考虑攻击角度和视场角约束的自适应终端滑模制导律

针对导弹拦截机动目标的末制导问题,基于有限时间滑模控制理论设计一种带有攻击角度和导弹视场角约束的制导律.首先,将导弹末制导问题转化为带有状态约束的制导系统稳定问题,设计一种新型的非奇异终端滑模面和时变的障碍Lyapunov函数,给出一种终端滑模制导律的设计方法,并针对目标机动的不确定性设计一种对目标机动上界的自适应估计;然后,通过稳定性理论证明制导系统的状态变量最终是有限时间收敛的,并且结合时变的障碍Lyapunov函数和滑模面的设计特性证明在末制导过程中视场角约束条件始终不会被违背,相比于现有的考虑视场角约束的制导律,该制导律不存在指令转换,能够加快制导系统收敛速率,增强制导系统的抗干扰能力;最后,通过仿真实验验证所提出制导方法的有效性.     

基于终端角度约束的自适应鲁棒制导律设计

针对空地导弹攻击地面目标的末制导问题,提出了一种新的基于终端角度约束的自适应鲁棒制导律;基于末制导中二维弹目相对运动学关系,考虑目标的运动特性,建立了描述弹目相对运动的数学模型;基于零化弹目视线角速率的思想,并将目标机动运动和系统结构摄动作为外部扰动,以命中点终端姿态角跟踪误差为性能指标,设计得到了非线性自适应鲁棒制导律,同时该方法利用Lya-punov稳定理论严格证明了制导系统的全局渐近稳定性;数字仿真表明这种制导律在不需要任何目标运动信息的情况下,仍然保证终端角度和制导精度的要求,具有很强的鲁棒性和适应性.     

考虑终端角度约束的自适应积分滑模制导律

针对机动目标拦截末制导问题,提出一种考虑终端角度约束的自适应积分滑模制导律.首先给出一种有限时间收敛的非线性积分滑模面,采用快速终端滑模设计趋近律;然后设计一种对目标机动加速度上界平方进行估计的自适应律,给出具有光滑特性的自适应积分滑模制导律;最后基于有限时间理论证明闭环系统的有限时间收敛特性,并给出滑模变量、视线角以及视线角速率的收敛域.数值仿真结果验证了所提出设计方案的有效性.     

一种基于许瓦兹不等式的最优末制导律设计

针对导弹和目标相对运动学关系,利用许瓦兹不等式,提出了一种新的基于制导品质最优的末制导律。在导弹和目标的三维相对运动关系的基础上,忽略三维制导平面的耦合因素,同时考虑二阶的弹体响应环节,建立了导弹制导系统的数学模型。基于在有限时间内零化弹目相对距离和零化弹目视线角速率,以及导弹机动能量最小的优化制导品质的思想,利用许瓦兹不等式推导出一种用解析形式表示的最优末制导律。这种最优制导律通过估算剩余时间,实现对目标的有效拦截。最后通过数字仿真,验证了在脱靶量、弹目视线角速率和机动能量的制导品质方面,所提出的最优制导律要优于一般的比例制导律。     

带攻击角度约束的非奇异快速终端滑模制导律

本文利用先进的终端滑模控制和李雅普诺夫稳定性理论设计了一种非奇异、本质上连续和有限时间收敛的带攻击角度约束的制导律,它可用于打击固定、匀速运动和机动目标.为了在有限时间内高精度地获得给定的攻击角度并不出现奇异问题,非奇异快速终端滑模函数被用于设计滑模面.快速终端滑模函数被用于设计趋近律,在整个到达阶段系统轨迹可以从任意初始状态快速地收敛到滑模面并形成本质上连续的制导律.由于非奇异、本质上连续和全局快速收敛的特性,和传统的终端滑模制导律相比,本文方法可以在更短时间内以更高精度的攻击角度对目标实施打击.大量的仿真算例表明了本文制导律的有效性.     

一种带时间协同和角度约束的多导弹三维协同制导律

针对多枚导弹在三维空间从不同初始位置同时拦截机动目标的问题,设计了一种带视线角约束的有限时间协同制导律.首先,给出三维空间的导弹–目标相对运动方程并建立了考虑视线角约束的多弹协同制导模型.其次,对视线纵向及法向方向分别设计了相应的协同制导律.其中在视线方向基于多智能体有限时间一致性理论设计了协同制导律,保证各拦截弹能够同时击中目标;基于一种新型的固定时间非奇异终端滑模控制方法设计了视线法向上的角度约束制导律,使各拦截弹的视线角能够在固定时间内收敛至期望值,实现空间上的协同;同时,构造了扩张状态观测器估计目标加速度.最后,对三枚导弹同时拦截同一机动目标的情况进行仿真对比,验证了本文所提出协同制导律的有效性.     

考虑自动驾驶仪与角度约束的制导律设计

以末端拦截高机动目标为背景,针对带有攻击角约束和自动驾驶仪动态特性情形下的二维平面制导问题进行了研究分析。在提出固定时间终端滑模面基础上,通过自适应算法在线估计干扰的上界值,针对带有攻击角约束和自动驾驶仪动态特性的制导系统模型设计了自适应终端滑模制导律,使得系统状态在有限时间内趋于零附近任意小的区域。利用李雅普诺夫理论对所设计制导策略给出了严格的稳定性证明,仿真结果验证了所提制导方案的有效性。     

一种新的具有攻击角度约束的末制导律设计

研究导弹末制导性能优化问题,在末端要满足攻击角度的约束条件,要求优化空地导弹末制导命中目标精度性能.针对导弹和地面目标所形成动态系统的非线性运动学关系,通过分析导弹在终端命中点角度约束条件,并利用零化视线角速率的设计思想,根据滑模变结构控制理论,提出了一种非线性滑模设计方法,得到了具有攻击角度约束的导弹的末制导律.同时利用Lyapunov稳定理论严格证明了制导系统的全局渐近稳定性.把末制导律应用于导弹系统并进行仿真,结果表明,在不需要任何目标运动信息的情况下,导弹都能获得期望的攻击角度约束和制导精度,证明导弹制导算法对地面目标有较强的鲁棒性.     

基于面向机动目标的协同攻击制导律

针对机动目标协同攻击问题，要求制导系统具备对目标的跟踪能力，基于固定时间收敛控制理论设计机动目标制导律，在此基础上，改进目标跟踪模型，将扩张状态观测器与扩张卡尔曼滤波结合，并且采用传感器一致性融合算法，实现了目标跟踪能够适应多变化有噪声的场景，估计精度和速度均显著提升。进一步介绍针对机动目标提出的制导律和固定时间收敛扩张状态观测器。最后利用仿真实验验证了所设计协同制导律的有效性。     

一种新型自适应RBF神经网络滑模制导律

针对导弹拦截问题,提出一种自适应RBF神经网络滑模制导律．首先根据准平行接近原理和变结构控制理论设计滑模面,然后将滑模面作为RBF神经网络的输入变量,输出量即为导弹的加速度．为了使得导弹系统能够到达滑模面,采用自适应算法实时在线调整RBF神经网络的连接权值．该导引律将目标机动视为干扰量,在拦截过程中不需要测量目标加速度,因此该导引律对目标机动具有较强的鲁棒性．在执行上,只用到了视线角速率,因而实现简单．仿真结果表明,所提出的导引律和比例导引相比在脱靶量、拦截时间等方面有了很大的提高．     

Distributed observer-based fixed-time cooperative guidance law against maneuvering target

This paper presents a fixed-time cooperative guidance law for leader-following missiles, comprising one leader missile with the target seeker and several seeker-less follower missiles. The aim is to achieve a simultaneous attack on a maneuvering target at desired impact angles. First, a guidance law with impact angle control for the leader missile against a maneuvering target is proposed based on nonsingular fast terminal sliding mode (NFTSM) control algorithm. Then, the design of cooperative guidance law for the follower missiles is composed of two parts: along the follower-to-leader line of sight (LOS) direction, the guidance command derived from bi-homogeneous property is designed to ensure that the follower-leader ranges keep proportional consensus with the range-to-go of the leader missile, thus avoiding the estimation of time-to-go ( $$); in the normal follower-to-leader LOS direction, considering the relative impact angle constraints which is determined by the leader LOS angle, the guidance command is proposed based on predefined-time sliding mode control method. What's more, a distributed fixed-time observer is designed for the follower missiles to compensate for unobtainable leader missile information. The fixed-time stability of the proposed methods is demonstrated using the Lyapunov theory and bi-homogeneous property. Finally, simulation results confirm the effectiveness and superiority of the proposed fixed-time cooperative guidance law with leader-following strategy.     

Adaptive nonsingular fast terminal sliding mode guidance law with impact angle constraints

This paper considers the terminal guidance problem of missiles intercepting maneuvering targets with impact angle constraints. Based on an advanced nonsingular fast terminal sliding mode control scheme and adaptive control, an adaptive nonsingular fast terminal sliding mode guidance law is proposed in the presence of the target acceleration as an unknown bounded external disturbance. In the design procedure, an adaptive law is presented to estimate the unknown upper bound of the external disturbance. Theoretical analysis shows that the proposed guidance law can guarantee the finite-time convergence in both the reaching phase and the sliding phase by applying a Lyapunov-based approach. Numerical simulations are presented to demonstrate the effectiveness of the proposed guidance law. Although the proposed guidance law is developed for the constant speed missiles, by the extensive numerical simulations with a realistic missile model, the performance is shown to be equally good for the varying speed missiles.     

Three‐Dimensional Impact Angle Constrained Guidance Laws with Fixed‐Time Convergence

In this paper, three dimensional coupled engagement dynamics are firstly transformed into a state‐space form without decoupling three dimensional engagement dynamics into two mutually orthogonal planes to avoid degrading the performance of the guidance law. Specially, fixed‐time guidance laws are proposed to guarantee that the line‐of‐sight (LOS) angular rates can be steered to zero before the final time of the guidance process at the same time. The exact convergence time can be set beforehand with respect to the LOS rates, and it is independent of initial conditions with respect to the guidance system. Moreover, impact angle constraint is taken into account, and these guidance laws are robust against maneuvering targets by sliding mode techniques. Simulation results validate the effectiveness of the proposed algorithms.     

Sliding Mode Guidance Law Considering Missile Dynamic Characteristics and Impact Angle Constraints

In order to improve the precision of guidance for the missile intercepting maneuvering targets, this paper proposes a sliding mode guidance law with impact angle constraints based on the equation of the relative motion of the missile and the target in a 2D plane. Two finite-time convergent guidance laws are proposed based on the nonsingular terminal sliding mode, while, two exponential convergent guidance laws involving dynamic delay are developed through applying the higher-order nonsingular terminal sliding mode. The simulations denote that, in all the four scenarios of the target’s maneuvering, the guidance laws are able to inhibit the chattering phenomenon of the sliding modes effectively; and from an expected aspect angle, the missiles could attack the targets with high precision and fast speed.     

Design of sliding mode guidance law with dynamic delay and impact angle constraint

A sliding mode guidance law with dynamic delay and impact angle constraints is designed for the relative motion between the missile and the target in the intercepting plane. First of all, the missile’s first order dynamic delay is involved into the system model to design the guidance law based on sliding mode variable dynamic method. Secondly, the target’s maneuvering is taken as the system disturbance, and a non-homogeneous disturbance observer is applied to estimate such maneuvering in finite time rapidly, which, through dynamic compensation, realizes the missiles precision attack to targets of different maneuvering at a desired line-of-sight (LOS) angle. Finally, numerical simulations are performed to demonstrate the effectiveness of the designed guidance law.

     

Adaptive terminal angle constraint interception against maneuvering targets with fast fixed‐time convergence

In this paper, a modified adaptive fast nonsingular terminal sliding mode guidance law is proposed based on the theory of fixed‐time convergence, which is applied for intercepting maneuvering targets considering terminal angle constraint. The proposed guidance law achieves system stabilization within bounded settling time independent on initial conditions and provides no singularity and globally rapid convergence property by accelerating the convergence rate when the system is close to the origin. The upper bound of settling time can be obtained in advance by the controller's parameters. Besides, in order to achieve chattering‐free property, a continuous adaptive switching control is introduced and the achieved acceleration‐magnitude constraints are rigorously enforced. Finally, the fixed‐time convergence of the sliding mode manifold and the system states is demonstrated by Lyapunov stability theory. Extensive numerical simulations are presented to validate the efficiency and superiority of the proposed guidance law.     

固定时间预测器下的欠驱动无人艇路径跟踪控制

无人艇是一类在水面自主移动的智能船艇, 具有无人自主, 航速高, 欠驱动的特点, 能应用到民用和军事的诸多领域. 针对欠驱动无人艇的路径跟踪问题, 本文在传统视线法制导律的基础上, 首次提出了一种新的固定时间收敛的预测器, 用于预测位置误差, 实现对干扰的估计和补偿. 与基于有限时间收敛的预测器的制导律相比, 固定时间预测器收敛时间不依赖于初始状态, 可以更快收敛. 此外, 为了保证跟踪控制器的有效收敛, 还设计了固定时间控制器, 将无人艇尾部的方向舵力矩作为控制器, 使无人艇航向角在固定时间收敛到期望艏向角. 最后通过仿真实验证明本文所提出的制导律和控制器能精确跟踪给定路径.     

Terminal angle constrained time-varying sliding mode guidance law with autopilot dynamics and input saturation

To intercept the maneuvering target at a desired terminal angle, this paper presents a time-varying sliding mode guidance law with consideration of the second-order autopilot dynamics and input saturation. To achieve the finite-time interception and satisfactory overload characteristics, a time-varying sliding mode guidance law is developed, which enables the line-of-sight (LOS) angle error to converge into a small neighborhood of the origin at the interception time. An auxiliary system is constructed to reduce the adverse effect generated from the input saturation. Moreover, with the aid of extended state observers, the proposed guidance law requires no information on the target acceleration and the acceleration derivative of the interceptor. The performance of this guidance law is verified via the numerical simulations.