有界控制导弹攻击防御性飞机的制导律

为提高攻击导弹同时面对目标飞机及其防御导弹情况下的命中概率,基于微分对策理论,对攻击导弹的制导律进行了设计。应对独立控制的多对象博弈问题,微分对策理论具有天然的优势,且相比于最优制导律,微分对策制导律对于目标机动估计误差和机动策略具有更强的鲁棒性。所推导的微分对策制导律进一步考虑了攻击导弹的控制有界性,且适用于攻击导弹、目标飞机和防御导弹具有高阶线性控制系统动态的情形。为验证制导律性能,进行了非线性系统仿真,结果表明该制导律在成功归避防御导弹的同时可实现趋于零脱靶量的目标拦截。攻击导弹为实现规避和攻击的双重任务,仅需要保持相比于防御导弹两倍左右的机动优势。     

带落角约束的多导弹分布式协同制导律

为实现多枚导弹协同攻击机动目标,基于具有推力可控能力的导弹,提出了一种带落角约束的多导弹分布式协同制导律。将制导律的设计分离为视线方向和视线法向上两个部分:视线方向上基于多智能体协同控制理论和超螺旋控制算法,设计制导律控制导弹剩余时间在有限时间内趋于一致;视线法向上运用零化视线角速率思想和有限时间滑模控制理论,设计制导律控制导弹击中目标的同时满足落角约束。并针对两部分制导律中存在的目标机动信息,分别设计非齐次干扰观测器进行估计。仿真结果表明,提出的制导律能够有效完成协同攻击任务,脱靶量和落角误差分别控制在0.13 m和0.02°以内,并且有效抑制了抖振现象,有利于提高导弹自动驾驶仪的跟踪精度。     

带有攻击角约束的多导弹协同制导律

针对带有攻击角约束的多导弹同时攻击机动目标问题,提出了一种带有攻击角约束的协同制导律。首先基于平面内的导弹-目标相对运动方程,建立了带有攻击角约束的协同制导模型;其次,把协同制导律的设计过程分离为两个部分:一是基于图论的有关内容,运用有限时间一致性理论设计沿着视线方向上的加速度指令来保证所有导弹与目标的相对距离在有限时间内到达一致,进而保证所有的导弹同时击中机动目标;二是利用非齐次干扰观测器对机动目标的加速度进行估计,并运用滑模控制设计视线法向上的加速度指令来保证每枚导弹与目标间的视线角速率收敛到零和视线角收敛到期望的终端视线角,即每枚导弹以期望的终端视线角成功击中目标;最后,对三枚导弹同时打击同一机动目标的情况进行仿真,仿真结果表明本文设计的带有攻击角约束的协同制导律的有效性和正确性。     

光学随动系统机械分系统的精度分析

—光学成像制导仿真系统机械部分由三轴仿真转台和光学随动系统（两轴台）组成，是检测导弹导引头制导精度的重要地面设备。用两轴台形式实现的光学随动系统在国内还是首次研制。本文介绍了光学随动系统机械分系统的总体布局，分析了机械分系统可能达到的静态位置精度、动态精度和结构固有频率     

基于改进序列凸优化的固体火箭入轨制导方法

针对推力大小与关机时间不可调节的耗尽关机固体火箭入轨制导问题,提出一种改进序列凸优化算法。首先利用Legendre-Gauss-Radau伪谱法对模型离散,将滑行时间增广为控制变量,解决点火时间不确定问题,保证求解最优性。其次对非凸推力矢量约束进行松弛凸化,并证明松弛手段的无损性;然后,对非凸运动方程与终端状态约束进行线性化,构建凸优化模型。最后设计初值生成器,为快速迭代构建良好的初始轨迹。仿真结果表明,该制导算法能够满足高精度入轨要求,且问题求解时间仅为伪谱法的6.72%,验证了改进序列凸优化算法有效性。为耗尽关机固体火箭入轨在线高精度快速制导提供重要参考。     

考虑输入受限和自动驾驶仪延迟的自适应滑模制导律

在输入受限的情况下,为了满足导弹拦截机动目标时高精度制导的需求,首先建立了满足输入受限和考虑导弹自动驾驶仪一阶动态特性的制导模型,其把目标加速度视为未知有界的外界干扰,通过设计自适应控制估计干扰的上界来避免对干扰上界的先验要求,同时结合滑模控制,设计了一种考虑输入受限和自动驾驶仪延迟的自适应滑模制导律,并且基于Lyapunov稳定性理论证明了制导系统状态渐进收敛到零。最后,在所设计的制导律下,对目标余弦机动和阶跃机动两种情况进行了仿真,得到的脱靶量分别为0.040 m和0.036 m,拦截时间分别为6.460 s和7.833 s。仿真结果表明所设计的制导律不仅保证导弹有效击中目标,并且具有较高的制导精度。     

末制导炮弹用位标器陀螺

本文讨论了末制导炮弹复合制导弹体制的位标器陀螺的结构、快速驱动方案和控制方法，并给出了一些关键的实验曲线     

双导弹拦截角度协同的微分对策制导律

为提高命中高价值目标的概率,基于线性二次型微分对策理论,对两枚导弹协同拦截单个目标的制导律进行了研究。单枚导弹在最小化自身脱靶量的同时,与另一枚导弹实现拦截角度上的协同,从而构成特定的拦截态势,以提高拦截机动目标的性能和末制导尾端对目标的可观测性。所推导的微分对策制导律考虑到了对策三方的控制系统动态,且具有解析解,形式上为零控脱靶量和零控协同拦截角误差的线性组合。基于推导结果完成了微分对策制导律的制导增益和对策空间分析,给出了鞍点解的存在条件,并进行了分析。非线性系统仿真结果表明由于导弹间存在显式的协同关系,拦截目标所需的加速度较低,且在设定的协同拦截角度收敛后,加速度会进一步减小。     

基于多块嵌套结构动网格的拦截弹防热保护罩的二维分离模拟

在末制导阶段,拦截弹上的红外热保护罩要进行分离,分离引起的气动力变化将直接影响到导弹的制导精度.采用多块嵌套结构动网格技术数值模拟了拦截导弹的热保护罩的二维分离过程.给出了在整个分离过程中,两片保护罩运动的轨迹,并且给出了各个时间步对应的压力云图.预测了由于前激波而产生的作用在导弹上气动力的振荡.跟踪了在各个时刻流场对于导弹上红外窗口的影响.     

基于修正牛顿迭代的固体运载火箭末修级制导方法

针对固体运载火箭发动机能量不可控及喷管控制精度有限导致的关机点轨道参数精度较低问题,提出一种基于修正牛顿迭代的固体运载火箭末修级入轨制导方法。首先,直接建立目标轨道参数与制导变量的非线性方程。然后,通过引入修正系数矩阵并采用牛顿迭代方法保证偏导矩阵范数逐次递减,提高了制导精度及迭代收敛性。仿真结果表明所提方法相对闭路制导,轨道半长轴偏差平均降低101.2 m、1 km以内入轨概率提高8.52%,工程适用性较强。     

Guidance law with circular no-fly zone constraint

The proposed guidance law is used for guiding a missile against a maneuvering target while satisfying a circular no-fly zone (NFZ) constraint. It consists of two parts: virtual-target guidance (VTG) and boundary-constraint handling scheme (BCHS). In order that the missile avoids the NFZ, VTG first maps the actual target to a virtual one, then obtains the relative motion between the virtual target and missile, and finally uses proportional navigation to steer the missile to the virtual target. The missile also hits the actual target when it hits the virtual target because the virtual and actual targets are coincident at this moment. In some cases, especially when the initial velocity vector of the missile points toward the center of the NFZ, if the evasive action taken by VTG is found to be insufficient, then BCHS will be enabled to keep the missile from entering the NFZ unless the target enters the NFZ.     

A self-tuning guidance and control system for marine surface vessels

An integrated guidance and control system has been developed to enable underactuated marine surface vessels to operate autonomously and yield robust tracking performance in spite of significant external disturbances and modeling imprecision. A nonlinear ship model, accounting for all six degrees-of-freedom of the ship, has been used as a test bed to assess the performance of the proposed scheme. The controller combines the advantages of the variable structure systems (VSS) theory with the self-tuning fuzzy logic scheme. It does not require an accurate dynamic model of the ship or the construction of a rule-based expert system. Its asymptotic stability is ensured by knowing the upper bounds on modeling imprecision and external disturbances and by forcing the tuning parameters to satisfy the sliding conditions. The guidance system is based on the concepts of the variable radius line-of-sight (LOS) and the acceptance circle around the waypoints. The current system varies the LOS radius exponentially with the cross track error in order to achieve a fast convergence rate of the ship to its desired trajectory. The simulation results demonstrate the robust tracking characteristic of the integrated guidance and control system in spite of significant modeling uncertainties and environmental disturbances.     

Virtual target approach-based optimal guidance law with both impact time and terminal angle constraints

Nonlinear Dynamics - To attack a stationary target with both impact time and angle constraints, a novel two-stage guidance strategy is proposed based on the virtual target approach. A moving...     

一种基于自适应去偏转换滤波的机动目标跟踪

针对于机动目标的跟踪问题,提出了一种基于交互式多模型的自适应去偏转换卡尔曼滤波器.该算法利用交互多模型算法来完成不同跟踪模型的相互切换;根据自适应去偏转换测量卡尔曼滤波算法来推导跟踪目标状态,同时自适应因子可以确保不正常测量时的鲁棒性.与传统的去偏转换卡尔曼滤波算法对比,该算法可以很好地改善所获量测信息在雷达被干扰时的目标跟踪精度.仿真结果表明了算法的有效性和可行性,且跟踪精度相对传统的去偏转换卡尔曼滤波算法减少9.38％的位置误差.     

一种可用于运载火箭的SINS/GNSS自主导航方案

研究了一种可用于运载火箭的SINS/GNSS自主导航方案。起飞前捷联惯组采用基于惯性系重力加速度积分的解析粗对准和卡尔曼滤波精对准,起飞后采用SINS/GNSS卡尔曼滤波组合导航反馈实时修正姿态、速度和位置。仿真结果表明捷联惯组水平自主对准误差0.01°,方位自主对准误差1.5°,起飞后经组合导航修正后的姿态误差小于0.2°,速度误差小于0.4m/s,位置误差小于40m,考虑所有误差的蒙特卡罗仿真结果满足火箭入轨精度要求,此方案具有较高的工程应用价值。     

On the self-induced motion of vortex sheets

An accurate numerical scheme has been devised to study the self-induced motion of an infinitely thin, free vortex sheet of finite span in an unbounded, inviscid, incompressible fluid. The new numerical scheme has been tested against two vortex sheet problems for which exact solutions have also been obtained. The agreement between the numerical and exact solutions is excellent. The scheme has been further tested against two more examples for which analytical solutions for small times were available. Here too the agreement is excellent.     

SMA智能混凝土材料裂缝修复机理及试验研究

混凝土结构的裂缝产生与扩张一直是土木工程领域亟待解决的难点问题之一。本文将形状记忆合金（SMA）材料植入混凝土材料中，构成一种基于SMA驱动的智能混凝土材料。由于形状记忆合金具有伪弹性，在混凝土产生裂缝的同时SMA将会产生回复力，阻碍裂缝的产生和扩展，根据SMA的形状记忆效应，在材料产生裂缝后对材料进行加热，其回复力将会起到修复裂缝的作用。文章分别对SMA智能混凝土材料的裂缝修复机理和裂缝修复试验进行研究，讨论了不同尺寸试件的裂缝修复过程和裂缝修复程度。本文研究可为形状记忆合金智能混凝土材料的进一步优化设计和工程应用提供理论指导。     

SMA智能混凝土材料裂缝修复机理及试验研究

混凝土结构的裂缝产生与扩张一直是土木工程领域亟待解决的难点问题之一。本文将形状记忆合金（SMA）材料植入混凝土材料中,构成一种基于SMA驱动的智能混凝土材料。由于形状记忆合金具有伪弹性,在混凝土产生裂缝的同时SMA将会产生回复力,阻碍裂缝的产生和扩展,根据SMA的形状记忆效应,在材料产生裂缝后对材料进行加热,其回复力将会起到修复裂缝的作用。文章分别对SMA智能混凝土材料的裂缝修复机理和裂缝修复试验进行研究,讨论了不同尺寸试件的裂缝修复过程和裂缝修复程度。本文研究可为形状记忆合金智能混凝土材料的进一步优化设计和工程应用提供理论指导。     

Distributed group cooperative guidance for multiple missiles with fixed and switching directed communication topologies

Distributed group cooperative guidance (DGCG) problems for multiple missiles with fixed and switching directed communication topologies are dealt with. In contrast to traditional cooperative guidance utilized to intercept one single target, the group cooperative guidance is applicable to multiple targets. In the group cooperative attack, multi-missile system is classified into multiple subgroups, and each subgroup attacks its respective target. Missiles in the same subgroup are required to reach the target simultaneously, while different subgroups may cooperate successively in terms of the impact time. To realize the group cooperative attack, a two-step guidance strategy is developed. The first step adopts a DGCG law based on local neighboring information for multiple missiles to realize group consensus on range-to-go and leading angle. The second step begins when the group consensus of missiles is achieved. During this step, each missile attacks the target under the proportional navigation guidance law. Derived from feedback linearization and convergence analysis, sufficient conditions for multiple missiles to realize the group cooperative attack with fixed and switching directed communication topologies are proposed, respectively. Finally, numerical examples with two subgroups are given to show the effectiveness of the two-step guidance strategy.     

Discrete-time sliding mode control for robust tracking and model following of systems with state and input delays

This paper presents a novel robust tracking and model following control scheme for a class of linear systems with mismatched state and input delays. The algorithm is based on discrete-time sliding mode control (SMC) and time-delay control theory. The proposed scheme ensures the stability and robustness against time delays without state transformation, and achieves the ultimate boundedness of the tracking error. The selection of sliding surface and the existence of sliding mode are two important issues, which have been addressed. Chattering phenomenon and reaching phase are avoided. Simulation results demonstrate the validity of the proposed scheme.