Drive Signal Frequency-Lock Method Based on 90° Phase Shift for Quartz Angular-Rate Sensor

A drive signal frequency-lock method for quartz angular-rate sensor is presented. The calculation result obtained by the equivalent volume force analytic method indicated that when taking the inherent frequency of the drive tines as the drive signal frequency the phase of the reference vibration is 90° behind that of the drive signal, and the square of amplitude is less than that of the maximal amplitude by 1/(4Q~2_d) merely. The curves derived from the finite element analytic method proved that near the inherent frequency the phase shift of the feedback voltage is identical to that of the reference vibration, and the amplitude is proportional to that of the reference vibration, and the phase shift is linear approximatively with the frequency shift. The frequency shift could be calculated according to the phase shift obtained by quadrature correlation detection, so the drive signal frequency could be locked at the inherent frequency of the drive tines by means of iteration.

High resolution angular-displacement sensor based on whispering gallery mode resonance in bent optical fibers

A simple fiber sensor to measure angular displacement with high resolution, which is based on whispering gallery mode （WGM） resonance in bent optical fibers,is proposed. The sensor is composed of a single loop formed by loosely tying a knot using single mode fiber. To measure the transmission spectra, a tunable laser and an optic power meter are connected to the two ends of fi- ber loop, respectively. Significant WGM resonances occur over the investigated wavelength range for all the sensors with different bend radius. The angular-displacement sensitivity is studied in the range from -0. 1°to 0. 1°. The detection limit of 1.49 × 10 ^-7 rad can be achieved for the detecting system with the resolution of lpm. The simple loop-structure fiber sensor has potential application prospect in the field of architecture or bridge building with low detection limit and low cost.

一种MHD角振动传感器动态本底噪声无偏高效测试方法

目前,磁流体动力学(MHD)角振动传感器动态本底噪声测试尚无统一方法,难以有效开展测试。首先,针对双通道和三通道方法系统误差不明确的问题,推导了两种方法的系统误差,指出了方法的适用条件;然后,针对双通道方法存在系统误差、三通道方法系统结构复杂的问题,提出了一种基于最小二乘的传感器动态本底噪声无偏高效测试方法,证明了所提方法不存在系统误差;最后,实验对比了三种方法的测试效果。结果表明,所提方法能够在时域和频域上准确分离传感器的动态本底噪声;相比双通道和三通道方法,所提方法的平均相对误差最小,分别为7.2%和3.7%;测试系统所需资源少、结构简单而且易于实现,满足MHD角振动传感器动态本底噪声的测试需求。

时栅动态性能在线检测系统研究

目前,时栅性能检测方法中并没有将时栅反馈到控制系统中,处于一种离线的工作模式,无法反映工作状态下的动态性能指标。为了弥补现有检测方法的不足,提出以时栅作为直驱电机反馈元件,以光栅为基准元件,以FPGA为数据采集卡核心器件采集动态数据,设计了一种时栅动态性能在线检测系统,并阐述了检测原理及软硬件设计,成功检测出时栅在线工作状态下的关键动态性能指标。实验结果表明:系统检测能反映时栅在线工作状态下的真实情况,可为进一步提升时栅的性能提供有效的检测手段。

单相激励电容式时栅角位移传感器研究

针对现有多相激励时栅角位移传感器在小体积时无法设置更多极对数进一步提升稳定性,导致精度和动态性能指标无法得到提升等问题,提出一种单相激励电容式时栅角位移测量方法。该方法采用单相激励耦合成四路空间正交的驻波信号,通过电路实现行波构造,从而实现角位移测量。文中介绍了多相激励时栅传感器存在的问题、单相激励时栅的测量原理,完成了传感器样机的研制,并通过实验验证该原理的有效性。实验结果表明,相同尺寸和相同电极数量情况下,单相激励传感器的精度和动态性能指标优于多相激励传感器,单相激励传感器精度为±20″,稳定性为10″,400 rpm转速下速度波动为±1.25%,跟随误差为±2.5″,满足直驱电机的使用要求。

基于自适应小波回声神经网络的光纤陀螺测角仪温度误差补偿技术

基于光纤陀螺的测角仪可以实现对各项角运动参数的一体化动态精密测量,但在实际应用中,光纤陀螺测角仪受到温度变化的影响,导致测量精度下降。针对这一问题,本文提出了一种基于自适应小波回声神经网络的光纤陀螺测角仪温度误差补偿技术。为了提高温度误差建模的进度,提高传统神经网络的逼近能力,通过自适应前向线性预测滤波器对建模用测角仪温度漂移数据进行预处理,并采用自适应小波回声神经网络建立温度漂移模型,能够避免传统神经网络结构设计的盲目性和局部最优等问题,增强了网络学习能力和泛化能力,并利用自适应律代替神经网络梯度进行网络训练,提升神经网络的逼近精度和收敛速度。实验结果表明,该模型可以提高光纤陀螺测角仪的测量精度和环境适应性,为光纤陀螺测角仪的性能优化和实际应用提供了可靠的技术支撑。

串联式齿轮传动大量程角位移传感器设计

旋转差动变压器式角位移传感器在机载领域具有广泛的应用,采用齿轮传动的方式可实现其量程的扩展。分析了传统并联式齿轮传动结构存在的不足,设计了串联式的齿轮传动结构。该结构相比于并联式具有结构紧凑、质量轻、成本低等优点。采用该串联式方案研制出了某型航空发动机双余度喷口角位移传感器,进行环境试验前、后的产品性能测试及产品质量测量。测试结果表明,传感器内部齿轮传动机构可实现角度的准确、可靠传递。串联式齿轮传动传感器在-65°~65°范围内具有优异的输出特性,与并联式齿轮传动结构的传感器相比,约减重32%。

一种结合角距特征的改进栅格星图识别算法

针对栅格算法易受邻域星点影响导致误匹配的问题,提出了一种结合角距特征的改进栅格星图识别算法。首先介绍了改进栅格算法的原理,其次设计了融合栅格识别模式和星角距识别模式的算法实现流程,最后开展了基于不同视角下的大视场仿真星图的算法试验验证和性能分析。结果表明,由于角距特征具有旋转不变性和不易受观测星邻域星点分布影响等特点,结合角距特征对失效观测星进行再匹配的改进栅格算法,在兼顾存储量需求小、运行速度快等优势的同时,识别率和鲁棒性也得到了提升,最高识别率可达98.88%,在位置噪声干扰以及缺失星干扰下,改进算法的识别率仍可保持在95%,说明算法鲁棒性强,具有较好的应用前景。

Application and analysis of functionally graded piezoelectrical rotating cylinder as mechanical sensor subjected to pressure and thermal loads

The exact thermoelastic analysis of a functionally graded piezoelectrical （FGP） rotating cylinder is investigated analytically. The cylinder is subjected to a com- bination of electrical, thermal, and mechanical loads simultaneously. The structure is a simplified model of a rotational sensor or actuator. The basic governing differential equation of the system is obtained by using the energy method. A novel term, named as the additional energy, is introduced to exact the evaluation of the energy functional. The solution to the governing differential equation is presented for two types of boundary conditions including free rotating and rotating cylinders exposed to the inner pressure. The effect of the angular velocity is investigated on the radial distribution of various components. The mentioned structure can be considered as a sensor for measuring the angular velocity of the cylinder subjected to the pressure and temperature. The obtained results indicate that the electrical potential is proportional to the angular velocity.

Direction finding of coexisted independent and coherent signals using electromagnetic vector sensor

The existing direction of arrival （DOA） estimation algorithms based on the electromagnetic vector sensors array barely deal with the coexisting of independent and coherent signals. A two-dimensional direction finding method using an L-shape electromagnetic vector sensors array is proposed. According to this method, the DOAs of the independent signals and the coherent signals are estimated separately, so that the array aperture can be exploited sufficiently. Firstly, the DOAs of the independent signals are estimated by the estimation of signal parameters via rotational invariance techniques, and the influence of the co- herent signals can be eliminated by utilizing the property of the coherent signals. Then the data covariance matrix containing the information of the coherent signals only is obtained by exploiting the Toeplitz property of the independent signals, and an improved polarimetric angular smoothing technique is proposed to de-correlate the coherent signals. This new method is more practical in actual signal environment than common DOA estimation algorithms and can expand the array aperture. Simulation results are presented to show the estimating performance of the proposed method.

结构参数约束下的磁场补偿式双层时栅角位移传感器研究

时栅角位移传感器广泛运用于数控机床、工业机器人等领域中的角度测量。针对双层时栅角位移传感器测量过程中时变磁场分布不对称问题,提出了一种磁场补偿驱动方案,该方案通过对双层平面线圈分层分幅值激励来提高时变磁场的对称性。首先建立了传感器时变磁场参数化数学模型,根据磁场补偿思路确定了两层激励信号幅值比与传感器结构参数的关系;然后构建了仿真模型,并搭建了传感器实验系统;最后,进行了原有驱动方案与磁场补偿式驱动方案的对比仿真与实验分析。仿真数据表明,磁场补偿驱动方案优化了磁场分布,有效地减小了传感器节距内互补位置的感应电动势幅值差,双层时栅角位移传感器节距内测量误差减小了37.4%;实验数据表明,磁场补偿驱动方案使节距内测量误差降低至(-20.8″,12.6″)。仿真与实验数据的对比验证了磁场补偿驱动方案的有效性。

基于AKF滤波器的时栅角位移动态误差抑制方法

动态测量下的谐波误差成分是制约高精度、高分辨率的时栅角位移传感器在动态测量领域运用的主要原因之一。针对动态测量下时栅角位移传感器中的谐波抑制难题,首先简述了时栅角位移传感器的系统模型,其次建立了时栅角位移传感器的动态误差数学模型,之后解释了传感器的动态误差产生机理,阐述了自适应卡尔曼滤波的基本原理,最后构建了基于自适应卡尔曼滤波的时栅角位移传感器的动态误差抑制模型。通过仿真分析证明了时栅角位移传感器在匀速和变速运行情况下,经自适应卡尔曼滤波后,动态误差均降低了约70%,且随着传感器转速的提高,对谐波误差的抑制效果越明显。在实验运用中,该滤波算法对时栅角位移传感器的测量值有很好的实时预测性,传感器能够更快速且稳定运行,在100 r/min的转速下测量误差降低约80%。结果证实了自适应卡尔曼滤波在时栅角位移传感器的动态谐波误差抑制中有着显著的作用,能极大地提高传感器的动态测量精度。

经验模态分解算法在角位移传感器信号去噪中的应用

当多个角位移传感器工作在多个电平时,线路间的串扰会导致内部噪声,影响传感器信号输入和输出。设计了角位移传感器线间串扰信号的多层分解去噪方法。在计算角位移传感器信号线间的串扰电压后,分别计算电容耦合和电感耦合的总串扰电压。利用经验模态分解算法对传感器信号进行逐层分解后,得到一定量的残差项和信号分量(IMF),并将其相加生成新的信号。重复分解计算产生新的信号,然后计算信号分量(IMF)中包含的串扰信号,并根据硬/软阈值消除串扰噪声。仿真结果表明,所设计的方法可以有效地消除角位移传感器线间串扰信号噪声的影响,使传感器采集的角位移测量电路的电压信号更接近无串扰的电压信号,从而保证角位移传感器信号的有效性。

Temperature compensation method for low cost three-axis MEMS digital angular rate gyroscopes

In recent years,a large number of small volume,low cost micro electro mechanical systems（MEMS）digital three-axis angular rate gyroscopes have been developed and widely used in civil and military fields.However,these kinds of gyroscopes have poor performances in initial zero-bias,temperature drift,In-Run bias stability,bias repeatability,etc.,their output errors need to be compensated before being used.Based on a lot of experiments,the temperature drift and the initial zero-bias are the major error sources in the MEMS gyroscopes output data.Due to the poor repeatability of temperature drift,the temperature compensation coefficients need to be recalculated every time before using.In order to recalculate parameters of the temperature compensation model quickly,a 1st-order polynomial model of temperature is established,then a forgetting factor recursive least squares estimator will be adopted to identify the model parameters in real time.Static and dynamic experimental data shows that this method removed/compensated the temperature drift and initial zero-bias from the output of the gyroscopes effectively.

Model of output characteristics of giant magnetoresistance(GMR) multilayer sensor

In this paper,the giant magnetoresistance(GMR)multilayer sensor is fabricated with a Wheatstone bridge,and it exhibits excellent performance with a sensitivity of 2.8349 mV/(V/Oe)(1 Oe=79.5775 A·m^-1)and a saturation field of 26 Oe along the sensitive axis.The GMR sensor is also characterized in a high magnetic field.The sensitivity decreases from 2.8349 mV/(V/Oe)at an angle of 0°to 0.0175 mV/(V/Oe)at an angle of 90°.Then,the sensor is placed in a series of rotating magnetic fields.We propose a model to express the output characteristics of the GMR multilayer sensor.The transfer curves of the sensor can be shown as two exactly symmetrical circles with an increasing radius when the magnetic field increases.The experimental results are consistent with the simulation results of the model.The advantage of this model is that it is simpler and more intuitive.

互补式双层时栅角位移传感器研究

针对当前研制的双层时栅角位移传感器感应信号幅值小、时变磁场的均匀有效面积利用率低等问题,在原有“八”字形半正弦结构的基础上提出了一种双层互补式时栅角位移传感器设计方案。根据双层时栅位移传感器的特点,建立了其空间磁场分布模型,验证了双层时栅角位移传感器的互补式结构在构成行波上的优势;根据激励线圈的磁场分布规律进行建模,得到该参数状态下双层平面激励线圈的间距为0.235 mm。最后进行了有限元仿真分析和实验验证。仿真分析表明:采用互补式结构能有效增大感应信号强度,传感器的短周期误差峰峰值显著降低,能够有效抑制角度误差中的1次谐波和4次谐波。实验数据表明:传感器短周期原始误差为(-13.61″,13.30″),修正后误差为(-3.01″,0.78″);传感器长周期原始误差为(-19.60″,21.96″),修正后误差为(-2.62″,3.30″);相比单层“U”字形结构,1次误差减小了66.3%,4次误差减小了25.3%。

基于零极点配置的宽频带角速度传感器信号融合方法

为满足在轨微角振动力学特性分析和主动补偿的测量需求,解决单一角速度传感器难以兼顾sub-μrad级低噪声与k Hz宽频带的问题,提出一种基于零极点配置的宽频带角速度传感器信号融合方法。通过调配不同测量带宽角速度传感器传递函数的极点来调整传感器传递特性,使传感器在非工作带宽的信号和噪声衰减后再进行融合,实现了带宽2 Hz-1000 Hz的MHD角速度传感器与带宽DC-22 Hz的MEMS陀螺仪的数据融合,并将所提方法与两种基于频域的数据融合算法进行对比。实验结果表明:当对MEMS陀螺仪进行零极点配置融合时,融合信号在0.1 Hz-700 Hz频段内最大幅值波动1.64 dB,等效噪声角速率0.2126°/sRMS。所提方法能够为宽频带角速度测量提供技术保障,并能为具体场景下融合算法的应用和选择提供指导。

基于机器视觉的数字式角振动传感器动态校准方法

低频角振动传感器在惯性导航、姿态估计及精密控制等领域具有广泛应用,其灵敏度校准精度是决定应用系统性能的关键。激光干涉法与圆光栅法是最常用的两种校准方法,然而前者需要昂贵与复杂的系统,后者的校准频率范围与应用场景有限,难以满足日益增长的高性能角振动传感器校准需求;通过采用具有亚像素级边缘提取精度的机器视觉法准确地测量低频角振动传感器的输入角激励,以实现宽低频范围的灵敏度可靠校准,同时保证校准精度与效率。与激光干涉法及圆光栅法的对比试验表明,机器视觉法与激光干涉法及圆光栅法在0.01~5.00 Hz范围内具有相似的校准结果,最大相对偏差分别约为0.6%和0.4%;此外,整个频率范围内,机器视觉法校准的最大灵敏度相对标准差约为0.5%。

一种对极数互质的高精度绝对式角位移传感器

提出了一种对极数互质的高精度绝对式时栅角位移传感器。在N对极的单圈增量电场式时栅角位移传感器的基础上增加一个M对极的传感器,实现组合测量,其中,2个增量式传感器对极数N和M为互质数,对极数多的作为精测部分,保证传感器的测量精度;对极数少的作为粗测部分,利用2个增量式传感器输出行波相位差和空间角度对应关系实现传感器的绝对角位移测量。采用差动感应电极结构消除共模干扰以保证测量精度,这种对极数互质组合测量传感器既能够较容易实现绝对定位,又能够保证传感器的高精度。采用印制电路板技术制造了外径154 mm、内径100 mm、厚度2 mm的传感器样机,搭建了实验平台进行测试,测试结果表明:该传感器的整周测量范围原始精度可达±1.8″。

基于MHD角速度传感器的面阵相机模糊图像复原

在轨卫星平台上普遍存在着宽频带、低幅值的微角振动,随着对航天相机探测能力和遥感图像空间分辨率要求的不断提高,微角振动对星载光学系统成像质量的影响更加突出.针对高频微角振动造成的图像模糊问题,提出使用磁流体动力学(magnetohydrodynamics,MHD)角速度传感器测量面阵相机受到的微角振动,并根据面阵相机角运动信息构建点扩散函数,进一步采用基于全变差正则化的图像复原算法实现图像复原,从而提高图像质量.首先,在分析航天相机受到微角振动干扰产生像移原因的基础上,建立像移模型,并根据像点在焦平面上的移动轨迹构建点扩散函数.其次,搭建实验系统模拟航天相机在微角振动环境下的成像过程,在垂直于光轴的方向上施加单频正弦角振动干扰,并使用MHD角速度传感器进行探测.最后,利用基于全变差正则化的图像复原优化算法对模糊图像进行复原,并基于图像的调制传递函数对复原图像质量进行评价.实验结果表明:当微角振动频率在20~300 Hz内,且产生的像移在13个像元以下时,复原图像的调制传递函数积分面积可达到静态图像积分面积的90%以上,图像细节清晰,对比度得到明显提升.对同一频点进行多次重复实验,结果表明该方法具有良好的重复性.相关实验结果表明,基于MHD角速度传感器的微角振动测量方法和图像复原算法相结合能够显著提高航天相机的成像质量.