Quasi-steady aerodynamic model of clap-and-fling flapping MAV and validation using free-flight data

Abstract

Flapping-wing aerodynamic models that are accurate, computationally efficient and physically meaningful, are challenging to obtain. Such models are essential to design flapping-wing micro air vehicles and to develop advanced controllers enhancing the autonomy of such vehicles. In this work, a phenomenological model is developed for the time-resolved aerodynamic forces on clap-and-fling ornithopters. The model is based on quasi-steady theory and accounts for inertial, circulatory, added mass and viscous forces. It extends existing quasi-steady approaches by: including a fling circulation factor to account for unsteady wing-wing interaction, considering real platform-specific wing kinematics and different flight regimes. The model parameters are estimated from wind tunnel measurements conducted on a real test platform. Comparison to wind tunnel data shows that the model predicts the lift forces on the test platform accurately, and accounts for wing-wing interaction effectively. Additionally, validation tests with real free-flight data show that lift forces can be predicted with considerable accuracy in different flight regimes. The complete parameter-varying model represents a wide range of flight conditions, is computationally simple, physically meaningful and requires few measurements. It is therefore potentially useful for both control design and preliminary conceptual studies for developing new platforms.

Modelling wing wake and tail aerodynamics of a flapping-wing micro aerial vehicle

“…The wing beat was assumed to be sinusoidal. While in the considered FWMAV the outstroke is slightly slower than the instroke, 12 this difference is small and was considered negligible, 12 particularly in view of the simplified nature of the aerodynamic model itself. More accurate mathematical representations of the kinematics, e.g., using a split-cycle piecewise representation, 37 or different functions such as the hyperbolic tangent would have increased the model complexity and interpretability, and are left for future work.…”

“…Significant effort has been spent on developing accurate aerodynamic models, particularly ones that are not excessively complex and can be applied for design, simulation and control. In an application context, the most widely used approach for this is quasi-steady modelling, [8][9][10][11][12] and, to a lesser extent, data-driven modelling. [13][14][15][16][17][18] However, the combination of wings and tail has not been widely studied, despite being used on many flapping-wing robots; instead the design of the tail in such vehicles so far has largely relied on an engineering approach.…”

Onboard/Offboard Sensor Fusion for High-Fidelity Flapping-Wing Robot Flight Data

“…eqs. [8][9][10][11][12][13][14][15][16][17][18][19] were found to converge in the static case, while during flight they vary to a limited extent, typically in conjunction with maneuvers. It can for instance be observed in fig.…”

“…consid- ering the effect of the flapping-related oscillations in the states, however it is particularly essential in aerodynamic studies. It has for instance been shown that some unsteady effects, such as clapand-fling, are visible clearly only at very high frequencies [14], which are typically only accurately observable in wind tunnel tests. At the same time, as mentioned in sec.…”

“…While significant insight is now available on both fronts, thanks to studies on insects and birds [1,2,3,4], and, more recently, increasingly on robotic test platforms [5,6,7,8,9,10,11,12,13,14,15], the high complexity of flapping flight still poses a considerable challenge to FWMAV development. Additionally, it is still considerably difficult to obtain realistic experimental data, particularly in free flight and in different flight regimes.…”