微型仿生扑翼飞行器机载单目视觉系统的设计

近年来仿生扑翼飞行器利用视觉系统自主飞行成为一个具有广泛前景的研究方向,然而,其有限的带载能力对视觉传感器的类型、尺寸和重量提出了严格要求。目前商用图像处理模块的尺寸和重量较大,且需要回传图像信息至地面控制系统处理,文章旨在设计一款轻量化机载单目视觉系统,帮助微型仿生扑翼飞行器获取外界信息并实现智能自主的飞行。相比于其他图像处理模块,此系统以国产高算力芯片K210为核心进行设计,可脱离电脑端完成图像处理,尺寸仅为2.2 cm×2.3 cm,重量仅为3 g,内部兼容轻量化网络模型实现分类识别,通过串口进行信息交互,控制扑翼飞行器实现手势识别和目标追踪。     

基于扑翼模型的鸟类目标动态RCS的仿真研究

提出了一种研究扑翼飞行鸟类的动态雷达散射截面(RCS)仿真方法。结合鸟类飞行中的3种典型扑翼姿态建立了对应的CAD模型,并基于FEKO计算了每种姿态的全空域静态RCS数据。建立了叠加位置扰动的鸟类飞行航迹模型,解算出雷达视线在目标坐标系中的视线角,计算鸟的扑翼频率,得到扑翼姿态随时间变化的序列。最后对全空域静态数据进行线性插值获得所需的RCS。仿真结果表明:鸟正侧方的动态RCS要大于前侧方和后侧方的RCS;考虑鸟扑翼的RCS比没有考虑扑翼的RCS振荡更加剧烈。该方法为研究雷达鸟类目标动态特性提供了参考。     

基于PVDF压电传感器的微型扑翼机升力特性研究

采用一种新型方法测量微型扑翼机升力变化特性.在微型扑翼机机翼表面布置一矩形聚偏氟乙烯(PVDF)压电薄膜作为传感器,根据PVDF输出信号判断微型扑翼机对应的升力变化,与传统扑翼机升力变化特性实验研究相比,该方法具有简单、快捷、准确等优势.同时该文研究了微型扑翼飞行器在水平放置及迎风状态时的升力特性曲线,探讨了扑翼频率、飞行速度及扑翼的迎角对扑翼飞行升力的影响.     

面向毫克级仿昆扑翼微飞行器的力-力矩传感器

毫克尺度微型仿生飞行器基于柔性高频翅拍运动的升力机制,具有柔性大变形、振动非线性、多自由度力-力矩耦合等特征,其有效升力/力矩范围处于mN/(μN·m)量级,通用力传感器较难准确测定力学参数,进而给微型仿生飞行器的设计与控制带来一定的困难。文章提出了一种面向微型扑翼飞行器的新型力-力矩传感器,它可以在固定约束条件下实现微飞行器高频扑翼运动产生的升力和力矩的测量,为扑翼飞行器控制力和力矩解耦研究提供精度较高的数据。该传感器采用对称式多悬臂梁柔顺机构将升力/力矩转化为微小形变,结合高带宽、高精度电容位移测量装置,可以采集高频振动条件下的微小升力/力矩。基于梁理论进行了传感器力学建模,并结合有限元仿真验证了原理的可行性。对被测对象微型仿生扑翼飞行器的主要测量参数范围开展结构与工艺设计,实验结果显示,该传感器的升力测量范围为-10~10mN,力矩测量范围为-20~20μN·m,特征频率为1kHz,升力和力矩的灵敏度分别为0.01mN和0.01μN·m,经验证,对整机重量在80~250mg、工作频率在1~200Hz范围的微型扑翼飞行器具有较强的适用性。     

微型扑翼飞行器控制系统设计

微型扑翼飞行器的控制是一个难点问题,不仅对体积和重量有一定限制,还需要使飞行器能够有一定的鲁棒性和自主飞行能力。本文设计的控制系统通过遥控和自主飞行相结合的方式,很好的实现了对微型扑翼飞行器的控制。并进一步通过飞行实验验证了控制系统的可行性,飞行效果良好。     

应用于微型扑翼飞行器的实时视觉系统设计

提出并设计了一套应用于小尺寸、高频抖动的微型仿生扑翼飞行器的实时视觉系统,包括构成硬件基础的微型摄像头模块、5.8GHz传输模块和无线图传接收模块,以及构成软件模块的两种算法,其中一种是利用角点检测与LK光流法、基于卡尔曼低通混合滤波的实时电子稳像去抖算法,另一种是基于YOLOv3的人像识别算法。进行了微型仿生扑翼飞行器的飞行硬件搭载测试实验,实验结果表明,所提出的电子稳像算法可以去除x轴66.56%、y轴73.15%的抖动,人像识别算法可以达到96%以上的准确率,同时图传分辨率在720×480像素时,稳像去抖算法时延为6.33ms,人像识别算法时延为20.5ms,总时延满足实时要求,完成了实时去抖与人像识别系统的设计目标。     

鸟类目标微多普勒分析及参数估计

鸟类扑动的翅膀产生的微多普勒包含了目标的尺寸与微动特征信息,可用于鸟类目标参数估计,对探鸟雷达目标识别具有重要意义。首先建立鸟类目标雷达回波模型,推导了鸟翅膀散射点的微多普勒数学表达式,并通过计算回波的自相关函数估计目标扑翼频率;然后对微多普勒表达式进行泰勒级数展开,利用展开系数与扑翼幅度之间的关系得到扑翼幅度的估计值;最后根据半翼展与微多普勒谱宽之间的关系得到半翼展的估计值。仿真实验证明了所提方法的有效性和抗噪性：对扑翼幅度大于30??、半翼展大于0.3 m的目标,在信噪比高于0 dB的噪声环境下估计精度高。     

基于Fluent的某小型无人机机翼布局对比研究

运用Solidworks对某规格的前掠翼、平直翼和后掠翼进行三维建模,利用CFD软件,采用三维N-S方程及SpalartAllmaras涡粘湍流模型对前掠翼、平直翼和后掠翼的空气动力学特性进行研究,每间隔2°计算迎角从0°~38°时的不同情况,对比分析各自的优势和不足,最后给出结论,为低速小型无人机的机翼布局选型提供了理论依据。计算结果表明低速飞行下平直翼布局升力系数较大,没有气流分离的情况,这种布局较为合理。     

仿生虾蛄眼偏振特性结构研究(简讯)

虾蛄眼具有强大的视觉系统,具有多光谱和偏振探测能力。以虾蛄眼微绒毛阵列结构为基础,进行仿生研究。针对偏振探测中的能量利用率以及空间分辨率的问题,仿生虾蛄眼微绒毛阵列结构,研究了孔阵列光子晶体结构,实现偏振滤波与光谱滤波的集成;根据虾蛄眼微绒毛具有光谱滤波及光信号吸收特性,以纳米线栅为仿生结构基础,实现偏振、光谱吸收特性的集成;依据虾蛄眼双向微绒毛阵列结构,以正交纳米线栅为仿生结构基础,实现单位像元的双向偏振吸收。     

投影梳状条纹插值法测量蜻蜓的翅膀变形

提出一种使用梳状条纹插值法测量昆虫运动的方法 ,并实现了对扇动中的蜻蜓翅膀的弓形变形和扭转变形的测量。结果表明在扇翅运动中蜻蜓翅膀产生较大的弹性变形。这种测量可以帮助流体力学建立更为精确的翅膀模型 ,从而对蜻蜓飞行中的升力来源给出更为精确、科学的解释     

Energetics-based design of small flapping-wing micro air vehicles

The energetics of a flapping-wing micro air vehicle (MAV) is analyzed with the objective of designing it. The salient features of this paper are as follows: 1) designing an energy storage mechanism in the air vehicle similar to an insect thorax that stores part of the kinetic energy of the wing as elastic potential energy during a flapping cycle; 2) inclusion of simplified aerodynamic wing models and inertia of the mechanism using rigid-body modeling techniques; 3) optimization of parameters of the energy storage mechanism using the dynamic models, so that energy input from the external actuators is minimized during a flapping cycle. A series of engineering prototypes based on these studies have been planned which will justify the use of these mathematical techniques.     

微型扑翼飞行器诱导角与几何攻角的研究

基于准稳态模型和动量理论,探讨了微型扑翼飞行器诱导角和最佳几何攻角的计算问题.针对高斯-牛顿法求解诱导角方程时存在的不收敛问题,使用能保证计算过程收敛的列文伯格-马夸尔特算法求解,得到实验样机的诱导角为15°.实验样机的实际升力为40 g,忽略诱导角后准稳态模型理论升力为46 g,而考虑诱导角的理论升力为37 g,验证了计算诱导角可以提高准稳态模型预测升力的准确性.基于实验样机翅膀被动扭转的实际,采用最小二乘法计算出实际最佳几何攻角为55°,能有效指导微型飞行器翅膀的设计,从而提高飞行器最大升力和飞行效率.     

Micro air vehicle: configuration, analysis, fabrication, and test

This paper presents the development of two electrically powered micro air vehicle (MAV) prototypes with wingspans of 380 and 360 mm, respectively. A miniature flight control system is constructed using small and light components. A vision system consisting of a micro radio frequency (RF) transmitter and a miniature vision-receiving antenna with a low-noise amplifier is designed, which exhibits advantages over commercial ones. The aerodynamics of several airfoil sections at low chord Reynolds numbers are theoretically analyzed, for the layout of on-board components and the airfoil design. A small-sized propulsion/power testing setup is developed to measure and analyze the static performance of the motor/propeller/battery combination used for MAV prototype. The materials and methods used to build MAV prototypes are also presented. Two MAV prototypes, TH380 and TH360, have been successfully tested in the flight, where TH360 MAV with a payload of a home-made micro vision system can acquire the images of objects and transmit them back to the ground station.     

展向变形飞行器机翼扭转时的鲁棒飞行控制与分析

为了研究机翼扭转变形对飞行器纵向飞行性能的影响,本文采用小扰动线性化方法建立展向扭转变形飞行器的变参数模型,运用鲁棒最优方法设计机翼扭转变形时的纵向飞行控制律,并用S函数编写展向变形飞行器模型,最后采用SIMULINK对设计的控制律进行仿真分析。仿真结果显示,设计的鲁棒最优控制律能够对变形飞行器进行飞行控制,并且机翼完全扭转能够辅助飞行器下降,机翼不完全扭转能够辅助飞行器爬升。     

Low-altitude road following using strap-down cameras on miniature air vehicles

This paper addresses the problem of autonomously maneuvering a miniature air vehicle (MAV) to follow a road using computer vision as the primary guidance sensor. We focus on low-altitude flight with the objective of maximizing the pixel density of the road in the image. The airframe is assumed to be a bank-to-turn fixed-wing MAV with a downward-looking strap-down camera. The road is identified in the image using HSV classification, flood-fill operations, and connected-component analysis. The main contribution of the paper is the derivation of explicit roll-angle and altitude-above-ground-level (AGL) constraints that guarantee that the road will remain in the footprint of the camera, assuming a flat earth. The effectiveness of our approach is demonstrated through high fidelity simulation and through flight results.     

基于电共轭液的人工肌肉及微手指研究

总结了几种传统人工肌肉的工作原理、特点及其在机器人驱动中的应用现状,分析了面向机器人驱动的传统人工肌肉技术的不足。在描述电共轭液的性能特性基础上,指出基于电共轭液的人工肌肉及微手指不仅在电能到机械能的转化过程中表现出显著的能量转换效率和高灵敏度等性能优点,而且与天然肌肉的驱动原理极其相似,在智能化的机器人驱动方面更具发展潜力。在此基础上,回顾了基于电共轭液的人工肌肉和微手指的研究进展,提出材料研究、作用机理和驱动电压低压化是基于电共轭液的仿生器件研究亟需解决的问题,以及未来的发展趋势及应用前景。     

Development of a small air vehicle based on aerodynamic model analysis in the tunnel tests

Tunnel tests play critical role to aerodynamics analysis, but few work has been done in this area for developing small air vehicles. This paper presents development of an electrically powered small air vehicle prototype based on aerodynamic analysis in wind tunnel and water tunnel tests. Firstly, two airframe models in triangle and square wing planforms, each with a wingspan of 100 mm, are analyzed with a small-scale low speed wind tunnel. The purpose of the wind tunnel test is to examine the practical characteristics such as lift and drag coefficients. The test in a water tunnel is further carried out to investigate the relationship between the vortex aerofoil design and turbulences created. In both wind tunnel and water tunnel tests, the airframe models, apparatus and the methodology are discussed, and the testing results show that the triangle wing aerofoil appears greater maximum lift coefficient and little occurrence of vortex and turbulences. Secondly, based on the verified wing planform in the tunnel tests, a small air vehicle prototype was designed and fabricated. The ground and onboard subsystems or components, such as flight control unit, vision system, and propulsion system etc., are studied. The materials and fabrication processes are also presented in the paper. Finally, the developed air vehicle prototype is successfully tested in the real flight.