激光捷联惯导系统的外场动态标定方法

激光捷联惯导系统的误差参数随着时间的推移会发生变化,为了实现惯导系统长期稳定使用且不拆装系统,需要对外场动态条件下激光陀螺捷联惯导系统的系统级标定方法进行研究.首先根据线性时变系统的可现测性判据详细地分析了动态条件下捷联惯导系统的可观测性,从而给出了完全激励惯导系统12个误差参数(加速度计零偏、标度因数误差以及陀螺零偏...     

车载SINS/DR组合导航系统的在线标定方法

惯导系统中陀螺漂移和加速度计零位存在逐次启动不重复性误差,需在一定时期内频繁拆卸进行标定,增加了较大的工作量。从工程实用和维护的角度出发,提出了一种针对于车载组合导航系统的在线标定方法。该方法用卡尔曼滤波作为估计工具,利用里程计获得辅助信息,将惯导系统与里程计的位置和速度的差值作为量测值,通过设计接近于一般跑车实验过程的路径对待标定的误差项进行有效激励。仿真卡尔曼滤波结果表明,在一定的时间内各误差项根据车行轨迹进行逐步收敛,实现了在一般跑车实验中不拆卸惯性器件而达到标定的目的,且在精度上较 SINS 有了明显的提高。这种在线标定的处理方法给实际使用和维护带来了很大的便利,具有一定的工程实用性。     

一种石英挠性加速度计非线性误差系统级标定方法

为提高大过载高动态环境下捷联惯导系统导航精度，需对捷联惯导系统中的石英挠性加速度计非线性误差参数进行精确标定。针对现有标定方法在加速度计非线性误差参数发生变化时无法满足免拆卸高精度标定的问题，设计了一种基于双轴精密离心机和捷联惯导系统转位机构交替旋转、依靠转位机构实现9位置标定路径的系统级标定方法。经理论分析和仿真验证，所提方法可实现加速度计二次项、交叉耦合项共九个非线性误差参数系统级高精度标定，二次项误差参数标定精度优于1.0×10^-6 g/g²，交叉耦合项误差参数标定精度优于1.5×10^-6 g/g²。     

一种锚泊条件下捷联惯导系统级标定方法

捷联惯导的误差参数标定,一般是在实验室静基座或外场轻微晃动干扰基座下进行的,不能满足舰船出海期间在锚泊条件下对捷联系统进行标定的需求。针对此问题,提出了一种舰船锚泊条件捷联系统级标定方法。通过设置合适的卡尔曼滤波器量测误差参数和延长系统级标定时间,来减小锚泊运动的影响,使系统级标定结果准确稳定。通过设置不同的惯导系统误差,进行多次锚泊条件系统级标定仿真,对所提方法进行验证。仿真结果表明,在经过系统级标定后,加速度计零偏误差小于10μg,陀螺和加速度计的刻度系数误差小于30ppm,两者的安装误差角小于10'。舰船锚泊条件系统级标定方法可以在舰船出海后不依赖外部测量信息标定惯导的部分参数,具有一定的应用参考价值。     

基于速度阻尼的双轴旋转式激光陀螺捷联惯导标定方法

惯性元件参数的长期稳定决定着惯导系统的精度,目前对于激光陀螺捷联惯导系统(RLG-SINS)主要是采用系统级旋转调制技术来实现高精度导航能力,同时系统级旋转也提高了初始对准精度以及惯性元件误差的可观测性。针对激光陀螺惯导系统惯性元件误差项的特点,同时结合分立式标定与系统级标定各自的优势,设计了一种水平阻尼模式下的Kalman滤波方案,利用双轴旋转机构,通过观测导航位置误差来实现初始对准以及部分惯性元件误差参数的标定,可以有效地减小惯性元件逐次启动误差对导航精度的影响。仿真结果表明,系泊状态零速度阻尼模式下工作4 h,可以标定出石英加速度计标度因数误差、零偏与激光陀螺零偏,共计9项误差参数。加速度计零偏估计误差小于2%,陀螺零偏估计误差小于8%,误差估计精度满足高精度惯性导航要求,该方法具备一定的工程实用性。     

激光陀螺捷联惯导系统外场快速标定新方法

针对激光陀螺具有标度因数稳定、漂移误差变化小的特点,建立了适合激光陀螺捷联惯导系统的陀螺及加速度计组件简化误差参数模型,推导出了适合激光陀螺捷联惯导系统外场快速自标定的误差模型,设计了激光陀螺捷联惯导系统9位置系统级标定方法,并通过试验验证了该方法可快速准确的标定出加速度计组件的标度因数、安装误差、零偏及激光陀螺安装误差等15个主要参数,方法简单易行。     

基于车辆运动约束的里程计误差在线标定方法

为了降低里程计误差对捷联惯导/里程计组合定位定向精度的影响,提出了基于车辆运动约束条件的里程计误差在线标定方法。通过对里程计标度因数误差进行建模,推导建立了航位推算的误差模型,将航位推算的速度输出沿车体横向、垂向的投影作为量测的一部分,将捷联惯导输出的速度、位置信息与航位推算输出的对应信息相减作为另一部分量测,通过卡尔曼滤波获得里程计标度因数误差等状态量的最优估计值,实现里程计误差的在线标定。仿真结果表明,该方法能够有效地标定出里程计标度因数误差,从而确保了捷联惯导/里程计组合定位定向的精度。     

旋转式捷联惯导系统精对准方法

针对静基座捷联惯导系统初始对准时可观测性差的缺点,提出了捷联式惯导系统四位置转停的单轴旋转方案,以及在此方案下的精对准方法。将陀螺常值漂移和加速度计零位误差调制成周期变量,通过改变惯导系统误差模型中的捷联矩阵改善系统的可观测性。为了使捷联惯导系统的误差方程适合卡尔曼滤波模型,将加速度计误差和陀螺漂移扩充为状态变量,采用卡尔曼滤波方法实现旋转式捷联惯导系统的精对准。仿真结果表明,IMU旋转状态下的对准方法大大提高了系统失准角的可观测性,从而提高了对准精度。     

基于飞行仿真的捷联惯导算法测试平台

针对捷联惯导算法测试中真实飞行轨迹数据难以获得的问题,建立了一种基于飞行仿真的捷联惯导算法测试平台.首先构建了测试平台的系统结构,在建立六自由度非线性飞机数学模型基础上,采用Stateflow实现了预定航迹多模态的飞行仿真,并通过坐标变换将飞行参数转换为测试基准轨迹数据;然后根据捷联惯导系统原理,由测试基准轨迹参数推导出陀螺仪和加速度计的理想输出,并对其误差进行建模,由此获得惯性组件的模拟输出数据;最后通过两种不同的姿态更新算法进行惯导解算并比较.仿真实验结果表明:产生的测试基准数据符合飞行力学的特点,很好地反映了飞机的动态特性,可以有效地评估不同捷联惯导算法的性能.     

基于导航误差的系统级标定方法中时间参数选取原则分析

介绍了捷联惯导系统基于导航参数的标定方法,给出了惯导系统绕三个轴翻滚过程中等效加速度计误差和等效陀螺误差与惯导系统速度误差变化率之间的关系,分析表明,只要精心设计转动顺序,通过观测不同位置、姿态下惯导系统的速度误差变化率,就可以分离出惯性器件各项误差。从实际工程应用出发,分析了标定过程中各位置之间的旋转时间、每个位置上的停止时间对速度误差变化率观测值的影响,在实际应用中,必须将这种不利于惯性器件误差参数估计的影响控制到最小。最后结合实际惯导系统的器件水平,给出了实际标定过程中相邻两位置间的旋转时间的选择范围,以及每个位置上停止时间的一种最优设计方法。     

Preface: Current research progress on mechanics of high speed rail

The construction and operation of high-speed rail（HSR）grid within the past two decades in China,in terms of the scale,may be possibly comparable to any national-wide construction in the history of China,even the Great Wall.By counting railways with commercial train service at the speed of200 km/h,China has the world’s longest HSR network with over 19 369.8 km of track in service today and this number     

ACTA MECHANICA SINICA 2014 ANNUAL SUBJECT INDEX

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人造地震动合成中的位移误差分析

三角函数级数法是合成人工地震动常用算法之一,但是通过对加速度积分求取位移时,却存在与零线漂移相类似的位移漂移现象。     

Hermitian space-time finite elements for estuarine mass transport

Space-time finite element solutions of the convection–dispersion equation using higher-order nodal continuity and Hermitian polynomial shape functions are described. Five separate elements ranging from a complete linear element with C^0,0 nodal continuity to a complete first-order Hermitian element with C^1,1 nodal continuity are subjected to detailed analysis. Wave deformation analyses identify the source of leading or trailing edge oscillations, trailing edge oscillations being the major source of difficulty. These observations are confirmed by numerical experiments which further demonstrate the potential of higher-order nodal continuity. The performance of the complete first-order Hermitian element is quite satisfactory and measurably superior to the linear element.     

Rainwater rivulets on a cable subject to windFilets d'eau de pluie sur un câble soumis au vent

Rainwater rivulets appear on inclined cables of cable-stayed bridges when wind and rain occur simultaneously. In a restricted range of parameters this is known to cause vibrations of high amplitudes on the cable. The mechanism underlying this effect is still under debate but the role of rainwater rivulets is certain. We use a standard lubrication model to analyse the dynamics of a water film on a cylinder under the effect of gravity and wind load. A simple criterion is then proposed for the appearance and position of rivulets, where the Froude number is the control parameter. Experiments with several geometries of cylinder covered with water in a wind tunnel show the evolution of the rivulets with the Froude number. Comparison of the prediction by the model with these experimental data shows that the main mechanism of rivulet formation and positioning is captured. To cite this article: C. Lemaitre et al., C. R. Mecanique 334 (2006).     

Cristallisation par onde acoustique : le cas de l'héliumCrystallization by acoustic waves: the case of helium

We establish a theoretical model to explain the nucleation of a crystal of helium by an acoustic over-pressure. We explain the interfacial laws for this ultra-fast cristallization, close to the sound speed. Assuming spherical symmetry and taking into account the experimental data, we recover the dynamics of the growth and melting during an over-pressure impulse. To cite this article: M. Ben Amar et al., C. R. Mecanique 331 (2003).     

Structure initiale et propriétés de liquéfaction statique d'un sableInitial structure and static liquefaction properties of sand.

Based on the use of two different preparation procedures for reconstituting triaxial samples of sand, i.e. wet tamping and dry pluviation, significant differences in associated mechanical behaviour are observed on a reference sand with respect to the phenomenon of ‘static’ liquefaction. Wet tamping favours the initiation of liquefaction instability, whereas dry pluviation favours a more stable behaviour, less susceptible to liquefaction. Microscopic observation of corresponding sand specimens allows us to identify two well differentiated structures, i.e., for wet tamping, an irregular structure with predominance of aggregates (aggregated grains) and macropores, very contractant and unstable and, for dry pluviation, a more regular structure, without macropores, more dilatant and more stable. These observations show the importance of further characterization, based on the introduction of appropriate parameters, of the initial structure of sandy materials, strongly dependant upon their mode of formation (natural or artificial). To cite this article: N. Benahmed et al., C. R. Mecanique 332 (2004).     

INFORMATION FOR CONTRIBUTORS

Contributions： The Journal, Acta Mechanica Solida Sinica, is pleased to receive papers from engineers and scientists working in various aspects of solid mechanics. All contributions are subject to critical review prior to acceptance and publication.     

The 7th International Conference on Fluid Mechanics May 24-27,2015,Qingdao,China

正http://www.icfm7.org First Announcement and Call for PapersThe objective of International Conference on Fluid Mechanics(ICFM)is to provide a forum for researchers to exchange new ideas and recent advances in the fields of theoretical,experimental,computational Fluid Mechanics as well as interdisciplinary subjects.It was successfully convened by the Chinese Society of Theoretical and Applied Mechanics(CSTAM)in Beijing(1987,