Optimal Compliant Flapping Mechanism Topologies With Multiple Load Cases

The conceptual design of effective actuation mechanisms for flapping wing micro air vehicles presents considerable challenges, with competing weight, power, authority, and life cycle requirements. This work utilizes topology optimization to obtain compliant flapping mechanisms; this is a well-known tool, but the method is rarely extended to incorporate unsteady nonlinear aeroelastic physics, which must be accounted for in the design of flapping wing vehicles. Compliant mechanism topologies are specifically desired to perform two tasks: (1) propulsive thrust generation (symmetric motions of a left and a right wing) and (2) lateral roll moment generation (asymmetric motions). From an optimization standpoint, these two tasks are considered multiple load cases, implemented by scheduling the actuation applied to the mechanism’s design domain. Mechanism topologies obtained with various actuation-scheduling assumptions are provided, along with the resulting flapping wing motions and aerodynamic force/moment generation. Furthermore, it is demonstrated that both load cases may be used simultaneously for future vehicle control studies: gradual transition from forward flight into a turning maneuver, for example.

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Aerodynamic Performance of a Passive Pitching Model on Bionic Flapping Wing Micro Air Vehicles

Applied Bionics and Biomechanics ◽

10.1155/2019/1504310 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12 ◽

Cited By ~ 2

Author(s):

Jinjing Hao ◽

Jianghao Wu ◽

Yanlai Zhang

Keyword(s):

High Efficiency ◽

Aerodynamic Force ◽

Leading Edge ◽

Micro Air Vehicles ◽

Flapping Wing ◽

Torsional Stiffness ◽

Important Goal ◽

Edge Vortex ◽

Yaw Moment ◽

Air Vehicles

Reducing weight and increasing lift have been an important goal of using flapping wing micro air vehicles (FWMAVs). However, FWMAVs with mechanisms to limit the angle of attack (α) artificially by active force cannot meet specific requirements. This study applies a bioinspired model that passively imitates insects’ pitching wings to resolve this problem. In this bionic passive pitching model, the wing root is equivalent to a torsional spring. α obtained by solving the coupled dynamic equation is similar to that of insects and exhibits a unique characteristic with two oscillated peaks during the middle of the upstroke/downstroke under the interaction of aerodynamic, torsional, and inertial moments. Excess rigidity or flexibility deteriorates the aerodynamic force and efficiency of the passive pitching wing. With appropriate torsional stiffness, passive pitching can maintain a high efficiency while enhancing the average lift by 10% than active pitching. This observation corresponds to a clear enhancement in instantaneous force and a more concentrated leading edge vortex. This phenomenon can be attributed to a vorticity moment whose component in the lift direction grows at a rapid speed. A novel bionic control strategy of this model is also proposed. Similar to the rest angle in insects, the rest angle of the model is adjusted to generate a yaw moment around the wing root without losing lift, which can assist to change the attitude and trajectory of a FWMAV during flight. These findings may guide us to deal with various conditions and requirements of FWMAV designs and applications.

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Wing Design, Fabrication, and Analysis for an X-Wing Flapping-Wing Micro Air Vehicle

Drones ◽

10.3390/drones3030065 ◽

2019 ◽

Vol 3 (3) ◽

pp. 65 ◽

Cited By ~ 1

Author(s):

Boon Hong Cheaw ◽

Hann Woei Ho ◽

Elmi Abu Bakar

Keyword(s):

Insect Flight ◽

Micro Air Vehicles ◽

Flapping Wing ◽

Indoor Environments ◽

Wing Design ◽

Thrust Generation ◽

Thrust Measurement ◽

Glue Method ◽

Controller Board ◽

Full Throttle

Flapping-wing Micro Air Vehicles (FW-MAVs), inspired by small insects, have limitless potential to be capable of performing tasks in urban and indoor environments. Through the process of mimicking insect flight, however, there are a lot of challenges for successful flight of these vehicles, which include their design, fabrication, control, and propulsion. To this end, this paper investigates the wing design and fabrication of an X-wing FW-MAV and analyzes its performance in terms of thrust generation. It was designed and developed using a systematic approach. Two pairs of wings were fabricated with a traditional cut-and-glue method and an advanced vacuum mold method. The FW-MAV is equipped with inexpensive and tiny avionics, such as the smallest Arduino controller board, a remote-control receiver, standard sensors, servos, a motor, and a 1-cell battery. Thrust measurement was conducted to compare the performance of different wings at full throttle. Overall, this FW-MAV produces maximum vertical thrust at a pitch angle of 10 degrees. The wing having stiffeners and manufactured using the vacuum mold produces the highest thrust among the tested wings.

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The Effects of Wakes on Aerodynamic Characteristics of Flapping Wings in Clap-and-Fling Motion at Re of ~104

Volume 1: Flow Manipulation and Active Control; Bio-Inspired Fluid Mechanics; Boundary Layer and High-Speed Flows; Fluids Engineering Education; Transport Phenomena in Energy Conversion and Mixing; Turbulent Flows; Vortex Dynamics; DNS/LES and Hybrid RANS/LES Methods; Fluid Structure Interaction; Fluid Dynamics of Wind Energy; Bubble, Droplet, and Aerosol Dynamics ◽

10.1115/fedsm2018-83112 ◽

2018 ◽

Author(s):

Jong-Seob Han ◽

Jae-Hung Han

Keyword(s):

Aerodynamic Force ◽

Force Production ◽

Micro Air Vehicles ◽

Aerodynamic Characteristics ◽

Flapping Wing ◽

Flapping Wings ◽

Water Tank ◽

Cross Sectional ◽

Robotic Arms ◽

Tip Vortices

In this paper, aerodynamic characteristics of two flapping wings in clap-and-fling motion at Re of ∼104, which corresponds to the flight regime of flapping-wing micro air vehicles, was investigated. The test employing dynamically scaled-up robotic arms installed on a water tank revealed that the wingbeat motion at such high Re in1duced the fully developed wake within two wingbeat cycles. This wake widely influenced the lift production covering the entire wingbeat period; the wings earned the additional lift during the entire downstroke, and lost the lift during the upstroke. Chordwise cross-sectional DPIV showed the massive downwash with enlarged tip vortices, when the wake was fully developed. The wake blew down the headwind and reduced the effective angles of attack. In the case of the clap-and-fling motion, the wake was leaned toward the dorsal part, in which the wings created the clap-and-fling motion, causing the global fluctuation of the aerodynamic force production.

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Airfoil design and aerodynamic force testing for flapping-wing Micro Air Vehicles

Proceedings of the 10th World Congress on Intelligent Control and Automation ◽

10.1109/wcica.2012.6359129 ◽

2012 ◽

Author(s):

Wen Xia ◽

Gang Su

Keyword(s):

Aerodynamic Force ◽

Micro Air Vehicles ◽

Flapping Wing ◽

Air Vehicles

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Lift and thrust generation by a butterfly-like flapping wing–body model: immersed boundary–lattice Boltzmann simulations

Journal of Fluid Mechanics ◽

10.1017/jfm.2015.57 ◽

2015 ◽

Vol 767 ◽

pp. 659-695 ◽

Cited By ~ 32

Author(s):

Kosuke Suzuki ◽

Keisuke Minami ◽

Takaji Inamuro

Keyword(s):

Lattice Boltzmann ◽

Lift Force ◽

Micro Air Vehicles ◽

Flapping Wing ◽

The Body ◽

Immersed Boundary ◽

Body Model ◽

Lattice Boltzmann Simulations ◽

Thrust Generation ◽

Boltzmann Method

AbstractThe flapping flight of tiny insects such as flies or larger insects such as butterflies is of fundamental interest not only in biology itself but also in its practical use for the development of micro air vehicles (MAVs). It is known that a butterfly flaps downward for generating the lift force and backward for generating the thrust force. In this study, we consider a simple butterfly-like flapping wing–body model in which the body is a thin rod and the rectangular rigid wings flap in a simple motion. We investigate lift and thrust generation of the model by using the immersed boundary–lattice Boltzmann method. First, we compute the lift and thrust forces when the body of the model is fixed for Reynolds numbers in the range of 50–1000. In addition, we estimate the supportable mass for each Reynolds number from the computed lift force. Second, we simulate free flights when the body can only move translationally. It is found that the expected supportable mass can be supported even in the free flight except when the mass of the body relative to the mass of the fluid is too small, and the wing–body model with the mass of actual insects can go upward against the gravity. Finally, we simulate free flights when the body can move translationally and rotationally. It is found that the body has a large pitch motion and consequently gets off-balance. Then, we discuss a way to control the pitching angle by flexing the body of the wing–body model.

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