A multi-objective multi-memetic algorithm for network-wide conflict-free 4D flight trajectories planning

Under the demand of strategic air traffic flow management and the concept of trajectory based operations (TBO),the network-wide 4D flight trajectories planning (N4DFTP) problem has been investigated with the purpose of safely and efficiently allocating 4D trajectories (4DTs) (3D position and time) for all the flights in the whole airway network.Considering that the introduction of large-scale 4DTs inevitably increases the problem complexity,an efficient model for strategic level conflict management is developed in this paper.Specifically,a bi-objective N4DFTP problem that aims to minimize both potential conflicts and the trajectory cost is formulated.In consideration of the large-scale,high-complexity,and multi-objective characteristics of the N4DFTP problem,a multi-objective multi-memetic algorithm (MOMMA) that incorporates an evolutionary global search framework together with three problem-specific local search operators is implemented.It is capable of rapidly and effectively allocating 4DTs via rerouting,target time controlling,and flight level changing.Additionally,to balance the ability of exploitation and exploration of the algorithm,a special hybridization scheme is adopted for the integration of local and global search.Empirical studies using real air traffic data in China with different network complexities show that the pro posed MOMMA is effective to solve the N4DFTP problem.The solutions achieved are competitive for elaborate decision support under a TBO environment.     

能量最优的航天器连续动态避障轨迹规划

针对传统脉冲避障算法在航天器轨迹规划应用中存在对瞬时推力依赖性强且燃料消耗量大的问题,提出能量最优的连续动态避障算法。该算法首先基于线性相对运动方程与有限时间的能量最优模型,建立了相对运动能量最优模型,同时验证了模型最优性;其次将动态障碍物的y向运动误差偏移与正态分布概率引入避碰安全距离模型,修正了追踪航天器动态避障的范围,确定了安全距离矢量长度,增强了规避障碍的可靠性;最后通过障碍物速度矢量与追踪器航天器速度矢量夹角确定动态避障点方向,减少燃料消耗的同时提高了避障的有效性、准确性。通过仿真验证,该算法可以自适应选取规避障碍点,有效规避动态障碍;工质燃料消耗较小,有效延长航天器在轨寿命。     

一种基于最优控制的航路规划方法

阐述了一种与地形紧密结合的基于最优控制理论的航路规划方法。该方法利用二维三次卷积插值法构造地形函数,采用三维的航路规划进行地形跟随,地形回避和威胁回避,并对俯仰角进行ＰＤ（比例微分）控制。该方法计算量小,大大减小了规划时间,提高了规划结果的实时性,最优控制理论结合ＰＤ控制使得航路的三维规划鲁棒性好,有效地抑帛最振荡和发散,为低空突防的飞行器提供了很好的参考飞行航路。     

基于自组网策略的多机编队与防撞任务研究

近年来多旋翼无人机编队飞行技术取得了巨大的突破,将无人机技术与自组网技术相结合将会促进无人机集群技术的发展。为了促进无人机编队飞行技术的发展,以5架六旋翼无人机为研究对象,重点研究了基于自组网策略的多旋翼无人机队形组成、队形保持、队形重构以及飞行过程中的避碰策略,设计了数据闭环的地面编队控制软件并进行试飞验证。测试结果表明,该数据闭环地面编队控制软件稳定可靠,实现了编队队形组成、保持、重构以及在队形变换过程中的机间避碰等功能,对多旋翼无人机编队飞行工程化实现具有一定的参考价值。     

基于相对轨道要素的航天器相对运动碰撞分析

采用基于相对轨道要素的方法,建立了计算碰撺概率的数学模型.在二体圆轨道条件下,推导验证了与基于Clohessy-wiltshire(C-W)方程的碰撞模型的等价关系,并解决了C-W方程存在的若干问题.在航天器近距离相对运动构型设计中提出了基于相对轨道要素的碰撞分析方法,突出了相对轨道要素在构型设计以及碰撞分析中的作用....     

浅议大学新生的心理矛盾及心理调适问题

大学新生中存在着种种不适应的心理现象，反映出大学新生的心理矛盾。根据大学新生的心理矛盾提出心理调适的具体措施以达到健康的心理。     

基于可拓规则推理的故障诊断方法

针对产生式规则推理方法存在的推理效率低、知识获取困难以及难以用于多故障诊断等问题,研究基于可拓规则推理的故障诊断方法。首先将基元理论和产生式规则相结合,得到可拓规则的基元表示;然后给出可拓规则匹配度计算公式,并提出按前件基元类型和属性数据类型不同对可拓规则进行分层匹配,对所有匹配成功的可拓规则,提出先删减再排序的冲突消解策略,在算法分析中讨论可拓规则推理的时间复杂度;最后通过应用案例说明可拓规则表示、匹配、推理和冲突消解的全过程,结果表明该方法适用于机载设备的多故障诊断。      

行为控制月球车的虚拟主体避障技术

论述了基于行为代理体的月球车避障技术。由月球地形高程图得到当地水平面下二色障碍图及着色障碍图，利用月球车代理体在障碍图及着色障碍图中进行避障学习与控制，将获得的控制量投影到月球车体坐标系下得到真实地形上的控制量，达到避障控制与运动规划的目的。利用障碍入侵月球车安全线的径向距离作为避障控制器输入，并由月球车目标趋向行为及避障行为输出融合突现出趋向目标的避障行为。仿真结果表明基于代理体的避障控制器设计方法使运行于真实环境下月球车的避障具有很高的可靠性。     

Collision free 4D path planning for multiple UAVs based on spatial refined voting mechanism and PSO approach

In this paper, a four-dimensional coordinated path planning algorithm for multiple UAVs is proposed, in which time variable is taken into account for each UAV as well as collision free and obstacle avoidance. A Spatial Refined Voting Mechanism(SRVM) is designed for standard Particle Swarm Optimization(PSO) to overcome the defects of local optimal and slow convergence.For each generation candidate particle positions are recorded and an adaptive cube is formed with own adaptive side length to indicate occupied regions. Then space voting begins and is sorted based on voting results, whose centers with bigger voting counts are seen as sub-optimal positions. The average of all particles of corresponding dimensions are calculated as the refined solutions. A time coordination method is developed by generating specified candidate paths for every UAV, making them arrive the same destination with the same time consumption. A spatial-temporal collision avoidance technique is introduced to make collision free. Distance to destination is constructed to improve the searching accuracy and velocity of particles. In addition, the objective function is redesigned by considering the obstacle and threat avoidance, Estimated Time of Arrival(ETA), separation maintenance and UAV self-constraints. Experimental results prove the effectiveness and efficiency of the algorithm.     

考虑断点续传的中继卫星调度模型及启发式算法

为提高中继卫星系统的应用效能及数传任务的完成率,在中继卫星调度中考虑了断点续传这一应用模式,即对单个数传任务进行合理拆分,使其在多个时间窗口内完成。首先构建面向断点续传的中继卫星单址天线的调度模型,然后提出一种基于冲突风险评估的冲突度量化方法,并设计考虑断点续传的两阶段调度算法。最后开展大量的仿真实验将该算法与贪婪算法、基于最小冲突度的启发式算法和基于任务优先级的启发式算法这3个不考虑断点续传的算法进行对比。实验结果表明,所提出的算法在任务完成率方面分别提高了7.67%、6.34%和8.67%。