光纤陀螺组件误差标定ARLS算法

捷联惯性导航系统误差参数标定的准确程度对于系统的导航和定位精度具有重要影响.针对常规速率标定法不能辩识陀螺零偏,未充分预热时光纤陀螺的误差标定易受温度变化影响这两个问题,提出了一种用于光纤陀螺捷联惯性导航系统的新标定算法--自适应递推最小二乘法(ARLS).在建立光纤陀螺误差及其补偿模型的基础上,通过大量温度实验研究了自适应遗忘因子的求取方法,详细推导了ARLS算法及其实现思路.最后通过算法仿真和速率试验证明了在器件特性不稳定条件下,ARLS算法能有效辨识陀螺的误差参数及减小温度变化对光纤陀螺误差标定的影响.     

分立标定中捷联惯导标定参数间的关联性影响

光学捷联惯导误差随时间积累,分立式标定作为一种误差补偿技术,是提高惯导精度的必要手段。惯导标定参数主要有标度因数、安装偏角、零偏,文章在阐述IMU标定原理的基础上,推导了标定过程中参数误差的传播途径,理论分析了标定参数之间的关联性影响,得到以下结果:零偏重复性误差对标度因数和安装偏角的标定无影响;标度因数非线性和重复性误差对安装偏角和零偏的标定无影响;零偏稳定性误差对标定因数和安装偏角的标定有影响;陀螺的角度随机游走对陀螺三个标定参数均有影响;加速度计的随机噪声对加速度计的三个标定参数均有影响;陀螺的标度因数不对称性对陀螺的安装偏角和零偏的标定有影响;安装偏角重复性误差对陀螺的零偏标定有影响而对标度因数标度无影响,对加速度计的标度因数和零偏的标定无影响。结论对于惯导系统性能评估、误差分配和器件设备选型具有重要意义。     

一种高精度的非线性相位误差校正方法

在相位测量轮廓术中,测量系统中投影仪等存在的非线性响应大大影响了相位测量的精度,因此,如何快速高效地消除系统中的非线性误差是提高测量精度的关键.本文建立了相位误差的精确模型,并提出了一种基于相位误差精确模型的相位提取方法,利用高步数相移算法预先标定各频谱分量的比例关系,再通过迭代运算即可得到高精度的相位分布.实验结果表...     

隔振系统布置及振动相位对基础响应影响的研究

对带有多个隔振系统的简支梁,利用四端参数法结合数学推导得出基础梁的位移响应表达式,指出隔振系统的坐落位置和机器的振动初相位是分析基础响应时不可忽略的因素.并利用有限元仿真建模对基础上坐落单个隔振系统和两个隔振系统的情况进行分析.结果表明:单个隔振系统坐落在基础梁中部时,基础梁的响应最大,算例中的响应位移极值比达到8.02;不同振动相位的两个隔振系统的激励在基础上叠加时,基础响应峰值差在17%以上;初相位会改变基础的波动表现形式.     

拉曼激光相位噪声对原子干涉重力仪测量分辨力的影响

原子干涉重力仪已获得当今g值测量的最高分辨力，使得其在前沿科学研究和精密计量中有广阔的应用前景，但其分辨力的提高受限于包括拉曼激光相位噪声在内的各种噪声。本文通过对拉曼激光相位噪声模型和原子干涉仪中噪声传递过程的研究，发现微波信号源贡献了拉曼激光相位噪声的主要部分；通过计算常见T，τ条件下拉曼激光相位噪声对干涉仪重力测量分辨力的影响，发现100～300 ms内T越大重力仪测量分辨力越高，其中在T =300 ms、τ=20 μs的条件下，单次测量时拉曼激光相位噪声对原子干涉仪相位波动的影响为19.6 mrad，相应对重力仪分辨力的影响为1.35 μGal（1 μGal=10-8 m/s2）。     

基于半互功率谱密度及响应面法的干气密封系统工作模态分析

干气密封装置的动态特性会直接影响密封的可靠性,针对具有复杂结构的干气密封装置,实现对其工作模态的研究。基于多参考点最小二乘复频域法(PolyLSCF),分别采用互功率谱函数(Cross Power Spectra)和半互功率谱密度函数(Cross Half PSD)实现对装置系统的工况模态分析及识别,并通过数学指标:模态置信度(MAC)、平均相位偏差(MPD)、模态相位线性度(MPC)、模态复杂性(MOV)以及模态指示函数(MIF)对两个函数的模态结果进行验证。结果表明:采用半互功率谱密度函数的模态分析结果好于互功率谱函数,半互功率谱密度函数更适用于此类复杂结构系统的工作模态分析;不同操作条件下的模态结果表明:转速对于系统模态的影响大于介质压力;同时建立了一种基于响应面方法的时变模态参数识别模型,以不同的操作条件(介质压力与转速)、方向和模态阶数为响应面变量,通过Box-Behnken试验设计选取合适的变量样本点,建立系统模态参数的完整二次多项式工作模态响应面模型并验证了其有效性,为实现时变模态的辨识提供了新的方法和技术支持。     

一种检测低信噪比响应信号的广义维纳滤波方法

根据所测动态响应信号拟合系统模型时,一个重要的问题是:在低信噪比的情况下如何提高系统参数的估计精度。采用线性平均方法能适当提高信噪比,但在一般试验条件下,据此所获得的部分系统参数仍具有较大的误差。本文采用了时域广义维纳滤波方法对测取的动态信号进行预处理,以尽可能少的激励次数,从较高的背底噪声中检测出真实信号。文中还说明了适用于工程系统测试中噪声功率估计的滤波器分组方法。以悬臂梁的模态测试及分析为例,检验了该方法的有效性。试验表明,作振型分析时,因测点信号信噪比低而导致数据误差大的问题得以解决,这对实验模态分析是具有重要意义的。所完成的计算机-FFT 谱分析器信号预处理程序有很大的实用价值。     

傅里叶变换轮廓术中三维坐标同时校准方法

在相位测量型光学三维面形测量中,最终都要将相位信息转换成被测物体的高度分布信息,这个过程往往是通过对已知世界空间坐标的特征点事先标定,获得测量系统的内外特征参数后,完成被测物体的三维坐标转换.因此,标定是三维面形测量的关键环节.本文基于双向二次相位-高度映射方法和摄像机针孔模型线性无畸变标定技术,充分利用傅里叶变换的频谱方向特性,提出了对含有特征点的二维标定物表面变形条纹的频谱进行方向滤波操作,同时获取测量系统XYZ三个方向上的标定数据,对测量系统进行立体校准的系统标定方法.结合旋转风扇叶片形变的测量系统,给出了该方法的标定结果:在XY面内(230mm×230mm)的标准偏差小于0.27mm;在Z方向上小于0.022mm,位移测量灵敏度优于0.05mm.该方法为测量系统的实用化奠定了基础.     

基于相位测量的摄像机标定方法

提出一种新的摄像机标定方法,该方法基于2D共面参照物摄像机标定方法和相移技术.首先由摄像机记录已知相位分布的平面,通过相移计算出相位分布.对任意标定平面,两个正交相位分布与平面坐标的对应关系已知,由此可以建立像素坐标与2D平面坐标的一一对应关系.将该已知相位分布的平面在空间中放置不同的位置,分别完成上述测量,即可根据2D共面参照物摄像机标定方法完成摄像机的高精度标定.该方法避开了复杂的标定特征点提取,大大增加了2D标定数据量,提高了标定精度.实验和计算机模拟表明,该方法简单、可靠和精度高.     

基于LabVIEW的捷联惯导测试系统的设计与实现

为了提高捷联惯导系统的精度,必须通过试验标定出系统中陀螺和加速度计的各误差参数,并对误差进行补偿。本文设计了一种捷联惯导测试系统,以工控机及数据采集与预处理系统为硬件平台采集捷联惯导的输出信号,上位机软件采用LabVIEW开发,对采集到的数据进行处理、显示及结果保存。最后,对捷联惯导系统进行了测试试验,试验结果表明该测试系统的正确性和可靠性,满足捷联惯导系统测试的技术要求,具有很强的应用价值和工程意义。     

Instantaneous phase method for readout signal processing of body dithered ring laser gyro

The readout signal of a body dithered ring laser gyro contains both useful information and the dither component. The dither component must be removed to get the useful information. The dither stripping method can get the useful information without latency. But the quadrature demodulator only has 1/4 pulse resolution, which means that the quantization noise will limit the short-term accuracy. The effect and the property of quantization noise are analyzed in detail. Taking advantage of high-speed analog-to-digital conversion (ADC), the analog values of the two beat frequency signals in quadrature are sampled. A novel instantaneous phase method is introduced, which can get the residual phase besides 4× resolution and the quantization noise can be removed radically. The Allan variance analysis of experimental results shows that the quantization noise coefficient using this method is only 1/7 of that using the original 4× resolution method.     

噪声源测量中修正转接头误差的一种方法

采用Y系数法对转接头的效率进行了测量,并分析了该方法对于噪声源输出噪声功率测量不确定度的影响。试验中采用同轴噪声测量系统对一个波导接头的气体放电管噪声源进行测量,由于使用了波导同轴转换接头,使其超噪比的测量不确定度由同轴系统的0.20 dB增加到0.23 dB。结果表明该方法可以简单而有效地修正转接头引入的误差。     

Resonator fiber optic gyro employing a semiconductor laser

Resonator fiber optic gyro (RFOG) based on the Sagnac effect has the potential to achieve the inertial navigation system requirement with a short sensing coil. Semiconductor laser is one of the key elements for integration and miniaturization of the RFOG. In this paper, an RFOG employing a semiconductor laser is demonstrated. The model of the laser frequency noise induced error in the RFOG is described. To attenuate the laser frequency noise induced error, active frequency stabilization is applied. An online laser frequency noise observation is built, as a powerful optimum criterion for the loop parameters. Moreover, the laser frequency noise observation method is developed as a new measurement tool. With a fast digital proportional integrator based on a single field programmable gate array applied in the active stabilization loop, the laser frequency noise is reduced to 0.021 Hz (1σ). It is equivalent to a rotation rate of 0.07°/h, and close to the shot noise limit for the RFOG. As a result, a bias stability of open-loop gyro output is 9.5°/h (1σ) for the integration time 10 s in an hour observed in the RFOG. To the best of our knowledge, this result is the best long-term stability using the miniature semiconductor laser.     

Design and calibration of a noise measurement system

The setup principle and calibration method of a noise measurement system for frequencies from dc to 10 kHz are described. This system measures the current noise power spectral density of some device, and consists of a low-noise current preamplifier, a voltage preamplifier, and a dynamic signal analyzer which implements the fast Fourier transform (FFT). The noise aspects of the whole system can be modeled as a serial noise voltage generator and a parallel noise current generator at the input port, plus a system free of noise. The cross correlation of the two noise generators is an imaginary number because the system input stage is composed of some junction field effect transistors (JFET's). Via the thermal noise measurement of several resistors, we derive the magnitudes of the noise generators in addition to the input impedance and the total system gain. The imaginary cross correlation is obtained by the noise measurement of pure capacitance. With a well-calibrated procedure, we can measure the noise power down to 2×10^-27 A²/Hz. Two systems with different input stages were calibrated with the same procedure and the noise measurement results of the various resistance values with the two systems all agree well with theoretical values. One of these with an input stage which has a much smaller noise current generator shows great improvement in the noise measurement of the high-impedance device     

Resolution limits in imaging ladar systems

We introduce a new design concept of laser radar systems that combines both phase comparison and time-of-flight methods. We show from signal-to-noise ratio considerations that there is a fundamental limit to the overall resolution in three-dimensional imaging range laser radar (ladar). We introduce a new metric, volume of resolution, and we show from quantum noise considerations that there is a maximum resolution volume that can be achieved for a given set of system parameters. Consequently, there is a direct trade-offbetween range resolution and spatial resolution. Thus, in a ladar system, range resolution may be maximized at the expense of spatial image resolution and vice versa. We introduce resolution efficiency eta(r) as a new figure of merit for ladar that describes system resolution under the constraints of a specific design, compared with its optimal resolution performance derived from quantum noise considerations. We analyze how the resolution efficiency could be utilized to improve the resolution performance of a ladar system. Our analysis could be extended to all ladars, regardless of whether they are     

复杂耦合系统的统计能量分析及其应用

文章综合导纳分析法、经典统计能量分析方法和经典功率流理论的各自优点，提出适合复杂耦合系统的统计能量分析方法，为研究实际机械结构之间的振动传递规律、复杂机械系统的声辐射特性提供理论依据，为实际工程结构的振动隔离、噪声治理提供理论指导。文章首次提出统计能量分析参数必须统一定义，将影响实际机械结构相互之间能量传递的若干要素各自分离，并引入相应的参数分别开展研究。利用理论研究的成果，发展后的统计能量分析首次应用于水下航行器振动和噪声特性分析，预报了水下航行器的振动传递规律和辐射噪声级。理论分析与实验测试结果符合较     

Analytic evaluation of sampled aperture ultrasonic imagingtechniques for NDE

This paper presents a theoretical comparison of three generic sampled aperture ultrasonic imaging systems for nondestructive evaluation. The imaging systems are categorized according to their source-receiver combination for data acquisition: common-source, back-scatter, and full-array imaging. First, forward modeling is performed for a point source and a point receiver. This is then used to model the received data set for each of the imaging categories. Subsequently, the inversion algorithm for each category is derived, and their performance is evaluated in terms of resolution, noise, and computation. We show that in terms of resolution, back-scatter imaging is the best, followed by full-array and common-source imaging. However, in terms of material noise, full-array imaging is the best, with back-scatter and common-source imaging having the same material noise response. Full-array imaging is the only system with inherent redundancy to reduce electronic noise, but at the expense of significantly more computation. The physical transducer is in the full-array category, allowing mechanical scanning to be traded for dynamic focusing and computational power     

机载光电陀螺稳定平台的伪微分反馈控制

为了克服外部干扰对机载光电陀螺稳定平台的影响,实现高稳定精度和隔离度,采用基于伪微分反馈的控制技术对系统的控制性能进行了研究.首先,介绍了伪微分反馈控制技术的基本结构,并对其进行了简化.从理论上分析了简化的伪微分反馈控制技术在控制结构和控制性能上较经典PI控制的优势;然后,提出采用试凑法对伪微分反馈控制器进行参数整定的整定策略;最后,以某型号机载光电陀螺稳定平台为研究对象,对伪微分反馈控制器和PI控制器在抗力矩扰动、隔离载机角速率扰动和控制对象模型摄动等方面进行了仿真对比实验.实验结果表明,在相同的闭环带宽情况下,采用简化的伪微分反馈控制器的机载光电陀螺稳定平台的阶跃响应具有更小的超调,更短的上升和调节时间.在陀螺噪声存在的情况下,该控制器能够有效地抑制力矩和载机的姿态扰动对系统性能的影响;并且对被控对象的模型摄动具有较强的鲁棒性.     

EL红外缺陷测试仪关键参量校准方法研究

基于空间频率响应测试方法,搭建了EL红外缺陷测试仪关键参量的校准装置。分析了对焦以及位置摆放对分辨率校准结果的影响;给出了便携式和固定式EL红外缺陷测试仪相应的测试方法及操作流程。提出了一种针对便携式的测试方法,可以实现无参考背景情况下的校准工作。基于该校准装置可对各类EL测试仪的分辨率参数进行校准,测量结果重复性较好。