Key Problems Study On Flapping-Wing Micro Aerial Vehicles

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.