IMPROVED UVLM FOR FLAPPING-WING AERODYNAMICS COMPUTATION

To calculate the aerodynamics of flapping-wing micro air vehicle（MAV） with the high efficiency and the engineering-oriented accuracy,an improved unsteady vortex lattice method （UVLM） for MAV is proposed. The method considers the influence of instantaneous wing deforming in flapping,as well as the induced drag,additionally models the stretching and the dissipation of vortex rings,and can present the aerodynamics status on the wing surface. An implementation of the method is developed. Moreover,the results and the efficiency of the proposed method are verified by CFD methods. Considering the less time cost of UVLM,for application of UVLM in the MAV optimization,the influence of wake vortex ignoring time saving and precision is studied. Results show that saving in CPU time with wake vortex ignoring the appropriate distance is considerable while the precision is not significantly reduced. It indicates the potential value of UVLM in the optimization of MAV design.

Modeling and Trajectory Tracking Control for Flapping-Wing Micro Aerial Vehicles

This paper studies the trajectory tracking problem of flapping-wing micro aerial vehicles(FWMAVs)in the longitudinal plane.First of all,the kinematics and dynamics of the FWMAV are established,wherein the aerodynamic force and torque generated by flapping wings and the tail wing are explicitly formulated with respect to the flapping frequency of the wings and the degree of tail wing inclination.To achieve autonomous tracking,an adaptive control scheme is proposed under the hierarchical framework.Specifically,a bounded position controller with hyperbolic tangent functions is designed to produce the desired aerodynamic force,and a pitch command is extracted from the designed position controller.Next,an adaptive attitude controller is designed to track the extracted pitch command,where a radial basis function neural network is introduced to approximate the unknown aerodynamic perturbation torque.Finally,the flapping frequency of the wings and the degree of tail wing inclination are calculated from the designed position and attitude controllers,respectively.In terms of Lyapunov's direct method,it is shown that the tracking errors are bounded and ultimately converge to a small neighborhood around the origin.Simulations are carried out to verify the effectiveness of the proposed control scheme.

Stress Analysis of Membrane Flapping-Wing Aerial Vehicle Based on Different Material Models

Recent studies of flapping-wing aerial vehicles have been focused on the aerodynamic performance based on linear materials. Little work has been done on structural analysis based on nonlinear material models. A stress analysis is conducted in this study on membrane flapping-wing aerial vehicles using finite element method based on three material models, namely, linear elastic, Mooney-Rivlin non linear, and composite material models. The purpose of this paper is to understand how different types of materials affect the stresses of a flapping-wing. In the finite element simulation, each flapping cycle is divided into twelve stages and the maximum stress is calculated in each stage. The results show that 1) there are two peak stress values in one flapping cycle;one at the beginning stage of down stroke and the other at the beginning of upstroke, 2) maximum stress at the beginning of down stroke is greater than that at the beginning of upstroke, 3) maximum stress based on each material model is different. The composite and the Mooney-Rivlin nonlinear models produce much less stresses compared to the linear material model;and 4) the ratio of downstroke maximum stress and upstroke maximum stress varies with different material models. This research is helpful in answering why insect wings are so impeccable, thus providing a possibility of improving the design of flapping-wing aerial vehicles.

基于DoDAF的低慢小飞行器综合处置体系架构设计

针对低慢小飞行器在综合处置中威胁环境复杂、多学科关键技术交互密切等现状,引入美国国防部体系架构框架(Department of Defense Architecture Framework,DoDAF)对低慢小飞行器综合处置体系进行顶层设计。对其视角视图进行“补充、裁剪、融合”,定义了各视角的建模顺序及各视角下视图的建模方法,形成一套面向各类复杂体系分析与设计问题完备的构建方法及一套体系架构快速设计方法。并以一种新型多元载荷协同作战的低慢小飞行器综合处置体系进行建模与仿真,验证了该方法能为低慢小飞行器的综合处置作战提供系统全面的描述和可靠的概念模型支撑、该模型可为作战体系架构设计与装备技术发展提供牵引。

RELIABILITY OF AEROCRAFT GEAR FATIGUE STRENGTH

With the method of group test, fourty pairs of carburization-quenching gears made from 16NCD13 steel for aerocraft were tested to research the contacting fatigue strength on tooth flank. As a result, the samples of fatigue life at the moments when the pitting appears and reaches failure criterion were obtained at four stressing levels respectively. The distribution rule of fatigue life were distinguished, and the distribution parameters were estimated by statistical analysis. Based on that, the R-S-N curves with confidence 95% of contacting fatigue on gear tooth flank were evaluated. Therefore, the basic data were provided for the reliability design of the gears and prediction of their life.

Controlled flight of a self-powered micro blimp driven by insect-sized flapping-wing thrusters

Micro aerial platforms face significant challenges in achieving long controlled endurance as most of the energy is consumed to overcome the weight of the body.In this study,we present a controllable micro blimp that addresses this issue through the use of a helium-filled balloon.The micro blimp has a long axis of 23 cm and is propelled by four insect-sized flapping-wing thrusters,each weighing 80 mg and with a wingspan of 3.5 cm.These distributed thrusters enable controlled motions and provide the micro blimp with an advantage in flight endurance compared to multirotors or flapping-wing micro aerial vehicles at the same size scale.To enhance the performance of the controlled flight,we propose a wireless control module that enables manipulation from a distance of up to 100 m.Additionally,a smartphone application is developed to send instructions to the circuit board,allowing the blimp to turn left and right,ascend and descend,and achieve a combination of these movements separately.Our findings demonstrate that this micro blimp is one of the smallest controlled self-powered micro blimps to date.

An Experimental Study on Response and Control of a Flapping-Wing Aerial Robot Under Wind Gusts

Bioinspired flapping-wing micro-air-vehicles(FWMAVs)have the potential to be useful aerial tools for gathering information in various environments.With recent advancements in manufacturing technologies and better understanding of aerodynamic mechanisms behind of the flapping flight,outdoor flights have become a reality.However,to fully realize the potential of FWMAVs,further improvements are necessary,particularly in terms of stability and robustness under gusty conditions.In this study,the response and control of a tailless two-winged FWMAV under the wind gusts are investigated.Physical experiments are conducted with a one-degree-of-freedom gimbal to focus on effects of wind gusts on the rotational motion of the FWMAV.Proportional-derivative and sliding-mode controls are adopted for the attitude control.Results present that the body angles changed in time and reached approximately 50°at the maximum due to the wing gusts.The sliding-mode controller can more effectively control the rotational angle in the presence of disturbances and both the wing speed and changes in wind speed have an impact on the effectiveness of attitude control.These results contribute to the development of of tailless two-winged,single-motor driven FWMAVs in terms of the design of attitude controller and testing apparatus.

Unpower aerocraft augmented state feedback tracking guaranteed cost control

Aimed at designing the unpower aerocraft attitude control system in a simple and practical way, the guaranteed cost control is adopted. To eliminate the steady-error, a novel tracking control approach--augmented state feedback tracking guaranteed cost control is proposed. Firstly, the unpower aerocraft is modeled as a linear system with norm bounded parameter uncertain, then the linear matrix inequality based state feedback guaranteed cost control law is combined with the augmented state feedback tracking control from a new point of view. The sufficient condition of the existence of the augmented state feedback tracking guaranteed cost control is derived and converted to the feasible problem of the linear matrix inequality. Finally, the proposed approach is applied to a specified unpower aerocraft. The six dimensions of freedom simulation results show that the proposed approach is effective and feasible.

Optimal Control of Aeroelastic StochasticVibration of Aerocraft

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Attitude Controller Design on Variable Rolling Velocity Aerocraft Based on ATmega16

Owing to the effect of crosswind, initial disturbance and the deviation of engine parameters.etc in the initial aviation, vari- able rolling velocity aerocraft will produce attitude angle deviation in the ideal orientations. This paper adopts AVR microcontroller atmega16 and relevant signal process circuit to design the attitude controller and take the method of frequency discrimination and am- plitude discrimination to process attitude angle deviation of aerocraft. Accordingly, it amends attitude angle deviation of aerocraft ef- fect and implements the self- adapting attitude control of aerocraft’s rolling velocity.

美军微型空射诱饵武器发展综述及启示

微型空射诱饵是美军一款空射型电子对抗飞行器,可执行侦察、诱骗、压制和打击等多样战场任务。该款诱饵弹依托诱饵平台,不断拓展其潜在能力,已由最初单纯的电子诱饵类消耗型武器发展为如今基于模块化载荷设计的射频综合类诱饵,在美军整个装备体系和作战模式中发挥重要作用。本文在概述介绍微型空射诱饵基础上,重点分析其战场运用模式和支撑作战的若干关键技术,并对综合射频类诱饵弹装备的未来发展和应用前景进行展望。

Autonomous flight control with different strategies applied during the complete flight cycle for flapping-wing flying robots

Flapping-wing flying robots(FWFRs),especially large-scale robots,have unique advantages in flight efficiency,load capacity,and bionic hiding.Therefore,they have significant potential in environmental detection,disaster rescue,and anti-terrorism explosion monitoring.However,at present,most FWFRs are operated manually.Some have a certain autonomous ability limited to the cruise stage but not the complete flight cycle.These factors make an FWFR unable to give full play to the advantages of flapping-wing flight to perform autonomous flight tasks.This paper proposed an autonomous flight control method for FWFRs covering the complete process,including the takeoff,cruise,and landing stages.First,the flight characteristics of the mechanical structure of the robot are analyzed.Then,dedicated control strategies are designed following the different control requirements of the defined stages.Furthermore,a hybrid control law is presented by combining different control strategies and objectives.Finally,the proposed method and system are validated through outdoor flight experiments of the HIT-Hawk with a wingspan of 2.3 m,in which the control algorithm is integrated with an onboard embedded controller.The experimental results show that this robot can fly autonomously during the complete flight cycle.The mean value and root mean square(RMS)of the control error are less than 0.8409 and 3.054 m,respectively,when it flies around a circle in an annular area with a radius of 25 m and a width of 10 m.

Autonomous Formation Flight Control of Large-Sized Flapping-Wing Flying Robots Based on Leader–Follower Strategy

Birds in nature exhibit excellent long-distance flight capabilities through formation flight,which could reduce energy consumption and improve flight efficiency.Inspired by the biological habits of birds,this paper proposes an autonomous formation flight control method for Large-sized Flapping-Wing Flying Robots(LFWFRs),which can enhance their search range and flight efficiency.First,the kinematics model for LFWFRs is established.Then,an autonomous flight controller based on this model is designed,which has multiple flight control modes,including attitude stabilization,course keeping,hovering,and so on.Second,a formation flight control method is proposed based on the leader–follower strategy and periodic characteristics of flapping-wing flight.The up and down fluctuation of the fuselage of each LFWFR during wing flapping is considered in the control algorithm to keep the relative distance,which overcomes the trajectory divergence caused by sensor delay and fuselage fluctuation.Third,typical formation flight modes are realized,including straight formation,circular formation,and switching formation.Finally,the outdoor formation flight experiment is carried out,and the proposed autonomous formation flight control method is verified in real environment.

国内高空风力发电技术应用现状

文章由2种高空风力发电理论,综述国内外3种高空风力发电技术发展现状和路线,概况市场应用前景和做出经济性分析研究,并分析目前发展遇到的困难,最后作出总结。

火箭橇试验方法综述

结合我国航天器、航空器、常规武器装备以及民用高新产品全面、快速发展的背景,针对以测试技术促进飞行器先进性、可靠性提升的总体需求,详细介绍了火箭橇试验系统,基于试验分类阐述了火箭橇试验能力并归纳总结了国内外火箭橇试验基础技术发展现状。旨在加深人们对火箭橇试验的认识,充分挖掘火箭橇试验的巨大潜力,使火箭橇试验真正成为支撑航天、航空、兵器、船舶、电子等各领域飞行器研制的一种地面高动态试验,更有效地发挥试验测试在国民经济发展和国防事业建设中的作用。

Investigation of electrostriction appliance and its applicationfor bionics flapping aircraft

A novel design for an electrostriction appliance derived from the theory and application of electromagnetics is presented. The working principle, that is the application of gravitation and elasticity together to realize the ＂shrinking＂ and ＂extending＂ effect from the distortion and transforming power into mechanical energy, is briefly explained. The characteristic parameter relationships are established and the experimental research is performed. Experimental results show that this sort of electrostriction appliance can perform well as regards driving force and beeline displacement, and furthermore, its self-weight is smaller. This makes it suitable for beeline drivers with a high application value, especially for the driver of the bionic appliance. In the application of the electrostriction appliance to a bionics-flapping aircraft, the wings can work with a flapping angle in the range of a certain value by controlling the ＂shrinking＂ and ＂extending＂ of the electrostriction appliance. It can reduce the startup power and the impact load of the driver. The flapping extent of the wings will change when the voltage which is put into the electrostriction appliance varies. This makes it more flexible as the bionics-flapping aircraft realizes different actions of flying.

天空偏振光分布的实验研究

生物能够进行偏振光导航定位,一方面是其本身具有对太阳光偏振方向极其敏感的视觉神经系统,另一方面是天空中存在一个可供感知的大气偏振光模式图。天空偏振光分布受观测波段、天气条件以及太阳高度等因子的影响,使大气偏振光模式图具有不稳定性,从而降低了偏振光导航的适用性。着力研究这些影响因子与天空偏振光分布之间的关系,利用全天空偏振测量方法,系统地对全波段以及红、蓝、紫3个波段的天空偏振光在不同天气条件下的分布进行了实验研究。研究结果系统地反映了观测波段、天气条件、太阳高度对天空偏振光分布的影响,表明在不同天气条件下不同波段天空偏振度分布有差异,且蓝波段更适合用于偏振光导航的探测波段。本研究为提高偏振导航的精度及实用化提供理论基础,也为大气的偏振遥感探测提供参考。

自主着陆／着舰技术综述

面对韩美军演、保钓争端等日趋严峻的国际形势,建设强大国防的必要性不言而喻。发展高科技武器,建设强大的海上力量是维持我国周边地区稳定的有效手段。对航空母舰相关技术的研究已经成为目前的热点问题。在对比介绍了陆基飞机和舰载飞机自主降落技术的优点和发展情况之后,从下滑轨迹和导航方式两方面论述飞机降落技术的研究动态,最后对自主着陆/着舰技术进行展望,提出值得继续研究的4个方面,重点指出利用信息融合技术对包括视觉、雷达及其它相关传感器信息进行融合处理是未来飞机降落技术发展的必然趋势。

一类C^3I系统仿真试验床的设计

研究了一类C3I (command,control,communication,and information)系统的构建问题。介 绍了目前较为通用的顶层设计原则和设计方法。在搭建的一类C3I系统平台上,研究了系统的飞行器模拟器节 点的特点及其功能。最后给出了仿真实例曲线图。

一种可行的高超声速飞行器跟踪算法

通过分析临近空间高超声速飞行器的运动特性,建立了高超声速飞行器运动模型,并运用交互式多模型(IMM)算法对其进行跟踪,通过100次蒙特卡罗实验,获得了误差较小的理想跟踪效果,说明了IMM算法用于高超声速目标跟踪中的可行性。