考虑目标安全性的最优协同拦截制导律研究

针对目标和其发射的拦截弹对来袭攻击弹进行协同拦截问题,设计了一种最优协同拦截制导律。建立描述目标、攻击弹和拦截弹三者相对运动关系的模型,引入零控脱靶量对模型进行降阶处理。考虑拦截弹对攻击弹的拦截精度、拦截末端时目标的安全性以及目标、拦截弹的控制能量问题,基于攻击弹-拦截弹零控脱靶量、攻击弹-拦截弹终端横向相对运动速度零控脱靶量、目标-攻击弹零控脱靶量以及目标和拦截弹的加速度,建立了性能指标函数,同时考虑目标和拦截弹加速度的有限性,基于极小值原理设计了最优协同拦截制导律。仿真结果表明,相比目标和拦截弹独立飞行的情况,采用协同拦截制导律,在考虑了目标安全性的前提下,机动性较弱的拦截弹能够以较平直的弹道成功拦截攻击弹。     

Differential-game-based guidance law using target orientation observations

Modern 4th generation air-to-air missiles are quite capable of dealing with today's battlefield needs. Advanced aerodynamics, highly efficient warheads and smart target acquisition systems combine to yield higher missile lethality than ever. However, in order to intercept highly maneuverable targets, such as future unmanned combat air vehicles (UCAV), or to achieve higher tracking precision for missiles equipped with smaller warheads, further improvement in the missile guidance system is still needed. A new concept is presented here for deriving improved differential-game-based guidance laws that make use of information about the target orientation, which is acquired via an imaging seeker. The underlying idea is that of using measurements of the target attitude as a leading indicator of target acceleration. Knowledge of target attitude reduces the reachable set of target acceleration, facilitating the computation of an improved estimate of the zero-effort miss (ZEM) distance. In consequence, missile guidance accuracy is significantly improved. The new concept is applied in a horizontal interception scenario, where it is assumed that the target maneuver direction, constituting a partial attitude information, can be extracted via processing target images, acquired by an imaging sensor. The derivation results in a new guidance law that explicitly exploits the direction of the target acceleration. The performance of the new guidance law is studied via a computer simulation, which demonstrates its superiority over existing state-of-the-art differential-game-based guidance laws. It is demonstrated that a significant decrease in the miss distance can be expected via the use of partial target orientation information.     

基于虚拟目标的超视距舰空导弹导引律设计

针对超视距舰空导弹拦截低空飞行的目标时,会导致在制导初段就出现导弹"掉海"的现象,提出一种虚拟目标的设计方法,并利用伪控制量的概念,应用线性二次型最优控制理论,设计了一种最优导引律。仿真结果表明,虚拟目标设计方法具有良好效果,所研制的最优导引律是可行的。     

Three-dimensional guidance law based on adaptive integral sliding mode control

For the terminal guidance problem of missiles intercepting maneuvering targets in the three-dimensional space, the design of guidance laws for non-decoupling three-dimensional engage-ment geometry is studied. Firstly, by introducing a finite time integral sliding mode manifold, a novel guidance law based on the integral sliding mode control is presented with the target acceler-ation as a known bounded external disturbance. Then, an improved adaptive guidance law based on the integral sliding mode control without the information of the upper bound on the target accel-eration is developed, where the upper bound of the target acceleration is estimated online by a designed adaptive law. The both presented guidance laws can make sure that the elevation angular rate of the line-of-sight and the azimuth angular rate of the line-of-sight converge to zero in finite time. In the end, the results of the guidance performance for the proposed guidance laws are pre-sented by numerical simulations. Although the designed guidance laws are developed for the con-stant speed missiles, the simulation results for the time-varying speed missiles are also shown to further confirm the designed guidance laws.     

Evasion and pursuit guidance law against defended target

This paper investigates a new approach for a scenario in which an Attacker attempts to intercept a defended aerial Target. The problem is formulated as a game among three players, an Attacker, a Defender, and a Target, with bounded controls. In the considered pursuit–evasion problem, the Target uses an optimal evasion strategy and the Defender uses an optimal pursuit strategy.The proposed approach focuses on the miss distance as the outcome of the conflict. The infeasible region for the initial Zero-Effort-Miss(ZEM) distance between the Attacker and the Defender, for a scenario in which the Attacker evades the Defender, is analyzed, assuming that the Attacker uses a control effort chosen from the permitted control region. The sufficient conditions are investigated under which, for ideal players, the Attacker can pursue the Target while evading the Defender launched by the Target. The guidance provided on how the Attacker can accomplish the task is divided into two parts. During the final time between the Attacker and the Defender, the Attacker chooses the control effort that guarantees the miss distance, and then uses the optimal pursuit strategy to accomplish the task. The derived guidance law is verified by nonlinear simulation.     

Self-organizing fuzzy learning CLOS guidance law design

A new self-organizing fuzzy logic control (SOFLC) design method is proposed. The proposed method is applied to the command line-of-sight (CLOS) guidance law design. The SOFLC contains two sets of fuzzy inference logic. One is the fuzzy logic controller and the other is the rule modifier. The new learning method of the rule modifier is developed based on a fuzzy learning algorithm. The modification value of each rule is based on the fuzzy firing weight, so that learning of the rule bases is reasonable. Finally, two engagement scenarios are examined, and a comparison between a fuzzy logic control (FLC), an optimal learning FLC, and the proposed SOFLC CLOS guidance laws is made. Simulation results show that the proposed SOFLC guidance law can achieve better guidance performance than the other guidance laws.     

一种攻击地面固定目标的变系数比例导引律

为了提高命中精度 ,减小控制能量的消耗 ,对攻击地面固定目标且速度随时间变化的追踪器 ,推导出一种以控制能量消耗最小为性能指标的最优导引律 ,其中剩余时间的估算不仅考虑到追踪器速度大小的变化 ,而且考虑了方向的变化。同时 ,为了满足某些追踪器在碰撞点垂直入射的要求 ,给出在铅垂面内攻击时具有修正项的变系数比例导引律。仿真结果表明 ,该导引律与常系数比例导引律相比 ,控制能量少 ,脱靶量小 ,命中精度高。     

基于SDRE法的非线性鲁棒滑模末制导律设计

从智能控制理论出发,针对拦截机动目标的燃料最优问题,提出将状态相关黎卡提方程法(SDRE)和滑模控制相结合的末制导律设计方法,即利用前者将非线性模型转化为基于状态系数的线性结构后设计次优制导律,利用后者实现对机动目标引起的不确定干扰项的补偿。仿真结果表明,与自适应滑模末制导律相比,该方法具有制导精度更高、更加节省燃料的优势。     

基于Lyapunov稳定性的扩展比例制导律设计

基于一般弹目平面运动模型,以视线角、视线角速率为状态变量将弹目运动关系转换为二阶控制系统状态空间表达,把制导律设计转化为系统控制律的设计问题.在此控制模型的基础之上,利用Lyapunov稳定性定理,以视线角速率平方项作为能量函数设计了一种新型的扩展比例导引律,与其他扩展比例导引律相比,该导引律不需要增加任何制导观测信息,可以有效抑制噪声影响,并将基于Lyapunov稳定性的末制导律设计方法推广到有终端角约束的制导律设计中.仿真结果比较表明,该制导律可以提高制导精度、有效减小制导信息中的噪声影响.     

基于自适应反演滑模的末制导律设计

针对三维导弹-目标相对运动模型,结合反演控制、滑模控制和自适应技术,设计了一种新的自适应反演滑模末制导律。针对目标机动加速度上界难以获取的问题,将目标机动加速度视作模型的干扰,设计了一种自适应律对其进行在线估计,并将估计值补偿到制导律中。运用李亚普诺夫稳定性理论证明了系统的全局渐进稳定性和误差的收敛性。仿真结果证明了所设计的自适应反演滑模末制导律对机动目标的鲁棒性和有效性。     

Frequency domain approach to guidance system design

The frequency domain approach to guidance system design is presented. The model of the guidance control system reflects the most important characteristics of the flight control system that combines airframe and autopilot dynamics (damping, natural frequency, time constant, and airframe zero frequency). The analytical expressions for frequency response and related expressions for missile system performance are given. The analytical results obtained can be utilized for missile system design.     

基于终端角度约束的滑模制导律设计

针对打击地面目标的制导问题,提出了一种新的具有终端角度约束的鲁棒滑模制导律。在建立地面目标和导弹的相对运动学关系的基础上,基于零化弹目视线角速率的思想,采用变结构控制理论的方法,通过选择理想的终端角度确定一个光滑的非线性滑动模态,代替传统末制导律设计的滑动模态,利用Lyapunov稳定理论设计得到了具有鲁棒性的滑模末制导律,实现了在有限时间精确打击目标,满足终端角度的要求。数字仿真表明,这种制导律对目标的运动具有很好的鲁棒性和适应性,并能获得良好的制导精度和指定的终端角度要求。     

A localizer design to improve missed approach guidance

A novel VHF localizer system has been designed, built and successfully tested to provide increased reliability and safety of commercial and general aviation air transportation. Additional benefits are more precise tracks for aircraft executing a missed approach, reduced volume of the airspace needed for missed approaches, and reduced sizes of areas affected by noise. The design uses contemporary instrument landing system (ILS) hardware to provide dual independent front and back course directional localizer operation with two carriers in the receiver passband offset 4 kHz from the nominal carrier frequency. An example is given of an application and solution to an ILS problem at Reno, NV. Relevant data are presented     

大攻角导弹的导引运动建模与导引律设计

介绍了在大攻角情况下,建立的导弹目标的追逃运动模型;阐明了在目标运动详细信息未知的条件下,应用基于李雅普诺夫稳定性理论的鲁棒控制方法,提出的一种非线性鲁棒制导算法.仿真结果验证了导引运动模型的正确性和制导算法的有效性.     

机动再入体的带落角约束扩展比例导引律设计

传统的各种制导律都是以获得最小脱靶量为最终目标,没有考虑到导弹击中目标时刻的末端落角.为了保证非自旋再入体完成精确打击目标的任务,针对非自旋再入体垂直打击目标的制导问题,设计了一种带落角约束的扩展比例导引律.仿真研究表明,所设计的末制导律能够保证非自旋再入体命中目标时的脱靶量和末端落角都能满足要求,可以为开展近空间非自旋再入体制导问题的研究提供测试平台.     

Backstepping design of missile guidance and control based on adaptive fuzzy sliding mode control

This paper presents an integrated missile guidance and control law based on adaptive fuzzy sliding mode control. The integrated model is formulated as a block-strict-feedback nonlinear system, in which modeling errors, unmodeled nonlinearities, target maneuvers, etc. are viewed as unknown uncertainties. The adaptive nonlinear control law is designed based on backstepping and sliding mode control techniques. An adaptive fuzzy system is adopted to approximate the coupling nonlinear functions of the system, and for the uncertainties, we utilize an online-adaptive control law to estimate the unknown parameters. The stability analysis of the closed-loop system is also conducted. Simulation results show that, with the application of the adaptive fuzzy sliding mode control, small miss distances and smooth missile trajectories are achieved, and the system is robust against system uncertainties and external disturbances.     

Approach and landing guidance design for reusable launch vehicle using multiple sliding surfaces technique

An autonomous approach and landing (A&L) guidance law is presented in this paper for landing an unpowered reusable launch vehicle (RLV) at the designated runway touchdown.Considering the full nonlinear point-mass dynamics,a guidance scheme is developed in threedimensional space.In order to guarantee a successful A&L movement,the multiple sliding surfaces guidance (MSSG) technique is applied to derive the closed-loop guidance law,which stems from higher order sliding mode control theory and has advantage in the finite time reaching property.The global stability of the proposed guidance approach is proved by the Lyapunov-based method.The designed guidance law can generate new trajectories on-line without any specific requirement on off-line analysis except for the information on the boundary conditions of the A&L phase and instantaneous states of the RLV.Therefore,the designed guidance law is flexible enough to target different touchdown points on the runway and is capable of dealing with large initial condition errors resulted from the previous flight phase.Finally,simulation results show the effectiveness of the proposed guidance law in different scenarios.     

An approach for formation design and flight performance prediction based on aerodynamic formation unit: Energy-saving considerations

The performance improvement of swarm drones through aerodynamic shape optimization may be challenging due to folded size constraints imposed by the specific launch approach.However, fixed-wing aircraft swarms can benefit from formation flight in terms of energy consumption. This study introduces the concept of the ‘‘aerodynamic formation unit”, which consists of two or three aircraft that form an inseparable unit of the formation. Considering the Unmanned Aerial Vehicle(UAV) distribution and wingtip vortex interference in the formation, two typical aerodynamic formation units are optimized by the variable-fidelity aerodynamic optimization method based on space mapping. The aerodynamic characteristics of the formation UAVs that affect flight performance, such as lift-to-drag ratio(L/D ratio) and static stability are analyzed by Computational Fluid Dynamics(CFD) simulations. The L/D ratio(cruising condition) of the following aircraft can be increased by 22.8% and 57.5% in the optimal units that involve two and three aircraft respectively. Moreover, this study conducts several CFD simulations for multi-aircraft formations formed by the units, which show that the average L/D ratio of the formation can be improved by more than 19%. These results verify the feasibility and effectiveness of the ‘‘aerodynamic formation unit” concept and the optimization framework for formation parameters.     

Cooperative guidance law with maneuverability awareness: A decentralized solution

In this paper, we propose a cooperative guidance law aimed to achieve coordinated impact angles with limited observation on target information. The primary challenge lies in establishing an appropriate communication graph among all missiles and devising an algorithm to estimate target acceleration information during engagements. To address this, we propose a specific communication topology and employ a numerical integration-based estimation method. Additionally, a distributed algorithm is introduced to facilitate consensus on target acceleration estimation.Building upon these foundations, we design an optimal-control-based distributed guidance law for each missile. Performance of the proposed guidance law is validated through numerical simulations.     

Identification of aircraft longitudinal aerodynamic parameters using an online corrective test for wind tunnel virtual flight

The identification of aerodynamic parameters is accomplished through the test data of the dynamic movement of scaled aircraft models flying dynamically in wind tunnel,which can real-ize the accurate acquisition of the aerodynamic model of the aircraft in the preliminary stage for aircraft design,and it is of great significance for improving the efficiency of aircraft design.How-ever,the translational motion of the test model in the wind tunnel virtual flight is subject to con-straints that result in distinct flight dynamics compared to free flight.These constraints have implications for the accuracy of aerodynamic derivatives obtained through the identification of wind tunnel test data.With this issue in mind,the research studies the differences in longitudinal dynamic characteristics between unconstrained free flight and wind tunnel virtual flight,and inno-vatively proposes an online correction test based wind tunnel virtual flight test technique.The lon-gitudinal trajectory and velocity changes of the model are solved online by the aerodynamic forces measured during the test,and then the coupled relationship between aircraft translation and rota-tion is used to correct the model's pitch attitude motion online.For the first time,the problem of solving the data approximation for free flight has been solved,eliminating the difference between the dynamics of wind tunnel virtual flight and free flight,and improving the accuracy of the aero-dynamic derivative identification results.The experiment's findings show that accurate aerodynamic derivatives can be identified based on the online correction test data,and the observed behaviour of the identified motion model has similarities to that of the free flight motion model.