考虑禁飞区的高超声速飞行器再入跟踪控制

为确立高超声速飞行器再入精确模型,参考NASA的研究数据对动力学方程中的气动参数进行拟合。基于飞行器结构的相关性质及战略应用背景,加入热流密度、动压、过载和禁飞区等参考约束的限制,融合成强非线性、复杂耦合的最优控制问题。采用改进自适应伪谱法求解模型所构建的微分方程组,通过设置自适应网格细化与配点,使单位时间内状态变量和控制变量波动过大的时间区间被进一步细划,并利用SNOPT求解器解算出符合条件的最优轨迹。设计闭环控制器,实现对最优轨迹的姿态变化的跟踪,测试系统的性能并进行评估。仿真结果表明:整个再入过程中,飞行器速度下降过程偏于平稳,再入轨迹可以满足约束条件,在避开禁飞区的同时取得最大横向航程;三通道角速度收敛可控,对姿态的跟踪较理想,控制器基本可以实现精确调姿。     

温度对半导体激光器退化的影响

采取等效电路模型仿真和加速退化试验相结合的方法研究温度对半导体激光器不同退化模式的影响规律。针对半导体激光器有源区退化和腔面退化进行分析,发现有源区退化会使半导体激光器阈值电流增大,而腔面退化会使半导体激光器斜率效率减小;进行了半导体激光器热特性建模与仿真,发现温度升高会使半导体激光器阈值电流增大;利用半导体激光器加速退化试验平台进行了半导体激光器加速退化试验。仿真与试验结果证明:温度升高会加剧半导体激光器腔面退化,而对有源区退化无显著影响。上述结论对进一步完善半导体激光器温度-退化仿真模型,研究温度对半导体激光器退化的作用机理和防护措施有积极作用。     

基于输入特性分析的光电跟踪内模控制设计

内模控制是一种基于对象教学模型进行控制器设计的新型控制策略,其设计思路是将对象模型与实际对象相并联,控制器逼近模型的动态逆.根据内模控制原理及光电跟踪系统参考输入及扰动输入特性,设计了一种新型位置控制器.并分析了IMC跟踪控制器的零稳念偏差及抗干扰性能.从仿真结果看,与常规PID控制相比,内模控制器参数调整简单、跟踪性能良好.特别是在针对目标突然机动的情况下.IMC控制器具有良好的稳态误差重构能力,即能迅速收敛到稳态误差.根据仿真结果数据统计,系统跟踪误差的均方根可减小到0.5 tarad,表明该控制器能够提高系统的跟踪精度,为高性能光电跟踪系统提供了一种新的控制策略.     

基于扩展卡尔曼滤波的机动目标航迹跟踪

针对高速飞行目标航迹跟踪问题,进行了扩展卡尔曼滤波的曲线拟和仿真试验研究.首先建立目标跟踪的数学模型,确定了系统对应的参数及状态方程,进而将线性卡尔曼滤波器进行扩展,将函数形式的滤波模型在函数自变量估计值附近进行泰勒级数展开,求导获得相应雅克比矩阵,在获得观测及系统误差的基础上,得到针对此问题的扩展卡尔曼滤波方程.仿真结果表明该方法的有效性.     

空间信息支持高能激光武器应用研究*

依据空间信息支持现代作战的主要内容,介绍了五大类空间信息状况,分析了新概念武器高能激光的基本原理,并就其应用过程建立了UML模型。在此基础上,设计了空间信息支持高能激光武器应用系统的框架,并就高能激光武器对空间信息的需求进行了重点分析,而后以信息的转换与传递为主线,探讨了高能激光武器运用空间信息的流程。最后对该领域研究的趋势和发展前景做出了展望,并提出对其未来发展的要求。     

一种基于滑模变结构观测器的故障检测方法

提出一种基于滑模变结构观测器的残差生成及故障检测方法.利用滑模变结构所具有的对未知输入扰动的不变性,移除外界扰动对残差的影响,使残差只对故障信号敏感,从而提高故障检测的准确性,较好地解决基于状态估计的故障检测方法中检测鲁棒性与灵敏度之间的矛盾.仿真验证结果表明了该故障检测方法有较高的检测鲁棒性,同时对小幅值故障较为灵敏.     

Linux下某型制导弹目标跟踪并行算法

针对某型电视制导弹的图像特点,在Linux平台上设计了一种并行算法用于完成目标跟踪.算法思想:将制导弹的目标跟踪任务划分为图像采集、纠旋、显示和目标跟踪,程序中创建两个线程用于完成该任务;其中线程1完成图像采集、纠旋和显示;线程2完成目标跟踪.实验表明该算法实现了Linux环境下图像的实时采集、纠旋、显示和目标跟踪,与Windows下的目标跟踪算法相比,该算法有效的节省了资源.     

基于部分可辨识振动系统的载荷恢复方法

在复模态分析和参数辨识的基础上,对部分可辨识振动系统的载荷识别问题进行了研究,提出了基于部分可辨识复模态参数的载荷恢复方法。恢复模型存在幅值模糊和相位模糊,不存在排列模糊。数值仿真验证了该方法的有效性,并讨论了提高恢复精度的方法。     

Experimental study on explosion dispersion process of a multi-layer composite charge under different initiation modes

The influence of initiation modes on the explosive dispersion process of the multi-layer composite charge (MCC) was studied. Overpressure sensors and high-speed photography system were used to investigate the energy release process of an MCC with a specific structure. The shock wave pressure and explosive dispersion characteristics of the MCC under different initiation modes were compared. The forming and expanding process of the shock wave of the composite charge under different initiation modes was determined. The separation position of the shock wave and fireball interface was determined. The calculation formulas of the shock radius and overpressure of the composite charge are presented. The radius of the shock wave of the composite charge was significantly affected by the initiation mode. Moreover, the development process of the composite explosive fireball under different initiation modes was analyzed, the variation rules of the composite charge dispersion radius and fireball dispersion velocity with time were obtained under the different initiation modes, the explosion energy release rate of composite charge under simultaneous initiation modes was the highest, and the peak overpressure under the simultaneous initiation mode was 1.61 times that of central single-point initiation.     

A novel noise reduction technique for underwater acoustic signals based on complete ensemble empirical mode decomposition with adaptive noise,minimum mean square variance criterion and least mean square adaptive filter

Underwater acoustic signal processing is one of the research hotspots in underwater acoustics. Noise reduction of underwater acoustic signals is the key to underwater acoustic signal processing. Owing to the complexity of marine environment and the particularity of underwater acoustic channel, noise reduction of underwater acoustic signals has always been a difficult challenge in the field of underwater acoustic signal processing. In order to solve the dilemma, we proposed a novel noise reduction technique for underwater acoustic signals based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), minimum mean square variance criterion (MMSVC) and least mean square adaptive filter (LMSAF). This noise reduction technique, named CEEMDAN-MMSVC-LMSAF, has three main advantages: (i) as an improved algorithm of empirical mode decomposition (EMD) and ensemble EMD (EEMD), CEEMDAN can better suppress mode mixing, and can avoid selecting the number of decomposition in variational mode decomposition (VMD); (ii) MMSVC can identify noisy intrinsic mode function (IMF), and can avoid selecting thresholds of different permutation entropies; (iii) for noise reduction of noisy IMFs, LMSAF overcomes the selection of decomposition number and basis function for wavelet noise reduction. Firstly, CEEMDAN decomposes the original signal into IMFs, which can be divided into noisy IMFs and real IMFs. Then, MMSVC and LMSAF are used to detect identify noisy IMFs and remove noise components from noisy IMFs. Finally, both denoised noisy IMFs and real IMFs are reconstructed and the final denoised signal is obtained. Compared with other noise reduction techniques, the validity of CEEMDAN-MMSVC-LMSAF can be proved by the analysis of simulation signals and real underwater acoustic signals, which has the better noise reduction effect and has practical application value. CEEMDAN-MMSVC-LMSAF also provides a reliable basis for the detection, feature extraction, classification and recognition of underwater acoustic signals.