Measuring height of high-voltage transmission poles using unmanned aerial vehicle (UAV) imagery

Aerial imagery is important in remote sensing applications. Unmanned aerial vehicle (UAV) has a wide range of applications in remote sensing and presents a substantial cost-effective solution when monitoring objects on the earth’s surface. Moreover, object detection and classification are important aspects of global information system, especially for remote sensing applications and power line monitoring, which are essential for the proper distribution of electricity to consumers. Manual inspection consumes much time and involves risk, especially in remote areas that host dangerous wildlife; hence, UAV-based approaches are more feasible for such monitoring. The authors propose an UAV approach that utilises a digital surface model and incorporates a stereo matching algorithm based on UAV stereo images. The proposed algorithm was based on a graph-cut (GC) algorithm that measured the disparity map. Results were compared with well-known algorithms; including, for example, global and local stereo matching algorithms. The proposed solution introduces and integrates ordering constraints along with a submodular energy minimisation function to/with the GC algorithm to enhance performance. The authors measured sensitivity and recall for all parameters against ground truth data for differently cropped images of 16 power poles. Results showed that the proposed model performed more accurately compared to extant methods.     

基于三维实景模型的水库无线视频监控系统

以前坪水库为例，水库建设期视频监控系统信号采用无线网桥传输，基于无人机航摄生成三维实景模型进行视频监控点及无线网桥布置设计。介绍了采用大疆无人机DJ1 PHANTOM4 PRO进行航飞倾斜摄影，采用Context Capture 3D生成三维实景模型的过程步骤，对基于三维实景模型优化监控点布设及视野和信道复核的方法进行了研究。实践表明，基于无人机三维实景模型的水库无线视频监控系统设计可靠，可为其他类似工程参考借鉴。     

无人机飞行训练仿真系统设计与实现

为了使领航人员更形象直观快速熟练地操控无人机按预定航路飞行,通过对前苏联体制坐标系下无人机的12阶非线性微分方程数学模型进行分析和研究,利用VC 6.0编程和网络技术实现了无人机飞行的计算机仿真.针对无人机实际飞行情况,仿真系统逼真地模拟了操作手战位和领航员战位情景,并通过网络传递信息.除了讲述系统的组成和各主要功能模块外,还提出了通过对无人机的实际飞行数据和仿真数据进行比对来修正和补偿数学模型中相关参数的方法,从而使仿真结果更趋于真实可信.结果表明,系统设计合理,功能齐全,符合实际飞行规律,可以使领航人员迅速掌握领航要领.     

无人机电子稳像技术中角点检测算法的改进

无人机航空遥感电子稳像系统中,稳像的关键技术之一是影像特征点的选取,其中图像角点是遥感影像中重要的特征信息,准确地选取角点可提高图像处理的精度。然而现有的图像角点检测算法多因计算速度慢不能满足视频图像数字稳像的实时性。因此提出了一种基TSUSAN角点检测算法的改进算法。新算法分析了影像中角点所在区域的灰度变化特征,改进了SUSAN角点检测算法中的判断准则,提高了算法的精度和速度。实验结果表明,改进的算法可较大幅度的提高运算速度,满足稳像技术对视频图像实时处理的要求。     

改进模糊层次分析法在虚拟维修训练评估中的应用

为更合理地对无人机虚拟维修训练进行综合评估,对传统层次分析法和模糊综合评估法进行改进。改进的层次分析法在确定指标权重时,引入拟优传递矩阵,无需进行一致性检验,避免了人为调整判断矩阵的盲目性;改进的模糊综合评估法利用加权平均型模型,对所有因素均衡兼顾,将评语集按等级进行区间化赋值,使计算得到的综合评价结果更加可信。以某型无人机的虚拟维修训练为例进行评估,结果表明,改进方法简单易行,在Virtools环境下进行工程实现与验证,可有效地记录受训人员的操作信息,系统针对操作记录自行打分,取得了较好的评估效果。     

基于气象无人机飞行状态的“野值”判定及剔除方法研究

气象无人机探测过程中误差较大的数据统称为野值数据,研究如何判定并能够成功剔除野值就成为了提高气象无人机测风精度的重要方法。首先通过判定并剔除气象无人机飞行状态中的加速度和角速度的野值数据,进而根据有效的加速度和角速度信息确定无人机飞行状态,建立了匀速直线、变速、转动、其它非惯性运动等四种飞行状态下的野值评判标准,并设定了相应的阈值,给出了基于不同飞行状态的野值判定、剔除方法,通过仿真分析结果表明,该方法明显剔除了误差较大的数据,成功降低由于测量总压波动所引起的风速误差,对提高气象无人机测风精度具有重要参考价值。     

阻力方向舵在飞翼式高空长航时无人机中的应用

根据飞翼式高空长航时无人机的风洞实验结果,分析了全机尤其是阻力方向舵的气动和操稳特性,据此采用经典方法设计了阻力方向舵的控制律,提出用阻力方向舵进行航向控制和速度控制的方案,并指出由于存在操纵耦合,有必要进行阻力方向舵和升降舵交联控制。非线性飞行仿真结果表明,阻力方向舵具有满意的航向和速度操纵能力,采用交联控制后速度响应更平稳,并可减小33的高度偏差和56的俯仰角偏差。     

复合材料与无人飞机

本文论述了无人机对复合材料的需求，给出了复合材料在无人机上应用的概况以及无人机复合材料技术发展研究的要点。     

Cooperative and Geometric Learning Algorithm (CGLA) for path planning of UAVs with limited information

In this paper, we propose a new learning algorithm, named as the Cooperative and Geometric Learning Algorithm (CGLA), to solve problems of maneuverability, collision avoidance and information sharing in path planning for Unmanned Aerial Vehicles (UAVs). The contributions of CGLA are three folds: (1) CGLA is designed for path planning based on cooperation of multiple UAVs. Technically, CGLA exploits a new defined individual cost matrix, which leads to an efficient path planning algorithm for multiple UAVs. (2) The convergence of the proposed algorithm for calculating the cost matrix is proven theoretically, and the optimal path in terms of path length and risk measure from a starting point to a target point can be calculated in polynomial time. (3) In CGLA, the proposed individual weight matrix can be efficiently calculated and adaptively updated based on the geometric distance and risk information shared among UAVs. Finally, risk evaluation is introduced first time in this paper for UAV navigation and extensive computer simulation results validate the effectiveness and feasibility of CGLA for safe navigation of multiple UAVs.     

基于FPGA的无人机SAR天线稳定平台控制系统设计

为了满足无人机SAR成像对天线波束指向平稳性的要求,设计了一种基于FPGA的天线稳定平台控制系统。FPGA接收姿态传感器和DGPS/INS组合系统输出的姿态信息,采用数字滤波、数字PID控制实现对SAR天线指向的平稳控制。该系统具有实时性好、集成度高、小型化、低成本、低功耗等特点。通过大量实验验证,实验结果表明该系统性能良好,满足设计要求。