火炮首发命中率试验脱靶弹数据处理方法

通过对出现脱靶弹情况下的散布特征参数估计方法进行研究,建立正态双边截尾样本均值和方差估计数学模型,并给出了数值计算方法,为火炮武器系统首发命中概率试验脱靶提供了理论依据。     

Angular velocity determination of spinning solar sails using only a sun sensor

The direction of the sun is the easiest and most reliable observation vector for a solar sail running in deep space exploration. This paper presents a new method using only raw measurements of the sun direction vector to estimate angular velocity for a spinning solar sail. In cases with a con-stant spin angular velocity, the estimation equation is formed based on the kinematic model for the apparent motion of the sun direction vector;the least-squares solution is then easily calculated. A performance criterion is defined and used to analyze estimation accuracy. In cases with a variable spin angular velocity, the estimation equation is developed based on the kinematic model for the apparent motion of the sun direction vector and the attitude dynamics equation. Simulation results show that the proposed method can quickly yield high-precision angular velocity estimates that are insensitive to certain measurement noises and modeling errors.     

基于Rodrigues参数的姿态估计算法

 以Rodrigues参数作为姿态描述参数提出一种快速的全姿态估计算法。Rodrigues参数具有简洁高效的特点,但它具有奇异性,不适用于大角度情况。首先将序贯旋转方法和Rodrigues参数相结合,提出了一种简洁、无奇异的姿态描述方法。然后应用该姿态描述方法,针对“矢量观测+陀螺”这种典型的姿态测量方案,讨论飞行器的姿态估计问题。在姿态估计算法设计中,给出了陀螺模型和观测矢量模型,推导了状态和状态误差协方差阵的预测方程和量测更新方程,并提出了预测方程的一种高效积分方法。仿真结果表明在估计精度等同的条件下,该姿态估计算法比四元数算法效率大约提高10%。     

DOA estimation using one-bit quantized measurements

The effects 1-bit quantization of the input samples has on the direction-of-arrival (DOA) estimation accuracy are considered. The signal model assumes a single stochastic Gaussian point source that is embedded in white Gaussian noise (WGN). The inherent limitations governed by the extreme clipping of the input data are analyzed using the Cramer-Rao bound (CRB) that is derived for a two-sensor array. In addition, several estimators for the I-bit estimation are discussed. Numerical and analytical analyses of the estimation error reveal weak dependency on signal-to-noise ratio (SNR) with singular behavior of the estimation error in certain DOA angles.     

小波分析在外测数据滤波中的应用研究

为提高弹道估计精度,提出了一种基于小波分析的滤波方法,滤除外测数据中AR（自回归）模型的随机误差。分析讨论了滤波过程中的几个关键问题,提出了利用基于偏自相关系数截尾检验的方法来确定分解层数,然后采用GCV（广义交叉确认）准则来确定均方差意义下最优阈值的方法。本文提出的外测数据滤波方法计算简单,不需要估计噪声的方差。仿真结果表明,该方法能有效滤除外测数据中的AR噪声。     

On joint track initiation and parameter estimation under measurement origin uncertainty

The problem of joint detection and estimation for track initiation under measurement origin uncertainty is studied. The two well-known approaches, namely the maximum likelihood estimator with probabilistic data association (ML-PDA) and the multiple hypotheses tracking (MHT) via multiframe assignment, are characterized as special cases of the generalized likelihood ratio test (GLRT) and their performance limits indicated. A new detection scheme based on the optimal gating is proposed and the associated parameter estimation scheme modified within the ML-PDA framework. A simplified example shows the effectiveness of the new algorithm in detection performance under heavy clutter. Extension of the results to state estimation with measurement origin uncertainty is also discussed with emphasis on joint detection and recursive state estimation.     

Simultaneous Detection., and Intensity Estimation of an Optical Image

A statistical model for simultaneous detection and single parameter estimation of a stochastic signal against background noise is obtained. Two strategies, Bayes and maximum likelihood, are discussed. The detection of an optical point source imaged on a photosensitive surface and the estimation of its intensity based on such strategies are examined. An almost optimum estimate is also proposed and its statistical properties are studied.     

全源定位与导航的统一理论框架构建

针对多导航传感器的信息融合复杂性的问题,提出了一种基于全源定位与导航的信息融合统一理论框架。该框架将目前导航领域的主要定位导航技术分成了与时间无关的定位导航技术方法以及与时间相关的定位导航技术。首先,主要从数学的角度将各种导航技术的测量模型抽象为统一的表达形式,提出了位置、姿态、速度函数的概念,讨论了各种测量方法的测量函数及其应用;其次,分析了航位、航姿、航速的推算方法;最后根据测量模型和运动模型构建了信息融合的基本方程,并讨论了基于贝叶斯估计的导航参数一般性估计方法。     

Study on segmented distribution for reliability evaluation

In practice, the failure rate of most equipment exhibits different tendencies at different stages and even its failure rate curve behaves a multimodal trace during its life cycle. As a result, traditionally evaluating the reliability of equipment with a single model may lead to severer errors. However, if lifetime is divided into several different intervals according to the characteristics of its failure rate, piecewise fitting can more accurately approximate the failure rate of equipment. There-fore, in this paper, failure rate is regarded as a piecewise function, and two kinds of segmented dis-tribution are put forward to evaluate reliability. In order to estimate parameters in the segmented reliability function, Bayesian estimation and maximum likelihood estimation (MLE) of the seg-mented distribution are discussed in this paper. Since traditional information criterion is not suit-able for the segmented distribution, an improved information criterion is proposed to test and evaluate the segmented reliability model in this paper. After a great deal of testing and verification, the segmented reliability model and its estimation methods presented in this paper are proven more efficient and accurate than the traditional non-segmented single model, especially when the change of the failure rate is time-phased or multimodal. The significant performance of the segmented reli-ability model in evaluating reliability of proximity sensors of leading-edge flap in civil aircraft indi-cates that the segmented distribution and its estimation method in this paper could be useful and accurate.     

民用飞机全寿命周期成本及经济性设计研究

总结了民用飞机全寿命周期成本研究方法,对民机型号研制中通常采用的成本估算方法和软件工具进行了介绍。在此基础上,一方面从民机运营经济性的角度对不同市场条件下的计算分析模型进行了对比,指出发展更可靠的直接维修成本（DMC）模型的必要性;另一方面,从民机研制的角度,通过将经济性分析模块有机融入传统飞机设计流程,提出面向经济性设计的总体思路,为实现民用飞机的多学科设计提供了基础。     

Space-based tactical ballistic missile launch parameter estimation

The author explores the influence of a priori uncertainties in launch time and trajectory fly-out profiles, along with sensor angle measurement errors, on the estimation of missile launch location and heading angle. An error model is developed to compute the statistics of the estimation errors using a single pair of angle measurements, one from each of two satellites, or both from the same satellite platform. The measurements and estimation methods are described, followed by a derivation of the estimation errors for the hypothetical case of perfect knowledge of trajectory and launch time. Using the ideal case as a framework, the errors are generalized to include trajectory and launch time uncertainties. The results are discussed with the aid of graphics which were run parametrically to highlight important dependencies and sensitivities     

油滴/金属壁面正碰撞的油膜动力学特性

为诠释轴承腔中润滑油滴与腔壁碰撞形成的沉积油膜流动铺展问题,采用流体体积(VOF)方法建立了油滴与金属壁面正碰撞的三维数值分析模型,在试验获得油滴与壁面静态接触角的基础上,通过数值计算,探讨了沉积油膜动态铺展和回缩过程,以及油滴直径和碰撞速度对沉积油膜铺展直径、特征厚度、铺展速度以及碰撞力等油膜动力学特性的影响。结果表明:沉积油膜在最大铺展直径时呈中心微凹的圆盘形状,进入回缩阶段后则蜕变为边缘薄中心厚的圆盘形状;沉积油膜的回缩速度和回缩阶段的碰撞力都非常小,其值接近于0,并保持基本恒定;随着油滴直径的增大,沉积油膜铺展直径、特征厚度、铺展速度以及碰撞力均增大;随着碰撞速度的增大,油膜铺展直径和碰撞力增大,特征厚度却随之减小。与相关试验结果的对比,验证了提出的数值分析模型的可靠性和正确性。      

表面热流辨识技术在边界层转捩位置测量中的应用初步研究

目前工程飞行试验中主要采用近壁热电偶测温法来确定飞行器表面流动的边界层转捩位置,由于测点离表面较近,对温度传感器量程和结构强度有较高要求。为此,提出了基于表面热流辨识技术确定转捩位置的基本思想和处理方法,测点可以距离表面相对较远。但是,当测点越远离受热面,辨识问题的不适定性会越强,因此需要采用仿真辨识方法来对传感器安装位置进行合理选取。在给出二维传热模型表面热流辨识算法的基础上,对两个算例进行了仿真辨识分析。结果表明：基于表面热流辨识技术确定转捩位置是可行的,能给出较为准确的转捩区域判断。     

Target State Estimation in a Multitarget Environment Using Multiple Sensors

An approach for target detection/state estimation that views theproblem as one of a finite state search over the target parameterspace is presented. This approach allows for a natural way toassociate different types of measurements, such as frequency andcoherence from multiple sensors, and also for dealing with multipletargets, dropouts, and clutter. We describe our model and present acomputationally efficient search algorithm for target detection andtarget state estimation in a multitarget environment based on thismodel. The results of a two-sensor, multitarget computer simulationare discussed.     

Antenna Performance in the Presence of Diffuse Multipath

Diffuse multipath is a random phenomenon that arises out of the diffraction of waves from rough surfaces. This form of multipath can in turn affect the angle estimation performance of monopulse antenna systems. In order to evaluate its effect, it is necessary to obtain the channel spread function that results. This function is basically the wave number spectrum of the resulting random field generated by the scattering. To do this, use is made of the Kodis-Barrick arrick scattering cross section and Wagner's shadowing function. The evaluation is performed for the specific geometry of a spherical earth. Evaluation of the system performance degradation is made for various angle estimation system configurations.     

Nonparametric methods for clutter removal

Methods of clutter rejection are discussed which furnish an inherent counterpart of target tracking and detection algorithms. We describe how nonparametric curve estimation methods reduce the original sensor data to a “signal-plus-noise” model which is well suited for various hypotheses testing and dynamical filtering algorithms. We also verify a “white noise” assumption for the model of residuals     

Position-Location Solutions by Taylor-Series Estimation

Taylor-series estimation gives a least-sum-squared-error solution to a set of simultaneous linearized algebraic equations. This method is useful in solving multimeasurement mixed-mode position-location problems typical of many navigational applications. While convergence is not proved, examples show that most problems do converge to the correct solution from reasonable initial guesses. The method also provides the statistical spread of the solution errors.     

Evaluation of estimation algorithms part I: incomprehensive measures of performance

Practical metrics for performance evaluation of estimation algorithms are discussed. A variety of metrics useful for evaluating various aspects of the performance of an estimation algorithm is introduced and justified. They can be classified in two different ways: 1) absolute error measures (without a reference), relative error measures (with a reference), or frequency counts (of some events), and 2) optimistic (i.e., how good the performance is), pessimistic (i.e., how bad the performance is), or balanced (neither optimistic nor pessimistic). Pros and cons of these metrics and the widely-used RMS error are explained. The paper advocates replacing the RMS error in many cases by a measure called average Euclidean error     

基于模型预测静态规划的自适应轨迹跟踪算法

轨迹跟踪是飞机自主运动控制的关键问题之一。跟踪模型预测静态规划（T-MPSP）是一种新近发展的基于非线性模型的轨迹跟踪算法,但对于飞行器受损等情况下,模型参数相较于标称模型具有较大的偏差时,则可能导致轨迹跟踪效果不理想。提出了基于参数估计的自适应轨迹跟踪算法,在模型预测静态规划（MPSP）的框架下得出解析解,实现了对参数的实时估计,据此更新跟踪模型预测静态规划算法中所使用的模型后,可以有效扩大对参数偏离的适应性,并保留模型预测静态规划计算效率高的特点。通过仿真对比得出,相较于已有的跟踪模型预测静态规划,改进后的算法对模型参数偏离的容忍性明显提高,且算法迭代效率高,适于在线应用。     

Noise effects on centroid tracker aim point estimation

An investigation of errors due to noise in centroid tracker aim-point estimation is presented. The centroid tracker discussed is similar to the tracker described by A.L. Gilbert et al. (1980). Simplifications to this algorithm were made so that the derived models would be consistent with the actual tracker algorithm. Two statistical models are derived which relate image noise effects to computation of the target centroid. The first model, the simplified aim-point error model, is derived by assuming that the probabilities of incorrectly classifying target and background pixels are equal. The second model, the extended aim-point error model, is derived by assuming that the probability of incorrectly classifying a target pixel can differ from the probability of incorrectly classifying a background pixel. These models are described and their mathematical implication is discussed. Simulation results which verify the models are presented