扰动基座下惯组信号消噪方法对比研究

针对捷联惯导系统在扰动基座下对准时,惯组信号中存在干扰角运动和线运动的特点,进行了车载扰动基座初始对准试验,对试验数据进行频谱分析,得到车载扰动基座环境的频域特性。根据分析结果,设计并实现了FIR数字滤波器滤波和小波滤波对惯组信号的消噪,频谱分析和惯性系粗对准的结果显示,这两种方法都能有效地消除惯组信号中的噪声。数据分析显示,小波滤波的效果要优于FIR数字滤波器滤波的效果。     

基于FPGA的FIR滤波器设计与实现

本文根据激光陀螺仪信号的解调原理,提出了一种利用数字信号处理技术并采用FPGA实现的解调方法。分析了FIR滤波器的工作原理,根据激光陀螺仪对滤波器的要求,给出了由FPGA设计实现FIR滤波器的基本原理,并利用IP核实现了FIR滤波器,满足了激光陀螺仪的需求。通过在国产激光陀螺仪上的应用,验证了方案的正确性。通过对激光陀螺仪脉冲计数的高速采样并利用数字滤波器处理,可以有效的消除抖动引起的信号噪声,得到所需要的惯性信息。采用FPGA设计实现,可以提高运算速度,并且可以缩短数据采样的延时。     

用CPLD实现FIR数字滤波器的设计

针对在CPLD中实现FIR滤波器的关键一乘法运算的高效实现进行了研究，给出了将乘法化为查表的DA算法，并采用这一算法设计了FIR滤波器。其实现的滤波器的性能优于用DSP和传统方法实现FIR滤波。     

MIMO随机振动试验控制的逆多步预测模型法

多输入多输出（MIMO）随机振动试验在产品可靠性验证中扮演重要角色。逆系统方法作为一种时域方法，直接由参考信号（即期望得到的响应信号）生成驱动信号，但容易产生不稳定的结果。本文以系统的有限差分模型为基础，推导了逆多步预测模型，并建立了该逆模型与矩阵幂次算法结合的MIMO随机振动试验方法。通过悬臂梁模型进行双输入双输出仿真试验，验证了逆多步预测模型进行MIMO随机振动试验驱动生成的可行性。在三轴振动台上进一步验证该方法进行MIMO随机振动试验控制的能力。     

正弦加随机振动控制技术的研究

振动是产品失效的主要环境因素之一 ,在实验室里 ,模拟实际振动环境 ,是降低成本 ,提高可靠性的基本途径。在航空、航天、机械和运输等工程技术领域 ,大量的环境振动是正弦加随机振动。由于正弦加随机振动的复杂性 ,人们通常把随机振动和正弦振动分开进行 ,但它不能真实地反映在随机振动和正弦振动共同作用下 ,结构损伤 ,疲劳破坏的程度 ,为了检查设备及部分结构的可靠性和耐振强度 ,必须做正弦加随机振动试验。因此研制正弦加随机振动控制设备具有非常重要的意义。把原始的正弦加随机组合信号分离为正弦信号和随机信号 ,是正弦加随机振动控制技术的关键。本文采用数字跟踪滤波器用软件的方法分离出正弦信号和随机信号 ,     

一种减少失速保护虚警率的混合滤波方法

针对飞机失速保护设计过程中易出现虚警的情况,提出一种基于FIR和传统滤波器相结合的混合滤波方法。结合飞机本体的运动特征,对参与失速保护逻辑运算的两个重要参数,即侧向加速度和迎角信号进行频率分析,基于信号的特征设计混合滤波器,然后采用Simulink滤波工具箱设计滤波器对信号进行滤波处理。仿真结果表明该方法能够减少虚警率的发生,特别是大背景噪声下的虚警率能够得到较好抑制,验证了滤波器设计正确性,从而提高失速保护功能对适航条款符合性。该滤波器设计方法,不但可以有效解决本文提到的问题,对于其他涉及信号处理的系统设计同样具有借鉴意义。     

应用数字滤波技术处理直升机地面靶试数据的研究

本文介绍在直升机地面靶试数据处理中应用FIR数字滤波器的设计和算术平均值滤波方法,通过合理选择滤波方法和巧妙设计有效抑制干扰信号,保证了试验数据的精度.     

任意采样率变换数字重构滤波器设计

针对理想重构函数在数字信号域不可实现而直接截取性能较差的情况,根据信号重构理论和FIR（Finite Impulse Response,有限脉冲响应）滤波器窗函数设计法,分析不同窗函数、不同截取长度对重构滤波器的影响,提出一种凯塞窗任意采样率变换数字重构滤波器设计方法.该方法通过选择合适的窗参数、截取长度、重构滤波器时域精度和量化位数,有效控制阻带最小衰减抑制数字重构镜像.设计的数字重构滤波器已成功应用于某卫星基带调制解调器,符合镜像抑制大于65 dB的性能要求.     

激光脉冲法背温信号中噪声信号的滤除方法

针对激光脉冲法背温信号中存在的噪声干扰,通过频谱分析确定了噪声信号的频率范围,设计了相应的FIR数字滤波器,并对滤波后存在的残留噪声进行了递推平滑滤波.滤波前后的数据对比表明,该方法能有效滤波背温信号中的噪声.     

多自由度非高斯随机振动控制

在振动试验台上进行多自由度(MDOF)随机振动激励时,传统的控制方法生成的驱动信号及试验台的响应信号都是高斯信号。但真实的振动干扰信号多是超高斯的;而相比于高斯激励,亚高斯激励可降低驱动信号的最大幅值。为实现多自由度亚高斯和超高斯振动控制,提出一种多自由度非高斯随机振动控制方法,该方法采用系统辨识解决系统耦合问题,而后通过选择特殊的相位生成非高斯伪随机驱动信号,再经过时域随机化得到真随机非高斯驱动信号。基于Hexapod平台的多自由度微振动试验台的亚高斯和超高斯实验表明,在试验台的响应功率谱(PSD)满足工程中常用的±3dB精度的同时,亚高斯驱动信号的最大幅值相比于高斯驱动信号的最大幅值降低了20%以上;超高斯响应信号的峭度与参考峭度的误差在0.2之内。实验结果验证了所提方法的有效性。     

基于逆系统方法的多输入多输出非高斯驱动信号生成

多输入多输出(MIMO)振动环境试验是振动试验的新方法,该方法比传统的单输入单输出(SISO)方法更真实地模拟了结构在实际工作下的振动环境。传统随机振动试验的频域方法所模拟的是平稳高斯信号,但是实际振动环境往往是超高斯的,且超高斯激励和高斯激励对结构的损害差异很大,因此对MIMO超高斯振动环境试验的研究十分重要。驱动信号的产生是振动环境试验的关键。提出一种基于逆系统的MIMO超高斯驱动信号生成方法。首先,根据给定的响应参考功率谱密度(PSD)和参考峭度值采用相位调节法生成参考响应超高斯伪随机信号;其次,利用逆系统方法生成超高斯伪随机驱动信号;最后,对伪随机驱动信号进行时域随机化处理得到超高斯真随机驱动信号。对一根两输入两输出的悬臂梁模型进行了仿真验证,结果表明,采用本文方法所得到的驱动信号加载在梁上后,其输出响应谱与给定参考谱之间的误差完全满足工程中常用的±3 dB的要求,而且峭度也与给定的参考值十分接近,证实了所提方法的有效性。     

DME Interference mitigation for L-DACS1 based on system identification and sparse representation

L-band digital aeronautical communication system 1 (L-DACS1) is a promising candi-date data-link for future air-ground communication, but it is severely interfered by the pulse pairs (PPs) generated by distance measure equipment. A novel PP mitigation approach is proposed in this paper. Firstly, a deformed PP detection (DPPD) method that combines a filter bank, correlation detection, and rescanning is proposed to detect the deformed PPs (DPPs) which are caused by mul-tiple filters in the receiver. Secondly, a finite impulse response (FIR) model is used to approximate the overall characteristic of filters, and then the waveform of DPP can be acquired by the original waveform of PP and the FIR model. Finally, sparse representation is used to estimate the position and amplitude of each DPP, and then reconstruct each DPP. The reconstructed DPPs will be sub-tracted from the contaminated signal to mitigate interference. Numerical experiments show that the bit error rate performance of our approach is about 5 dB better than that of recent works and is closer to interference-free environment.     

Constrained Least-Squares Synthesis of Coefficients for Arrays of Sensors and FIR Digital Filters

A general method is presented for synthesizing weighting coefficients for arrays of sensors or for finite-impulse-response (FIR) digital filters. The beam pattern of the array or the frequency response of the digital filter is a weighted, least mean-square (LMS) approximation to a desired function, subject to constrained pattern values at specified points. The method is applied to the problem of producing beam patterns of a line array for the rejection of interfering point sources. For this case, we show that adaptive array processing can be based on modification of the roots of the array polynomial.     

Filtering of moving targets using SBIR sequential frames

In this paper three-dimensional (3-D) finite-impulse response (FIR) filters are proposed for moving target detection and tracking from multiframe space-based infrared (SBIR) data. An optimal, in the l_p sense, 3-D FIR filter design technique is proposed which is suitable for the above application. This technique is the first 3-D FIR design of its kind presented in the open literature. Directional, matched, and adaptive 3-D filtering techniques are proposed. Prior to the filtering, clutter mean estimation and mean subtraction are required. Real time implementation of directional and/or matched filters for processing maneuvering targets is discussed and filter design methods are proposed. Finally, performance comparisons of the proposed and other available 3-D FIR and infinite-impulse response (IIR) filters, on real SBIR data, are presented in which the advantages of the proposed 3-D filters are shown     

Creating complex signal samples from a band-limited real signal

A very efficient method of creating complex signal samples from a band-limited real signal is presented. Because the method employs a simple mixer followed by one analog-to-digital (A/D) converter, plus a finite-duration impulse response (FIR) filter for image band rejection, there is no phase distortion in the resulting sampled signal. The method is more efficient than competing methods based on infinite-duration impulse response (IIR) filters     

利用时延神经网络的动载荷倒序识别

将时延神经网络引入动载荷识别研究中,结合时延神经网络的"记忆"特性、因果有限长冲激响应（FIR）系统理论与振动响应的求解原理,提出一种利用时延神经网络的时域动载荷倒序识别方法。对一个受两点随机动载荷作用的舵面模型结构进行载荷识别验证实验,结果表明,用本文方法识别的两个激励点上识别载荷样本的时间序列与真实载荷样本的时间序列之间的均方根误差分别为0.635 4和2.543 7,识别载荷样本时间序列与真实载荷样本时间序列的相关系数分别为0.965 7和0.826 2,功率谱密度曲线也能够较好吻合。本文提出的方法具有不需要结构动力学模型、识别精度高的优点。     

Precise navigation using adaptive FIR filtering and time domainspectral estimation

This paper introduces a new low cost, short range, positioning system based on adaptive finite impulse response (FIR) filtering and time domain spectral estimation. The system can determine absolute positions with a high degree of accuracy and is well suited for real time navigation. The approach is based upon signal processing techniques and a priori knowledge of the system transfer function. The first step is to measure the phase response of the linear transfer function and then using a FIR filter the time response of the system can be determined. The FIR filter computes the time response by performing a deconvolution between the measured phase response, and the complex conjugate of the transfer function. By correlating the known input impulse response with the output of the FIR filter, an error term is generated. The time delay of the system is determined by adjusting the FIR filter coefficients to minimize the error term. Simulated analysis of the system indicates a worst case error of ±16 cm     

Enhanced motion and sizing of bank in moving-bank MMAE

The focus of this research is to provide methods for generating precise parameter estimates in the face of potentially significant parameter variations such as system component failures. The standard multiple model adaptive estimation (MMAE) algorithm uses a bank of Kalman filters, each based on a different model of the system. Parameter discretization within the MMAE refers to selection of the parameter values assumed by the elemental Kalman filters, and dynamically redeclaring such discretization yields a moving-bank MMAE. A new online parameter discretization method is developed based on the probabilities associated with the generalized chi-squared random variables formed by residual information from the elemental Kalman filters within the MMAE. This new algorithm is validated through computer simulation of an aircraft navigation system subjected to interference/jamming while attempting a successful precision landing of the aircraft.     

多滤波器并联方式解决直升机动力传动链扭振耦合

为了解决直升机动力传动链扭振系统与动力控制系统的耦合不稳定性问题,提出了一种采用多个陷波滤波器并联组合、根据发动机不同的工作模态选择不同滤波器实现扭振滤波的方法。对陷波滤波器进行了改进,使得引入控制系统通频带的附加相移减小,降低了对系统控制性能的影响。通过直升机联合试验,验证了该方法是有效的。      

液压管路系统随机振动下疲劳分析

民用飞机液压管路系统受到飞机振动环境的影响,可能产生振动引发的管路及安装结构疲劳破坏。为了分析液压管路系统在飞机振动环境下的承受能力,参考RTCA/DO-160G中对于固定翼飞机振动环境的定义及要求,对某民用飞机液压管路进行振动模态和随机振动响应分析。通过有限元分析得出了液压管路及安装结构的随机振动Von Mises均方根应力,采用基于高斯分布和Miner线性累计损伤定律的三区间法,计算管路系统的随机振动疲劳损伤,得到了疲劳薄弱部位及疲劳分析结果,为民用飞机液压管路在随机振动环境下的疲劳分析提供参考。