Effect of Autopilot Structure on Proportional Navigation Guidance

The dynamic characteristics of acceleration autopilot and attitude autopilot are discu.ssed in detail. Also, a comparison study was made between these two different types of control schemes for guidance loop. By means of simulation, it is concluded that the guidance accuracy is mainly determined by the slowest subsystem among different system dynamics. For air-to-ground missiles, with limited terminal guidance time, the control scheme of acceleration autopilot combined with proportional navigation guidance （PNG） law is the better choice.     

攻击时间和攻击角度控制的非奇异终端滑模制导律

为提高导弹的突防能力并增强毁伤效果,对导弹攻击时间和攻击角度控制问题进行了研究,以导弹和目标相对运动模型为基础,提出了一种非奇异滑模导引律.利用成型理论设计了以时间多项式描述的、同时满足攻击时间和攻击角度约束的导弹视线角表达式.采用优化方法确定表达式系数.由于非奇异终端滑模理论具有使滑模面能够在有限时间内快速收敛的特点,故利用该理论构造关于视线角误差的滑模面,设计了一种无奇点的攻击时间和攻击角度控制制导律.该制导律可使导弹的实际视线角按照设计的理想视线角变化,使导弹满足攻击时间和攻击角度的双重约束.通过理论分析,证明了该制导律满足Lyapunov稳定性条件,能够实现攻击时间和攻击角度控制且不存在奇点.在多种情形下对所设计制导律进行了数值仿真.仿真结果表明,采用该制导律可在不同条件下有效实现导弹的攻击时间与攻击角度控制,与现有文献相比具有一定优势,当存在一定程度的外界干扰时仍能完成攻击时间和攻击角度控制.     

一种新型的最优末制导指令研究

研究了一种中远程战术导弹的捷联复合制导系统最优末制导指令的设计,重点研究了增加速率陀螺和加速度计反馈时对系统的影响。基于最优控制理论的二次型性能指标,将弹体－自动驾驶仪惯性设计为三阶受控对象,导出了最优制导指令的解析表达式,数字仿真结果表明,所作分析与设计是有效的。     

变轨迹制导律技术研究及发展动态

变轨迹制导律的设计是在现代空间飞行器、高超声速飞行器、导弹设计过程中的关键技术。将变轨迹制导律划分为带末端约束的末制导律及标称制导律,概述了2类变轨迹制导律的技术难点,对带末端碰撞约束角的末制导律、标称制导律的在线规划算法,以及标称制导律的轨迹跟踪方法进行了综述,并分析了其可能的研究方向。     

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 time-varying 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 shaping guidance law with terminal impact angle constraint

In order to strike hard targets underground or warships and tanks with expected impact angle by missiles or guided bombs,trajectory shaping guidance law with terminal position and impact angle constraints is derived based on linear quadratic optimal control theory.The required acceleration expressed by impact angle and heading error is obtained in lag-free guidance system in order to find the optimal relationship of those angles in terminal phase.The adjoint systems of miss distance and impact angle error of first-order guidance system are established based on statistical linearization adjoint method(SLAM)in order to study the impact performances of the guidance law.Simulation results show that the miss distance and impact angle error of trajectory shaping guidance law are both according with the impact position and angle constraint and the required acceleration at impact can be decreased by an optimal relationship of impact angle and heading error.     

多约束导引控制一体化的自适应鲁棒滑模设计方法

在攻击机动目标的末制导段, 为使舰炮制导炮弹能够同时满足攻击角、视线角速率测量受限、执行器控制饱和等多项约束, 基于自适应鲁棒控制与动态面滑模设计了一种导引控制一体化设计方法. 首先, 在纵平面内, 建立了弹体的导引控制一体化设计模型. 然后, 设计扩张状态观测器迅速准确地估计出视线角速率与目标机动等未知干扰. 其次, 运用自适应指数趋近律设计了非奇异终端滑模, 以确保视线角跟踪误差与视线角速率在有限时间内收敛至零. 进而, 结合自适应鲁棒项构造动态面滑模与虚拟控制量用以镇定串级系统并削弱变结构项的抖振. 进一步地, 通过设计自适应Nussbaum增益函数, 较好地补偿了由舵机偏转受限引入的控制饱和非线性问题. 运用Lyapunov稳定性理论严谨地证明了终端视线角跟踪误差、视线角速率的有限时间收敛性, 以及系统的一致最终有界性. 仿真实验表明, 所提出的设计方法能够使舰炮制导炮弹在打击具有不同机动形式的目标时, 均具备较好的导引控制性能.     

一种基于θ-D次优控制的三维末制导律设计

最优制导律在求解Hamilton-Jacobi-Bellman(HJB)方程时十分困难。θ-D方法是一种基于State Dependent Riccati Equation(SDRE)方法的新型次优控制方法,能够获得HJB偏微分方程的近似闭环解。针对最优制导律在求解HJB方程时十分困难的问题,文章在考虑导弹自动驾驶仪动态特性和末制导的三维真实拦截情况下,建立导弹和目标的三维相对运动方程,基于θ-D次优控制方法,经状态重定义后对模型方程的伪线性化处理,得到闭环形式的θ-D三维末制导律。为验证所提出制导律的制导性能,分别针对目标不机动和机动的拦截情况进行了数值仿真。仿真结果表明,相比自适应变结构制导律,文中设计的θ-D三维闭环末制导律能克服自动驾驶仪动态延迟对制导性能的影响;对于目标作大机动逃逸的情况,其制导性能更优。     

Proportional Navigation Guidance Law with Variable Coefficient Gravity Compensation

Based upon a discussion on the merits and limitations of proportional navigation (PN) guidance law in which constant gravity compensation is included as a part, a counterpart having varying compensations, which changes with pitching angle and line-of-sight angle, is substituted. Flight trajectory simulation over a submissile model is conducted, resulting in increased impact angle, shorter miss distance, smaller maximum normal overload and narrower terminal angle of attack.     

Homing Guidance Law with Falling Angle and Flying Time Control

In this paper, a new homing guidance method is used to control the flying time and falling angle for guided missiles. Through this approach, it finds the approximate solution to the quadratic equation of time-to- go, which is used for the formula derivation of the flying time control command. In this guidance law design, the acceleration rate control command is adopted. The guidance law is composed of a PN guidance command and a flying time control command. Firstly, it obtains a desired falling angle with accurate guidance. Secondly, it introduces to satisfy the constraint of flying time. The flying time control requires an assumption on the future evolution of missile, which is called time-to-go. To cope with the time-varying speed of missiles, a method of compensating the estimation of time-to-go is presented. The new guidance law is evaluated by using a simulation of typical terminal guidance for rocket-propelled torpedo. The simulation results show that the guidance achieves excellent control performance and exhibits insensitivity to initial trajectory parameter over a widen flight envelope.     

Time-to-go weighted optimal trajectory shaping guidance law

For maneuvering target,the optimal trajectory shaping guidance law which can simultaneously achieve the designed specifications on miss distance and final impact angle was deduced using optimal control theory based on the time-to-go weighted function.Based on the same cost function,the closed-form solutions of the guidance law were derived when the initial displacement of missile,final impact angle,heading error and target maneuver was introduced into the lag-free guidance system.To validate the closed-form solutions,the simulation of the lag-free system was done and the simulation results exactly matched the closed-form solutions and only when the exponent is greater than zero,the final acceleration approaches to zero.     

带有双曲正切加权函数的落角约束最优制导律

为降低末制导律对初始状态误差的敏感度、提高导弹的末端抗干扰能力,针对带有落角约束的末制导问题,考虑基于双曲正切函数的一类加权函数,提出了一种基于间接Gauss伪谱法的最优末制导律. 首先,基于目标位置和期望落角建立了落角坐标系,并在该坐标系中建立了导引运动关系方程,得到了带有落角约束的末制导模型;然后,根据极小值原理推导出了用于求解最优制导律的两点边值问题,运用Gauss伪谱法进行离散,把两点边值微分方程转换为一系列代数方程;最后,通过显式求解代数方程快速得到了最优控制律,该方法避免了求解黎卡提微分方程,不需要进行繁琐的积分运算,计算量小. 所提制导律在推导过程中不依赖于加权函数的具体形式,可非常方便地处理复杂加权函数. 仿真结果表明:通过设计不同形式的加权函数,可灵活改变导弹运动轨迹及制导指令的分布,以实现不同的制导目标;所提方法能有效降低制导律对初始状态误差的敏感度,而且还可以提高导弹的末端抗干扰能力,在很大程度上提高了制导律的设计灵活性.     

战术导弹的PID型比例最佳制导

本文提出了一种PID型导引方法。这种导引方法以广义视线角误差(视线角速度积分,比例,微分的函数)绝对值极小为准则,可以实现准平行接近法导引,它对弹体的过载要求低,可以攻击高机动目标。线性制导方式即为PID型比例导引,它是一种次最佳制导策略。PID型比例导引使制导系统的稳定性,动态品质和准确度得到协调提高,对制导参数,导弹自动驾驶仪参数摄动的鲁棒性高。本文的PID型比例导引克服了[3]的PID型比例导引结构上存在的缺陷,仿真结果证明了上述结论。     

弹目信息在纯方位末制导中的应用

在考虑“被动测量”的条件下，探讨了通过综合利用弹目信息来获取制导所需信息的方法，设计了一种适合被动雷达寻的末制导的运动跟踪滑模制导律；根据自适应推广Kalman滤波技术设计了目标跟踪滤波器；给出了简化的末制导数学模型，并进行了仿真计算。结果表明：所给方法可以较好地提高导弹的制导精度。     

捷联中制导系统的一体化设计

研究了对抗活动目标的捷联中制导系统的一体化设计概念和方法，包括设计失调估计器以实施初始对准；设计导航滤波器以估计目标运动状态，进而构造有关导航参数；考虑高阶受控对象数学模型来设计最优中制导律。数字仿真结果表明，本设计能在飞行过程中实施快速初始对准，并能获得极小的交班误差．     

Three-dimensional suboptimal guidance law for fly-over and shoot-down smart ammunition via virtual target

An optimal burst height is required for the fly-over and shoot-down smart ammunition with an EFP warhead at the instant of explosion which brings a special requirement to the miss distance of the terminal guidance law.In this paper,aguidance law based on the virtual target scheme is proposed.First,the practical pursuit-evasion issue between the ammunition and the target with specific miss distance is transformed into a virtual pursuit-evasion problem with zero miss distance.Secondly,a complete three-dimensional pursuit-evasion kinematics model is established without any simplifications.And then,a suboptimal guidance law is designed based on theθ-D method which has constraints of the elevation and azimuth angular velocity of the virtual line of sight(LOS).Finally,in order to verify the performance of the proposed guidance law,three test cases are conducted.Numerical results show that under the proposed terminal guidance law,the smart ammunition not only can fly above the target with an optimal burst height but also have a smaller normal acceleration on the terminal trajectory.     

可重复使用运载器预测制导与鲁棒容错控制

为实现可重复使用运载器(Reusable launch vehicle, RLV)的再入段准确制导与鲁棒容错控制,提出了一种基于改进预测校正制导律和鲁棒容错姿态控制联合的方法.首先,设计改进倾侧角幅值模型和航迹方位角走廊的预测校正制导律,结合标称迎角剖面,在线计算得出姿态系统的输入指令;然后,针对控制系统的不确定/干扰及舵面部分失效问题,提出一种改进跟踪微分干扰观测器来估计不确定/干扰和舵面失效作用,通过在观测器中增加前馈项进一步提高了复合干扰的估计精度;最后,针对舵面饱和问题设计辅助抗饱和系统,并应用sigmoid饱和函数来改善姿态系统中角速率回路反步法的控制性能.制导与控制系统的六自由度联合仿真实验表明,在考虑姿态回路复合干扰、舵面部分失效及饱和的情况下,RLV准确跟踪了姿态角指令,其飞行轨迹能够到达再入终端落点区域并满足约束条件,因此提出的方法实现了再入段准确制导,较好解决了姿态回路不确定、舵面部分失效及饱和问题,具备良好的鲁棒容错控制性能.     

考虑禁飞圆的高超声速飞行器再入预测制导

针对大升阻比高超声速飞行器同时满足过程约束、终端约束及禁飞圆约束的再入制导问题,提出了一种新的规避禁飞圆的预测校正制导方法,利用拟平衡滑翔条件将过程约束转化为倾侧角约束,结合数值预测校正方法设计倾侧角数值大小,将禁飞圆区域约束实时转化为航向角约束,设计并运用航向角偏差走廊动态补偿策略,形成新的偏差走廊来控制倾侧角符号,从而导引规避禁飞圆.分析及仿真结果表明:该方法不依赖于标准轨迹,对不同的禁飞圆具备自适应能力,能满足终端约束和过程约束,成功规避禁飞圆,制导和落点精度高,并具有鲁棒性.     

纯比例导引律解析解与三维碰撞角约束制导

为提高空地导弹碰撞角约束制导的精度和鲁棒性,增强其对防空系统的突防能力和对目标的打击效果,基于纯比例导引律（pure proportional navigation,PPN）拦截固定目标的解析解,提出了一种新的三维碰撞角约束制导律（three-dimensional PPN-based impact-angle-control guidance law,3D-PPNIACG）。首先,基于PPN拦截固定目标解析解,分析了基于PPN的二维碰撞角约束制导律（two-dimensional PPN-based impact angle constraint guidance law,2D-PPNIACG）的拦截制导性能,包括最大过载、能量消耗与捕获区域。其次,基于2D-PPNIACG和三维拦截制导的垂直分解方法,结合对空间几何关系的深入分析,提出了控制铅垂面内落角和水平面内碰撞角的三维碰撞角约束制导律（3D-PPNIACG）,并对该制导律的实用性和鲁棒性进行了充分讨论。最后通过数值仿真,验证了3D-PPNIACG在碰撞角约束制导中的有效性和鲁棒性。研究和仿真结果表明,所提出的3D-PPNIACG结构简单、易于实现、鲁棒性好,在考虑测量误差、动力学响应延迟等现实因素的情况下,可有效实现水平面内的碰撞角约束制导和铅垂面内的落角约束制导,具有良好的应用前景。     

Three-dimensional nonlinear coupling guidance for hypersonic vehicle in dive phase

Three-dimensional (3D) nonlinear diving guidance strategy considering the coupling between longitudinal and lateral motions for hypersonic vehicle is investigated in this paper. It constructs the complete nonlinear coupling motion equation without any approximations based on diving relative motion relationship directly, and converts it into linear state space equation with the same relative degree by feedback linearization. With the linear equation, slide mode control with strong robustness is employed to design the guidance law, and 3D diving guidance law which can satisfy terminal impact point and falling angle constraints with high precision is obtained by substituting the previous control law into the origin nonlinear guidance system. Besides, regarding lateral overload as the standard, hybrid control strategy which can take full advantage of the excellent characters of both bank-to-turn (BTT) and skid-to-turn (STT) controls is designed to improve the guidance accuracy further. Finally, the results of CAV-H vehicle guidance test show that the algorithm can realize high accuracy guidance even if serious motion coupling exists, and has strong robustness to the path disturbances and navigation errors as well.