Flapping flight for biomimetic robotic insects: part I-system modeling

This paper presents the mathematical modeling of flapping flight inch-size micro aerial vehicles (MAVs), namely micromechanical flying insects (MFIs). The target robotic insects are electromechanical devices propelled by a pair of independent flapping wings to achieve sustained autonomous flight, thereby mimicking real insects. In this paper, we describe the system dynamic models which include several elements that are substantially different from those present in fixed or rotary wing MAVs. These models include the wing-thorax dynamics, the flapping flight aerodynamics at a low Reynolds number regime, the body dynamics, and the biomimetic sensory system consisting of ocelli, halteres, magnetic compass, and optical flow sensors. The mathematical models are developed based on biological principles, analytical models, and experimental data. They are presented in the Virtual Insect Flight Simulator (VIFS) and are integrated together to give a realistic simulation for MFI and insect flight. VIFS is a software tool intended for modeling flapping flight mechanisms and for testing and evaluating the performance of different flight control algorithms.     

Flapping flight for biomimetic robotic insects: part II-flight control design

In this paper, we present the design of the flight control algorithms for flapping wing micromechanical flying insects (MFIs). Inspired by the sensory feedback and neuromotor structure of insects, we propose a similar top-down hierarchical architecture to achieve high performance despite the MFIs' limited on-board computational resources. The flight stabilization problem is formulated as high-frequency periodic control of an underactuated system. In particular, we provide a methodology to approximate the time-varying dynamics caused by the aerodynamic forces with a time-invariant model using averaging theory and a biomimetic parametrization of the wing trajectories. This approximation leads to a simpler dynamical model that can be identified using experimental data from the on-board sensors and the voltage inputs to the wing actuators. The overall control law is a periodic proportional output feedback. Simulations, including sensor and actuator models, demonstrate stable flight in hovering mode.     

基于气动参数调节的无人机抗扰动控制算法

无人机飞行受到气动阻尼扰动,从而导致控制稳定性不好。当前采用翼型截面气动参数调节的方法进行无人机抗扰控制,以扭角以及振动方向等参数为约束指标,参数调节的模糊度较大,对气动姿态参数调节的稳定性不好。文中提出基于气动参数调节的无人机抗扰动控制算法。该算法根据无人机的飞行工况构建各阶模态对应的气弹耦合方程,在速度坐标系、体坐标系、弹道坐标系三维坐标系下构建无人机的飞行动力学和运动学模型;采用卡尔曼滤波方法实现对无人机飞行参数的融合调节和小扰动抑制处理,并采用末端位置参考模型进行无人机飞行轨迹的空间规划设计;在卡尔曼滤波预估模型中实现对动力学模型的线性化处理,采用气弹模态参数识别方法进行无人机的飞行扰动调节;将姿态控制作为内环,获得位置环状态反馈调节参数;以无人机的升力系数和扭力系数作为气动惯性参数进行飞行姿态的稳定性调节,从而实现无人机抗扰动控制律的优化设计。采集飞机的俯仰角、横滚角和航向角作为原始数据在Matlab中进行仿真分析,仿真结果表明,采用所提方法进行无人机抗扰动控制的稳定性较好,对气动参数进行在线估计的准确性较高,航向角误差降低12.4%,抗扰动能力提升8dB,收敛时间比传统方法缩短0.14 s,无人机飞行的抗扰动性和飞行稳定性得到提高。所提方法在无人机飞行控制中具有很好的应用价值。     

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.     

仿鸟扑翼飞行器仿真研究

针对仿鸟扑翼飞行器的柔性翼动力学仿真需要,在非定常空气动力学原理下,用修正的准定常气动力计算模型估算出了扑翼的动力学模型,并建立了其相应的状态空间方程,进而分析研究了在Matlab语言和Simulink环境下,对其仿真系统设计得需求和要求。     

Dissection of a Flexible Wing's Performance for Insect-Inspired Flapping-Wing Micro Air Vehicles

We present a computational study on the aerodynamic performance of flexible wings aiming to facilitate the design of insect-inspired flapping-wing micro air vehicles (FMAVs). First, we propose using a two-dimensional mechanical model for a flapping wing to help understand the mechanism underlying its unsteady deformation when exposed to aerodynamic and inertia forces. This is followed by comparative analyses of both flexible wings and fixed wings in flight. In particular, a 'swaying propulsion' mechanism is proposed to mimic the flapping of the winged insects, and a new concept of 'initial torsion angle' is introduced to provide an equivalent means to account for the asymmetry of the torsional stiffness of the thorax muscle during upstroke and downstroke flapping. Subsequently, the aerodynamic forces and power requirements for a bumblebee's wings under various flight conditions are systematically examined. Our results indicate that flexibility of the wings largely contributes to the high lifts and that gliding forces play a significant role in improving flight performance, suggesting that optimal design of the structure and flapping motions of wings could achieve improved efficiency in FMAVs. These studies promote a brand new design concept for future insect-inspired FMAVs.     

From insects to machines

Insects and hummingbirds remain unmatched in their aerodynamic ability to hover in place in addition to other acrobatic feats such as flying backward and sideways by exploiting flapping-wing motion [1]. Although this remarkable ability is key to making small-scale aircraft, flapping-hovering behavior has been difficult to reproduce artificially because of the challenging stability, power, and aeroelastic phenomena involved. Recent interest in small-scale unmanned air vehicles, especially those capable of hovering like insects and hummingbirds, is driven by many potential applications. A number of flapping machines have been developed [2]-[8], but only two are capable of untethered hovering flight [9], [10]. A key challenge is to demonstrate a stable untethered flapping-hovering ability at a weight and power approximating that of insects and birds where flapping-hovering flight is observed in nature. Here we demonstrate, for the first time, a passively stable 24-g machine capable of flapping-hovering flight at a Reynolds number similar to insects (Re = 8 × 10³). This architecture, particularly the passive stability, may help in the design of insect-sized hovering vehicles as well as shed light on the aeroelastic dynamic principles underlying insect flight.     

仿昆扑翼飞行器全解耦控制

针对仿昆扑翼飞行器飞行控制所面临的欠驱动问题,基于平均理论,提出采用周期时变反馈策略控制仿昆扑翼飞行器的策略,并给出了设计周期时变反馈控制器的输入参数化设计方法．该方法对飞行昆虫的扑翼运动进行仿生模拟,通过调整根翅运动参数,实现了对6个方向气动力和力矩的独立控制．本质上就是用参数表示欠驱动系统的输入,并以此构造周期时变反馈函数;从而在原系统中引入更多数目的独立控制量,将原系统转化为完全能控系统．然后,将此可控系统线性化,并利用线性反馈控制器设计工具设计其反馈控制律．仿真结果表明,基于该策略设计的控制器具有响应速度快、稳定误差小、鲁棒性强等特点．     

Attitude Stabilization of a Biologically Inspired Robotic Housefly via Dynamic Multimodal Attitude Estimation

In this paper, we study sensor fusion for the attitude stabilization of micro aerial vehicles, particularly mechanical flying insects. Following a geometric approach, a dynamic observer is proposed that estimates attitude based on kinematic data available from different and redundant bioinspired sensors such as halteres, ocelli, gravitometers, magnetic compass and light polarization compass. In particular, the traditional structure of complementary filters, suitable for multiple sensor fusion, is specialized to the Lie group of rigid-body rotations SO(3). The filter performance based on a three-axis accelerometer and a three-axis gyroscope is experimentally tested on a 2-d.o.f. support, showing its effectiveness. Finally, attitude stabilization is proposed based on a feedback scheme with dynamic estimation of the state, i.e., the orientation and the angular velocity. Almost-global stability of the proposed controller in the case of dynamic state estimation is demonstrated via the separation principle, and realistic numerical simulations with noisy sensors and external disturbances are provided to validate the proposed control scheme.     

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.     

仿生扑翼“0”形轨迹机构的设计及气动力特性

针对仿生扑翼飞行器的驱动结构进行设计,提出了一种空间摇杆式的驱动机构与机翼扭转机构,实现机翼扑动过程中的"0"形空间运动轨迹.针对机翼的空间"0"字形运动,建立仿生飞行器气动分析模型,采用动网格与非定常数值计算方法,对机翼拍动过程中不同相位下的升阻特性进行分析,并通过空气动力效率与流场对比分析,得到不同参数条件下的气动效率,为仿生扑翼飞行器的设计及扑动模式的选择提供参考.通过气动力测量实验、台架姿态标定和外场飞行测试,验证了结构设计的合理性.     

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.     

某飞机着陆的数值计算

为合理设计飞机着陆程序,采用数字仿真和高精度计算技术,通过分析飞行实际情况研究起落架、襟翼和地面效应对飞机空气动力特性的影响,建立某飞机着陆的精确数值模型,并用差分法离散该模型.编制数值计算程序实现飞机的地面滑跑和空中运动仿真,并利用该程序进行飞机着陆的数值分析.该研究有利于智能选择飞机最优着陆程序、保障飞行安全、提高...     

卫星编队相对动力学方程数值解法

随着卫星技术的迅速发展,编队飞行技术得到了广泛的应用,而相对动力学数学精确模型是卫星编队飞行首先要解决的问题.为了保证卫星飞行保持稳定轨道,按Hill方程的圆轨道编队设计方法应用于椭圆轨道编队设计中,分析了相对动力学方程的精确模型.在满足椭圆轨道编队周期性运动的一般性初始化条件基础上,采用椭圆轨道编队相对动力学方程中周期解的要求,提出了一种新的数值解法.通过仿真,利用STK仿真工具,得到主从卫星的相对位置变化曲线,并对误差进行了分析,进而验证了方法的有效性和可行性.     

某型直升机飞行性能仿真建模与验证

主要研究并建立直升机飞行性能仿真模型,在直升机动力学和运动学微分方程的基础上重点解算作用在直升机各部件上的气动力和力矩模型,建立旋翼和尾桨的气动仿真模型,对旋翼挥舞运动进行了分析研究,还考虑了平尾、垂尾、机身和重力的仿真模型。最后通过对各飞行性能指标及其验证原理方法的分析研究,验证了静态性能指标,应用标量指标法验证动态性能指标。     

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．     

机动弹头六自由度运动建模研究

机动弹头的应用是弹道导弹提高突防能力和命中精度的有效选择。为了深人研究机动弹头的制导与控制规律,该文针对机动弹头再人机动飞行的特点,给出了气动控制力和控制力矩的计算模型,并应用六自由度一体化建模理论建立了较为精确的动力学和运动学数学模型,而且基于MATLAB／Simulink对其数学模型进行了转化,建立了可在计算机上实现的数字仿真模型,并给出了部分仿真结果。结果表明,所建立的机动弹头六自由度运动模型能够充分表征其再入机动飞行的特点,为制导和控制系统的六自由度一体化建模与仿真提供了基础和前提。     

D-P算法的改进及其在飞行轨迹回放中的应用

飞行参数记录了飞行器飞过的位置、姿态和飞行状态,飞行结束后,对飞行参数进行可视化回放,无论是实际的飞行训练中,还是飞行仿真中都是必不可少的,但在回放时,如果逐点显示这些数据,将会消耗大量的系统资源.本文提出一种基于限定俯仰角和航向角变化率的道格拉斯—普克(Douglas-Poiker,D-P)压缩算法对将要显示的轨迹点进行压缩,并对算法进行了验证,效果良好.     

基于模型的空投任务飞行品质试飞设计及评估

针对飞机执行空投任务的飞行品质试飞安全控制及缺少设计及评估方法问题,建立空投过程数学模型,预测空投过程飞机响应、指导飞行试验实施,在空投试飞前,为评估飞机空投构型飞行品质、确保空投试飞的安全性,分析空投货物时飞机响应特点,确定载机平台飞行品质试飞内容;以飞机姿态控制为目标,确定重力空投、牵引空投过程飞机飞行状态、给出飞行员操纵建议,设计了空投过程评价要素表,形成基于模型的空投任务飞行品质试飞设计及评估技术,保障试飞安全、指导试飞设计。     

机翼伸展对低速飞行状态的影响

变翼飞行器在飞行过程中因机翼构型、面积等发生变化,引起质量分布、惯性及气动特性发生相应改变,飞行动力学因此受到影响.基于Lagrange方程,本文首先建立变形机翼飞行器的动力学模型,简化后得到伸展变翼的纵向运动方程,并通过气动仿真获得伸展机翼飞行器的低速气动特性.然后,借助线性插值确定气动参数随翼展的变化关系,研究了伸展变翼过程对于飞行器平飞、爬升、俯冲和盘旋的作用.结果表明,因变翼过程中升阻系数改变,飞行器将发生变速沉浮运动,此时为保持飞行状态的稳定,需对飞行器加以控制.