Suppression of the G-sensitive drift of laser gyro in dual-axis rotational inertial navigation system

The dual-axis rotational inertial navigation system(INS)with dithered ring laser gyro(DRLG)is widely used in high precision navigation.The major inertial sensor errors such as drift errors of gyro and accelerometer can be averaged out,but the G-sensitive drifts of laser gyro cannot be averaged out by indexing.A 16-position rotational simulation experiment proves the G-sensitive drift will affect the long-term navigation error for the rotational INS quantitatively.The vibration coupling and asymmetric structure of the DRLG are the main errors.A new dithered mechanism and optimized DRLG is designed.The validity and efficiency of the optimized design are conformed by 1 g sinusoidal vibration experiments.An optimized inertial measurement unit(IMU)is formulated and measured experimentally.Laboratory and vehicle experimental results show that the divergence speed of longitude errors can be effectively slowed down in the optimized IMU.In long term independent navigation,the position accuracy of dual-axis rotational INS is improved close to 50%,and the G-sensitive drifts of laser gyro in the optimized IMU are less than 0.0002°/h.These results have important theoretical significance and practical value for improving the structural dynamic characteristics of DRLG INS,especially the highprecision inertial system.

Research on feasibility of missile attitude control based on laser gyroscope

According to the disadvantages of traditional mechanical gyro inertial measurement unit('IMU') for steering system not being available for missile attitude control, a concept based on laser gyro IMU is proposed to realize navigation & positioning and attitude control. The concept will save three single-axis rate gyros compared with traditional missile attitude control system, and is available both for strapdown and platform inertial navigation systems. Firstly, this article analyzes the selection requirements of sensitive device for missile attitude control system, and then analyzes the feasibility of missile attitude control based on laser gyro theoretically, on this basis, from four aspects of error characteristics, anti-vibration characteristics, temperature characteristics and dynamic characteristics, validate the feasibility of the concept practically. Secondly according to the strict requirements of dynamic characteristics on attitude control system, a special design is made for gyro signal filtering used for attitude control. By changing the traditional high order FIR filter to adaptive filter and low order FIR filter, laser gyro's signal phase delay is reduced. The delay time of theoretical design is 1.5 ms. Lastly, this design is validated through an angle vibration test, and test curve indicates that the dynamic characteristics of laser gyro completely meets the requirements of the attitude control system, and the maximum delay time is 1.6144 ms, which satisfies with the attitude update rate of 2 ms per frame. This concept can simplify the missile guidance system design, at the same time, it does not reduce missile guidance accuracy, and also provides reference for the broadening of the application of laser gyro.

Dynamic model and simulation of aseismatic system about laser gyro strapdown inertial measure assembly based on MSTMM

The precision of the laser gyro used in tactical missiles is poor because of dithering frequency,actuating by vibration,shock and overload in dynamical environment.This paper introduces the transfer matrix method of the multibody system（MSTMM）,establishes the dynamic model of the laser gyro strapdown inertial measure assembly aseismatic system,and analyzes the precision affected by dithering of the laser gyro and shocking of the tactical missile.And the dynamic response of the laser gyro strapdown inertial measure assembly aseismatic system is obtained by simulating the multibody system model.The simulation result indicates a theoretical idea to design the vibration isolation for the laser gyro strapdown inertial measure assembly.

Polarization properties in a prism laser gyro with mechanical dither bias

Theoretical analysis and experimental research on the polarization properties of output light in gyro are carried out to investigate the phenomenon that the amplitude of an output voltage signal is modulated by dither bias in laser gyros consisting of totally reflecting prisms. Taking the effect of prism stress birefringence into account, an analytical formula of the output light intensity in the gyro and the relationship between the polarization parameter and the amplitude modulation of the output signal are obtained and discussed. For the first time, the polarized power value of the output light is adopted as a basis to estimate the output signal amplitude fading extent of laser gyros. Experimental results demonstrate that when the value of polarized power of output light is below 25.5% of that in ideal static case, the standard error is over 0.0337 dBm, and the displacement extent of the prism is higher than 53% of the radius of the beam waist in the gyro cavity, the amplitude modulation extent of gyro output signal can reach up to 16%, which badly influences the measurement accuracy of the laser gyro. Using this polarized power detecting measurement method can repair the gyro immediately during its fabrication process, improve the testing and production efficiency and shorten the product development cycle.

Signal processing circuit of laser gyro based on FPGA and DSP

This is a paper about laser gyro sign a l processing circuit which is designed based on field-programmable gate array(FPGA) and digital signal processor(DSP).Through a pre-amplifier circuit,FPGA and DSP,a weak current signal is converted and transferred,then sent to the computer to display the final results.Through the laser gyro performance te sting,the obtained results coincide with those of the existing methods.Thus th e d esigned circuit realizes the function of laser gyro signal processing.

New interpretation of laser gyro drifts

Discuss and develop some contents which are relevant to the IEEE Std 647TM-2006 in this paper. The IEEE Std only involves Allan variance, and decomposes it into five primary noise terms, in which, however, the noise nature of the so called "rate random walk noise" and the "rate ramp" is doubted by the IEEE Std editors. Here we use a mathematical identity to entirely affirm the first query and partially the second query as mentioned above. Besides, we argue that only the classical variance can be used in navigation, not the Allan variance. In order to seek the true nature of all drift terms in the variance, we adopt our original work that represents the noises as damped oscillations, to obtain the power spectral density (PSD) of the noises which is then transformed back into time domain. When the damped time constant is much longer than the sampling interval, the re-sulting slow variation term may be expanded into three terms: ordinary bias instability, rate random walk, and rate ramp. Therefore, these "noise terms" are not independent, and they are more of deterministic errors than random noises, and can be explained quantitatively. The resulting fast variation drift may be expanded into two terms. The first term is the same as angle random noise, while the second term adds to the true quantization noise term to form a new combined term called "quantiza-tion noise term". As the result of our research, not only the IEEE Std editors’ suspicions above are answered completely, but a new theory to analyze the laser gyro drifts is also presented, with several supporting examples to explain and verify the theory.

AN IMPROVED ROTATION VECTOR ATTITUDE ALGORITHM FOR LASER STRAP-DOWN INERTIAL NAVIGATION SYSTEM

The laser gyro is most su it able for building the strap down inertial navigation system (SINS), and its acc uracy of attitude algorithm can enormously affect that of the laser SINS. This p aper develops three improved algorithmal expressions for strap down attitude ut ilizing the angular increment output by the laser gyro from the last two and cur rent updating periods according to the number of gyro samples, and analyses the algorithm error in the classical coning motion. Compared with the conventional algorithms, simulational results show that this improved algorithm has higher precision. A new way to improve the rotation vector algorithms is provided.

Algorithm implementation of high-speed laser g yro signal demodulation filter

Based on the characteristics of field-programmable gate array(FPGA) such as multi-task,high-speed,parallelity,etc,a filtering algorithm is presented to filter the output signal of laser gyr o with high-speed and high accuracy.The filter is composed of basic logic cell s,multipliers an d memory inside FPGA.By using an multiplication decomposition method and design ing reliable time-sequence,the filter is realized,which is easy to be transpl anted and of low cost.Furthermore,all the signal demodulation algorithms of t he laser gyr oscope can be integrated in only one FPGA,which reduces the cost and complexity of the system.

基于超短脉冲激光刻蚀的双解耦MEMS陀螺仪调频技术研究

以双解耦双质量硅微陀螺仪为主要研究对象,从微观结构入手,分析其工作原理和双解耦运动模型,并提出影响模态特征频率的因素。提出一种改变陀螺仪弹性梁结构厚度来调整其特征频率的方法,建立模型通过Comsol软件仿真陀螺仪梁厚度变化对特征频率的影响关系,并选择皮秒激光刻蚀系统刻蚀陀螺弹性梁厚度,测试其两模态特征频率。测试结果表明:对应频率变化符合理论推导和仿真趋势。

激光陀螺实验中谐振腔调节的分析与讨论

本文在非傍轴近似条件下利用几何光学理论推导了激光陀螺实验中谐振腔大小、反射镜曲率及偏转角度等因素与腔内自再现谐振激光空间位置关系的公式,比较了其与通常傍轴近似下矩阵光学结果的差异,讨论了实验时调节反射镜偏转角度对谐振腔有效腔长、光路面积、陀螺比例因子及激光出光位置的影响规律,对激光陀螺实验中谐振腔的调节有指导意义.

激光陀螺全温度下选模控制策略设计

针对激光陀螺稳频装置易受温度变化的干扰的问题,为保证全温度范围内激光陀螺的稳频效果,提出了一种选模控制策略:根据陀螺扫模过程中得到的不同模态,通过比较各个模态下背向散射特征电压的大小,在常温下筛选出合适的陀螺及其控制模态,再经过温循实验进一步筛选出合适的模态,并固定用于全温度下的稳频控制以保证陀螺全温精度。最后通过实验验证,使用该筛选策略下获得的最佳模态,实现激光陀螺全温下稳定工作,满足实际工作要求。

基于激光陀螺测角仪的角度计量动态特性分析

为了使动态角度测量结果可靠、可信,在使用激光陀螺测角仪进行动态角度测量前,需要对其动态特性进行分析。首先,通过同步触发装置将激光陀螺测角仪分布与转台和激光干涉仪分别同步触发;然后,使转台模拟出脉冲响应运动、阶跃响应运动和正弦运动;最后,比较分析在不同运动过程中激光陀螺测角仪与转台的圆光栅和激光干涉仪的输出数据。结果表明,激光陀螺测角仪具有良好的动态特性,且在不同频率下激光陀螺测角仪的动态测角精度在0.6″左右,为激光陀螺测角仪进行动态角度测量结果的可靠性提供了保证。

采用激光光源线宽展宽的光纤陀螺标度因数性能提升技术

光纤陀螺中使用激光光源代替传统宽谱光源有利于提升性能和降低成本,但激光光源作为一种窄线宽的高相干光源,将其用于光纤陀螺又会引入瑞利散射、克尔效应和偏振交叉耦合等干扰,因此有必要对激光光源进行线宽展宽。首先对基于高斯白噪声外部相位调制的激光光源线宽展宽方法进行理论分析,建立光谱展宽卷积模型。其次采用延迟自相关测量方法验证了高斯白噪声外部相位调制对激光光源线宽的展宽效果。最后基于仿真分析结论,搭建了激光器线宽展宽光源装置,将激光光源的光谱展宽成线宽20 GHz的光谱,应用于光纤陀螺并验证了标度因数性能,为激光光源在光纤陀螺中的应用提供了理论基础,具有一定的工程应用价值。

激光陀螺单轴旋转惯性导航系统

高精度的惯性导航系统是提高舰船综合作战性能的基础。为了提高惯性导航系统的精度,采用单轴旋转惯性测量组件的方法,研制了激光陀螺单轴旋转惯性导航系统。介绍了系统的硬件组成,主要包括系统基本结构,惯性器件的主要技术参数和导航计算机的组成。描述了系统的多位置初始对准方式和温度补偿方案。对该系统进行了长时间静态导航实验和跑车实验,实验结果表明:四次长时间静态导航实验峰值定位误差5d优于1nm,10d优于2nm;两次跑车实验峰值定位误差77h优于1.4nm、15d优于2.5nm。

小波域中值滤波在激光陀螺信号处理中的应用

各种随机噪声是导致激光陀螺产生误差的主要因素,且其性质特殊,很难用传统的滤波方法去除。为了减小激光陀螺的随机误差,提高测量精度,提出了小波域的中值滤波器滤波方法,对激光陀螺零漂数据进行了滤波,并采用Allan方差法对滤波效果进行了定量分析。结果表明,此方法的滤波效果优于中值滤波和小波软阈值滤波效果,能有效地减小激光陀螺零漂信号中的角度随机游走、角速度随机游走、速率斜坡、零偏不稳定性和量化噪声,提高激光陀螺零漂输出的稳定性。

激光陀螺锁区特性的研究

从理论和试验两个方面,研究了四边形腔环行激光陀螺的锁区特性·利用环行腔中背向散射光束具有相干性,导出了环行谐振腔综合背向散射与反射镜、反射镜之间的相对位置的关系·在有两个位移反射镜的四边形谐振腔中,理论上得到了综合背向散射系数与谐振腔腔长具有双波长周期·利用综合背向光强实验及锁区与陀螺工作模数实验分别验证了理论的正确性·试验证实散射光的强度与谐振腔的工作模数存在双模周期性,综合背向散射系数大,陀螺锁区大,反之亦然·

基于姿态匹配的船体形变测量方法

针对激光陀螺船体形变测量系统,提出了一种新的基于姿态匹配的形变测量解算方法。该方法不同于以角速度差作为观测量的惯性测量匹配法,而是基于两套激光陀螺系统的姿态信息。确立了新的形变测量滤波观测量,并建立线性量测方程。两套激光陀螺系统直接利用激光陀螺输出的角增量数据相对于惯性空间进行姿态更新,惯性坐标系取为各自初始时刻的载体坐标系,完全回避了系统初始对准问题,且充分利用了激光陀螺角度测量精度高的特点。仿真结果表明,该方法能够有效实现船体形变的高频精确测量,仿真测量精度优于15″,为激光陀螺船体形变测量技术进入工程应用打下了基础。

环形激光陀螺的最新发展

环形激光陀螺是当前高精度捷联惯导系统中最重要的设备之一,它在军用领域和商用领域获得了广泛的应用。近几年,和环形激光陀螺相关的进展主要可以概况为三个方面:激光陀螺研制技术的进步;对激光陀螺系统研究方法的深入和激光陀螺应用领域的扩展。激光陀螺发展的最新动态,对国内激光陀螺工业有重要的参考价值,将有助于提高我国环形激光陀螺技术水平。

激光陀螺SINS/GPS组合导航车载试验系统

SINS GPS组合导航系统已经应用于许多不同的领域。介绍一种已经进入试验阶段的低成本激光陀螺SINS GPS组合导航系统。根据系统的硬件结构,设计实现了与实际系统相匹配的组合导航滤波器,根据车载试验的结果,着重分析了系统车载试验中不同导航模式对系统性能的影响,最后给出了一些有益的结论。

激光陀螺惯性测量单元系统级标定方法

传统的分立标定方法必须依靠高精度的转台提供姿态基准,不满足带减振器的惯性测量单元(IMU)和现场标定需求。首先建立了附加约束条件的陀螺和加速度计安装坐标系数学模型,根据陀螺和加速度计的输出误差方程,从惯性导航基本误差方程出发推导了惯性测量单元的系统级误差参数标定Kalman滤波模型,该模型包含了陀螺和加速度计零偏、比例因子、安装误差在内共21维标定误差状态变量,且仅以速度解算误差为观测量。依据所建立的模型和设计的标定路径对此系统级标定方法进行了仿真,仿真结果表明,陀螺和加速度计零偏估计精度分别优于0.005o/h和0.005 mg,安装误差估计精度优于1′′,比例因子误差优于1ppm,满足高精度惯导系统的标定需求。