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.     

Extended dynamic system modulation for real-time obstacle avoidance

In this paper, a novel real-time obstacle avoidance method based on Dynamic System(DS), is proposed. The proposed method ensures the impenetrability of multiple convex obstacles by online modulating the original velocity field of the DS. It can be applied to perform obstacle avoidance in the state space of the DS with both autonomous and non-autonomous DS-based controllers. While realizing the obstacle avoidance, the equilibrium points of the original DS can be saved. The modulation matrix form ...     

无人机航迹规划算法的初步研究

航迹规划算法是无人机的关键技术之一,本文初步综述了近年来国内外在该领域的主要研究成果。首先给出了航迹规划的描述和涉及的关键问题,然后着重介绍了几种较为常用的规划算法,如A-Star算法、遗传算法、神经网络、Voronoi图、PRM(ProbabilisticRoadmap)、RRTs(RapidlyExploringRandomTrees)、人工势场法、基于案例的算法等,最后讨论了航迹规划算法存在的问题和面临的挑战,指出飞行中实时重规划的研究是航迹规划未来主要的发展方向。     

基于极值搜索的四旋翼无人机自抗扰控制

为了提高四旋翼无人机飞行过程中的抗干扰能力,提出了基于极值搜索算法的自抗扰控制技术。首先,建立了四旋翼无人机非线性数学模型;然后,设计了基于极值搜索的自抗扰控制器,对无人机的位置和姿态进行控制;同时,设计扩张状态观测器估计系统内部及外部总扰动,对系统扰动进行补偿。仿真结果表明,所提方法不仅能抑制外界干扰,而且能显著改善飞行控制系统的瞬态性能和稳态性能。     

燃料电池无人机动力系统方案设计与试验

针对燃料电池为主能源的无人机（UAV）动力系统,设计了纯燃料电池动力系统、燃料电池/蓄电池（简称燃蓄）被/主动混合动力系统3种拓扑结构方案。以空冷质子交换膜燃料电池为例,搭建了燃料电池动力系统方案一体化试验平台。考虑阶梯型和阶跃型2种加载形式,试验研究了燃料电池自身的动态特性和启动特性。以阶梯型功率剖面的加载形式,试验研究了纯燃料电池动力系统放电特性;以无人机典型任务剖面作为加载形式,开展燃蓄被/主动混合动力系统对比试验研究。试验结果表明：纯燃料电池动力方案适用于低机动小型无人机,燃蓄被动混合方案可满足小型无人机大机动飞行,燃蓄主动混合方案系统可适应中大型无人机更长航时飞行。     

四旋翼无人机非奇异终端滑模位置控制器设计

针对四旋翼无人机存在模型不确定性、在野外飞行时易受外界环境干扰问题,首先采用牛顿-欧拉法进行系统建模;然后按照内外环控制结构,外环位置控制器输出姿态指令作为内环姿态控制器的输入,内环采用串级PID控制器,重点针对外环设计了一种非奇异终端滑模控制器,并基于Lyapunov理论证明了位置子系统的稳定性,得出系统误差能够在有限时间收敛到0的结论;最后,通过定点控制和轨迹跟踪仿真,表明控制器具有较快的响应速度和良好的抗干扰性能,能够快速精确地进行轨迹跟踪。     

无人机和巡航导弹用涡扇/涡喷发动机的设计特点

无人机和巡航导弹发动机有许多共性,人们有时候会把它们混淆。本文详细分析了无人机和巡航导弹的区别,对比研究了它们对发动机的要求和关键属性,随后分析了无人机和巡航导弹对涡扇/涡喷发动机的特殊要求与设计特性,以及目前正在开发的先进技术。     

一种电动无人机的激光射束驱动系统

介绍和分析了国内外无人机无线能量传输系统,在此基础上提出一种用于中小型电动无人机的由地面能量发射机和机载能量接收机组成的激光射束驱动系统,并规划相应的工作模式,以实现电动无人机飞行工作状态下的无线充电。此系统将极大地提高电动无人机的续航能力。     

Optimal video communication strategy for intelligent video analysis in unmanned aerial vehicle applications

For Unmanned Aerial Vehicles (UAV), the intelligent video analysis is a key technology in intelligent autonomous control, real-time navigation and surveillance. However, poor UAV wireless links would degrade the quality of video communication, leading to difficulties in video analysis. To meet the challenges of packet-loss and limited bandwidth in adverse UAV channel environments, this paper proposes a parameter optimization mechanism for UAV intelligent video analysis. In the proposed method, an Optimal Strategy Library (OSL) is designed to optimize the parameters for video encoding and forward error correction. Adapted to the packet-loss rate and bandwidth in practical UAV wireless network, the proposed OSL can facilitate the encoding of video sequences and the recovery of degraded videos with optimal performance. Experimental results demonstrate that the proposed solution can keep intelligent video analysis working efficiently with adverse UAV wireless links, and is capable of maximizing the inference accuracy of Multi-Object Tracking (MOT) algorithms in various scenarios.     

涵道风扇式无人机的优先级控制分配

涵道风扇式无人机是一种冗余配置操纵面的飞行器，其控制分配问题通常使用伪逆法求解，然而伪逆法不能对任意可达的期望力矩都返回容许控制，使冗余的操纵面牺牲了部分控制能力。提出一种优先级控制分配方法，该方法先对期望力矩进行矢量分解并划分优先级，再求解约束最优化问题得到容许控制。相比于伪逆法，所提出的方法可对更大范围的期望力矩返回容许控制，而且当期望力矩不可达时，可以防止系统因执行器饱和而产生输出耦合。将所提出的方法应用到涵道风扇式无人机的控制分配中，仿真及飞行试验验证了该方法的有效性。