Effects of aerodynamic modeling on the optimal wing kinematics for hovering MAVs

Abstract

The effects of aerodynamic model assumptions on the optimal wing-kinematics for hovering microair-vehicles are determined. Specific kinematic functions for the wing motion are specified and the parameters of these functions are considered as the design variables for the optimization problem. Four aerodynamic models having different levels of fidelity that capture various physical aspects of hovering aerodynamics are considered to assess the effects of these different aspects on the optimal wing kinematics. These physical aspects include the leading edge vortex, rotational lift, non-circulatory contributions, and flow unsteadiness. Conventional models for pitching wings are not adequate as they predict considerably high rotational lift and too little power requirements, which makes the optimizer, unrealistically, leans toward almost pure rotational motion with little flapping. In addition, quasisteady modeling overestimates the generated lift and, as such, leads to a more optimal, but unrealistic, performance. Therefore efficient unsteady modeling is essential in design optimization of flapping-wing micro-air-vehicles.

Design of a Flapping Wing Mechanism to Coordinate Both Wing Swing and Wing Pitch

“…A study of flapping wing designs for micro-air vehicles [7] shows that planar crank-rocker linkages with a passive position of the wing pitch provide effective wing performance. However, Yan et al [20] show that coordinated control of the wing pitch and wing swing movement improves the aerodynamics of a micro-air vehicle.…”

Synthesis of a Flapping Wing Mechanism Using a Constrained Spatial RRR Serial Chain

“…2 where the S-joints C and F are mounted to interconnected cranks that simultaneously drive wing swing, link AD, and wing pitch, link DE. The joint trajectories for the RRR chain that move this system as recommended by Yan et al [3] are giving by…”

“…The result is the following set of design equations: Fig. 3 The wing swing and wing pitch functions recommended by Yan et al [3] B 2 : 1:96mp À 1:94mq þ 0:5mr þ 4:41m þ 1:79np þ 2:19nq þ 0:87nr À 0:66n þ 0:89op À 0:46oq þ 0:27or þ 2:36o þ 0:38p À 4:87q À 1:23r þ 6:36 ¼ 0 B 3 : À0:0072np þ 3:95mp À 0:38mq þ 0:2mr þ 10:71m þ 2:92nq þ 1:78nr À 8:61n þ 0:43op þ 1:73oq þ 1:1or þ 2:62o þ 11:05p À 3:72q À 7:72r þ 48:91 ¼ 0 B 4 : 2:19mp þ 1:91mq À 0:57mr þ 16:58m À 0:4np þ 2:59nq þ 1:87nr À 9:74n À 1:95op þ 0:06oq þ 1:57or À 3:58o þ 6:97p þ 12:83q À 13:01r þ 95:64 ¼ 0 B 5 : 1:15mp þ 0:38mq À 1:77mr þ 16:75m À 1:81np þ 1:78nq þ 0:82nr À 3:4n þ 0:04op À 1:95oq þ 1:56or À 8:91o À 4:23p þ 12:24q À 14:27r þ 92:86 ¼ 0 B 6 : 2:47mp þ 0:71mq À 1:81mr þ 9:85m À 1:39np þ 0:83nq À 0:82nr þ 3:13n þ 1:35op À 1:46oq þ 1:78or À 7:62o À 5:02p þ 7:19q À 9:38r þ 41:21 ¼ 0 B 7 : 1:36mp þ 1:51mq À 1:14mr þ 3:98m À 1:23np þ 0:75nq À 0:96nr þ 2:09n þ 1:44op À 0:4oq þ 0:67or À 0:35o À 2:82p þ 1:77q À 3:05r þ 5:09 ¼ 0…”

“…Flapping-wing micro-air vehicles are designed to fly like birds or insects that exploit unconventional aerodynamic mechanisms to generate high lift at low speeds and to stabilize their bodies in flight [1]. While most micro-air vehicles such as the Nano-Hummingbird [2] rely on passive positioning of the wing pitch, Yan et al [3] show that coordinated control of the pitch and wing movement improves the aerodynamics of a micro-air vehicle. They demonstrate that increased aerodynamic performance can be achieved by coordinating the swing and pitch control functions.…”

Aerodynamics of a two-dimensional flapping wing hovering in proximity of ground

“…In addition to the above-mentioned studies mainly based on experiments and simulations, Yan et al. 15,16 also carried out some analysis researches. They developed a semi-analytical, potential flow model for airfoil undergoing large amplitude maneuvers and assessed the effects of aerodynamic model on the optimal wing kinematics.…”