仿生扑翼飞行机器人研究中若干问题的思考

在成功研制仿生扑翼飞行机器人样机的基础上，提出仿生扑翼飞行机器人研究中值得思考的若干问题。有关低雷诺数问题,提出以动量定理为基础分析昆虫翅膀产生高飞行升力方法具有合理性的观点；有关非定常微分方程问题，提出非定常微分方程并非解决一切问题之关键的观点；有关翅变形问题，提出采用柔性翅的模型翅膀进行研究的观点。     

仿生变形飞行器的飞行特性研究

随着无人飞行器的小型化甚至微型化发展,扑翼飞行的优势逐渐显现出来。受鸟类及昆虫飞行运动的启发,分析鸟类及昆虫的扑翼运动特性,设计了一种鸟类扑翼飞行方式,使用涡格法进行了扑翼的气动计算,并采用质点弹道学模型分析了仿生飞行的轨迹特性。仿真结果表明,设计的扑翼运动效果良好。     

扑翼的非定常水动力特性数值研究

研究水下推进装置结构优化设计问题,建立了扑翼的简谐运动模型,根据有限体积法和非结构动网格技术,完成了对扑翼运动的非定常建模研究.通过计算得到了扑翼运动的水动力特性及流场的变化规律,提出了扑翼产生的涡的特点及其作用机制.计算结果表明:在简谐运动驱动下,扑翼运动能产生较大的推力,而产生的升力较小;扑翼运动过程中伴随着涡的生成和脱离,尾涡能有效地提高扑翼产生的推力,前沿涡能抑制推力的产生和延缓升力的下降趋势.以上研究为水下推进装置优化设计提供了参考依据.     

仿鸟类扑翼飞行器研究进展

仿生扑翼飞行器有着优异的气动性能和灵活的飞行能力,在军民领域均有广泛的应用前景,学者们在原理样机研制、扑翼气动机理、驱动机构、飞行控制等多领域取得了一系列重要进展.本文从总体设计方法、驱动机构设计与优化、气动机理等方面综述了仿鸟类扑翼飞行器技术的发展历程与研究进展.首先,从扑翼总体设计方法入手,总结了仿鸟类扑翼飞行器仿生构型,归纳了总体设计参数估算方法;其次,综述了多种构型曲柄连杆机构在扑翼驱动中的应用与优缺点;接着总结了扑翼气动机理研究的实验方法与数值计算方法,分析了不同扑翼气动算法针对不同应用场景在计算成本和准确度方面的优劣情况;最后,对仿鸟类扑翼飞行器系统设计研究现状进行总结,针对原理样机研制过程提出展望.     

导弹异形卷弧翼安装选型

为在空中发射武器外形设计中引入异形卷弧翼,将其作为导弹主升力面,研究其相对于弹身的安装选型问题．模型设计采用1对异形卷弧翼,并将其沿弹体纵向平面对称布置．定义异形卷弧翼相对于弹身的安装位置角和安装偏角参数,选取2组计算模型,基于计算流体力学（Computational Fluid Dynamics,CFD）仿真计算评估这2个角度的变化对异形卷弧翼-弹身组合体纵向超音速气动参数的影响,得到组合体升力因数、阻力因数以及升阻比随2个角度参数变化而变化的规律．结果表明,在设计任务中,当安装位置角等于120°,安装偏角等于-10°时,组合体的升力因数和升阻比达到最大值．该方法可以改善导弹的升力特性,提高导弹的升阻比,使导弹获得更好的飞行性能．     

基于滑移网格海龟扑翼推进数值仿真研究

为了探讨海龟翼摆动时产生的流体推进力与摆动频率、幅度以及来流速度之间的关系,对海龟翼在不同工况下进行了数值仿真计算.针对海龟翼在粘性介质中运动,采用滑移网格技术,结合扑翼运动规律,建立扑翼推进数值计算模型,模拟海龟二维剖面翼以特定规律运动时的流体动力特性.通过数值仿真,得出扑翼推进力与摆动频率、摆动幅度以及来流速度之间的关系.经实践证明:翼静水中摆动平均推力随着摆动频率、幅度的增加而增大,且频率较大时随频率增大得更为明显,为下一步扑翼驱动机构设计打下基础,具有一定的实践指导意义.     

独立驱动的仿鸟扑翼飞行机器人的系统设计与实验EI北大核心CSCD

扑翼飞行机器人模仿自然界中的飞行生物,通过扑动翅膀拍打空气驱动飞行.它们机动性好、飞行效率高、噪音小,在某些应用场景比传统的固定翼飞机和旋翼飞机更有优势.目前扑翼飞行机器人的研究大多集中在机理研究和理论的建模与控制,鲜有实现室外的自主飞行,难以应对复杂的实际应用需求.在本文中,设计了一种独立驱动的仿鸟扑翼飞行机器人USTBird,通过两个舵机独立驱动左右翅膀可实现无可控尾翼的机动飞行.通过搭载自主设计的微型飞控板、GPS以及惯性导航模块,采用PD控制实现了扑翼飞行机器人的室外自主巡航飞行.设计了针对扑翼机器人的轻型两自由云台,很大程度上消除了机翼扑动飞行引起的图像抖动问题.针对机身振动和GPS测量误差带来的位置误差,采用无迹卡尔曼滤波算法对GPS采集的位置信息进行估计,提升了位置估计精度.设计了面向扑翼飞行机器人的地面站系统.考虑到扑翼飞行机器人存在的转向滞后问题,对偏航角设计双闭环分段PD控制器,最终实现了在外圆半径40 m和内圆半径10 m的圆环内的自主巡航任务.     

基于Wagner函数的卷弧翼非定常气动力分析

为研究卷弧式尾翼的气弹特性,基于Wagner函数,建立了卷弧尾翼在非定常气动条件下的升力及滚转力矩模型。以此为基础,针对在特定振荡频率的攻角激励作用下,不同张开角度、弦长及分布数量翼片的升力,不同安装及滚转方向翼片的滚转力矩,进行了数值仿真分析,并利用fluent仿真软件进行了建模仿真验证。结果表明升力响应幅值随着张开角及弦长的增大单调递增,不同分布数量尾翼的升力近似相等,反装反旋安装方式有效降低了尾翼滚转力矩。对于卷弧尾翼弹箭的优化设计,颤振特性分析以及锥形运动的抑制等问题具有积极意义。     

仿鸟扑翼飞行器姿态镇定研究

针对仿鸟扑翼飞行器的欠驱动特性,提出了一种简化其飞行控制问题并实现其局部渐近稳定的控制方法．建立并分析了仿鸟扑翼飞行器的动力学和运动学模型,证明其控制问题等价于升力、推力独立可控情况下的姿态控制问题．进一步分析的结果表明,仿鸟扑翼飞行器的升力、推力都是独立可控的,其姿态控制为耦合输入下刚体的姿态控制问题．通过设计光滑时变反馈控制律实现姿态控制的局部渐近稳定,从而解决扑翼飞行器的飞行控制问题．     

毫米级静电微扑翼驱动器的结构设计、工艺与测试

针对仿昆虫扑翼飞行器核心动力装置——微驱动器的结构特点和研究难点,设计了一种基于静电驱动原理的毫米(mm)级微扑翼驱动器,并针对各个部件研究了整套加工工艺与测试方法.运动优化与升力测试结果表明:微扑翼驱动器(翼展9 mm,重量3 mg)以91 Hz的频率实现了±40°的拍动和±25°的扭转运动,输出1.5 mg的升力,升重较以往静电微扑翼驱动器有大幅提升.研究成果为实现仿昆虫微型飞行器的自主飞行提供了新的方向,并奠定了理论与试验基础.     

Ability to forecast unsteady aerodynamic forces of flapping airfoils by artificial neural network

The ability of artificial neural networks (ANN) to model the unsteady aerodynamic force coefficients of flapping motion kinematics has been studied. A neural networks model was developed based on multi-layer perception (MLP) networks and the Levenberg–Marquardt optimization algorithm. The flapping kinematics data were divided into two groups for the training and the prediction test of the ANN model. The training phase led to a very satisfactory calibration of the ANN model. The attempt to predict aerodynamic forces both the lift coefficient and drag coefficient showed that the ANN model is able to simulate the unsteady flapping motion kinematics and its corresponding aerodynamic forces. The shape of the simulated force coefficients was found to be similar to that of the numerical results. These encouraging results make it possible to consider interesting and new prospects for the modelling of flapping motion systems, which are highly non-linear systems.     

Bio-inspired wing-folding mechanism of micro air vehicle (MAV)

Over the past few years, many researchers have shown an interest in micro air vehicle (MAV), since it can be used for rescue mission and investigation of danger zone which is difficult for human being to enter. In recent years, many researchers try to develop high-performance MAVs, but a little attention has been given to the wing-folding mechanism of wings. When the bird and the flying insects land, they usually fold their wings. If they do not fold their wings, their movement area is limited. In this paper, we focused on the artificial wing-folding mechanism. We designed a new artificial wing that has link mechanism. With the wing-folding mechanism, the wing span was reduced to 15%. In addition, we set feathers separately on the end of wings like those of real birds. The wings make thrust force by the change of the shape of the feathers. However, the wings could not produce enough lift force to lift it. Therefore, we have come to the conclusion that it is necessary to optimize the wings design to get stronger lift force by flapping.     

低雷诺数湍流模型的网格特征

低雷诺数模型目前主要应用于二维简单流动的数值仿真中,为研究该湍流模型在三维复杂流动计算中的网格特征,选取不同系列的车身面网格尺寸、车身壁面第一层边界层与壁面法向高度以及边界层层数等3组网格参数,利用ANSYS对阶背式MIRA模型外流场进行数值仿真.数值仿真结果与风洞试验的结果对比表明：数值计算得到的车身表面平均y+值随面网格尺寸增加而呈现减小趋势;网格方案对气动力因数和车身表面压力因数分布影响显著,气动阻力因数仿真值与试验值误差的变化区间为0.83%~7.93%,气动升力因数误差变化区间为10%~104%;气动阻力因数和气动升力因数均随着边界层层数的增加而增大,边界层层数为5时可以得到兼顾气动力因数精度和车身表面压力因数精度的较优仿真结果.     

Passive torque regulation in an underactuated flapping wing robotic insect

Recent developments in millimeter-scale fabrication processes have led to rapid progress towards creating airborne flapping wing robots based on Dipteran (two winged) insects. Previous work to regulate forces and torques generated by flapping wings has focused on controlling wing trajectory. An alternative approach uses underactuated mechanisms with tuned dynamics to passively regulate these forces and torques. The resulting ??mechanically intelligent?? devices execute wing trajectory corrections to realize desired body forces and torques without the intervention of an active controller. This article describes an insect-scale flapping wing mechanism consisting of a single piezoelectric actuator, an underactuated transmission, and passively rotating wings. Wing stroke velocities are passively modulated to eliminate net airframe roll torque. A theoretical model predicts lift generating wing trajectories and quantifies the passive reduction in roll torque. An experimental structure provides an at-scale demonstration of passive torque regulation.     

Towards efficient flight: insights on proper morphing-wing modulation in a bat-like robot

In this article, we address the question of how the flight efficiency of Micro Aerial Vehicles with variable wing geometry can be inspired by the biomechanics of bats. We use a bat-like drone with highly articulated wings using shape memory alloys (SMA) as artificial muscle-like actuators. The possibility of actively changing the wing shape by controlling the SMA actuators, let us study the effects of different wing modulation patterns on lift generation, drag reduction, and the energy cost of a wingbeat cycle. To this purpose, we present an energy-model for estimating the energy cost required by the wings during a wingbeat cycle, using experimental aerodynamic and inertial force data as inputs to the energy-model. Results allowed us determining that faster contraction of the wings during the upstroke, and slower extension during the downstroke enables to reduce the energy cost of flapping in our prototype.     

迷你翼梢小翼增升减阻效应

选取某窄体客机的翼梢小翼为研究对象,采用Spalart Allmaras模型对无翼梢小翼、全尺寸翼梢小翼和迷你翼梢小翼3种机翼构型进行数值模拟,通过流场分析和速度分解等手段,研究翼梢小翼的增升减阻机理。结果表明：迷你翼梢小翼有恢复涡核流速、减弱涡流掺混程度和梳理翼梢气流的作用;增升减阻的关键在于迷你翼梢小翼对气流方向的修正;翼梢小翼的局部流动差异会对整体机翼近场造成影响。由于尺寸较小,迷你翼梢小翼能在较大攻角范围内改善传统翼梢小翼的性能,具有一定的实践意义。     

Coupled adjoint aerostructural wing optimization using quasi-three-dimensional aerodynamic analysis

This paper presents a method for wing aerostructural analysis and optimization, which needs much lower computational costs, while computes the wing drag and structural deformation with a level of accuracy comparable to the higher fidelity CFD and FEM tools. A quasi-three-dimensional aerodynamic solver is developed and connected to a finite beam element model for wing aerostructural optimization. In a quasi-three-dimensional approach an inviscid incompressible vortex lattice method is coupled with a viscous compressible airfoil analysis code for drag prediction of a three dimensional wing. The accuracy of the proposed method for wing drag prediction is validated by comparing its results with the results of a higher fidelity CFD analysis. The wing structural deformation as well as the stress distribution in the wingbox structure is computed using a finite beam element model. The Newton method is used to solve the coupled system. The sensitivities of the outputs, for example the wing drag, with respect to the inputs, for example the wing geometry, is computed by a combined use of the coupled adjoint method, automatic differentiation and the chain rule of differentiation. A gradient based optimization is performed using the proposed tool for minimizing the fuel weight of an A320 class aircraft. The optimization resulted in more than 10 % reduction in the aircraft fuel weight by optimizing the wing planform and airfoils shape as well as the wing internal structure.     

乘波体组合高压捕获翼构型的性能分析

针对高速飞行器大容积、高升力、低阻力和高升阻比的设计需求,提出高压捕获翼(High pressure zone Capture Wing,HCW)的概念.在高速巡航条件下,合理配置HCW可以充分利用来流压缩产生的高压气体,从而提高飞行器升力;HCW采用与来流平行的薄板装置,其附加阻力较小,可以大幅提高升阻比.采用CFD分析工具,比较不同容积的乘波体构型与HCW组合前后的气动性能.结果表明,在不同容积构型下升阻比均有明显提高,最小提升量可达10%.此外,容积越大,升力和升阻比增加效果越明显.     

扑翼飞行的气动建模与仿真分析

用计算流体力学的数值仿真方法对微扑翼飞行的非定常空气动力学问题进行了建模与仿真研究。在对昆虫扑翼飞行运动的仿生模拟基础上,建立了简化的扑翼运动二维翼型的运动学与空气动力学模型。利用任意拉格朗日欧拉（ALE）有限元方法求解出N-S方程的数值解,将流场仿真结果与实验进行了对比,并分析了扑翼运动产生的前缘漩涡对升力的作用。文中的建模、分析方法和结论对微扑翼飞行器的分析设计和应用提供了一定的理论依据。