Three-dimensional time-varying sliding mode guidance law against maneuvering targets with terminal angle constraint

This paper deals with the problem of intercepting maneuvering targets with terminal angle constraints for missiles subjected to three-dimensional non-decoupling engagement geometry.To achieve the finite-time interception and satisfactory overload characteristics, a time varying sliding mode control methodology is developed based on a time base generator function. The main feature of the proposed guidance law guarantees the Line-of-Sight(LOS) angles to converge to small neighborhoods of the desir...     

Adaptive block dynamic surface control for integrated missile guidance and autopilot

A novel integrated guidance and autopilot design method is proposed for homing missiles based on the adaptive block dynamic surface control approach. The fully integrated guidance and autopilot model is established by combining the nonlinear missile dynamics with the nonlinear dynamics describing the pursuit situation of a missile and a target in the three-dimensional space. The integrated guidance and autopilot design problem is further converted to a state regulation problem of a time-varying nonlinear system with matched and unmatched uncertainties. A new and simple adaptive block dynamic surface control algorithm is proposed to address such a state regulation problem. The stability of the closed-loop system is proven based on the Lyapunov theory. The six degrees of freedom (6DOF) nonlinear numerical simulation results show that the proposed integrated guidance and autopilot algorithm can ensure the accuracy of target interception and the robust stability of the closed-loop system with respect to the uncertainties in the missile dynamics.     

环境激励下基于chirplet变换的线性时变系统参数识别

提出了针对时变系统响应的短时频率线性时变假设,通过将时变响应拟合成多分量线调频信号,根据线调频信号互相关理论推导了随机白噪声激励下时变系统的物理参数识别方法。该识别方法只需基于结构的加速度响应,便能识别结构的时变质量和刚度。由于引入了调频斜率刻画响应信号的短时频率线变特征,该方法相比传统识别方法能更好地追踪快变甚至突变参数,对实际工程中的时变问题具有重要的应用价值。仿真算例中构造了1个3自由度时变结构模型,针对线性时变、周期时变和突变等情况进行了物理参数的识别,误差分析显示识别误差均在5%以内,仿真结果验证了方法的正确性和适用性。     

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.     

基于预测模型迭代优化的改进比例导引律

为了提高对加速度时变机动目标的制导精度,将预测决策理论与传统比例导引(PN)相结合,提出了一种通过泰勒级数预测模型迭代控制加速度修正项的改进比例导引律。首先,以预设的低阶泰勒级数预测模型预测特定时间的位移,并计算位移预测值与测量值的差值;然后,通过迭代方法逐阶增加泰勒级数预测模型阶数,直至满足精度要求;最后,计算泰勒级数预测模型的二阶导数,修正比例导引律的加速度指令。仿真结果表明,传统PN和APN的脱靶量分别约为195 m和95 m,提出的改进比例导引律的脱靶量约为8.3 m,极大地提高了制导精度。     

Biased PNG law for impact with angular constraint

A new homing guidance law is proposed to impact a target with a desired attitude angle. It is a variation of the conventional proportional navigation guidance (PNG) law which includes a supplementary time-varying bias. The proposed guidance law does not require a time-to-go estimation and has a simpler form. Analytic conditions for fulfilling the guidance goal are also provided. Simulation results demonstrate that the proposed guidance law has wider launch envelopes than the previous one and shows a good performance even against a maneuvering target     

射手模型优化与辨识及其对图像制导的影响

基于数据链通信的人在回路制导模式额外引入了射手动力学而且存在图像信号延时,含有射手动力学的控制回路会对目标在视场（LOS）中的误差角进行跟踪补偿,从而提升图像制导弹药的制导控制性能。为探究射手动力学和图像信号延时对人在回路制导性能的影响,基于真实的图像导引头模型及参数,设计校正网络以满足导引头稳定回路的性能需求;引入两类射手模型,针对射手模型2,优化模型结构并通过贴近真实环境的辨识实验得到动力学参数,弥补了现有建模的不足。基于射手对不同图像信号延时的适应性,对比研究了两类射手模型与不同图像信号延时对导引头控制系统稳定性、快速性和人在回路比例导引制导精度的影响。仿真结果表明：图像信号延时越长,导引头跟踪速度越低、误差角越大,制导系统的收敛时间越长;优化后的射手模型2及其参数辨识更准确地描述了射手的操作行为,对制导系统的影响较低且满足系统性能要求。     

圆形轨迹导引下的无人机事件触发抗干扰环绕控制

针对内部不确定性以及外部环境摄动的目标环绕控制问题,在基于反步法的双层制导框架下,利用级联控制思想,提出了一种圆形轨迹导引下的四旋翼无人机事件触发抗扰环绕控制方法。在轨迹回路中,构建了可满足持续激励条件的目标位置估计器,保证仅通过视线方位角就能获取可满足最终一致有界条件的目标估计项。随后,基于目标的位置估计结果,设计了目标环绕控制律生成线速度指令,并通过方向向量场验证了该环绕制导律的有效性,消除了现有李雅普诺夫向量场制导(LVFG)对相对位置和目标速度的依赖。在姿态回路中,通过采用扩张状态观测器(ESO)补偿系统的集总不确定性,设计了基于相对阈值事件触发控制的姿态控制器,在有效降低控制器到执行机构之间信号传输频率的同时,实现了四旋翼无人机对静止/移动目标环绕。然后,借助输入状态稳定性定理证明了系统的稳定性。仿真结果表明,所提控制方案能够实现圆形轨迹导引下四旋翼无人机对静止/移动目标的环绕监视。     

Empirical virtual sliding target guidance law design: an aerodynamic approach

We present a novel empirical virtual sliding target (VST) guidance law for the midcourse phase of a long range surface-to-air missile that uses the simplicity of the conventional proportional navigation (PN) guidance law while exploiting the aerodynamic characteristics of a missile's flight through the atmosphere to enable the missile to achieve superior performance than that achieved by conventional PN guidance laws. The missile trajectory emulates the trajectory of an optimal control based guidance law formulated on a realistic aerodynamic model of the missile-target engagement. The trajectory of the missile is controlled by controlling the speed of a virtual target that slides towards a predicted intercept point during the midcourse phase. Several sliding schemes, both linear and nonlinear, are proposed and the effect of the variation of the sliding parameters, which control the sliding speed of the virtual target, on the missile performance, are examined through extensive simulations that take into account the atmospheric characteristics as well as limitations on the missile in terms of the energy available and lateral acceleration limits. Launch envelopes for these sliding schemes for approaching and receding targets are also obtained. These results amply demonstrate the superiority of the proposed guidance law over the conventional PN law.     

带有攻击角度和攻击时间控制的三维制导

 在三维空间导引动力学与运动学模型的基础上,假设目标静止,而导弹本身以恒速运动,根据实际的攻击角度与设定的攻击角度误差,分析和设计了期望的视线（LOS）角运动学,基于李雅普诺夫稳定性理论设计了带有攻击角度控制的三维导弹导引律。为了对攻击时间进行预测与控制,假设导弹本身以恒速或者匀加/减速运动,先将导弹导引到预定的攻击角度上,根据待飞直线距离对待飞时间进行估算,再根据预测时间误差,确定导弹按照特定的圆弧轨迹机动飞行的指令和机动飞行的时间,通过机动飞行来对时间误差进行补偿,最后,再利用所设计的导引律攻击目标。给出了仿真结果。     

基于微分对策的导弹攻击策略

利用建立的垂直平面内交战双方攻击模型,应用微分对策理论,得到导弹的最优攻击策略,对比微分对策导引律与比例导引律在多种仿真环境下的结果,说明在近距离交战中,基于微分对策理论的导引律设计具有更大的优越性。     

神经网络最优闭环制导律设计

对于复杂的非线性导弹制导系统 ,很难求得其解析的最优制导律 ,只能求得开环的数字解 ,不能适用于具有时变不确定性的导弹制导系统。利用神经网络的学习和推广能力 ,对开环的数字最优制导律进行离线的学习 ,作为闭环的神经最优制导律在线应用。研究分别选择系统状态变量和视线角速率等不同的神经网络输入对制导系统性能的影响 ,以及各种制导律的鲁棒性问题 ,并采用模块化神经网络结构提高神经网络的学习和推广能力 ,仿真结果得到一些有益的结论。     

一种无人机定距盘旋跟踪制导律及稳定性证明

对地面目标的定距盘旋跟踪问题是无人机（UAVs）在任务应用阶段需要面临的重要问题之一,如何在传感器信息受限的情况下完成跟踪任务是目前的研究热点。首先针对地面固定目标设计了一种仅依赖测距传感器的制导律,不再需要传统的视线角信号以及目标和无人机自身的定位信息;其次,设计了李雅普诺夫函数对该制导律的稳定性进行了严格数学证明;最后,将该制导律推广到对地面匀速和变速移动目标的跟踪制导。相比于现有制导律,所提出的制导律结构更为简洁,仅有一个设计参数,并且制导策略更为合理。仿真结果表明所提出的制导律能够实现无人机对地面固定和移动目标的稳定跟踪。     

Multiple-constraint cooperative guidance based on two-stage sequential convex programming

An improved approach is presented in this paper to implement highly constrained cooperative guidance to attack a stationary target. The problem with time-varying Proportional Navigation (PN) gain is first formulated as a nonlinear optimal control problem, which is difficult to solve due to the existence of nonlinear kinematics and nonconvex constraints. After convexification treatments and discretization, the solution to the original problem can be approximately obtained by solving a sequence of Second-Order Cone Programming (SOCP) problems, which can be readily solved by state-of-the-art Interior-Point Methods (IPMs). To mitigate the sensibility of the algorithm on the user-provided initial profile, a Two-Stage Sequential Convex Programming (TSSCP) method is presented in detail. Furthermore, numerical simulations under different mission scenarios are conducted to show the superiority of the proposed method in solving the cooperative guidance problem. The research indicated that the TSSCP method is more tractable and reliable than the traditional methods and has great potential for real-time processing and on-board implementation.     

Roll-pitch-yaw autopilot design for nonlinear time-varying missile using partial state observer based global fast terminal sliding mode control

The acceleration autopilot design for skid-to-turn (STT) missile faces a great challenge owing to coupling effect among planes, variation of missile velocity and its parameters, inexistence of a complete state vector, and nonlinear aerodynamics. Moreover, the autopilot should be designed for the entire flight envelope where fast variations exist. In this paper, a design of inte-grated roll-pitch-yaw autopilot based on global fast terminal sliding mode control (GFTSMC) with a partial state nonlinear observer (PSNLO) for STT nonlinear time-varying missile model, is employed to address these issues. GFTSMC with a novel sliding surface is proposed to nullify the integral error and the singularity problem without application of the sign function. The pro-posed autopilot consisting of two-loop structure, controls STT maneuver and stabilizes the rolling with a PSNLO in order to estimate the immeasurable states as an output while its inputs are missile measurable states and control signals. The missile model considers the velocity variation, gravity effect and parameters’ variation. Furthermore, the environmental conditions’ dynamics are mod-eled. PSNLO stability and the closed loop system stability are studied. Finally, numerical simula-tion is established to evaluate the proposed autopilot performance and to compare it with existing approaches in the literature.     

考虑驾驶仪动态性能的指令滤波反演制导律

针对攻击机动目标的制导问题,设计了一种考虑自动驾驶仪性能、输入项约束的指令滤波反演制导律。首先,基于三维空间内弹目相对运动模型,采用反演递推方式设计制导律。针对传统反演控制存在的"微分膨胀"问题,引入指令滤波器对虚拟量进行过滤计算。考虑硬件计算能力的约束,引入自动驾驶仪二阶动力学模型减少控制过程延迟,并利用饱和函数和低通滤波器对输入项进行约束。此外,针对机动目标设计了一种扩张状态观测器来获取其加速度。通过Lyapunov理论证明了所设计闭环制导系统的稳定性。通过仿真实验验证了该制导律相有效性及优越性。     

Adaptive nonlinear guidance law considering control loop dynamics

A new adaptive nonlinear guidance law is proposed here. The fourth order state equation for integrated guidance and control loop is formulated taking into consideration the target uncertainties and control loop dynamics. The state equation is further changed into the normal form by nonlinear coordinate transformation. Using the normal form of state equation, an adaptive nonlinear guidance law is proposed to compensate for the uncertainties in both target acceleration and control loop dynamics. The proposed law adopts the sliding mode control approach with adaptation for unknown bound of uncertainties. The present approach can effectively solve the existing guidance problem against target maneuver and the limited performance of control loop. We have provided the stability analyses and performed simulations comparing favorably our approach to the state of the art.     

中远程空地导弹末制导自适应控制

讨论了中远程空导弹的自适应控制规律,基于古典控制器模型,设计了自适应自动驾驶仪：通过适当选择自适应参数,保证了系统良好的动态品质和干扰抑制特性;提出了一种基于李亚诺夫稳定性理论的飞行控制系统方案,推导了自适应控制规律,并对导弹多种飞行高度和初如条件进行了仿真计算,仿真结果表明,所设计的自适应控制系统性能明显优于古典控制回路,具有较好的应用价值。     

Numerical simulation of a cabin ventilation subsystem in a space station oriented real-time system

An environment control and life support system(ECLSS) is an important system in a space station. The ECLSS is a typical complex system, and the real-time simulation technology can help to accelerate its research process by using distributed hardware in a loop simulation system. An implicit fixed time step numerical integration method is recommended for a real-time simulation system with time-varying parameters. However, its computational efficiency is too low to satisfy the real-time data interaction, especially for the complex ECLSS system running on a PC cluster. The instability problem of an explicit method strongly limits its application in the ECLSS real-time simulation although it has a high computational efficiency. This paper proposes an improved numerical simulation method to overcome the instability problem based on the explicit Euler method. A temperature and humidity control subsystem(THCS) is firstly established, and its numerical stability is analyzed by using the eigenvalue estimation theory. Furthermore, an adaptive operator is proposed to avoid the potential instability problem. The stability and accuracy of the proposed method are investigated carefully. Simulation results show that this proposed method can provide a good way for some complex time-variant systems to run their real-time simulation on a PC cluster.     

Finite time L1 Approach for Missile Overload Requirement Analysis in Terminal Guidance

This article analyzes the problem about the missile overload requirement in a homing terminal guidance under various engagement scenarios. An augmented proportional navigation guidance (APNG) model is introduced on the basis of linear kinematics. To analyze the peak-to-peak performance of the terminal guidance system, a new finite time L₁ performance measure for a linear time-varying (LTV) continuous system is proposed. Then, according to the idea of the adjoint system, a novel method for computing the L₁ norm of a linear continuous system is first derived. Within the finite time L₁ framework, the quantitative relation between the guidance loop dynamics and the maximum missile-target maneuver ratio is offered. This relation is expressed in the form of graphs and formulas that can be used to synthesize some of the major subsystem specifications for the missile guidance system. The illustrative examples show that a significant performance improvement is achieved with the proposed guidance loop dynamics.