智能微位移主动隔振控制系统的研究

针对精密加工设备的微位移隔振问题,设计了一种以压电陶瓷为作动器的新型智能微位移主动隔振控制系统,在NI PXI数据采集系统和BK激振器的基础上,搭建了该系统的实验平台,提出将有源噪声控制理论应用到微位移振动的主动控制中,开发了在Lab VIEW软件环境下整个系统的数据采集和F-XLMS控制算法的控制程序,分别在正弦、扫频和随机激励信号下进行微位移主动隔振实验研究,结果表明三种激励信号受控后的振动位移大幅度降低,验证了该系统对微位移主动隔振的有效性,为精密仪器、微纳米设备的微位移智能主动隔振系统设计奠定了基础。     

非规则封闭声腔在PVDF压电薄膜激励下的响应分析

在噪声主动控制领域,尽管PVDF压电薄膜相对于压电陶瓷而言应变压电常数以及扬氏弹性模量都较小,很少作为作动器使用,但由于它具有良好的柔韧性,能够大面积地覆盖在结构表面,产生大范围的分布应力,能承受较压电陶瓷大得多的电压,因此是一种很有潜力的作动器.为了分析PVDF压电薄膜对于非规则封闭声腔内部声压的控制机理,本文研究弹性边界上有一对压电薄膜作动器激励的非规则封闭声腔响应特性.文中首先以弹性边界的振动方程以及经典波动方程为基础,描述了结构-声之间的耦合作用;然后结合压电薄膜本构方程和弹性边界振动方程,给出了机电耦合的描述.结合这两种描述,本文给出了整个系统在输入交变电场的作用下,如何通过压电薄膜对结构的作用将激励传递到内部声场的理论分析,并且给出了仿真结果.     

基于压电致动器的微动隔振平台系统

为实现微仪器隔振平台的自适应控制,对第三代压电致动器顶杆部件进行了改进,并将其直接应用于微隔振系统,隔振效果不是很理想。为此,对致动器进行了系统在线建模,从理论上分析了导致结果不理想的原因,给出了一种改进方法,通过理论建模分析和试验研究,结果表明:该方法虽然降低了致动器位移增益,但具有较好的隔振效果。     

压电层合板高阶计算模型

压电复合(层合)结构可应用于结构振动控制、形状保持、健康监测等,建立压电层合结构精确的机电耦合计算模型成为了研究的焦点.针对表面粘贴或内部嵌入压电片的压电层合板结构,基于高阶位移场和高阶电势模型,根据Hamilton原理建立了机电耦合高阶有限元模型.该模型适用于薄板和中厚板,并且能够捕捉压电层内沿厚度方向呈抛物线型分布的诱导电势.以压电双晶片简支板为例,进行了作动器构型和开环、闭环状态传感器构型的数值分析.结果指出,诱导电势对压电传感器有重要影响,而压电作动器可忽略这种电势.     

基于模态应变能分布的压电致动器/传感器位置优化遗传算法

本文由线弹性压电结构有限元动力方程,推导了压电智能结构的振动控制方程。建立了准确模拟层合压电结构动力行为的有限元模型。基于主结构模态应变能分布提出了一种新的优化目标函数,将压电致动器/传感器位置编号作为优化变量,建立了离散变量表示的智能结构优化问题,并通过二进制编码的遗传算法（GA）求解了该最优问题。以四边固支复合层合压电智能板为数值算例,采用比例反馈控制, 研究了最优位置配置致动器/传感器智能结构目标模态的控制效果。数值结果表明基于模态应变能分布的遗传算法所得优化解具有较好的振动控制效果。     

复合作动器复合方式对平台主动隔振影响分析

为实现微隔振平台在较宽频带内的主动控制,将一弹性体和第三代压电致动器相串联,设计了一种复合式压电致动器。将复合致动器应用到微隔振平台,并对其整体建模、控制仿真时发现：弹性体相对于作动器位置不同时,在不同的外扰下对控制力的影响不同。为此,设计了一个针对不同外扰对控制力影响的评价函数,通过不同位置对评价函数影响的仿真,结果表明：当隔振平台系统受直接干扰时,弹性体位置对控制力的影响较大;当平台受地基扰动时,弹性体位置对控制力影响不显著。所以,复合作动器的布置形式取决于外扰的类型,且在实验室环境中,两种布置要达到相同的隔振效果,弹性体在上布置所耗费的能量小于其在下布置时的状态。     

双弯曲管式螺杆型压电作动器

提出一种基于压电金属复合梁双向弯曲振动的螺杆型作动器,其压电换能器中每一个压电片都工作在Kt模态。首先,以细直梁在空间的一阶弯曲振型为基础确定了作动器结构形式;其次,对定子材料、结构参数与固有频率及端面振幅的关系进行了有限元分析,其中特别讨论了材料的参数E/ρ对一阶固有频率的影响规律;然后,根据分析结果确定了作动器结构尺寸,并试制了样机;最后,测试了样机的主要输出特性。结果表明,作动器的最佳激振频率约为15.8k Hz,启停时间在20 ms左右;在300 V驱动电压下,作动器最大空载速度为1.146 mm/s,最大轴向力为2.5 N。     

压电堆式JG型复合隔振器结构设计与实验研究

复合式隔振器是由剪切型橡胶隔振器与惯性式压电堆作动器组合而成,复合式隔振器结合了主被动隔振器的优点,将主动构件与被动装置串联、并联,不仅提高了主动构件的稳定性,也改善了被动隔振的有效频带。通过理论与实验的方法对惯性式压电堆作动器的工作原理与动力学特性进行了分析,利用所设计的复合式隔振器搭建了双层隔振台架,采用滤波x-LMS自适应算法对台架进行主动控制。结果表明,在单频正弦激励下,压电推复合隔振器比单纯的被动隔振装置具有更好的隔振效果,80Hz、90Hz和110Hz隔振效果分别提高25dB、38dB和25dB。     

新型贴片式扭振压电作动器的设计与实验研究

提出了一种新型贴片式扭振压电作动器,采用沿厚度方向极化的方形压电陶瓷片,通过特殊的布置方式来激发矩形梁结构的扭转振动.该压电作动器通过不同的激励方式,可以激发出奇数阶和偶数阶扭转振动,具有结构简单、紧凑、易于加工和安装等特点.为了验证所提出的扭振压电作动器设计方案和工作原理的正确性,建立了理论模型,并采用有限元方法对其...     

压电堆式JG型复合隔振器结构设计与实验研究

复合式隔振器由剪切型橡胶隔振器与惯性式压电堆作动器组合而成,复合式隔振器结合主被动隔振器的优点,将主动构件与被动装置串联、并联,不仅可提高主动构件的稳定性,还能拓展被动隔振的有效频带。通过理论与实验方法对惯性式压电堆作动器的工作原理与动力学特性进行分析,利用所设计的压电堆式JG型复合式隔振器搭建双层隔振台架,采用滤波x-LMS自适应算法对台架进行主动控制。结果表明,在单频正弦激励下压电堆式JG型复合隔振器比单纯被动隔振装置具有更好隔振效果,80 Hz、90 Hz和110 Hz处隔振效果分别提高15 dB、16 dB和15 dB。     

一种采用PVDF压电薄膜的弯张换能器

本文提出了一种采用PVDF压电薄膜代替弯张换能器的金属外壳的新型弯张换能器,即一种采用PVDF压电薄膜的弯张换能器。用阻抗分析仪、激光扫描测振仪和水声测量系统分别测量了采用PVDF压电薄膜的弯张换能器的谐振频率、带宽、发送电压响应、水平指向性。通过对比分析实验结果,可以看出该新型换能器与传统换能器一样可以将压电晶堆纵的振动转化为壳体的径向振动。     

磁悬浮主被动隔振系统自适应控制及非线性补偿

 In order to effectively control the low frequency vibration of ship machinery,a passive-active hybrid vibration isolation mount using maglev actuator was designed. Maglev actuator is excellent for active vibration isolation, with non-contact structure, low stiffness and rapid response. However, the actuator’s nonlinearity has to be restrained by control algorithm. The nonlinearity of maglev actuator was analyzed, the nonlinear reverse model of actuator was built through theoretical analysis and experimental correction, and an improved FxLMS algorithm based on reverse model linearization and frequency range division control was put forward, which has the advantage of low computation load for real time control. Experiments were performed on a multiple-DOF active vibration isolation system, results show that the improved FxLMS algorithm could effectively reduce the vibration energy at targeted frequency, and well restrain the nonlinearity-induced vibration.  

      

轮带系统横向振动变结构控制方法

针对由主从动轮、作动器及皮带构成的典型轮带系统模型,皮带横向振动与主、从动轮及作动器振动相耦合,其横向位移受主、从动轮及作动器影响,给出皮带在谐波激励下横向振动位移精确表达式,利用变结构理论,采用指数趋近律设计出有效控制力以控制张紧臂方向,从而抑制皮带横向振动。在初始条件和与激励作用下,利用Matlab进行数值仿真。结果表明：在谐波激励下,皮带横向振动位移得到有效抑制,验证控制力的有效性。     

Contact-Type Vibration Sensors Using Curved Clamped PVDF Film

This paper describes a new type of contact vibration sensor made by bonding a piezoelectric polyvinylidene fluoride (PVDF) film to a curved frame structure. The concave surface of the film is bonded to a rubber piece having a front contact face. Vibration is transmitted from this face through the rubber to the surface of the PVDF film. Pressure normal to the surface of the film is converted to circumferential strain, and an electric field is induced by the piezoelectric effect. The frequency response of the device was measured using an accelerometer mounted between the rubber face and a rigid vibration exciter plate. Sensitivity (voltage per unit displacement) was deduced from the device output and measured acceleration. The sensitivity was flat from 16 Hz to 3 kHz, peaking at 6 kHz due to a structural resonance. A contact vibration sensor theory has been developed, which accounts for the effect of the radiation medium. It has been found that the imaginary part of the radiation impedance has an effect equivalent to the addition of mass to the curved PVDF film structure, which reduces the resonance frequency by about one order. Calculations predicting performance against human tissue (stethoscope or contact microphone) show results similar to data measured against the metal vibrator. This implies that an accelerometer can be used for calibrating a stethoscope or contact microphone. The observed arterial pulse waveform from the new PVDF sensor showed more low-frequency content than a conventional electronic stethoscope.     

Vibration suppression of laminated composite beams with a piezo-electric damping layer

An analytical formulation is derived for modelling the behaviour of laminated composite beams with integrated piezoelectric sensor and actuator. The major difference in approach to the solution compared to previous studies is that the analytical solution for active vibration control and suppression of smart laminated composite beams is presented in this paper. The governing equation is based on the first-order shear deformation theory (Mindlin plate theory), which is applicable for both thin and moderately beams, and includes the coupling between mechanical and electrical deformations. The voltage generated by the sensor layer and response of the beam to the actuator voltage can be computed independently. In this study, the new assumption of harmonic vibration is introduced, which includes both of the sine and cosine terms. Another contribution of this paper is introducing the transformation method of complex numbers to reduce the order of the governing equation of smart laminated beams. Thus, the exact solution of the reduced governing equation can be obtained by using MATLAB and the entire numerical results are presented. The behaviour of the output voltage from the sensor layer and the input voltage acting on the actuator layer is also studied. Graphical results are presented to demonstrate the ability of closed-loop system to actively control the vibration of laminated beams and it shows a good control effect. The influence of stacking sequence on the controlled transient response of the laminated beam is examined. Finally, the experiential formulation of the amplitude of beam vibration varying with the negative velocity feedback control gain has also been evaluated. The present method has a general application in this field of study.     

超精密装置PID振动控制系统的仿真研究

 在仿生啄木鸟头部独特生物构造和隔振机理的基础上，采用主动隔振技术建立了超精密装置隔振系统结构及动力学模型． 结合超精密装置隔振系统的结构特点和性能要求，采用闭环PID主动控制系统，用Matlab软件进行了仿真分析．仿真分析结果表明，该振动控制系统宽频率范围内具有良好的减振效果，该系统可应用于超精密\测量、超精密制造设备的隔振领域．     

弯振复合型超声驱动器振动特性研究

为了避免模态复合型超声驱动器中普遍存在的频率简并问题,作者在前期研究中提出了一种新型的弯振复合型超声驱动器。该驱动器采用压电金属复合梁两个正交弯振模态的复合在两个驱动足处激励出椭圆轨迹振动。本文对该驱动器的振动特性进行深入研究,旨在获得驱动区域质点的真实运动轨迹。首先,建立了矩形截面梁在弯振复合模态下末端区域质点振动轨迹的数学模型;然后,借助有限元瞬态分析,对驱动足振动轨迹进行仿真,实现对所建立振动轨迹数学模型的验证。振动轨迹方程和仿真结果均表明：两个驱动足表面质点振动轨迹均为三维的椭圆,垂直于驱动器轴线的平面内的椭圆振动更适合用于致动输出。最后,分析了该驱动器存在的不足之处,提出了一种改进方案,采用对称设置压电陶瓷片实现两个驱动足振动特性的一致;通过瞬态分析在两个驱动足处得到了一致的振动轨迹,改进的样机实现了输出特性的显著提高。     

Mesh‐free models for static analysis of smart laminated composite beams

This paper is concerned with the development of mesh‐free models for the static analysis of smart laminated composite beams. The overall smart composite beam is composed of a laminated substrate composite beam and a piezoelectric layer attached partially or fully at the top surface of the substrate beam. The piezoelectric layer acts as the distributed actuator layer of the smart beam. A layer‐wise displacement theory and an equivalent single‐layer theory have been used to derive the models. Several cross‐ply substrate beams are considered for presenting the numerical results. The responses of the smart composite beams computed by the present new mesh‐free model based on the layer‐wise displacement theory excellently match with those obtained by the exact solutions. The mesh‐free model based on the equivalent single‐layer theory cannot accurately compute the responses due to transverse actuation by the piezoelectric actuator. The models derived here suggest that the mesh‐free method can be efficiently used for the numerical analysis of smart structures. Copyright © 2016 John Wiley & Sons, Ltd.     

主动隔振作动器刚度放大与控制误差分析

研究了主动隔振系统中作动器的刚度放大与控制误差问题。主动隔振系统中作动器的刚度应与其负载刚度相匹配,如果负载较大或者作动器刚度较小,可以利用作动器与小刚度弹簧串联的方式放大输出刚度。分析了控制器的输出误差均匀分布时主动隔振系统的隔振性能,分析表明,对作动器刚度放大时,需要同时提高控制器的相对精度与作动器的行程才能保证原有的隔振效果,作动器的输出刚度与控制器相对精度、作动器的输出行程两参数具有等效性与替代性。这为设计主动隔振系统时控制器与作动器在更广阔的范围内选择提供了依据。