机载计算机电磁兼容性设计分析

对机载计算机电磁兼容设计的关键技术进行了分析,详细介绍了滤波连接器的结构和功能,并结合实际的计算机电磁兼容设计要求,给出了采用穿心电容C型滤波网络连接器的具体措施。     

Fast alignment and calibration algorithms for inertial navigation system

Algorithms for fast estimating the azimuth misalignment angle and calibrating gyro drift rates are approached from the point of view of control theory. By introducing the Lyapunov transformation, the equivalence of Strapdown Inertial Navigation System (SINS) and Gimbaled Inertial Navigation System (GINS) is discussed, and it shows that the analysis results of GINS can be applied to SINS directly by using such kind of equivalence. A similar transformation that based on physical essence is introduced, so that the true states can be replaced by the so-called pseudo-states, and then the observable states of INS can be dynamically decoupled with the unobservable states. Consequently, the best completely observable subsystem model of INS can be obtained. Based on the simplified subsystem model of INS, the algorithms for fast estimating the azimuth misalignment angle and calibrating gyro drift rates are proposed. The proposed algorithms show that the azimuth misalignment angle and gyro drift rates can be estimated from the rates of leveling misalignment angles without using the gyro output signals.     

近似二阶扩展卡尔曼滤波方法研究

 在综合考虑计算量和估计精度的情况下,提出一种新的非线性滤波方法——近似二阶扩展卡尔曼滤波（AS-EKF）方法。该方法基于线性最小方差递推滤波框架,对均值的非线性变换采用二阶近似,其精度高于扩展卡尔曼滤波（EKF）采用的一阶近似。通过计算机仿真表明该滤波方法对非线性系统的滤波精度高于EKF,且计算量明显低于无迹滤波（UKF）,该方法适用于对估计精度和计算量都有所要求的非线性系统滤波器设计。     

飞机防滑刹车系统鲁棒控制器的设计与研究

 首先对系统进行了详细的分析,并建立了系统的数学模型,然后针对飞机防滑刹车系统在地面滑跑时存在的各种外干扰问题,提出了一种基于自适应滤波的鲁棒控制方法.通过对系统施加各种外干扰所进行的数字仿真表明,该方法在提高系统的鲁棒性方面是行之有效的.     

近地卫星利用光学敏感器的自主导航方法

基于光学敏感器的卫星自主导航技术是利用红外地球敏感器（IRES）和星敏感器（ST）等姿态测量部件提供的测量信息,通过计算含有轨道信息的星光角距和地球视半径角,修正由轨道动力学模型递推得到的轨道参数。通过系统状态模型和观测模型的离散化和线性化,得到扩展卡尔曼滤波算法的递推关系,并在此基础上进行数学仿真。仿真结果表明,该方法的收敛速度和收敛精度都比较好。由于该方法不需要增加额外的星载敏感器,因此具有很好的应用前景。     

A Tracking Filter in Spherical Coordinates Enhanced by De-noising of Converted Doppler Measurements

Tracking problem in spherical coordinates with range rate (Doppler) measurements, which would have errors correlated to the range measurement errors, is investigated in this paper. The converted Doppler measurements, constructed by the product of the Doppler measurements and range measurements, are used to replace the original Doppler measurements. A de-noising method based on an unbiased Kalman filter (KF) is proposed to reduce the converted Doppler measurement errors before updating the target states for the constant velocity (CV) model. The states from the de-noising filter are then combined with the Cartesian states from the converted measurement Kalman filter (CMKF) to produce final state estimates. The nonlinearity of the de-noising filter states are handled by expanding them around the Cartesian states from the CMKF in a Taylor series up to the second order term. In the mean time, the correlation between the two filters caused by the common range measurements is handled by a minimum mean squared error (MMSE) estimation-based method. These result in a new tracking filter, CMDN-EKF2. Monte Carlo simulations demonstrate that the proposed tracking filter can provide efficient and robust performance with a modest computational cost.     

Directional Filtering Due to Mesospheric Wind Shear on the Propagation of Acoustic-gravity Waves

Gravity waves with periods close to the Brunt-V?is?l? period of the upper troposphere are often observed at mesopause altitudes as short period, quasi-monochromatic waves. The assumption that these short period waves originate in the troposphere may be problematic because their upward propagation to the mesosphere and lower thermosphere region could be significantly impeded due to an extended region of strong evanescence above the stratopause. To reconcile this apparent paradox, an alternative explanation is proposed in this paper. The inclusion of mean winds and their vertical shears is sufficient to allow certain short period waves to remain internal above the stratopause and to propagate efficiently to higher altitudes. A time-dependent numerical model is used to demonstrate the feasibility of this and to determine the circumstances under which the mesospheric wind shears play a role in the removal and directional filtering of short period gravity waves. Finally this paper concludes that the combination of the height-dependent mean winds and the mean temperature structure probably explains the existence of short period, quasi-monochromatic structures observed in airglow images of mesopause region.      

基于无奇点根数的空间相对导航插值滤波算法

为了提高椭圆轨道航天器的相对导航精度,将基于Stirling公式的多项式插值滤波方法（DDF2）引入导航算法,降低了传统的卡尔曼滤波方法中泰勒级数展开线性化     

复杂背景中红外弱小目标检测技术研究

对复杂背景中红外弱小目标检测识别的一种图像处理技术进行了研究。用最大中值滤波进行预处理以抑制孤立噪声影响,采用时域方差滤波抑制背景信息,对滤波后的图像根据直方图信息进行自适应二值化处理,由多帧轨迹确定目标。用实验与基于形态学算子滤波的目标检测算法进行了比较,结果表明该算法能获得较满意的目标检测结果,两种滤波方法的组合可有效提高信噪比。     

耦合位置误差的机载惯性/星光组合算法研究

针对星敏测量输出的是惯性系下姿态信息,无法直接应用于实际的机载地理系下姿态组合导航,提出了地理系下耦合位置误差的机载惯性/星光组合滤波算法。该算法分析了
惯性姿态到地理系姿态之间的相互转换关系,在建立的地理系下姿态线性化量测方程基础上,通过引入导航位置误差转换矩阵,建立了星敏测量的惯性姿态到惯性导航计算输出的地理系姿态之间的耦合误差模型;同时针对姿态观测时高度通道不可观的特点,增加了气压高度输出为系统的观测量;实现了基于星敏测量的惯性系下姿态对地理系下惯性导航误差的直接修正。姿态耦合误差仿真结果表明该组合导航算法设计成功可行,为星敏在机载环境下的组合导航应用提供了新的思路。