智能型表面测振系统

本文采用加速度传感器测量振动频谱的原理，对表面振动测量系统的实现进行了较为详细的描述，并用所研制的测振系统进行了实际测量，得到较为理想的实验结果．     

自由活塞斯特林发动机活塞位移测量

自由活塞斯特林发动机活塞往复振动位移对研究发动机特性具有重要意义,然而该类发动机活塞位于高压封闭腔体内且结构较为紧凑,其活塞往复振动位移难于直接进行测量。加速度传感器具有尺寸小、安装方便和工作稳定等特点,提出了采用加速度传感器测量活塞位移的方法。根据加速度传感器测量位移的原理,建立了一套加速度传感器测量自由活塞斯特林发动机活塞位移的标定试验系统,以位移传感器为基准测试并分析了不同活塞振幅和不同振动频率下加速度传感器测量位移的误差大小。实验结果表明,在活塞振幅小于8 mm,振动频率大于20 Hz条件下,加速度传感器测量位移的误差小于5%。因此加速度传感器可以用于测量自由活塞斯特林发动机的活塞往复运动位移。最后成功把加速度传感器测量的自由活塞斯特林发动机活塞振动位移用于发动机循环指示功的实验研究。     

用智能手机传感器测量弹簧的劲度系数

本文提供了一个用智能手机做实验工具的例子, 实验中智能手机既做弹簧的振子, 也可测量弹簧的振 动周期, 用智能手机加速度传感器测量极短暂的振动周期, 从而提高了实验的测量精度, 降低了实验误差     

低频振动传感器的设计

为了测量精密仪器运输过程中所产生的振动和进行仪器抗振试验,以及为了对保护仪器而设计的减振系统之减振效果进行检验,均需要使用低频振动传感器及其相应的测试系统。 目前,测量低频振动所产生的加速度一般采用压晶式、电感式或电阻式传感器。 本文叙述了我所研制成的一种电阻式低频振动传感器的基本设计原理,结构参数选择原则及标定方法,并举例说明了它的应用。     

具有温度补偿功能的光纤振动测量系统

针对光纤振动传感器受温度影响和灵敏度低的问题,设计了具有温度补偿功能的光纤振动测量系统.为减小温度对振动测量的影响,系统利用光纤布喇格光栅测量环境温度,对振动加速度值进行补偿;采用可调谐法布里-珀罗滤波器进行波长解调,并将其作为光纤反射镜,以提高传感器的灵敏度.分析并测试了振动和温度同时测量时的相互影响,结果表明,振动对光纤布喇格光栅中心波长的影响很小,通过数据处理的方法,可消除法布里-珀罗滤波器扫描对振动测量的影响;实验测得,温度变化25℃时,振动加速度最大相对测量误差为1.65%,振动测量的灵敏度为107.70mV/g.     

飞机尾翼转角测量系统设计

针对飞机尾翼转角测量及远距离监控问题,设计了一种基于数字式MEMS加速度传感器测量飞机尾翼转角的测量系统。分析了电容式加速传感器测角原理;利用数字式MEMS加速度传感器ADXL345,结合无线ZigBee技术采用CC2430模块,以嵌入式STM32单片机作为控制器构建了一种测量飞机尾翼转角大小的测量系统。采用三维转台对飞机尾翼转动进行了模拟,完成了±90°范围内转角的测量。实验结果表明,在±90°转角范围内,测量误差的最大值为0.277°,满足小于0.3°的误差要求。该测量系统可以有效地完成飞机尾翼转角测量工作。     

YBCO堆叠高温超导磁体的磁悬浮振动传递特性实验研究

在YBCO堆叠磁体与永磁轨道构成的高温超导磁悬浮系统中,永磁轨道的振动通过电磁作用传递给YBCO堆叠磁体.本文通过实验研究了振动在YBCO堆叠磁体磁悬浮系统中的传递效率与基振加速度幅值和基振频率的关系.研究表明:在YBCO堆叠磁体磁悬浮系统中,YBCO堆叠磁体自由振动频率在9 Hz左右;一定低频条件下,振动的传递效率与基振加速度幅值呈正相关趋势,与基振频率呈负相关趋势.     

微型扬声器振动系统阻尼频率特性研究

受材料黏弹性的影响,微型扬声器振动系统的力阻与频率有关。通过理论推导建立了力阻与频率之间的模型,得到了微型扬声器振动系统力阻的计算公式,利用激光测振法测量得到的微型扬声器阻抗曲线和位移曲线可以方便地得到微型扬声器振动系统力阻频率响应,表明了其随频率增加而减小的频率特性。实验表明,采用该频率相关力阻模型计算阻抗曲线、位移曲线和频率响应曲线,与测量值吻合很好,明显好于传统频率非相关力阻模型所得曲线。     

基于全光纤微振动传感器的定位系统研究

以噪声性质存在的微振动信号是造成干扰和影响机械加工精度的主要因素之一,消除干扰的前提是对微振源的准确测量和定位。针对现有基于光纤的定位系统存在的不足,设计了一种基于全光纤微振传感器的微振源定位系统,该系统要求最少4个微振传感器,通过同时测量3个传感器相对于另一个传感器的振动信号到达时间差(TDOA)来计算微振源的位置。通过实验对传感器和定位系统的性能进行验证,相对定位误差低于0.56%,且系统稳定可靠。     

在线转子振动参数的光电检测

为了测量在线转子的振动信息,以半导体激光器为光源,以PSD(position sensitive detector)为探测器,基于光电三角测量法,建立了一套包括软、硬件在内的激光测振系统。通过对该系统的标定实验表明,实际位移与所测得的位移呈线性关系。在数据处理中,对所得到的复杂时域振动信号进行了离散傅里叶变换(DFT),从而在频率域获得了转子的振动频率和振幅信息。通过采用多线程高级编程技术,解决了数据处理时间、图像及数据显示、存储时间之间的冲突,实现了在线测量。经测试表明,该测振系统的测量频率分辨率可达到0.6Hz,振幅不确定度小于±10μm。     

A novel interferometric vibration measurement sensor with quadrature detection based on 1/8 wave plate

In-phase and quadrature-phase (I/Q) signals often need to be formed in the laser interferometric vibration measurement technique. To avoid the disadvantages of traditional I/Q signals forming methods such as effect of piezoelectric ceramic (PZT) for generating high frequency carrier, or optical configuration with complicated structure, a novel interferometric vibration measurement sensor with quadrature detection is proposed. The sensor utilizes simple optical configuration which contains 1/8 wave plate to generate two I/Q signals, then the signals were processed by arctangent algorithm which is compiled by Labview software through data acquisition card. Theoretical analysis and experimental Lissajous figures synthesis prove the phase orthogonality of the two signals. The experimental results indicate that the system can measure the vibration displacement accurately.     

基于矢量阵的运动声源柱面聚焦定位方法试验研究

本文基于被动合成孔径原理, 在建立运动声源矢量阵近场柱面聚焦测量模型的基础上, 分别研究了适用于单频线谱信号和宽带连续谱信号的矢量阵柱面聚焦定位方法, 通过数值仿真计算了该方法在多种误差条件下的定位精度, 并进一步通过舱段模型试验对该方法的工程实用性和正确性进行了详细的分析和论证. 舱段模型试验结果表明, 柱面聚焦定位结果与壳体振动能量分布规律符合较好, 该方法不仅能真实反映声源位置信息, 而且能反映不同频带内声源能量分布的相对大小, 具有良好的定位效果.     

Laser Vision Measurement System and Assessment Method for SMIC Lead Coplanarity

In this paper, a successful application of line-structured laser sensor, involved in SMIC chip lead coplanarity measurement, is presented. With the experimental measurement system and its corresponding mathematics model, a contact-datum-plane assessment of SMIC chip lead coplanarity is developed to provide method for on-line measurement.     

Ground vibrations detection with fiber optic sensor

In this paper, a fiber optic sensor based on fiber Bragg grating (FBG) is employed to measure the ground vibrations which may be generated by earthquakes, debris flows, landslides, and rock impacts on the ground. The detected vibration signals were analyzed by both fast Fourier transform (FFT) and Gabor transform to obtain the frequency response. The performance of fiber optic sensor was examined and compared with the conventional ground vibration geophone sensor. From the results of field tests, the fiber optic sensor shows highly similarity with conventional geophone sensor for low frequency measurement. The fiber optic vibration sensing system presented in this research is appropriate for sensing ground vibration in the frequency ranges of 10–250 Hz. The sensor proved to be an alternative option for ground vibrations monitoring system.     

Laser Vision Measurement System and Assessment Method for SMIC Lead Coplanarity

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一种新型Sagnac式光纤电流传感器

为了消除震动对Sagnac式电流传感器测量结果的影响,提出一种光路改进方法来消除传感器对震动的敏感性,其基本原理是抵消Sagnac效应而不影响法拉第磁光效应。利用琼斯矩阵对改进后的光路结构进行了偏振态分析,理论分析和实验结果吻合,表明改进后的传感器其输出与震动无关。耦合半波片后Sagnac式光纤电流传感器的震动敏感性被消除了,为Sagnac式光纤电流传感器的工程化实现提供了一种可行的方法。     

Self-mixing interference in an all-fiberized configuration Er-Yb codoped distributed Bragg reflector laser for vibration measurement

Self-mixing sensing technique can be used for measuring distances, displacements, velocities and vibration. In this paper, for good sensitivity vibration measurement system, self-mixing vibrator using an all-fiberized configuration Er³⁺-Yb³⁺ Distributed Bragg Reflector (EYDBR) laser is proposed and investigated for the first time. Results obtained demonstrate that all-fiberized configuration EYDBR laser present a powerful tool for the advancement of self-mixing vibration sensor and provide a potential remote measurement of the vibration compared with the optical feedback in other traditional fiber lasers.     

Mode shape expansion using perturbed force approach

A new approach for expanding incomplete experimental mode shapes is presented which considers the modelling errors in the analytical model and the uncertainties in the vibration modal data measurements. The proposed approach adopts the perturbed force vector that includes the effect of the discrepancy in mass and stiffness between the finite element model and the actual tested dynamic system. From the developed formulations, the perturbed force vector can be obtained from measured modal data and is then used for predicting the unmeasured components of the expanded experimental mode shapes. A special case that does not require the experimental natural frequency in the mode shape expansion process is also discussed. A regularization algorithm based on the Tikhonov solution incorporating the generalized cross-validation method is employed to filter out the influence of noise in measured modal data on the predictions of unmeasured mode components. The accuracy and robustness of the proposed approach is verified with respect to the size of measured data set, sensor location, model deficiency and measurement uncertainty. The results from two numerical examples, a plane frame structure and a thin plate structure, show that the proposed approach has the best performance compared with the commonly used existing expansion methods, and can reliably produce the predictions of mode shape expansion, even in the cases with limited modal data measurements, large modelling errors and severe measurement noise.     

Coupling analysis of a matched piezoelectric sensor and actuator pair for vibration control of a smart beam

This paper presents a theoretical and experimental study of the in-plane and out-of-plane coupling of a matched piezoelectric sensor/actuator pair bonded on a beam. Both the sensor and actuator are triangularly shaped polyvinylidene fluoride (PVDF) transducers and are intended to provide a compact sensor/actuator system for beam vibration control. The measured sensor-actuator frequency response function has shown an unpredicted increase in magnitude with frequency, which was found, to be due to in-plane vibration coupling. An analytical model has been developed to decompose the sensor-actuator response function into an in-plane contribution and an out-of-plane contribution. This in-plane coupling can limit the feedback control gains when a direct velocity feedback control is applied. A method called the j omega s compensation method is proposed to identify the effect of the in-plane vibration coupling at low frequencies. Even after this compensation, however, there was unexpected strong out-of-plane coupling at even modes, which may have been caused by a lack of accuracy in the shaping of the PVDF sensor and actuator. Numerical simulations have confirmed the sensitivity of the matched sensor/actuator pair with shaping errors.     

Measuring vibration by using fiber Bragg grating and demodulating it by blazed grating

A method of measuring vibration by using fiber Bragg grating (FBG) and demodulating the spectrum by blazed grating is introduced. The sensor system is made of a simple supported beam with a FBG adhered to its upper surface. A blazed grating is used to demodulate the changing spectrum that is got from the sensor system, and a line charge-coupled device (CCD) is used to accept the diffraction spectrum.Through analyzing the number of the CCD's pixels, we can get the amplitude of vibration and the change of the temperature. The experimental results show that the vibration amplitude of the exciter matches the detected signal under the stable frequency. The temperature shift and vibration signal are also successfully separated.