自贡有人机与无人机双跑道运行安全风险分析

通过研究自贡凤鸣通用机场现状、飞行人员跑道识别能力、空管保障能力,分析可能存在的风险和隐患,以人防、技防、物防等手段,从管理、技术、设施设备入手,完善双跑道联防联控机制,达到双跑道安全运行标准。本研究发现,通用航空作为航空领域的重要分支,无人机产业发展迅速,有人机跑道加无人机专用跑道的双跑道运行可能成为将来通用航空机场和支线机场标配,必须对其空管标准、运行流程和进离港程序等进行全方位梳理、再造和优化,引入更先进和高效的管理方法和技术来保障运行安全。

西交利物浦大学体育馆结构设计

西交利物浦大学体育馆为钢筋混凝土框架结构,典型的柱网尺寸为9 m×13 m,羽毛球馆为27 m×39 m的大空间,屋面采用钢桁架结构,为满足建筑设计要求抽掉羽毛球馆底层的一排边柱,造成屋面桁架梁悬挑9 m,并通过吊柱来承受2层的羽毛球馆楼板的荷载。篮球馆为45 m×39 m的大空间,在5.1 m的标高设有空中内跑道,屋面采用网架结构。由于存在结构空旷、跨度大、大悬挑和底层抽柱等特点,造成平面和竖向多项不规则,设计中针对建筑的不规则采用多种抗震技术措施,通过SATWE和PMSAP两种结构计算软件,分别对结构进行整体和分块计算,结果表明,在小震弹性、中震弹性和大震不屈服的作用下,结构的整体指标和承载力满足规范要求,关键构件的设计满足中震弹性的性能化设计目标,确保了结构安全,可供类似的工程设计参考。

一种基于单幅跑道图像的无人机降落位姿测量新方法

提出了一种在无人机降落并接近跑道的过程中,在已知跑道宽度的前提下,基于单幅跑道图像测量其位姿参数的新方法。通过分析跑道消影点与无人机位姿的关系,得到消影点的图像坐标与姿态角的关系。依据摄像机共线方程,推导出了无人机位姿与跑道的世界坐标方程系数及像直线方程系数的关系。通过合理假设,对位姿参数进行了简化,求解出无人机降落过程中的位姿状态。仿真实验结果证明,方法易于实现,可满足无人机自主降落导航的应用需求。

基于直线特征的航拍图像机场跑道自动识别算法

针对航拍图像中机场跑道的区域灰度特征和边界直线特征,提出了一种基于直线特征的机场跑道自动识别算法。首先对航拍图像进行边缘检测;然后在归一化的边缘检测幅度图像中进行直线提取,并对提取的直线进行三次连接;再进行机场跑道边界平行直线对的提取;最后根据区域灰度特征对机场跑道区域进行验证,完成机场跑道的识别和定位。大量实验结果表明,本算法对云层遮挡等具有较强的鲁棒性,并且定位准确,是一种有效的机场跑道识别算法。

利用地平线与跑道边缘线估计无人机着陆参数

研究了一种基于机器视觉的无人机着陆参数计算方法,通过利用图像处理得到的地平线、跑道两条边缘线在图像像素坐标系下的直线方程,可以获得无人机着陆过程中的5个飞行参数:高度、侧偏距、滚转角、俯仰角、偏航角。介绍了视觉测量的一般理论;给出了飞行姿态角测量方法;提出了无人机高度和与机场跑道中线的距离的计算方法。利用实拍的一段无人机着陆视频验证了提出的方法,实验研究表明:该方法可以有效地获得5个飞行参数,为无人机自主着陆提供着陆参数。

在航拍图像中自动识别机场跑道的算法

提出了一种用于在航拍图像中自动识别机场跑道的方法。首先,根据机场跑道的诸多特征,构造出机场跑道的模型;然后采用假设、检验的方法,在边缘检测后的图像中,进行搜索、连接、合并,将图像中的跑道识别出来。大量的实验证明:这种方法可以自动在航拍图像中准确、快速地识别出机场跑道。

用于UAV视觉导航的跑道检测与跟踪

跑道检测与跟踪是UAV视觉导航研究的重点内容。针对UAV着陆过程中跑道变化情况,提出一种新的方法,利用单目视觉信息,基于距离跑道的远近不同采用不同的策略实现跑道检测与跟踪,帮助UAV自主降落在安全区域。当距离较远时,利用地平线检测和模板匹配的方法对跑道进行定位;结合模板更新策略实现跑道跟踪;当距离较近时,在融合远距离跑道方位信息的基础上利用改进型Canny算子和Hough变换对跑道边缘进行更精确的描述。实验结果表明,利用该方法可以有效地对跑道进行检测和跟踪,并且具有较快的处理速度。

低能见度前下视航拍图像中机场跑道的自动检测

提出了一种针对低能见度、前下视航拍机场图像中自动检测机场跑道的方法 .首先 ,采用基于递归的Otsu分割方法 ,从复杂背景中提取机场的主要轮廓 ;然后 ,利用基于形态学的开运算和膨胀进行形态滤波 ,开运算是为了滤除一些孤立噪声点 ,而膨胀运算是为了将分割后的机场成分连成一个完整的整体 ;最后 ,对形态滤波处理后的图像进行其区域生长 ,从而对机场主跑道进行定位 .试验证明 :这种方法对低能见度、前下视的航拍机场图像能够快速准确地检测、定位机场主辅跑道 .

Development of a Bird-like Flapping-wing Aerial Vehicle with Autonomous Take-off and Landing Capabilities

The lack of autonomous take-off and landing capabilities of bird-like flapping-wing aerial vehicles(BFAVs)seriously restricts their further development and application.Thus,combined with the current research results on the autonomous take-off and landing technology of unmanned aerial vehicles,four types of technologies are studied,including jumping take-off and landing technology,taxiing take-off and landing technology,gliding take-off and landing technology,and vertical take-off and landing(VTOL)technology.Based on the analytic hierarchy process(AHP)-comprehensive evaluation method,a fuzzy comprehensive evaluation model for the autonomous take-off and landing scheme of a BFAV is established,and four schemes are evaluated concretely.The results show that under the existing technical conditions,the hybrid layout VTOL scheme is the best.Furthermore,the detailed design and development of the prototype of a BFAV with a four-rotor hybrid layout are carried out,and the vehicle performance is tested.The results prove that through the four-rotor hybrid layout design,the BFAV has good autonomous take-off and landing abilities.The power consumption analysis shows that for a fixed-point reconnaissance mission,when the mission radius is less than 3.38 km,the VTOL type exhibits longer mission duration than the hand-launched type.

太阳能无人机空中起飞设计

通常情况下,太阳能无人机从地面起飞需要消耗大量能量,必须携带质量较大的电池组,很大程度上降低了无人机的续航能力。基于此设计了无人机空中起飞系统,该系统由地面控制台、升空动力模块、传感器模块、空中定位及位置保持模块、起飞弹射系统和空中滑跑辅助系统组成。通过理论推导构建物理模型,对比了空中起飞和地面起飞的能量消耗,从而得出无人机空中起飞的方案。

A multi-strategy pigeon-inspired optimization approach to active disturbance rejection control parameters tuning for vertical take-off and landing fixed-wing UAV

In this paper.Active Disturbance Rejection Control(ADRC)is utilized in the pitch control of a vertical take-off and landing fixed-wing Unmanned Aerial Vehicle(UAV)to address the problem of height fluctuation during the transition from hover to level flight.Considering the difficulty of parameter tuning of ADRC as well as the requirement of accuracy and rapidity of the controller,a Multi-Strategy Pigeon-Inspired Optimization(MSPIO)algorithm is employed.Particle Swarm Optimization(PSO),Genetic Algorithm(GA),the basic Pigeon-Inspired Optimization(PIO),and an improved PIO algorithm CMPIO are compared.In addition,the optimized ADRC control system is compared with the pure Proportional-Integral-Derivative(PID)control system and the non-optimized ADRC control system.The effectiveness of the designed control strategy for forward transition is verified and the faster convergence speed and better exploitation ability of the proposed MSPIO algorithm are confirmed by simulation results.

Robust Optimal Higher-order-observer-based Dynamic Sliding Mode Control for VTOL Unmanned Aerial Vehicles

This paper investigates the precise trajectory tracking of unmanned aerial vehicles(UAV) capable of vertical take-off and landing(VTOL) subjected to external disturbances. For this reason, a robust higher-order-observer-based dynamic sliding mode controller(HOB-DSMC) is developed and optimized using the fractional-order firefly algorithm(FOFA). In the proposed scheme, the sliding surface is defined as a function of output variables, and the higher-order observer is utilized to estimate the unmeasured variables,which effectively alleviate the undesirable effects of the chattering phenomenon. A neighboring point close to the sliding surface is considered, and as the tracking error approaches this point, the second control is activated to reduce the control input. The stability analysis of the closed-loop system is studied based on Lyapunov stability theorem. For a better study of the proposed scheme, various trajectory tracking tests are provided, where accurate tracking and strong robustness can be simultaneously ensured. Comparative simulation results validate the proposed control strategy′s effectiveness and its superiorities over conventional sliding mode controller(SMC) and integral SMC approaches.

Liftoff of a New Hovering Oscillating-wing Micro Aerial Vehicle

Hovering ability forms the basis for space operations of Micro Aerial Vehicles(MAVs).The problem of uneven load puts high demands on the wing design.In this paper,a new hovering-mode for MAVs,inspired by flapping flight in bees and hummingbirds but using high-aspect-ratio and low-stress wings,is proposed.Different from the flapping actuations that occur at the wing roots,the two wings are driven back and forth in a straight line.To simplify the design and control the angle of attack,passive wing rotation is employed.The numerical results and analysis show that the maximum stress of the oscillating wing is approximately 1/6 of that of the flapping wing when the lift of the oscillating wing is twice that of the flapping wing.A theoretical aerodynamic model of the kinematics of the vehicle's driving mechanism was developed to fulfill its design.Force measurements indicate that the vehicle generates a sufficiently high cycle-averaged vertical thrust(71 g)for liftoff at a maximum frequency of 5.56 Hz,thereby validating the proposed aerodynamic model.Moreover,liftoff performance is presented to visually demonstrate the vertical take-off capabilities and hovering potential of the aeromechanical solution.

基于视觉导引的固定翼无人机自主着陆算法研究

研究了使用视觉导引系统进行固定翼无人机自主着陆时的相关问题,主要针对提高视觉导航系统获取导航参数的速度及精度展开研究。视觉导航系统获取参数分为两步:跑道检测识别、固定翼无人机相对位姿估计。提高导航系统参数获取速度,主要通过提高耗时较高的跑道检测识别算法的检测识别效率来完成。利用跑道在序列图像中的时空一致性进行候选区域提取,在不影响召回率的情形下减少无效候选区域,从而提高跑道检测效率,最终提高视觉导引系统获取导引参数的速度。为提高估计的导引参数精度,结合跑道上的点线特征进行位姿估计,通过增加可利用的特征数量来提高位姿估计精度。实验仿真结果表明,所提方法有效提高了视觉导航系统获取导航参数的速度及精度。