基于改进最小二乘支持向量机的惯性测量组件故障在线检测方法

为提高惯导系统工作的可靠性和导航性能,对其惯性测量组件的故障模式和检测模型进行了分析。针对最小二乘支持向量机(LS-SVM)回归算法做了两点改进,具体方法是先对输入样本观察窗平移更新的每个样本数据进行异常点滤波判断并用牛顿插值法进行处理,接着通过对在线LS-SVM回归过程的研究,提出了一种递推求解的快速算法,将惯性测量组件的输出量、舵偏角改变量并辅以环境因素作为观测样本序列,应用该算法来提高模型检测的准确性和时效性。最后对惯性测量组件无故障和出现卡滞、恒偏差时的故障模式进行了仿真实验,结果表明,与应用LS-SVM、SVM和BP神经网络算法相比,提出的惯性测量组件故障在线检测方法具有较强的鲁棒性和较快的速度。     

INS辅助的GNSS欺骗干扰辨识与抑制方法

GNSS欺骗干扰已经成为导航装备应用中面临的重要威胁之一。现有的基于INS/GNSS组合的抗欺骗算法大多只进行欺骗检测,不能恢复正确的定位结果。针对该问题,将多径抑制算法中的Multi-correlator结构用于真实信号和欺骗信号的参数估计,利用INS短期精度高的特性,实现欺骗信号的辨识。然后将辨识结果反馈跟踪环路抵消欺骗信号,保证接收机跟踪环路始终锁定真实卫星信号。最后,在INS/GNSS组合导航解算过程中引入抗差卡尔曼滤波算法,减小参数估计和辨识结果中粗差对定位结果的影响。利用公开数据集进行试验测试,欺骗干扰条件下定位误差由600 m降为10.0 m,而且在GNSS信号中断90 s重新恢复后,所提算法依旧能够实现欺骗信号的辨识和抑制。试验结果表明所提算法能够保证接收机在欺骗条件下锁定真实卫星信号,连续输出高精度的导航和授时信息。     

基于一类SVM的综合导航系统信息故障检测方法

为了提高舰艇综合导航系统的可靠性,并考虑到系统准确建模和大量故障数据获取的困难性,提出了一种基于一类支持向量机的信息故障检测方法。该方法主要包括两个过程:第一个过程是根据实测数据,并利用一类支持向量机的分类原理和主元分析法对导航信息进行离线建模;第二个过程是结合主元分析法将该模型应用到实时的信息故障检测中。该方法不依赖于系统模型而且只需要正常的小样本数据对模型进行训练,具有简便易于实现的优点。仿真试验表明,该方法对导航系统的硬故障和软故障都具有较好的检测能力和较短的检测延迟时间,而且该方法对径向基核函数参数的变化具有较低的敏感性,避免了复杂的调参过程。     

基于因子图导航的伪距故障检测与自适应隔离方法

为了实现城市峡谷、电磁扰动等复杂场景下因子图优化导航的故障检测与自适应融合,提出了一种基于因子图优化的综合利用惯性导航系统和全球卫星导航系统原始伪距信息的故障检测与自适应隔离方法.首先,结合惯性导航信息与全球卫星定位原始伪距进行导航系统故障检测,实现故障卫星伪距信息和故障惯性信息的有效定位;而后,基于故障检测结果针对因...     

一种基于故障检测与模糊逻辑的姿态估计方法

提出了一种融合惯性数据的飞行器航姿估计算法。使用MIMU（微惯性测量单元）作为飞行器的惯性航姿系统,利用MIMU中的陀螺仪,通过测量飞行器的角速率计算姿态角;同时,利用MIMU中的加速度计,通过测量当地的重力加速度,计算飞行器的姿态角。文中采用一种自适应故障检测方法,根据模糊理论构造加权系数,将飞行器的运动加速度与当地重力加速度分离,融合MIMU的数据,估计飞行器的姿态角。使用该方法既可以避免使用陀螺仪解算姿态角时误差的积累,又提高了使用加速度计计算姿态角时的动态性能,并经数据仿真验证说明该方法能达到预期的效果。     

A boundary element method for small-amplitude viscous fluid sloshing in couple with structural vibration

A boundary element method is presented for the coupled motion analysis of structural vibration with small-amplitude fluid sloshing in two-dimensional space. The linearized Navier-Stokes equations are considered in frequency domain and transformed into boundary integral equations. An appropriate fundamental solution for the Helmholtz equation with pure imaginary constant is found. The condition of zero-stress is imposed on the free surface, and non-slip condition of fluid particles is imposed on the walls of the container. For rigid motion models, the expressions for added mass and added damping to the structural motion equations are obtained. Some typical numerical examples are presented.     

混合χ~2检测法在组合导航系统故障检测中的应用

为提高SINS/GPS组合导航系统的可靠性,在分析了残差χ~2检测法和双状态χ~2检测法的基础上,提出一种混合χ~2检测法。该方法中残差χ~2检验法和双状态χ~2检验法并行工作且共用同一个卡尔曼滤波器,同时残差χ~2检验法的检测结果决定了对双状态χ~2检验法的两个状态递推器的操作:当残差χ~2检验法检测到组合导航系统故障时,则通过控制开关使卡尔曼滤波结果不对两个状态递推器进行状态重置,反之,如果残差χ~2检验法检测系统正常,则允许卡尔曼滤波结果对状态递推器进行状态重置,从而有效地解决了残差χ~2检验法对软故障不敏感的问题和双状态χ~2检验法的两个状态递推器易受污染的问题,组合导航系统故障诊断结果由残差χ~2检测法和双状态χ~2检测法共同决定。仿真实验分析表明,该方法能够降低虚警率,有效地提高组合导航系统故障诊断的准确性和可靠性。     

基于AR建模的组合导航系统渐变故障双阈值检测方法

针对传统残差χ2检测方法在组合导航系统中渐变故障检测率不高的问题,为了及时有效地检测故障信息,提高系统可靠性,提出了一种基于AR量测建模的组合导航系统渐变故障双阈值检测方法.该方法通过建立无故障条件下量测数据的AR模型,结合卡尔曼滤波模型得到量测预报值进行残差计算,提高故障检测的灵敏度;搭建双阈值检测门限,对误警率和漏...     

Chaotic motions and fault detection in a cracked rotor

Applying the theory of Lyapunov exponents for nonsmooth dynamical systems, chaotic motions and strange attractors are found in the case of a cracked rotor. To detect the crack and establish a clear relation between shaft cracks in turbo rotors and induced phenomena in vibrations measured in bearings, a model-based method is applied. Based on a fictitious model of the time behaviour of the nonlinearities, a state observer of an extended dynamical system is designed resulting in estimates of the nonlinear effects.     

Reduced-order fault detection filter design for switched nonlinear systems with time delay

This paper investigates the problem of reduced-order robust fault detection filter (RFDF) design for a class of switched nonlinear systems with time-varying delay. The nonlinearities are assumed to satisfy global Lipschitz conditions. By using a generalized form of observer-based fault detection filter as a residual generator, the problem is formulated in the framework of H _∞ filtering. Based on the average dwell time approach and the Lyapunov functional technique, a sufficient delay-dependent criterion on the existence of the RFDF is derived to ensure the exponential stability and a prescribed L ₂-gain bound of the residual error system. Furthermore, the parameters of an admissible filter are obtained from the solution of a convex optimization problem. A practical example is provided to illustrate the effectiveness of the proposed results.     

Modelling of gearbox dynamics under time-varying nonstationary load for distributed fault detection and diagnosis

Fault detection and diagnosis in mechanical systems during their time-varying nonstationary operation is one of the most challenging issues. In the last two decades or so researches have noticed that machines work in nonstationary load/speed conditions during their normal operation. Diagnostic features for gearboxes were found to be load dependent. This was experimentally confirmed by a smearing effect in the spectrum.In order to better understand the involved phenomena and to ensure agreement between simulation and experimental results, two models of gearboxes (a fixed-axis two-stage gearbox and a planetary gearbox) operating under varying load conditions are proposed. The models are based on two mechanical systems used in the mining industry, i.e. the belt conveyor and the bucket wheel excavator. An original transmission error function expressing changes in technical condition and load variation is presented.Energy based parameters (the signal RMS value or the arithmetic sum of the amplitudes of spectral gearmesh components) are adopted as the diagnostic features. Simulation results show a strong correlation between load values, changes in condition and the diagnostic features. The findings are key to condition monitoring. Thanks to the use of the models one can better understand the phenomena identified through an analysis of vibration signals captured from real machines.     

CORS基站周跳探测与修复方法

针对在CORS系统初始化后,周跳的出现将严重影响移动用户定位精度,CORS网中基站坐标已知,可精确预报对流层、电离层等系统误差,以及整周模糊度确定的特点,分析了周跳对双差模型的影响,通过分析普通卫星产生的周跳仅对一个双差观测方程产生影响,可以作为粗差,参考卫星的周跳会引入所有观测方程,从而对模型产生系统性误差,进而提出了使用附有系统参数的抗差估计方法,对CORS基站中的载波观测值进行整体平差,根据改正数V判断普通卫星的周跳,根据系统参数x2判断参考卫星的周跳。实验表明,该方法能将所有可见卫星进行整体的周跳探测,并且能实现高度角低于10°时的周跳探测和修复。