Time-varying parameters estimation with adaptive neural network EKF for missile-dual control system

In this paper, a filtering method is presented to estimate time-varying parameters of a missile dual control system with tail fins and reaction jets as control variables. In this method, the long-short-term memory(LSTM) neural network is nested into the extended Kalman filter(EKF) to modify the Kalman gain such that the filtering performance is improved in the presence of large model uncertainties. To avoid the unstable network output caused by the abrupt changes of system states,an adaptive correction factor is introduced to correct the network output online. In the process of training the network, a multi-gradient descent learning mode is proposed to better fit the internal state of the system, and a rolling training is used to implement an online prediction logic. Based on the Lyapunov second method, we discuss the stability of the system, the result shows that when the training error of neural network is sufficiently small, the system is asymptotically stable. With its application to the estimation of time-varying parameters of a missile dual control system, the LSTM-EKF shows better filtering performance than the EKF and adaptive EKF(AEKF) when there exist large uncertainties in the system model.

Optimal Guidance Law to Maximize Terminal Velocity for Missiles with Impact Angle Constraint

In this paper,an optimal guidance law for missiles with impact angle and miss distance constraints is proposed to achieve the maximal terminal velocity. The normal acceleration command that includes the timevarying coefficients is introduced to satisfy the desired impact angle as well as zero miss distance according to the geometric relation and relative motion parameters between missile and target. The problem is formulated as an optimal control problem by defining the angle of velocity error and flight-path angle as state variables and maximizing a performance index of the terminal velocity. The analytical form of the proposed guidance law is obtained as the solution of the optimal control problem combining optimal control theory and numerical value computation method. Nonlinear simulations of various situations demonstrate the performance and feasibility of the proposed optimal guidance law.

Trajectory design and simulation in injection phase for hyper-velocity kinetic energy missile

A movement law of laser beam facula is designed for the injection trajectory of hyper-ve- locity kinetic energy missile to eliminate the influence of motor exhaust smoke on laser signal trans mission. Taking guidance loop of hyper velocity kinetic energy missile as plant, a closed loop control system with desired step response characteristics is constructed and the movement law of laser beam facula for the missile injection trajectory is designed based on the output signal of the closed loop controller under a step input. Six degree of freedom trajectory simulations show that by the guidance of the laser beam facula moving with designed law, the missile can finish transition from the initial trajectory to a stable tracking trajectory without overshoot within the required time.

Evaluation and optimization of strapdown velocity numerical integration algorithms for SINS in spinning ballistic missiles

The error of the conventional velocity numerical integration algorithm was evaluated through the Taylor series expansion. It is revealed that neglecting the second- and higher-order terms of attitude increments will lead to the velocity numerical integration error, which is proportional to the triple cross product of the angular rate and specific force. A selection criterion for the velocity numerical integration algorithm was established for strapdown inertial navigation system (SINS) in spinning missiles. The spin angular rate with large amplitude will cause the accuracy of the conventional velocity numerical integration algorithm in SINS to decrease dramatically when the ballistic missile is spinning fast. Therefore, with the second- and higher-order terms of attitude increments considered, based on the rotation vector and the velocity translation vector, the velocity numerical integration algorithm was optimized for SINS in spinning ballistic missiles. The superiority of the optimized algorithm over the conventional one was analytically derived and validated by the simulation. The optimized algorithm turns out to be a better choice for SINS in spinning ballistic missiles and other high-precision navigation systems and high-maneuver applications.

Position Measurement Based Slave Torque Feedback Control for Teleoperation Systems With Time-Varying Communication Delays

Bilateral teleoperation system is referred to as a promising technology to extend human actions and intelligence to manipulating objects remotely.For the tracking control of teleoperation systems,velocity measurements are necessary to provide feedback information.However,due to hardware technology and cost constraints,the velocity measurements are not always available.In addition,the time-varying communication delay makes it challenging to achieve tracking task.This paper provides a solution to the issue of real-time tracking for teleoperation systems,subjected to unavailable velocity signals and time-varying communication delays.In order to estimate the velocity information,immersion and invariance(I&I)technique is employed to develop an exponential stability velocity observer.For the proposed velocity observer,a linear relationship between position and observation state is constructed,through which the need of solving partial differential and certain integral equations can be avoided.Meanwhile,the mean value theorem is exploited to separate the observation error terms,and hence,all functions in our observer can be analytically expressed.With the estimated velocity information,a slave-torque feedback control law is presented.A novel Lyapunov-Krasovskii functional is constructed to establish asymptotic tracking conditions.In particular,the relationship between the controller design parameters and the allowable maximum delay values is provided.Finally,simulation and experimental results reveal that the proposed velocity observer and controller can guarantee that the observation errors and tracking error converge to zero.

基于视线角速度精度的导引系统抗干扰性能评估指标研究

针对传统抗干扰性能评估指标集中在导弹制导系统层面,无法满足导引系统抗干扰性能评估的问题,本文在分析抗干扰过程中制导系统内部误差传递原理的基础上,基于导引系统的测量误差,提出了基于视线角速度精度的导引系统抗干扰性能评估指标,从而在导引系统研制过程中,能够及时对其抗干扰性能进行评估。由于视线角速度精度在外场试验中不易测量,为了提高该指标的测试效率,基于比例导引制导原理,给出了视线角速度精度的简化计算方法,并针对非比例导引制导场景,给出了利用识别时间对视线角速度精度进行等效测试的方法。外场数据测试结果表明,该指标能够反映导弹在不同场景下的抗干扰性能,具有一定合理性。

弹载芯片在强冲击环境下的损伤边界

针对弹载芯片结构在强机械冲击环境下冲击响应谱损伤边界不确定和不准确的问题,将芯片等效为单自由度无阻尼系统并进行冲击响应分析,建立结构应力响应与伪速度冲击响应谱之间的联系;对弹载芯片结构在不同频率范围内冲击载荷下的响应进行分析,构造损伤边界并通过临界加速度信号对冲击响应谱损伤边界进行修正;采用有限元仿真软件对冲击载荷下的弹载芯片结构进行仿真分析,结果表明,临界应力值与修正后损伤边界符合较好。研究结果可以为集成电路在强机械冲击环境下的可靠性设计和失效分析提供理论依据。

飞行速度可调导弹三维制导律研究

为获得更好的制导性能,针对一类采用流量可调发动机的导弹,利用其所增加的飞行速度控制自由度,提出一种三维空间下比例导引+飞行速度控制的双重控制滑模制导律;以比例导引作为基础,在对二维、三维零控脱靶量分析的基础上,以零控脱靶量为跟踪目标选取合适的滑模面,并进一步使用辅助滑模面和有限时间超螺旋干扰观测器对滑模面中的不确定项进行估计,推导了减少脱靶量的速度控制制导律;仿真结果表明,相比于经典的比例导引,在考虑空气阻力的场景下,所设计的制导律脱靶量更小,弹道更平滑,滑模面收敛情况理想,实现了导弹飞行速度的主动控制。

Impact time control using biased proportional navigation for missiles with varying velocity

A feasible guidance scheme with impact time constraint is proposed for attacking a stationary target by missiles with time-varying velocity.The main idea is to replace the constant velocity with the future mean velocity;therefore, the existing time-to-go estimation algorithm of the proportional navigation guidance law can be improved to adapt to varying conditions.In order to obtain the prediction of the velocity profile, the velocity differential equation to the downrange is derived, which can be numerically integrated between the current downrange and the target position by the on-board computer.Then, a third-order polynomial is introduced to fit the velocity profile in order to calculate the future mean velocity.At the beginning of each guidance loop, the future mean velocity is predicted and the time-to-go information is updated, based on which a novel biased proportional navigation guidance law is established to achieve the impact time constraint.Finally,numerical simulation results verified the effectiveness of the time-to-go estimation algorithm and the proposed law.

高超声速风洞马赫数4.5喷管气动设计和数值验证

常规跨超声速风洞进行马赫数4.5试验时,常常伴有空气液化现象,造成试验数据可信度低,在高超声速风洞研制马赫数4.5喷管,具有对气流加热的能力,可以提供更加准确的试验数据。目前国内0.5 m量级高超声速风洞还不具备马赫数4.5的试验能力。通过无黏流计算方法计算轴对称喷管型面,并采用Sivells-Payne方法进行附面层修正,然后进行数值验证,证明了计算出的型面满足国军标对马赫数的设计要求,可以投入加工生产。

预制破片对战斗部冲击起爆数值模拟

分析了高速条件下预制破片冲击起爆巡航导弹战斗部的作用机理,采用Lee-Tarver点火增长模型和AUTO-DYN程序对高速预制破片冲击起爆战斗部进行了数值模拟,着重分析了破片材料、直径、形状和被起爆战斗部装药及壳体对冲击起爆的影响.结果表明,对于相同质量的破片,大密度和不规则的破片更容易冲击起爆战斗部;通过采用重金属材料,增大破片直径,采用柱形或其它不规则破片,可以提高破片速度来提高破片冲击起爆战斗部的能力.

截锥形弹体斜穿甲花瓣型破坏模型

根据截锥形弹体斜穿甲的破坏过程及破坏机理,提出了一种新的花瓣型破坏模式,推导了扩孔耗能、弹道极限及剩余速度公式。公式计算结果与有限元分析结果比较表明,两者吻合较好。

弹道导弹在被动段突防的脉冲式轴向加速方法

弹道导弹由于其沿着固定的弹道飞行而容易被拦截,突防技术的发展是提高弹道导弹生存能力的重要手段之一。根据弹道导弹的飞行特点,提出了基于脉冲发动机的脉冲点火轴向加速的被动段机动变轨突防方法。给出了限制脉冲点火的约束方程,并给出了基于泰勒展开的约束方程求解方法。利用这个方法设计出来的弹道是由几条不同的椭圆孤段组成,这种弹道不同于经典弹道和其它弹头机动弹道。给出了两个仿真实例。仿真结果显示,用本文方法设计出来弹头机动弹道具有好的突防效果,这说明所提出弹头机动弹道设计方法是可行的。

超音速射流气膜冷却效果的试验研究

以二维平板模拟高速导弹头罩上的探测窗口，用电加温产生的热气流模拟导弹飞行时的气动加热，对采用气膜冷却控制导弹探测窗口温度的效果及规律进行了研究。着重探讨了气膜冷却临界长度ＬＣ与气膜冷却有效度η随射流缝高ｓ、喷射率λ及主射流夹角α等参数的变化规律，并总结出一个相关参数及一些经验公式。研究结果与国外有关文献基本一致。

高速动能导弹及超高速导弹用固体火箭推进剂

综述了国外几种主要动能拦截导弹、战术动能导弹和超高速导弹以及其所用固体推进剂的配方和主要性能,在此基础上分析了高速动能导弹和超高速导弹对固体推进剂在性能方面的需求。推进剂的高压燃烧稳定性问题以及采用新型含能材料组分的NEPE类配方是高速动能导弹发射推进剂研究开发的重点技术领域和发展趋势;燃气清洁、快速点火响应以及能在高过载条件下稳定工作等是当前KKV轨/姿控系统对固体推进剂性能的主要要求。尽管在实用性能上存在很多问题,但凝胶推进剂应用于轨/姿控系统具有更加灵活的能量输出控制能力,可使KKV更具智能飞行和快速机动的能力,是KKV控制用推进剂的发展方向。

高速动能导弹起飞质量设计方法研究

根据高速动能导弹动力系统的特点,以导弹在有效射程范围内命中目标的最小速度要求为约束条件,建立了起飞质量优化设计的数学模型,给出了此模型对高速动能导弹起飞质量进行优化设计的初步结果。

中段弹道目标宽带回波仿真与速度补偿

中段弹道目标的主要特征是高速平动和微动。因此测量得到的目标多普勒频移值是模糊的,而且同时被目标微多普勒调制。这给估计目标微多普勒带宽和提取目标微多普勒参数造成了困难。在充分考虑目标运动特征的条件下,首先研究和建立了目标的宽带雷达回波数学模型。然后提出了基于简化分数阶傅里叶变换(simplified fractional Fourier transform,SFRFT)的速度补偿方法。推导了方位向信号起始频率和调频斜率的估计误差方差,证明了算法的有效性。仿真结果表明,该方法能够给出精确的参数估计结果,并能对平动多普勒频率进行准确补偿。即使在信噪比较低的情况下,该方法仍表现出较好性能。该方法为目标微多普勒参数的提取提供了前提条件。

速燃发动机在战略导弹助推段突防技术中的应用研究

助推段拦截是美国NMD、TMD系统的一个重要组成部分。这一作战方式对弹道导弹的突防提出了更高的要求。采用速燃发动机降低助推段高度、缩短助推时间是反助推段拦截的有效手段。以一种假定的三级固体助推洲际导弹为对象 ,分析了提高燃速对导弹射程及助推段性能的影响 。

导弹协同编队H_∞制导律设计

在导弹协同编队飞行过程中,为使从弹制导系统在满足干扰抑制指标要求的同时,具有良好的动态响应特性,提出一种基于H_∞控制理论的比例积分制导律算法。在三维空间中建立新的领从弹相对运动方程,将领弹加速度信息视为有界扰动,以相对距离和从弹加速度作为状态量和控制量,得到从弹制导系统的状态方程。通过状态变换和系统增广,将从弹制导律设计问题转换为H_∞控制问题,得到满足H_∞性能指标的比例积分控制器,实现了导弹编队队形的生成、跟踪和保持。仿真结果验证了算法的有效性。

某型导弹模型参考自适应控制系统设计

采用自适应控制理论与经典控制理论相结合的方案 ,用 Popov超稳定理论设计了模型参考自适应控制 (MRAC)系统 ,给出数字仿真结果。