Design and Simulation of TF and TA Controller for Missile

A nonlinear terrain following(TF) and terrain avoidance(TA) controller is proposed for missile control systems. Based on classical TF algorithm (adaptive angle method), a new method for TF controller is proposed by using angle of attack. A method of obtaining terrain outline data from digital elevation map (DEM) for TF control is discussed in order to save store space. A TA algorithm is proposed by using bank-to-turn technique. The block control model, which is suitable for backstepping design, is given for nonlinear model of missile. Making full use of the characteristics of the system and combining block control principle and backstepping technique, a robust controller design method is proposed. Uncertainties in every sub-block are allowed, and can be canceled by using the idea of nonlinear damping. It is proved that the state tracking errors are converged to a neighborhood of the origin exponentially. Finally, nonlinear six-degree-of-freedom simulation results for the missile model are presented to demonstrate the effectiveness of the proposed control law.     

Analysis of hydrodynamic characteristics of unmanned underwater vehicle moving close to the sea bottom

The accurate research on the hydrodynamics of unmanned underwater vehicle （UUV）, which moves close to the sea bottom, has a great significance for its maneuverability. The structured grid of the computational models with different distances to the sea bottom and attack angles is generated by Ansys ICEM, and the flow field near the sea bottom is simulated using CFX. The characteristics of the drag, lift, pitching moment influenced by the distance to sea bottom and the attack angle are studied. The result shows that the drag coefficient increases with the decrease of distance, while it increases with the increase of attack angle. There exists attraction force when UUV moves close to the sea bottom, and the attraction force increases with the decrease in distance. The lift coefficient increases with the increase in attack angle. The absolute value of the pitching moment coefficient increases with the decrease in distance and the increase in attack angle.     

Study of Load Modeling Technology on Hardware-in-the-Loop Simulator of Gun Servo System

A hardware-in-the-loop (HWIL) simulator for gun servo system is described in this paper, and its load modeling technologies,such as road spectrum model,sea wave model are studied. The simulation results show that the models can be used in HWIL and satisfy the requirements of hardware-in-the-loop simulator of gun servo system.     

Design Method of Equipment Optimization Development Based on Standardization Theory

The matters of equipment optimization development are usually discrete, fuzzy and non-quantitative. It is difficult directly to optimize the equipment development with a mathematical model. A set of methods for designing the equipment optimization development with six di- mensions and eight main elements is established based on the theory and method of standardization. The top-tier design space of systematic development of equipment is built up by the relations of basic models, series and model spectrums. The relations of time and space for equipment optimization development are established. The design processes of a six dimension systematic space are expounded. The connotation of each plan in the main system space is analyzed. A design method for an entire equipment is established with standardization theory. The coordinating design methods of equipment technical system and the optimization design methods of equipment integration are discussed. The design methods for universalization and serialization of components and parts are established. The design methods of equipment optimization development highlight the relations of the basic model of platform, the serialization of platform basic models, the modularization of equipment functions, the model spectrum of variant equipment, and the universalization and serialization of components and parts.     

Waveguide Invariant and Passive Ranging Using Double Element

The sea-trial results indicate that the stable interference structure can be observed in low-frequency continuous spectra sound field.And the equation of the interference striation have been derived in light of the comcept of waveguide invariant, indicating that the striations are a family of quasi hyperbolas. The heading angle φ, waveguide invariant β and r0/v(r0 is the range of the closest point of approach and v is the navigating velocity of target) are estimated by using Hough transform for the image processing of the LOFARgram and bearing-time records. Four passive ranging algorithms based on double element or double array model are proposed. The simulation research shows that the first positioning algorithm should be adopted when the target heading angle is less than 10°; otherwise, the latter three algorithms are used to range, and the larger the heading angle is, the higher the positioning accuracy is. The relative ranging errors of the four methods are less than 10% under the simulation conditions used in this paper.     

Improvement of Intercept Probability Algorithm for Anti-ship Missile Based on Search Theory

Traditional intercept probability model has some drawbacks and can not meet the demands of command and control system. Aiming at this problem, a new calculation method based on search theory, terminal control area distribution function of anti-ship missile, target distribution function and missile's radar scan feature is proposed. Under the condition of common target distribution, an intercept probability model for present point attacking is determined. The simulation verifies its effectiveness and establishes the selecting model for aiming point when enemy ships evade in high speed.     

Single channel source separation of radar fuze mixed signal based on phasedifference analysis

A new method based on phase difference analysis is proposed for the single-channel mixed signal separation of single-channel radar fuze. This method is used to estimate the mixing coefficients of de-noised signals through the cumulants of mixed signals, solve the candidate data set by the mixing coefficients and signal analytical form, and resolve the problem of vector ambiguity by analyzing the phase differences. The signal separation is realized by exchanging data of the solutions. The waveform similarity coefficients are calculated, and the timeefrequency distributions of separated signals are analyzed. The results show that the proposed method is effective. Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

Conversion of Torpedo＇s Lake and Sea Test Data Based on Grey System Theory

As only a little information can be obtained from torpedo＇s lake and sea tests, and the torpedo＇s life does not distribute typically. If conventional methods are used to convert the environment factor for torpedo＇s lake and sea tests, their results can not reflect the actual conditions. A conversion model of the environment factor for torpedo＇s lake and sea tests is set up based on the GM（1,2） model of the grey system theory. For the merit of the grey system, the problem of uncertain life distributions and few samples can be solved. The calculation results show that the method is easy, realistic and high precise.     

Numerical Simulation for Ventilated Supercavitation High Speed Underwater Vehicle

Supercavitation is a revolutionary technique to achieve high drag reduction for underwater vehicle. It can help us to break through the conventional speed barrier. This article presents a numerical algorithm for ventilated supercavitation flow field based on mixture multiphase flow model, briefs the calculation results and compares them with that tested in high-speed water tunnel and towing tank. The mathematical model, its numerical calculation method, computational region and boundary conditions are discussed in detail. Some pertinent nondimensional parameters about the ventilated supercavitation, such as geometrical configuration of supercavity, drag coefficient and ventilation rate are investigated. Reynolds number is selected to predict gas ventilation rate instead of Froude number. Finally, based on the test and simulation results, a semi-empirical formula of the ventilation rate estimation suitable for different conical angle caritators is proposed.     

Numerical simulation of base flow with hot base bleed for two jet models

In order to improve the benefits of base bleed in base flow field, the base flow with hot base bleed for two jet models is studied. Twodimensional axisymmetric NaviereStokes equations are computed by using a finite volume scheme. The base flow of a cylinder afterbody with base bleed is simulated. The simulation results are validated with the experimental data, and the experimental results are well reproduced. On this basis, the base flow fields with base bleed for a circular jet model and an annulus jet model are investigated by selecting the injection temperature from 830 K to 2200 K. The results show that the base pressure of the annular jet model is higher than that of the circular jet model with the changes of the injection parameter and the injection temperature. For the circular jet model, the hot gases are concentrated in the vicinity of the base. For the annular jet model, the bleed gases flow into the shear layer directly so that the hot gases are concentrated in the shear layer. The latter temperature distribution is better for the increase of base pressure. Copyright . 2014, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.     

大入射余角下无线电引信海杂波模型

为解决无线电引信的超低空对抗海杂波干扰这一技术难题,对大入射余角下的无线电引信海杂波模型进 行研究。根据试验数据研究引信在大入射余角下的海面后向散射系数,通过物理海面建模和网格划分,建立引信的 随机海面回波模型,提供海杂波功率理论计算方法。对比仿真结果与引信的试验结果表明：模型与实测数据一致性 较好,为引信的海杂波特性分析提供了理论基础。     

不同入射余角情况下海面电波特性对雷达导引头的影响分析

介绍了影响海面后向散射系数和反射系数的各项因素，给出了雷达波束有效照射面积与入射余角、弹目距离、雷达脉宽和波束宽度在各种不同情况下的关系式，讨论了海杂波和多路径效应对雷达导引头工作性能的不良影响并提出了解决问题的若干对策．     

重频捷变对雷达导引头检测性能的影响

分析了重频捷变电路对雷达导引头在杂波环境下目标检测性能的影响,提出了一种在时域设计滤波器引入杂波相关特性并动态更新滤波器的仿真方法。仿真结果表明:在重频捷变模式下,杂波幅度分布概率密度曲线变得尖锐,杂波相关性减弱。得出的结论:重频捷变可以提高导引头的目标检测性能。     

基于概率定义扩展样本的机载雷达空间和时间相关海杂波数据仿真方法

海杂波背景下的目标检测性能是机载预警雷达的重要指标之一。为了给机载雷达海杂波抑制方案的有效设计提供数据来源,需要仿真模拟出满足实际分布特性和相关性的海杂波。针对实测海杂波数据具有的显著时间相关性和空间相关性,提出了一种新的海杂波数据产生方法。该方法基于概率密度定义及相关性的本质,运用蒙特卡罗思想和Cholesky分解来产生空间和时间相关的海杂波。这种方法不仅简化了海杂波数据产生流程,同时提高了海杂波幅度和相关性吻合效果。分别利用实测和仿真数据验证了所提方法的有效性。     

一种改进型二维恒虚警参考窗

对于环境复杂的海面,雷达回波中包含了目标回波、海杂波、气象杂波以及干扰信号等.由于海杂波特性随时间变化存在较大的随机性,因此预警雷达在强杂波环境下探测微弱目标时,海杂波抑制成为一个关键环节.恒虚警率(CFAR)处理技术是减小海杂波影响的一项有效措施.本文从海面雷达回波特性入手,分析了海杂波的空间幅度特性,提出一种改进的...     

基于实测数据的海杂波建模方法

为解决海杂波模型过于简单、逼真度不高及杂波模拟缺乏针对性等问题,提出一种基于实测数据的海杂 波建模方法。在分析经典海杂波统计模型基础上,利用导引头采集不同海况下的实测数据,采用拟合度检验及参数 估计的方法,结合SIRP 法模拟生成仿真杂波数据,通过对经典统计模型进行修正,得到实用的海杂模型。仿真结果 表明,该方法对于提高射频仿真系统中海杂波模型逼真度及置信度具有参考价值。     

不同环境下海杂波特征仿真与试验研究

海杂波是影响雷达目标检测的主要因素,而海洋大气环境又通过影响电磁波传播路径而改变海杂波特征。分析了不同海洋大气环境下海杂波特征差异的成因,综合海面反射率经验模型,建立了基于“对等距离冶法的海杂波特征量计算方法,并对文献[9] 试验中1998 年4 月2 日观测的海杂波数据进行了仿真,经过4 个方向对比表明,仿真值与实测平均值比较吻合。结合模拟的不同环境条件和雷达参数,对标准大气、蒸发波导及表面波导等环境下的海杂波特征进行了仿真,结果表明:相比于标准大气环境,波导环境下海杂波功率特征呈现增强的趋势,而且在表面波导环境下的第一跳跃盲区内还会呈现弱杂波或无杂波特征。     

多雷达含缺损信息外弹道解算方法研究

为解决雷达测量信息受地、海杂波的强烈干扰,导致雷达俯仰角测量难以构成有效闭环,目标俯仰角信息超差严重,并通过坐标系变换,向目标各维坐标传导超差信息的问题,该文综合考虑地、海杂波对方位角和斜距信息影响较小,以及海上靶场雷达测量网的布站特点,提出了一种利用多台雷达共有段落的方位角和斜距信息,构建联合处理模型,解算目标弹道的方法。数据测试证明,该方法可以有效解决雷达部分测量信息超差问题,提高靶场雷达测量数据处理的精度和可靠性。     

无线电引信海面后向散射系数仿真分析

针对无线电引信在海杂波背景下目标检测问题的需要,在分析入射余角、工作频率、极化方式以及海面状态对后向散射系数影响的基础上,给出了海杂波对引信信杂比的影响,并对Morchin模型和双尺度粗糙面复合模型两类海面后向散射模型进行仿真和拟合;仿真结果表明:在大入射余角条件下,较双尺度粗糙面复合模型,Morchin模型能够取得更好的拟合效果,更有效地反映无线电引信超低空工作时海面后向散射系数.     

基于K分布雷达海杂波建模与仿真

海杂波的仿真对杂波环境下弹载雷达检测性能的研究具有重要意义。文章首先建立了海杂波回波模型,其次分别对海杂波后向散射系数、复散射截面积以及起伏调制函数进行了建模分析,最后结合海杂波幅度分布特性和时间相关特性,利用零记忆非线性法对海杂波进行了仿真。结果表明,该方法可以有效地模拟雷达海杂波,从而为雷达信号处理器的设计奠定了基础。