponding sensor only and the gain matrix has got all off‐diagonal terms zero and this makes the control design a robust decentralized one. Then, the performance of the designed smart system is evaluated for Active Vibration Control (AVC). The robust decentralized FOS controller obtained by the designed method requires only constant gains and hence may be easier to implement in real time.     

VIBRATION CONTROL OF A SMART STRUCTURE USING PERIODIC OUTPUT FEEDBACK TECHNIQUE

Active vibration control is an important problem in structures. One of the ways to tackle this problem is to make the structure smart, adaptive and self‐controlling. The objective of active vibration control is to reduce the vibration of a system by automatic modification of the system's structural response. This work features the modeling and design of a Periodic Output Feedback (POF) control technique for the vibration control of a smart flexible cantilever beam system for a Single Input Single Output case. A POF controller is designed for the beam by bonding patches of piezoelectric layer as sensor/actuator to the master structure at different locations along the length of the beam. The entire structure is modeled in state space form using the Finite Element Method by dividing the structure into 3, 4, 5 elements, thus giving rise to three types of systems, viz., system 1 (beam divided into 3 finite elements), system 2 (4 finite elements), system 3 (5 finite elements). POF controllers are designed for the above three types of systems for different sensor/actuator locations along the length of the beam by retaining the first two vibratory modes. The smart cantilever beam model is developed using the concept of piezoelectric bonding and Euler‐Bernouli theory principles. The effect of placing the sensor/actuator at various locations along the length of the beam for all the three types of systems considered is observed and the conclusions are drawn for the best performance and for the smallest magnitude of the control input required to control the vibrations of the beam. The tip displacements with the controller is obtained. Performance of the system is also observed by retaining the first 3 vibratory modes and the conclusions are drawn.     

Output feedback stabilization of a clamped-free beam

We consider a Euler–Bernoulli beam, clamped at one extremity and free at the other, to which are attached a piezoelectric actuator and a collocated sensor touching the clamped extremity. We provide an output feedback law and characterize the sensor/actuator lengths for which the strong stabilization holds. Finally, we prove that the energy decreases to zero in a polynomial way for almost all lengths, and in an exponential way for lengths admitting a certain coprime factorization.     

Application of discrete-time model reference adaptive control to a flexible single-link robot

This article addresses the feasibility of applying discrete-time model reference adaptive control techniques to the flexible link of robot mechanisms. The method of separation of variables is used to represent the deflection of the link. A nonlinear model is obtained using a Lagrangian equation, and the candidate frequencies and the associated mode functions are obtained using Bernoulli-Euler beam theory. By considering the effect of flexibility as an internal disturbance torque acting on the rigid body motion of the system, a discrete-time MRAC is determined for a single non-rigid link. The control algorithm is implemented for a collocated sensor and actuator system, and for a noncollocated end-point sensor and actuator system. Results of computer simulation show the feasibility of this approach and the advantage of using an end-point sensing system.     

Distributed identification and control of spatially interconnected systems with application to an actuated beam

This paper presents a case study on modelling and control of spatially interconnected systems. Considered is a vibration control problem, with experimental results on a flexible beam that is equipped with an array of piezo sensors and actuators. The sensor–actuator array induces a spatial discretization of the beam into an array of interconnected subsystems. Models are experimentally identified that have the structure of spatially interconnected systems. Based on the identified models, distributed control schemes are designed by solving a linear matrix inequality (LMI) problem that has the size of a single subsystem. Modelling and control is considered for both spatially invariant and spatially varying systems; in the latter case the system is represented as linear parameter-varying (LPV) system that is scheduled not over time but over space. Simulation and experimental closed-loop results demonstrate the practicality and efficiency of the underlying framework.     

Experimental Comparison Research on Active Vibration Control for Flexible Piezoelectric Manipulator Using Fuzzy Controller

Space manipulators are flexible structures. Vibration problem will be unavoidable due to motion or external disturbance excitation. Model based control methods will not maintain the required accuracy because of the existence of nonlinear factors and parameter uncertainties. To solve these problems, fuzzy logic control laws with different membership function groups are adopted to suppress vibrations of a flexible smart manipulator using collocated piezoelectric sensor/actuator pair. Also, dual-mode controllers combining fuzzy logic and proportional integral control are designed, for suppressing the lower amplitude vibration near the equilibrium point significantly. Experimental comparison research is conducted, using fuzzy control algorithms and the dual-mode controllers with different membership functions. The experimental results show that the adopted fuzzy control algorithms can substantially suppress the larger amplitude vibration; and the dual-mode controllers can also damp out the lower amplitude vibration significantly. The experimental results demonstrate that the proposed fuzzy controllers and dual-mode controllers can suppress vibration effectively, and the optimal placement is feasible.     

适应连续外扰的时滞加速度反馈控制器

在采用加速度传感器的振动主动控制平台中,为了有效抑制外力可用微分方程描述的含输入时滞受迫振动响应,基于积分变换和状态导数极点配置法,提出了一种适应连续外扰的时滞加速度反馈控制器设计方法.以粘贴有压电陶瓷和加速度传感器的受正弦激励的智能梁为仿真控制对象,仿真结果表明,此控制器能在任意输入时滞下有效抑制智能梁的持续受迫振动响应.与不考虑时滞的同类控制器相比,该控制器有较好的稳定性及控制效果.