Data Analysis and Modeling of Fiber Optic Gyroscope Drift

A data gathering system is designed for the interferometric fiber optic gyroscope (IFOG) of land strapdown inertial system. IFOG is tested and the testing curve is given. The test data of IFOG are analyzed with Allan variance method and each error coefficient is identified. Furthermore, a random drift error model for IFOG is built by the method of time series analysis. The conclusion provides supports for improving IFOG design and compensating for errors of IFOG in practice.

Filtering of long-term dependent fractal noise in fiber optic gyroscope

Stochastic noises of fiber optic gyroscope （FOG） mainly contain white noise and fractal noise whose long-term dependent component causes FOG a rather slow drift. In order to eliminate this component, a two-step filtering methodology is proposed. Firstly, fractional differencing （FD） method is introduced to trans-form fractal noise into fractional white noise based on the estima-tion of Hurst exponent for long-term dependent fractal process, which together with the existing white noise make up of a gener-alized white noise. Further, an improved denoising algorithm of wavelet maxima is developed to suppress the generalized white noise. Experimental results show that the basic noise terms of FOG greatly decrease, and especially the slow drift is restrained effectively. The proposed methodology provides a promising ap-proach for filtering long-term dependent fractal noise.

Effect of radiation-induced mean wavelength shift in optical fibers on the scale factor of an interferometric fiber optic gyroscope at a wavelength of 1300 nm

In order to analyze the effect of wavelength-dependent radiation-induced attenuation （RIA） on the mean trans- mission wavelength in optical fiber and the scale factor of interferometric fiber optic gyroscopes （IFOGs）, three types of polarization-maintaining （PM） fibers are tested by using a 60Co γ-radiation source. The observed different mean wave- length shift （MWS） behaviors for different fibers are interpreted by color-center theory involving dose rate-dependent absorption bands in ultraviolet and visible ranges and total dose-dependent near-infrared absorption bands. To evaluate the mean wavelength variation in a fiber coil and the induced scale factor change for space-borne IFOGs under low radiation doses in a space environment, the influence of dose rate on the mean wavelength is investigated by testing four germanium （Ge） doped fibers and two germanium-phosphorus （Ge-P） codoped fibers irradiated at different dose rates. Experimental results indicate that the Ge-doped fibers show the least mean wavelength shift during irradiation and their mean wavelength of optical signal transmission in fibers will shift to a shorter wavelength in a low-dose-rate radiation environment. Finally, the change in the scale factor of IFOG resulting from the mean wavelength shift is estimated and tested, and it is found that the significant radiation-induced scale factor variation must be considered during the design of space-borne IFOGs.

Effect of radiation-induced color centers absorption in optical fibers on fiber optic gyroscope for space application

The effects of color centers＇ absorption on fibers and interferometric fiber optical gyroscopes（IFOGs） are studied in the paper. The irradiation induced attenuation（RIA） spectra of three types of polarization-maintaining fibers（PMFs）, i.e.,P-doped, Ge-doped, and pure silica, irradiated at 100 Gy and 1000 Gy are measured in a wavelength range from 1100 nm to1600 nm and decomposed according to the Gaussian model. The relationship of the color centers absorption intensity with radiation dose is investigated based on a power model. Furthermore, the effects of all color centers＇ absorption on RIA and mean wavelength shifts（MWS） at 1300 nm and 1550 nm are discussed respectively. Finally, the random walk coefficient（RWC） degradation induced from RIA and the scale factor error induced by MWS of the IFOG are simulated and tested at a wavelength of 1300 nm. This research will contribute to the applications of the fibers in radiation environments.

LMS自适应滤波算法在FOG数据处理中的应用

针对光纤陀螺(fiber optic gyroscope,FOG)输出数据的随机噪声问题,提出将变步长最小均方(leastmean square,LMS)自适应滤波算法应用于FOG数据处理中。根据FOG数据特点,构造变步长LMS自适应滤波器,对FOG输出数据进行实时预处理,自动地调节参数,达到降低FOG随机漂移及角度随机游走的目的。采用Allan方差对滤波前后的FOG数据进行分析,结果表明所提出的算法在FOG数据处理中效果明显,可以优化FOG的零偏稳定性0.019(°)/h及角度随机游走0.001 5(°)/h1/2。

光纤陀螺仪(FOG)技术及发展应用

介绍了当前惯性导航领域一门新型技术光纤陀螺仪(FOG)的基本原理、类型及两种典型光纤陀螺仪的结构,分析了光纤陀螺仪的误差及消除误差的方法,通过介绍光纤陀螺技术发展的过程及世界各主要国家在光纤陀螺实用化方面取得的进展,指出了光纤陀螺仪与其它光学陀螺相比具有的优点及良好的发展前景。

开环FOG中PZT调制器的在线研究

从理论上分析了ＰＺＴ（ 压电型） 光纤相位调制器在开环ＦＯＧ（ 光纤陀螺）中的应用特点，研究了它的调制系数和调制相位延迟变化对开环ＦＯＧ 性能的影响；并设计了两种独立的在线测试方法对它们进行了温度特性研究，利用所得数据，用最小二乘多项式拟合的方法分别得到了它们的温度模型．研究表明，在实验温度范围内，开环ＦＯＧ 的相位调制系数ＫＧＰ随温度呈线性变化，而调制相位延迟α随温度呈二次的变化．

消除FOG-ARW对初始对准影响的研究

光纤陀螺(FOG)作为光学惯性敏感器,与传统机械陀螺相比,具有角度随机游走(ARW)等一些特有的性能指标,ARW对导航系统性能具有重要影响。从光纤陀螺的光路、电路结构分析随机游走产生的机理,并从数学的角度阐述角度随机游走的定义;分析角度随机游走对初始对准的影响;提出利用卡尔曼滤波器有效消除角度随机游走对初始对准影响的方案并通过仿真验证了此方案的有效性。

基于时间序列分析方法的FOG随机漂移建模与辨识

为了对光纤陀螺(FOG)随机漂移(启动漂移、慢变漂移和快变漂移)的各项参数进行快速有效的辨识,建立了含未知模型参数(慢变漂移的相关系数)的FOG随机漂移状态方程模型,通过对FOG随机漂移进行时间序列分析,辨识了未知的模型参数以及慢变漂移和快变漂移的白噪声方差,以卡尔曼滤波/平滑技术计算了FOG随机漂移的3项分量。对实测的FOG随机漂移数据进行了模型辨识与适用性检验,结果表明,该方法能够准确计算FOG随机漂移的各项参数和分量。通过建立FOG随机漂移的状态方程模型,首次将时间序列分析方法与卡尔曼滤波/平滑技术相结合,快速计算了启动漂移、慢变漂移的相关系数以及慢变漂移和快变漂移的白噪声方差,这对于修正FOG单独工作或与其他设备组合时的导航误差具有重要的参考价值。

Y波导残余强度调制对IFOG性能的影响

本文首先通过正弦波调制下干涉信号光强分析解调出光纤陀螺的输出信号,进而得出残余强度调制存在的情况下陀螺输出信号的变化情况,同时,通过分析陀螺信号的变化说明残余强度调制对光纤陀螺性能的影响与陀螺精度要求有关,精度越高,其影响越明显。其次,具体分析了数字闭环光纤陀螺受残余强度调制影响的情况下,其解调输出电压变化引起的数字阶梯高度变化,并通过残余强度调制系数与数字阶梯高度的关系式,说明了残余强度调制对光纤陀螺零偏和标度因数的影响。最后,对所得出的残余强度调制系数与光纤陀螺标度因数稳定性的关系进行了Matlab仿真,通过仿真结果,更进一步说明残余强度调制对数字闭环光纤陀螺标度因数稳定性的影响。

闭环 FOG 的自诊断及在 RSDIMU 中的应用

首先阐述了闭环干涉型光纤陀螺（ＩＦＯＧ）中回路的特点，揭示了它的自诊断能力．由此给出了一种具有自诊断能力的闭环干涉型光纤陀螺并将它应用于一种容错捷联惯性测量单元（ＲＳＤＩＭＵ）中，针对该单元，设计了一种容错算法．该算法除了利用陀螺的输出外，还引入了它的自诊断信息，从而实现了仪表级的信息冗余，使这种ＲＳＤＩＭＵ的容错能力由原来的故障运行（ＦＯ）故障运行（ＦＯ）故障安全（ＦＳ）上升到ＦＯＦＯＦＯＦＯＦＳ．用Ｍａｒｋｏｖ可靠性估计模型对该系统的估计表明，其可靠性也有了很大的提高．

一种缩短闭环干涉式光纤陀螺仪(IFOG)预热时间的方法

光纤陀螺仪的启动阶段,温度的变化导致光纤陀螺仪性能的不稳定。通过分析影响光纤陀螺仪启动阶段热稳定性的因素,提出了一种基于DSP系统的可以实现光纤陀螺快速稳定的方案。这种方法适用于导弹发射、飞机导航等对光纤陀螺仪预热时间要求高的场合。

采用小波降噪和神经网络的FOG温度漂移补偿方法

光纤陀螺(FOG)输出易受环境温度的影响,发生漂移导致光纤陀螺测量精度降低。采用传统的BP神经网络容易陷入局部极小值,导致网络训练失败。为了优化BP神经网络,本文提出了一种粒子群(PSO)优化BP神经网络与小波降噪相结合的光纤陀螺温度漂移补偿方法。首先分析了光纤陀螺温度漂移产生的原因;然后在不同温度下对光纤陀螺进行测试,最后采用该方法建立了光纤陀螺温度漂移模型并根据模型对光纤陀螺进行补偿,结果表明采用该方法补偿后光纤陀螺在不同温度下的输出标准差降低了60.19%,与传统的BP神经网络相比补偿效果显著提高。

IUKF neural network modeling for FOG temperature drift

A novel neural network based on iterated unscented Kalman filter （IUKF） algorithm is established to model and com- pensate for the fiber optic gyro （FOG） bias drift caused by temperature. In the network, FOG temperature and its gradient are set as input and the FOG bias drift is set as the expected output. A 2-5-1 network trained with IUKF algorithm is established. The IUKF algorithm is developed on the basis of the unscented Kalman filter （UKF）. The weight and bias vectors of the hidden layer are set as the state of the UKF and its process and measurement equations are deduced according to the network architecture. To solve the unavoidable estimation deviation of the mean and covariance of the states in the UKF algorithm, iterative computation is introduced into the UKF after the measurement update. While the measure- ment noise R is extended into the state vectors before iteration in order to meet the statistic orthogonality of estimate and mea- surement noise. The IUKF algorithm can provide the optimized estimation for the neural network because of its state expansion and iteration. Temperature rise （-20-20℃） and drop （70-20℃） tests for FOG are carried out in an attemperator. The temperature drift model is built with neural network, and it is trained respectively with BP, UKF and IUKF algorithms. The results prove that the proposed model has higher precision compared with the back- propagation （BP） and UKF network models.

动态Allan方差改进算法及其在FOG启动信号分析中的应用（英文）

针对动态Allan方差运用固定长度的分析窗截取信号导致样本数据量减少,长相关时间下方差估计值置信度降低,首先,针对动态信号跟踪能力与置信度的提高不能兼顾的问题提出了一种改进算法。引入截断窗内峭度值作为表征信号短时稳定度的参数,并建立以峭度为变量的窗宽函数,该函数可以使截断窗长随着信号的平稳程度自动变化。其次,再用窗宽自适应的滑动窗分段截取陀螺随机误差,分别对每个截断窗内样本进行总方差计算以增加方差估计的自由度。最后,计算延伸后样本的Allan方差,并将其以三维形式排列出来。结果表明:应用该方法对光纤陀螺启动信号进行分析,该算法既能更有效地跟踪信号的非平稳变化,又能大幅降低长相关时间下方差的估计误差。

Comparative Assessment on the Performance of Open-Loop and Closed-Loop IFOGs

In this paper, we evaluated comprehensively the structure and operation of open-loop interferometric optical fiber gyroscopes (IFOG). To complete the previous works, a digital approach to derive the rotation angle in optical fiber gyroscopes is investigated theoretically. Results are simulated by the MATLAB software;therefore we could compare the results in simulated area with the values derived from theory. Also, feedback Erbium-doped fiber amplifier (EFDA) FOGs, called FE-FOG, is categorized in closed-loop IFOGs. The procedure of finding the Sagnac shift for open-loop and closed-loop IFOG have been studied and compared to one another. The signal processing in the open-loop IFOG was simulated using Matlab software and for the closed-loop IFOG by PSCAD. In the open-loop IFOG the analogue formulation of the IFOG in order to extract the phase shift is analyzed. A novel and promising method for derivation of Sagnac phase shift based on digital finite impulse response filtering is proposed. Based on our simulation results, the reliability and accuracy of the method is determined. In the closed-loop IFOG, the shift was derived through frequent use of Sagnac loop. The output signal is injected in the input again as feedback. The shift phase between clockwise and counterclockwise waves in each complete route, including primary and feedback route, is identified as Sagnac shift phase.

Temperature Drift Modeling of FOG Based on LS-WSVM

Large temperature drift is an important factor for improving the performance of FOG.A trend term of temperature drift of FOG is obtained using stationary wavelets transform,and an FOG drift algorithm with least squares wavelet support vector machine(LS-WSVM) is developed.The algorithm used Maxihat wavelet as a kernel function of LS-WSVM to establish an FOG drift model.It has better modeling precise than LS-WSVM model with Gauss kernel.Results indicate the efficiency of this algorithm of LS-WSVM.

光纤陀螺仪光纤尾纤装配动力学建模仿真与应力计算方法

光纤陀螺仪(FOG)中光纤尾纤的装配主要依靠工人手工完成,装配应力控制凭借人工经验,一致性难以保障。针对光纤装配应力定量控制的难题,提出一种基于离散微分几何理论的光纤动力学建模仿真方法。首先,基于离散微分几何理论建立了光纤运动学框架,并由弹性势能推导了包含拉伸、弯曲和扭转变形的光纤动力学方程以及应力计算方法。其次,提出了基于Newmark隐式算法的光纤动力学方程数值求解方法,并设计了光纤在装配过程中与周围物体的碰撞检测与响应策略。随后,进行了光纤圆周布设和弯扭变形的仿真测试。结果表明,光纤控制端与固定端之间的自由长度越短,光纤圆周布设的位置越精确;光纤截面半径越大,在同样的扭转角下光纤产生的弯扭变形程度越大。最后,设计了一种光纤陀螺仪装配布局,并通过动力学仿真得到了光纤装配过程的应力分布及最大应力变化,为陀螺仪光路低应力装配与路径规划提供了理论支撑。

光学陀螺旋转调制惯导系统及关键技术发展

面向长航时、高精度的自主导航技术需求,系统梳理光学陀螺旋转调制惯导系统的发展历程及关键技术现状具有重要的现实意义。首先,基于惯导系统误差特性,阐述了旋转调制技术的基本原理。其次,系统回顾和梳理欧美等西方国家旋转惯导系统发展历程,分析了系统发展演变后的技术逻辑,总结了我国旋转惯导系统的研制现状。最后,立足于提高系统自主导航精度,从旋转策略优化、误差标校、初始对准3个方面分析了旋转惯导系统需解决的关键技术及研究现状。在总结光学陀螺旋转调制惯导系统及关键技术发展基础上,针对后续旋转惯导系统研究提出了几点思考,为高精度自主导航技术研究提供参考。

谐振式光纤陀螺谐振腔传输模型仿真方法

谐振式光纤陀螺(RFOG)是一种以光纤环形谐振腔为核心敏感器件的惯性传感器。为提高仿真效率和适用性,提出了一种谐振式光纤陀螺快速运算仿真方法,搭建了谐振式光纤陀螺信号处理和闭环控制模型,其中模拟谐振腔多圈干涉耦合采用多核并行运算,包含光场叠加和传递函数两种形式。仿真结果表明所提方法仿真效率较高,平均在16s左右完成仿真,相比于原始模型的锁频程序运行效率提升了57.6%。同时两种仿真形式均适用于精度范围0.0001~1(°)/√h的谐振光纤陀螺仿真,有效适应不同仿真参数的测试要求。其中传递函数形式相较于光场叠加形式仿真效率提升了5.4倍,在±600(°)/s动态范围内标度因数非线性度降低了17%,而光场叠加形式的零偏不稳定性减小到0.652(°)/h,易于观察偏振波动误差特性。