【作者】 王元钦；

【导师】 谭久彬；

【作者基本信息】 哈尔滨工业大学 ， 仪器科学与技术， 2012， 博士

【摘要】 随着常规武器技术的发展，特别是武器系统命中精度的不断提高，对武器系统靶场试验与鉴定中的弹丸运动特征测量技术提出越来越高的要求，迫切需要测量弹丸的旋转速度、章动角、进动周期和弹轴姿态角等绕质心运动特征。雷达技术是测量弹丸运动特征有效手段，但是目前现有的靶场测速雷达处理方法对于弹丸绕质心运动特征测量存在可测参数少、精度低和作用距离短等问题，不能对弹丸绕质心运动特征进行有效地精确测量。弹丸绕质心运动特征测量成为武器试验领域亟待解决的关键技术难题。课题“基于雷达极化的弹丸运动特征处理方法研究”的目的是研究利用雷达测量技术对弹丸绕质心运动特征参数进行精确测量，重点探讨一种采用雷达发射水平线性极化电磁波，在弹丸底部构造具有雷达极化散射特性的结构，通过对雷达回波信号中幅度调制指数的处理，实现弹丸绕质心运动特征测量的方法。通过分析雷达信号中弹丸绕质心运动特征的作用机理和表现形式，构建了反映弹丸运动特征的弹丸雷达散射特性模型，提供了通过雷达信号测量弹丸运动特征的处理方法，实现了基于雷达极化特性的弹丸运动特征测量。本文首先分析弹丸结构特征和运动特征产生的弹丸雷达散射特性的机理，建立了底部刻槽弹丸雷达回波的模型，在雷达回波信号中寻找了弹丸幅度调制指数作为特性参量，来反映弹丸运动特征变化。确定了弹丸绕质心运动特征与雷达回波信号参数间的相互关系，为从雷达回波中处理弹丸转速、进动周期以及飞行姿态等运动特征奠定了理论基础。传统数字解调方法影响弹丸旋转速度处理精度的主要因素是谱线分辨率和旋转信号的信噪比，采用基于线性调频Z变换的高分辨转速处理方法提高了弹丸旋转速度测量精度，又避免了降采样处理带来准平稳信号问题。针对某些特殊弹丸旋转调制的信噪比低情况，采取基于加速度补偿的旋转速度测量方法，大幅度增加积累时间，有效提高弹丸旋转速度处理精度，增加作用距离30%。研究提出了基于Hilbert变换的弹丸回波调幅指数高精度处理方法，避免回波信号调幅和调频项的交叉影响干扰，采取基于时频域交替迭代的滑动Clean-IFFT法，减少频谱泄漏，获得高精度弹丸回波调制指数。深入分析了进动周期和章动周期在弹丸回波调制指数中的关系，确定了弹丸回波调幅指数低频成分和高频成分分别反映弹丸的进动和章动特征。采用基于经验模式分解，构造调幅指数低频和高频分量的弹丸进动、章动周期处理方法。仿真分析表明，通过直接查找极值法和基于快圆调幅指数自相关法实现弹丸进动周期和章动周期处理精度高。弹丸进动周期和弹丸章动周期测量精度可以达到1%。研究分析了弹丸飞行姿态变化对回波幅度调制指数的影响机理，通过数值计算方法事先建立弹丸飞行姿态与特征参数映射关系，从靶场射击试验的弹丸回波中处理出特征参数幅度调制指数。针对存在通过一个弹丸幅度调制指数无法解算α和β两个姿态角的矛盾，提出一种由先验的映射关系和弹丸角运动约束条件解算姿态角的方法，采用参数辨识技术获得弹丸飞行姿态。仿真分析和数据处理验证了弹丸飞行姿态解算方法的有效性，姿态角测量精度优于0.5度。最后，对课题所研究的基于雷达极化的弹丸运动特征处理方法进行了靶场射击试验和雷达测试数据处理，实验结果显示：通过4发不同弹丸的试验和数据处理，验证了转速处理方法、弹丸运动周期处理方法以及飞行姿态处理方法有效性和可行性。首次获得了非刻槽的底排弹的旋转速度、刻槽的弹丸的进动周期和弹丸飞行姿态试验结果。弹丸进动周期和飞行姿态角，与理论分析相符，目前国内没有更高精度的测量手段相对比。但数据分析也表明，对于进动周期和飞行姿态处理方法只在雷达稳定跟踪后的直线段，即雷达电轴与弹底法线夹角较小，一般在5度以内有效。章动周期的处理效果直接受弹丸调幅指数的大小影响。当调幅指数较小时，章动形成的调制较弱，本文的方法难以有效处理出章动周期，应采用适当的刻槽方式，增大调制度，以提高章动周期处理效果。更多还原

【Abstract】 With the development of the conventional ordnance technology, especially theimprovement of weapons system hitting accuracy, more precise techniques onprojectile motion features measurement are indispensable to weapons test andapproval. And the methods for measuring centroidal motion features, such asspinning rate, nutation angle, precession period and flying attitude, are neededurgently. Though radar based techniques are effective to acquire projectile motionfeatures, they have the disadvantages of less acquirable parameters, lower precisionand shorter tracking distance. It is difficult to measure centroidal motion features ofprojectiles effectively at present. The issues on mesasuring projcetile centroidalmotion features become a key difficult problem in the field of ordance test.The aim of the dissertation EXTRACTION OF PROJECTILE MOTIONFEATURES BASED ON RADAR POLARIZATION is to investigate a radar basedmethod to measure centroidal motion features of projectile by processing the indexof echo amplitude modulation, which emphasizes on discussing the realization ofprojectile centroidal motion measurement while radar transmits linear polarizedelectromagnetic wave and the projectile has polarized scatering structures. Throughanalyzing the mechanism and representation of projectile centroidal motion, radarscattering model which can express projectile motion features is established, themethods to extract motion features through radar echo is provided, projectile motionfeature measurement based on radar polariztion characteristics is realized.The scatering mechanism caused by the characteristics of geometric structureand motion is analyzed first. Echo model of the projectile with slots at the base isestablished. The index of amplitude modulation is founded as the parameter whichexpress the features of projecitle centroidal motion directly. The relationshipsbetween the parameter of radar echo and feature of projectile centriodal motion issettled, which is the theoretical basis for projectile spinning rate, precession periodand flying attitude processing.As for traditional digital demodulation method, the main factors that deterioratethe precision of spinning rate are the frequency resolution and the signal to noiseratio of the spinning component. A high resolution method based on the Chirp ZTransform is suggested, which can improve the precision of measurement and avoidnon-stationary problem induced by data downsample. As for the special types ofprojectile echo that the signal to noise ratio is comparatively low, a method based onacceleration compensation is proposed, which can improve the precision of spinningrate measurement and increase valid distance about30percent. An accurate method to process the index of amplitude modulation from radarecho is proposed based on Hilbert Transform, which can avoid the mutualinterference of the amplitude modualtion item and the frequency modualtion item.By adopting the moving Clean-IFFT method which based on iteration in the timeand the frequency domain, the spectral leakage is alleviated and the accurate indexof modulation is obtained. The relationships between the index of modulation andthe periods of precession and nutation show that the lower frequency componentsand the higher frequency components represent the features of precession andnutation respectively. The lower frequency components and the higer frequencycomponent can be constructed using the method of Empirical Mode Decomposition.Simulation and analysis show that the direct searching based precession periodprocessing method and the auto-correlation function based nutation periodprocessing method both can achieve accurate results, whose precisions are about onepercent.The effect of projectile attitude on the index of amplitude modulation of radarecho are analyzed. By the means of numerical computing, the relationship betweenthe attitude and the index that represents the attitude is established. The index isextracted from radar echo. As for the issue that α and β can not be resolve out withone equation, a method based on theoretical knowledge about the relationship andangular motion restriction is proposed. The attitude was solved out by parameteridentification technique. Simulation and data precessing results validate the methodof projectile attitude solution. The accuracy is about0.5degree.At last, ordance shooting tests and the recorded radar data processing arecarried out to testify the methods of projectile motion features extraction. Theresults of four projectile shooting tests show the validation and feasibility of themethods of spinning rate, motion periods and the attitude proposed here. Thespinning rate of base bleed projectile, the precession period and the attitude ofprojectile with slots at the base are obtain using radar for the first time. The resultsof the precession period and the attitude can be consistent with the theoreticalanalysis. There is no more accurate comparison measurement techniques in ourcountry. However, the results aslo show that the methods of the precession periodand the attitude measurement can be applicable only in the initial stage of thetrajectory that radar can track steadily, which the angle between the LOS of radarand the normal of projectile base. Usually it is valid when the angle is less than5degree. The results of nutation period processing are affected by the value of the AMindex directly. When the AM index is low, the modulation by nutation is relativeweak. And the method suggested here can not extract the period effectively. Thusproper manner of slotting grooves at the base of projectile should be adopted toincrease the AM index so as to improve the processing results.更多还原