Hybrid hierarchical trajectory planning for a fixed-wing UCAV performing air-to-surface multi-target attack

This paper considers the problem of generating a flight trajectory for a single fixed-wing unmanned combat aerial vehicle （UCAV） performing an air-to-surface multi-target attack （A/SMTA） mission using satellite-guided bombs. First, this problem is formulated as a variant of the traveling salesman problem （TSP）, called the dynamic-constrained TSP with neighborhoods （DCT- SPN）. Then, a hierarchical hybrid approach, which partitions the planning algorithm into a roadmap planning layer and an optimal control layer, is proposed to solve the DCTSPN. In the roadmap planning layer, a novel algorithm based on an updatable proba- bilistic roadmap （PRM） is presented, which operates by randomly sampling a finite set of vehicle states from continuous state space in order to reduce the complicated trajectory planning problem to planning on a finite directed graph. In the optimal control layer, a collision-free state-to-state trajectory planner based on the Gauss pseudospectral method is developed, which can generate both dynamically feasible and optimal flight trajectories. The entire process of solving a DCTSPN consists of two phases. First, in the offline preprocessing phase, the algorithm constructs a PRM, and then converts the original problem into a standard asymmet- ric TSP （ATSP）. Second, in the online querying phase, the costs of directed edges in PRM are updated first, and a fast heuristic searching algorithm is then used to solve the ATSP. Numerical experiments indicate that the algorithm proposed in this paper can generate both feasible and near-optimal solutions quickly for online purposes.

Short Range Top Attack Trajectory Optimum Design Based on Genetic Algorithm

A flying-body is considered as the reference model, the optimized mathematical model is established. The genetic operators are designed and algorithm parameters are selected reasonably. The scheme control signal in short range top attack flight trajectory is optimized by using genetic algorithm. The short range top attack trajectory designed meets the design requirements, with the increase of the falling angle and the decrease of the minimum range. The application of genetic algorithm to top attack trajectory optimization is proved to be feasibly and effectively according to the analyses of results.

Integrated guidance and control design of the suicide UCAV for terminal attack

A novel integrated guidance and control (IGC) design method is proposed to solve problems of low control accuracy for a suicide unmanned combat aerial vehicle (UCAV) in the terminal attack stage. First of all, the IGC system model of the UCAV is built based on the three-channel independent design idea, which reduces the difficulties of designing the controller. Then, IGC control laws are designed using the trajectory linearization control (TLC). A nonlinear disturbance observer (NDO) is introduced to the IGC controller to reject various uncertainties, such as the aerodynamic parameter perturbation and the measurement error interference. The stability of the closed-loop system is proven by using the Lyapunov theorem. The performance of the proposed IGC design method is verified in a terminal attack mission of the suicide UCAV. Finally, simulation results demonstrate the superiority and effectiveness in the aspects of guidance accuracy and system robustness.

UAVs cooperative task assignment and trajectory optimization with safety and time constraints

This paper proposes new methods and strategies for Multi-UAVs cooperative attacks with safety and time constraints in a complex environment.Delaunay triangle is designed to construct a map of the complex flight environment for aerial vehicles.Delaunay-Map,Safe Flight Corridor(SFC),and Relative Safe Flight Corridor(RSFC)are applied to ensure each UAV flight trajectory's safety.By using such techniques,it is possible to avoid the collision with obstacles and collision between UAVs.Bezier-curve is further developed to ensure that multi-UAVs can simultaneously reach the target at the specified time,and the trajectory is within the flight corridor.The trajectory tracking controller is also designed based on model predictive control to track the planned trajectory accurately.The simulation and experiment results are presented to verifying developed strategies of Multi-UAV cooperative attacks.

Performance Assessment of a Calm Flapping Wind Turbine with Small Attack Angle

The objective of this research is mainly focused on environment-friendly and moderately slow flapping wind turbine which can easily operate in or near urban areas or rooftops owing to scale merit with low-frequency turbine noise, installation cost, avian mortality rate and safety consideration etc. The authors are focusing on lift based (LB) slow flapping wind turbine operated within a small attack angle amplitude whereas the previous research treated a lift and drag based (LDB) flapping turbine. Here, a unique trajectory for the wing motion was yet designed by using the Chebyshev dyad linkage mechanism as well as the previous report. The wind energy transferred to the mechanical rotation, adopting a single symmetric wing NACA0012. To obtain a smooth flapping motion for the blade, we optimize all fundamental parameters with our simulation model for optimum performance of the turbine. Both static and dynamic analysis has been conducted to confirm the feasibility of the present design. In addition, wind turbine performance was studied for a suitable range of free stream wind velocities. This report confirms that the developed flapping wind turbine can drive at slow speed with suitable energy extraction rate at different wind velocities. Moreover, we made a simple comparative study of the outcomes obtained from our previous lift and drag based flapping wind turbine with present one, i.e., lift based flapping turbine.

Clustered trajectories anonymity in wireless sensor networks

This paper proposes a clustered trajectories anonymity scheme （CTA） that enhances the kano nymity scheme to provide the intended level of source location privacy in mobile event monitoring when a global attacker is assumed. CTA applies isomorphic property of rotation to create traces of the fake sources distributions which are similar to those of the real sources. Thus anonymity of each trajectory and that of the clustered is achieved. In addition, location kdiversity is achieved by dis tributing fake sources around the base station. To reduce the time delay, tree rooted at the base sta tion is constructed to overlap part of the beacon interval of the nodes in the hierarchy. Both the ana lytical analysis and the simulation results prove that proved energy overhead and time delay. our scheme provides perfect anonymity with improved energy overhead and time delay.

基于车辆轨迹预测对抗性攻击与鲁棒性研究

针对常规车辆轨迹预测数据集中较少包含极端交通场景信息的问题,本文提出一种新型对抗性攻击框架来模拟此类场景。首先,为了判定不同场景中对抗性攻击是否有效提出了一种阈值判定的方式;然后,针对攻击目的的不同分别设计了两种对抗性轨迹生成算法,在遵守物理约束和隐蔽性前提下,生成更具对抗性的轨迹样本;此外,提出3个新的评价指标全面评估攻击效果;最后,探究了不同的防御策略来减轻对抗攻击影响。实验结果显示,基于扰动阈值的快速攻击算法(attack algorithm based on perturbation threshold for fast attack,PTFA)和基于动态学习率调整的攻击算法(attack algorithm based on dynamic learning rate adjustment,DLRA)在NGSIM数据集上的攻击时间和扰动效果均优于现有算法,更高效发现模型弱点。本研究通过模拟极端情况丰富了轨迹样本,深入评估了模型鲁棒性,为后续优化奠定了基础。

效用增强的差分私有轨迹合成方法

轨迹数据对各种应用都具有重要的价值,然而共享与利用轨迹数据的同时保护用户隐私是一个长期的挑战。目前流行的轨迹共享隐私保护方法是基于差分隐私技术来生成与真实轨迹高度相似的完整合成轨迹,然而这些方法会造成合成轨迹可用性低且易遭受位置隐私推理攻击的问题。为此,提出一种效用增强的差分私有轨迹合成方法 (UtiE-DPT)。该方法通过多次空间划分真实轨迹数据集,构建了细粒度的自适应密度网格来离散化真实轨迹,并设计了适合于自适应密度网格的差分私有马尔可夫移动模型、轨迹行程分布和轨迹长度分布计算模型来更精确地提取真实轨迹的效用保持关键统计特征,有效增强了合成轨迹的效用。为了防止轨迹隐私泄露,对提取的关键统计特征进行差分私有扰动。根据提取的特征并结合抗攻击约束策略生成抵御推理攻击的合成轨迹。在模拟与真实数据集上的大量实验结果表明,与现有的轨迹合成隐私保护方法 DP-Star和AdaTrace相比,UtiE-DPT在保护轨迹隐私和抵御位置隐私推理攻击的同时增强了合成轨迹的可用性。在不考虑抵御推理攻击时,UtiE-DPT生成合成轨迹的查询误差比AdaTrace降低了21%~27%,比DP-Star降低了32%~53%;在抵御推理攻击后,虽然合成轨迹的弹性比比AdaTrace降低了约1%~2%,但查询误差比AdaTrace降低了16%~21%,在隐私保护与效用之间达成更好的均衡。

滑翔制导炮弹多炮齐射协同弹道规划与协作范围确定方法

针对滑翔制导炮弹多炮齐射打击固定目标的协同攻击场景,为充分发挥整体控制能力,增强打击效果,研究着眼于弹群的协同方案弹道规划问题。首先,考虑到攻击不同距离目标时飞行方案的侧重点与弹道特性差异,为滑翔制导炮弹进行战区划分,并在此基础上建立寻优指标因战区而异的全弹道协同规划模型。其次,针对实战中的战斗队形配置问题,提出一种简单通用的协作范围确定方法。随后,针对现有协同方式在处理多阶段规划问题时存在的适用性或最优性方面的局限,提出一种双层自适应协同策略。最后,分析特殊作战任务引入的额外约束条件对战区划分与协作范围的影响。仿真结果表明,所提方法可以简捷有效地确定可行工况,辅助战斗队形的配置;同时,相比于传统的分布式策略,在所提的协同策略作用下,不同战区内的方案弹道均具有优越性。

复杂场景下推力可调空空导弹弹道优化研究

本文研究了推力可调空空导弹在复杂场景下的攻击能力和潜在优势。论文设想了一种具有推力可灵活调节特征的空空导弹概念,针对此类概念建立了三维轨迹动力学模型,引入轨迹优化方法研究空空导弹的攻击能力。针对目标丢失再捕获和发射后变更目标两种作战场景开展了飞行性能仿真研究,并且与传统固体火箭动力的空空导弹进行了对比。仿真结果表明:在目标丢失再捕获的场景下,当初始弹目距离为70~100 km时,推力可调空空导弹允许的目标最大丢失时长比传统动力空空导弹增加大约20~40 s,允许的目标最晚丢失时间比传统动力空空导弹晚约20 s;在发射后变更目标的场景下,当初始弹目距离为70~100 km、新旧目标横向距离为30 km时,推力可调空空导弹允许的最晚目标变更时间容忍裕度比传统动力空空导弹推迟大约10~70 s。

基于强化LSTM的网络高隐蔽性入侵轨迹预测研究

网络高隐蔽性入侵信息的维度难以确定,导致入侵轨迹预测困难增加,因此研究基于强化LSTM的网络高隐蔽性入侵轨迹预测方法。设置强化LSTM预测模型基础架构,根据历史数据特征取值结果,求解标记参数,利用这些参数标记入侵数据轨迹节点。确定高隐蔽性入侵行为的表现强度从而确定入侵向量。结合入侵信息维度实现网络高隐蔽性入侵轨迹预测。实验结果表明,在强化LSTM模型的作用下,高隐蔽性入侵信息维度的预测结果完全属于该信息所处轨迹维度参数实际取值范围之内,说明该方法的预测结果更为精准。

基于聚类杂交的隐私保护轨迹数据发布算法

传统关于轨迹数据发布的隐私保护研究大多采用聚类技术,其相关算法只关注每条轨迹的隐私保护,忽视对轨迹聚类组特征的保护.通过理论分析和实验验证发现,对采用聚类发布技术产生的轨迹数据进行二次聚类,可得到原始轨迹数据在发布之前的聚类组特征,从而可能导致隐私泄露.为了有效预防二次聚类攻击,提出一种(k,δ,Δ)-匿名模型和基于该模型的聚类杂交隐私保护轨迹数据发布算法CH-TDP,算法CH-TDP对采用(k,δ)-匿名模型及相关算法处理得到的聚类分组先进行组间杂交,而后再进行组内扰乱,其目标在防止出现二次聚类攻击的前提下,保证发布轨迹数据的质量不低于阈值Δ.实验对算法CH-TDP的可行性及有效性与同类算法进行比较分析,结果表明算法CH-TDP是有效可行的.

滑翔增程弹滑翔弹道设计

在滑翔段上采用法向加速度等于零和升阻比最大两种方式进行滑翔弹道设计,导出俯仰舵偏角和平衡攻角的表达式,得到滑翔射程的一般关系式,分析了决定制导炮弹射程的主要因素。仿真结果表明,采用这两种方式设计的滑翔弹道各有特点,在工程实现中可以根据不同的使用要求和实际情况进行选择。

无人作战飞机轨迹规划研究综述

无人作战飞机(UCAV)轨迹规划是实现其自主攻击技术的重点和难点,通过对该领域文献的广泛研究和细致梳理,建立了UCAV轨迹规划问题的一般模型,系统归纳了目前用于该问题求解的基本算法、求解思路、存在不足和最新发展动向,并重点对UCAV隐身突防轨迹优化和不确定环境下的在线轨迹规划方法进行综述。

一维弹道修正弹对海上目标射击误差及射程扩展量研究

为提高落点密集度,一维弹道修正弹采用增阻方式对射程进行修正,在射击距离上增加扩展量计算发射诸元,射程扩展量若取大或取小都不利于落点密集度。为确定一维弹道修正弹对海上目标射击的最佳射程扩展量,在研究射击原理和射击误差的基础上,建立了射程扩展量的计算模型。仿真计算表明:依照此模型计算射程扩展量,修正后具有最多的命中弹数。

基于Web行为轨迹的应用层DDoS攻击防御模型

为了有效防御应用层分布式拒绝服务攻击(DDoS),定义了一种搭建在Web应用服务器上的基于Web行为轨迹的防御模型。把用户的访问行为抽象为Web行为轨迹,根据攻击请求的生成方式与用户访问Web页面的行为特征,定义了四种异常因素,分别为访问依赖异常、行为速率异常、轨迹重复异常、轨迹偏离异常。采用行为轨迹化简算法简化行为轨迹的计算,然后计算用户正常访问网站时和攻击访问时产生的异常因素的偏离值,来检测针对Web网站的分布式拒绝服务攻击,在检测出某用户产生攻击请求时,防御模型禁止该用户访问来防御DDoS。实验采用真实数据当作训练集,在模拟不同种类攻击请求下,防御模型短时间识别出攻击并且采取防御机制抵制。实验结果表明,Web行为轨迹的防御模型能够有效防御针对Web网站的分布式拒绝服务攻击。

基于伪谱法的定向定时航迹规划方法

为提高导弹的突防概率和协同攻击目标,需要对攻击角度和攻击时间同时进行协调,针对此,研究了Gauss伪谱法,并将其引入到导弹的航迹规划中。基于导弹的质点模型,通过Gauss伪谱法将存在边值、过载和禁飞区等约束条件的导弹最优航迹设计问题转化成一个非线性规划问题,并进行求解;对传统过载性能目标函数进行了改进,使导弹后期飞行轨迹平滑,过载需求降低,对多导弹协同攻击静止目标进行了仿真验证。仿真结果表明,利用Gauss伪谱法可在10s内获得一条满足要求的平滑飞行航迹,过载满足要求并降低了末段控制压力,提高了导弹的突防能力。

弹头形状对侵彻多层靶弹道的影响

为了提高侵彻弹斜侵彻多层混凝土靶过程弹道稳定性,提出了头部刻槽形弹体结构和尖卵形弹体结构设计。基于LS‑DYNA软件开展数值模拟计算,并进行了两种弹体侵彻10层混凝土靶试验。研究表明:在侵彻单层混凝土薄靶的过程中,随初始攻角增大弹体姿态偏转角度增大,刻槽形弹体相对尖卵形弹体姿态偏转相对较小。对比侵彻10层混凝土靶试验结果,刻槽形弹体相对尖卵形弹体可显著减少弹体偏转姿态,具有较好的侵彻弹道稳定性。

无人作战飞机侦察/打击一体化自主控制关键技术探讨

为了适应未来战争的发展趋势,迫切需要实现无人作战飞机的自主控制,提高其自主水平和智能程度。首先给出了自主控制的概念,自主控制发展阶段以及自主水平的层次划分;然后分析了无人作战飞机侦察/打击一体化的作战过程、特点及系统的典型构造方案,并介绍了侦察/打击一体化无人作战飞机型号背景以及发展趋势;结合无人作战飞机自主控制系统的工作流程,建立了基于侦察/打击一体化的自主控制系统结构;最后探讨了无人作战飞机侦察/打击一体化自主控制中的关键技术,并提出了相应的解决方案。

基于Voronoi图和离散微粒群优化算法的UCAV攻击轨迹决策

根据UCAV可发射区简化模型,提出了UCAV攻击轨迹决策问题。提出了UCAV攻击轨迹决策的分层设计方法,并将其转化为优化问题。首先根据已知的飞行环境,采用Voronoi图生成初始轨迹;然后通过建立攻击轨迹约束条件模型、飞行距离模型和威胁模型,以飞行距离和威胁代价为优化目标函数,构建了UCAV攻击轨迹决策模型,并在此基础上提出了一种离散微粒群优化(Discrete Particle Swarm Optimization,DPSO)算法对攻击轨迹决策模型进行求解。仿真结果表明,通过Voronoi图和DPSO算法能够较好地解决UCAV攻击轨迹决策问题,并能够在多约束条件下对目标函数进行组合优化。