【作者】 左德参；

【导师】 陈文元；

【作者基本信息】 上海交通大学 ， 微电子学与固体电子学， 2007， 博士

【摘要】 微型飞行器(Micro Aerial Vehicle—MAV)和微型飞行机器人(Micro Aerial Robot—MAR)具有携带方便、操作简单、较低的制造成本、隐蔽性好、机动灵活等特点,因此无论是在军事领域还是在民用领域,都有十分诱人的应用前景。正是在这一背景下,本文从仿生的角度来研究微型飞行器的飞行机理与样机制作;通过查阅文献中对自然界中昆虫翅膀运动的观察与测量,获取了昆虫翅膀的运动方程;采用UG建模技术,建立昆虫的几何模型;采用网格划分方法,获取昆虫在流场运动时的三维网格;运用CFD方法模拟翅膀运动时周围的流场,获取昆虫运动时的升阻力特性,进而来研究昆虫的飞行机理;在此基础上,通过现有可用的材料加工制作仿生微型飞行器。具体来讲,文章的主要内容如下:在低雷诺数下对昆虫在悬飞过程中的流场进行了数值模拟,建立了昆虫的几何模型,通过模拟昆虫在悬飞过程中翅膀的运动,求解非稳态流场下的N-S方程,获得了昆虫在悬飞过程中周围的压力场、速度场以及翅膀在运动过程中分布在翅膀表面及翅膀周围的非稳态涡和相应的轴向流;并且获得了翅膀在不同时刻的升力系数和阻力系数。通过对昆虫飞行机理的研究,建立了昆虫扑翼飞行时的数学模型;模型包括翅膀运动学方程、空气动力学模型、姿态运动学方程以及质心的动力学方程等,是从仿生的角度去建立模型,即采用数学工具来描述昆虫飞行时的运动特征,如采用高速摄像机来获取昆虫飞行时翅膀的运动参数,采用曲线拟合的方法建立翅膀的运动学方程;运用CFD方法来模拟昆虫在飞行时周围的空气流场及昆虫的升阻力系数;通过经典力学建立昆虫的姿态运动学方程和质心动力学方程,并采用模糊控制策略对昆虫姿态和数学模型进行了仿真研究。自主飞行是仿生微型飞行器重要的研究内容之一,它主要是通过把接收到的地面指令转换为飞行任务,通过自身对环境的感知,规划出一条可行的飞行路径,然后跟随规划出的路径飞行,来完成预定的任务。本文通过对自然界中昆虫飞行时其自身控制特性的研究,概念性地提出了分层控制机理,把仿生微飞行器的复杂控制问题转换为简单的层与层之间的控制问题,通过不同层控制单元的信息交互,实现复杂的控制任务;文中提出了在未知环境中航迹规划算法,初步研究了仿生微型飞行器的自主飞行。仿生微型飞行器飞行时不仅存在静态障碍物,同时也存在动态障碍物,并且飞行的全局环境是未知的,这些条件增大了航迹规划的难度,算法中运动物体只要根据局部探测到的信息,在当前点和目标点之间进行迭代运算,可以保证每步运动的最优性,仿真结果表明了该算法的快速性和高效性。根据自然界中昆虫飞行的特点和和结构特征,我们简化了昆虫模型,采用UG建模技术和微机械加工方法,对扑动机构、翅膀以及胸腔和尾翼进行设计,制造了完整的扑翼飞行样机,然后对其性能进行测试,并对仿生微型飞行器的控制系统进行设计;在此基础上,对获取的仿生微型飞行器样机进行了结构优化,并且获得了运动合理,结构轻巧的仿生微飞行器的样机。为了更加深入的研究仿生微型飞行器在扑翼不断拍打过程中周围的流场,我们设计了小型的风洞模型,进行了相应的PIV试验,研究了扑翼拍打过程中周围流场的变化,并与数值模拟的结果进行了分析对比,研究了仿生微型飞行器在不同频率、不同攻角、不同振幅、不同飞行速度、不同的翅膀初始位置下的非稳态流场;计算了仿生微飞行器在不同运动模态下的升阻力系数;分析了影响仿生微飞行器空气动力学的特性的不同因素;为研究仿生微飞行器的飞行机理和样机建造提供了理论依据。更多还原

【Abstract】 Micro Aerial Vehicles (MAV) or Micro Aerial Robots(MAR), with the promising characteristics of extraordinary flight capabilities, unmatched maneuverability, low-cost fabrication, easier operation, has been very active researching area both in civil and military applications. Just under this background, studying on the flight mechanism of flapping-wing MAV and sample fabrication from the bionics are conducted in this dissertation. The kinematics equations of insect wings can be acquired by the observation and measurement on the natural insect in researching paper. The geometry model of insect is established by UG technology. The three dimensional grid during the insect moving in the flow field is achieved which adopted grid generation method. The characteristic of lift and drag are attained by simulation the surround flow field during the locomotion of wings, and the flight mechanism of insect is discussed. Based on this study, the physical flapping-wing MAV is fabricated by the acquirable materials and parts of apparatus in existence. Described concretely, the contents of this thesis as follows:The flow field during insect hovering flight at low Reynolds number is simulated. The geometry model of insect is established, and the N-S equation at unsteady flow field is solved through simulation the kinematics of insect wings. Based on these studies, the pressure flow field, velocity flow field, unsteady vortex which distributed along the surface and surrounding of wings during the process of wing motion and the corresponding axial flow are achieved during the insect hovering flight. The lift and drag coefficient are attained through integral the pressure components and viscid of wing surface.The mathematics model during insect flapping wing is established through study on insect flight mechanism. The model is constituted from the aspect of bionics which including the wing kinematics equation, aerodynamics model, attitude kinematics equation and the dynamics equation. That is to say, the motion characteristic of insect flight is described by mathematics tool, such as the kinematics parameters of wing acquired by high-speed video, the kinematics equation of wing attained by curve fitting, the lift and drag coefficient achieved and the flow field simulated were based on CFD method. The attitude kinematics and centroid dynamics equation are established by classic mechanics, and the attitude and the mathematics model are simulated by fuzzy control strategy.Self-determination flight is one of the important researching contents about flapping-wing MAV, it is mainly refer to how to convert the instruction from the ground into the flight task, and through detecting the information of local environment by itself, planning a suitable flying path, then flowing the planning path, so that accomplishing the prearranged flying task. The hierarchical strategy based on the study about the flying insect in nature during its flying is presented in this dissertation, which convert the complicated control problem into the control cell between the different layers, and at the same time present the dynamic unknown environment flight path planning arithmetic, primarily study the self-determination flight of flapping-wing MAV. There exist not only static obstacles but also dynamic obstacles during the process of MAV/MAR flight and the global environment information is almost unknown, which would increase the difficulty of fight path planning. The planed path between the present position and the goal is judged at every iterative step in this algorithm, which can guarantee the mostly optimized for every step, has the characteristic of speediness and efficiency.According to the flight characteristic and structure of natural insect, the insect mode is simplified. The flapping structure, wings, thorax and empennage are designed which adopted the UG modeling technology and micro mechanical process method. The integrated flapping-wing MAV sample is fabricated and the corresponding measurement is conducted, and the control system is designed for flapping-wing MAV. The structure of flapping-wing MAV sample is optimized based on the above research and the new flapping-wing MAV sample is achieved with the characteristics of reasonable motion & smart structure.For further study the flow field characteristic of flapping-wing MAV flight, the tiny wind tunnel is designed and the corresponding PIV experiment is conducted. The changing flow field of flapping-wing MAV is studied, and the comparison between the numerical simulation and PIV results is analyzed. The flapping motion and unsteady flow field of flapping-wing MAV in different frequencies, different angles of attack, different velocities, different amplitudes and different initialized positions of wing are simulated. The lift and drag coefficient of flapping-wing MAV in different motion modes are calculated. The factors that influence the characteristic of aerodynamics of flapping-wing MAV are analyzed, which provided the academic warrant for the flying mechanisms and fabrication of flapping-wing MAV.更多还原