Approximate Model for Cycle-Averaged Aerodynamic Forces, and its Application to Stability and Control of Bird-Scale Flapping-Wing Aircraft

This article outlines a new control approach for flapping-wing micro-aerial vehicles (MAVs), inspired both by biological systems and by the need for lightweight actuation and control solutions. In our approach, the aerodynamic forces required for agile motions are achieved indirectly, by modifying passive impedance properties that couple motion of the power stroke to the angle of attack (AoA) of the wing. This strategy is theoretically appealing because it can exploit an invariant, cyclical power stroke, for efficiency, and because an impedance-adjusting strategy should also require lower bandwidth, weight, and power than direct, intra-wingbeat control of AoA. We examine the theoretical range of control torques and forces that can be achieved using this method and conclude that it is a plausible method of control. Our results demonstrate the potential of a passive dynamic design and control approach in reducing mechanical complexity, weight and power consumption of an MAV while achieving the aerodynamic forces required for the types of high-fidelity maneuvers that drive current interest in autonomous, flapping-wing robotics.

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Dynamics and Control of a Flexible Flapping Wing Aircraft

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.246-247.537 ◽

2012 ◽

Vol 246-247 ◽

pp. 537-542

Author(s):

Zhuang Zhao ◽

Hai Yuan Jiang ◽

Hua Chang ◽

Jing Guo

Keyword(s):

Lift Coefficient ◽

Leading Edge ◽

Research Area ◽

Aerodynamic Performance ◽

Flapping Wing ◽

Aerodynamic Forces ◽

Dynamics And Control ◽

Wind Velocities ◽

Set Up ◽

And Control

To investigate the aerodynamic performance of a flexible flapping wing aircraft, a flapping-wing system were design and an experiment were set up to measure the unsteady aerodynamic forces of the flapping motion. The thrust formula and resistance formula described aerodynamic forces. The lift and thrust of this mechanism were measured for different angles of attack and wind velocities. Results indicate that the thrust increases with the flapping frequency and the lift increase with the wind velocity, while the lift coefficient decreases while the velocity increases. It is realized that the wing’s transformation which imitated birds leads less resistance when flapping upward which impacts the aerodynamic lift generation and the bionic winglet leads to a change in the leading edge vortex and span-wise flow structures, which decrease the airflow’s backward pull. Models were introduced which were used in the design process and show its aerodynamic performance. The flexible flapping wing vehicle is still an open research area.

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A CFD-informed quasi-steady model of flapping-wing aerodynamics

Journal of Fluid Mechanics ◽

10.1017/jfm.2015.537 ◽

2015 ◽

Vol 783 ◽

pp. 323-343 ◽

Cited By ~ 35

Author(s):

Toshiyuki Nakata ◽

Hao Liu ◽

Richard J. Bomphrey

Keyword(s):

Aerodynamic Force ◽

Element Model ◽

Flapping Wing ◽

Tip Vortex ◽

Unmanned Aerial Systems ◽

Aerodynamic Forces ◽

Cfd Modelling ◽

And Control ◽

Aerial Systems ◽

Wing Aerodynamics

Aerodynamic performance and agility during flapping flight are determined by the combination of wing shape and kinematics. The degree of morphological and kinematic optimization is unknown and depends upon a large parameter space. Aimed at providing an accurate and computationally inexpensive modelling tool for flapping-wing aerodynamics, we propose a novel CFD (computational fluid dynamics)-informed quasi-steady model (CIQSM), which assumes that the aerodynamic forces on a flapping wing can be decomposed into quasi-steady forces and parameterized based on CFD results. Using least-squares fitting, we determine a set of proportional coefficients for the quasi-steady model relating wing kinematics to instantaneous aerodynamic force and torque; we calculate power as the product of quasi-steady torques and angular velocity. With the quasi-steady model fully and independently parameterized on the basis of high-fidelity CFD modelling, it is capable of predicting flapping-wing aerodynamic forces and power more accurately than the conventional blade element model (BEM) does. The improvement can be attributed to, for instance, taking into account the effects of the induced downwash and the wing tip vortex on the force generation and power consumption. Our model is validated by comparing the aerodynamics of a CFD model and the present quasi-steady model using the example case of a hovering hawkmoth. This demonstrates that the CIQSM outperforms the conventional BEM while remaining computationally cheap, and hence can be an effective tool for revealing the mechanisms of optimization and control of kinematics and morphology in flapping-wing flight for both bio-flyers and unmanned aerial systems.

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Aerodynamics, sensing and control of insect-scale flapping-wing flight

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2015.0712 ◽

2016 ◽

Vol 472 (2186) ◽

pp. 20150712 ◽

Cited By ~ 56

Author(s):

Wei Shyy ◽

Chang-kwon Kang ◽

Pakpong Chirarattananon ◽

Sridhar Ravi ◽

Hao Liu

Keyword(s):

Flapping Wing ◽

Integrated System ◽

Wind Gust ◽

Mass Ratio ◽

Stability And Control ◽

Flying Insects ◽

Surrounding Environment ◽

Wing Structures ◽

Body Mass Ratio ◽

And Control

There are nearly a million known species of flying insects and 13 000 species of flying warm-blooded vertebrates, including mammals, birds and bats. While in flight, their wings not only move forward relative to the air, they also flap up and down, plunge and sweep, so that both lift and thrust can be generated and balanced, accommodate uncertain surrounding environment, with superior flight stability and dynamics with highly varied speeds and missions. As the size of a flyer is reduced, the wing-to-body mass ratio tends to decrease as well. Furthermore, these flyers use integrated system consisting of wings to generate aerodynamic forces, muscles to move the wings, and sensing and control systems to guide and manoeuvre. In this article, recent advances in insect-scale flapping-wing aerodynamics, flexible wing structures, unsteady flight environment, sensing, stability and control are reviewed with perspective offered. In particular, the special features of the low Reynolds number flyers associated with small sizes, thin and light structures, slow flight with comparable wind gust speeds, bioinspired fabrication of wing structures, neuron-based sensing and adaptive control are highlighted.

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